Converter device and control method for the converter device

Abstract

To provide a converter device and a control method of a converter device capable of interrupting, at high speed, short circuit current generated by a short circuit accident of a DC power bus.SOLUTION: A converter device 100 comprises: a parallel circuit 110 which has a plurality of legs 111 and 112 connected parallelly between terminals of a capacitor 120, and in which a first connection point U that is a middle point in the first leg 111 among the plurality of legs is connected to a power supply 10 through a first reactor 21; and a control circuit 130 controlling the parallel circuit 110. In a first mode in which a second connection point W that is a middle point in the second leg 112 among the plurality of legs is used as a power supply output terminal, the control circuit 110 controls the first leg 111 to boost voltage between the terminals of the capacitor 120, and controls the second leg 112 to control a second semiconductor switch 320 that switches whether or not to connect a positive electrode of the capacitor 120 to the power supply output terminal.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a converter device and a control method for the converter device.

Background Art

[0002] Patent Document 1 describes that "a short-circuit current interruption circuit that rapidly interrupts a short-circuit current due to a short-circuit accident in a DC power supply bus is provided." [Prior Art Document] [Patent Document] [Patent Document 1] JP 2020-124025

Summary of the Invention

[0003] In a first aspect of the present invention, a converter device is provided. The converter device has a plurality of legs connected in parallel between terminals of a capacitor, and a parallel circuit in which a first connection point that is a midpoint in a first leg among the plurality of legs is connected to a power supply via a first reactor, and a control circuit that controls the parallel circuit. In a first mode in which a second connection point that is a midpoint in a second leg among the plurality of legs is used as a power supply output terminal, the control circuit controls the first leg to boost the voltage between the terminals of the capacitor, and controls the second leg to switch whether to connect the positive electrode of the capacitor and the power supply output terminal.

[0004] In the converter device, the first leg includes a first rectifying element connected to the positive electrode of the capacitor and a first semiconductor switch connected in series on the anode side of the first rectifying element. In the first mode, the control circuit may control the first semiconductor switch to boost the voltage between the terminals of the capacitor.

[0005] In any of the converter devices, the second leg includes a second rectifier element connected to the negative terminal of the capacitor and a second semiconductor switch connected in series with the cathode side of the second rectifier element, and the control circuit may, in the first mode, control the second semiconductor switch to switch whether or not to connect the positive terminal of the capacitor and the power output terminal.

[0006] In any of the converter devices, the first rectifier element may be a first freewheeling diode connected in antiparallel to a transistor constituting a third semiconductor switch, and the second rectifier element may be a second freewheeling diode connected in antiparallel to a transistor constituting a fourth semiconductor switch.

[0007] In any of the converter devices, the control circuit may control the first semiconductor switch and the fourth semiconductor switch to boost the voltage across the terminals of the capacitor in a second mode in which the second connection point is connected to the power supply via a second reactor and the positive terminal of the capacitor is the power supply output terminal.

[0008] In any of the converter devices, the control circuit may switch between the first mode and the second mode in response to an external signal.

[0009] In any of the converter devices, in the parallel circuit, a third connection point, which is the midpoint of the third leg among the plurality of legs, is connected to the power supply via a third reactor, and the control circuit may, in the first mode, control the first leg and the third leg to boost the voltage between the terminals of the capacitor.

[0010] In any of the converter devices, the control circuit may, in the first mode, control the second leg to disconnect the connection between the positive terminal of the capacitor and the power output terminal in response to the detection of a short circuit at the power output terminal.

[0011] Any of the converter devices may further include a sensor for detecting a short circuit at the power output terminal.

[0012] In any of the converter devices, the sensor may be a current sensor that detects the current flowing to the power output terminal.

[0013] In any of the converter devices, the power source is a secondary battery, and the control circuit may control the parallel circuit to charge the secondary battery.

[0014] A second aspect of the present invention provides a method for controlling a converter device. The converter device comprises a parallel circuit having a plurality of legs connected in parallel between the terminals of a capacitor, wherein a first connection point, which is the midpoint of a first leg among the plurality of legs, is connected to a power supply via a first reactor. The method for controlling the converter device comprises, in a first mode in which a second connection point, which is the midpoint of a second leg among the plurality of legs, is a power supply output terminal, controlling the first leg to increase the voltage between the terminals of the capacitor, and controlling the second leg to switch whether or not to connect the positive electrode of the capacitor to the power supply output terminal.

[0015] It should be noted that the above summary of the invention does not enumerate all of its features. Furthermore, subcombinations of these features may also constitute an invention. [Brief explanation of the drawing]

[0016] [Figure 1] An example of a connection diagram showing the converter device 100 according to this embodiment connected in the first connection configuration is shown. [Figure 2] An example of a connection diagram showing the converter device 100 according to the first modification connected in the first connection configuration is shown. [Figure 3] An example of a connection diagram showing the converter device 100 according to the first modified example connected in the second connection configuration is shown. [Figure 4]An example of a connection diagram showing the converter device 100 according to the second modified example connected in the first connection configuration is shown. [Figure 5] An example of a connection diagram showing the converter device 100 according to the third modified example connected in the first connection configuration is shown. [Figure 6] An example of a connection diagram showing the converter device 100 according to the third modified example connected in the second connection configuration is shown. [Figure 7] An example of a connection diagram showing the converter device 100 according to the fourth modification connected in the first connection configuration is shown. [Modes for carrying out the invention]

[0017] The present invention will be described below through embodiments, but these embodiments are not intended to limit the scope of the claims. Furthermore, not all combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0018] In this specification, expressions such as "connected" are not limited to direct connections without other elements, but also include indirect connections via other elements. Furthermore, in this specification, expressions such as "connected between... and..." or "provided between... and..." do not limit the physical arrangement, but mean "electrically connected to... and...".

[0019] Figure 1 shows an example of a connection diagram in which the converter device 100 according to this embodiment is connected in a first connection configuration. In this figure, the power supply 10, the first reactor 21 (collectively referred to as "reactor 20" together with the second reactor 22 and the third reactor 23 described later), and the converter device 100 are shown. The converter device 100 according to this embodiment provides a power output cutoff function when connected in the first connection configuration.

[0020] The power supply 10 is a source of electrical energy. The power supply 10 may be a DC power supply, for example, it may be a battery. As an example, the power supply 10 may be a secondary battery such as a lithium-ion battery. However, it is not limited to this. The power supply 10 may also be a primary battery.

[0021] The reactor 20 is a passive element for accumulating / discharging energy. The reactor 20 may be, for example, a copper wire with an insulating coating wound around a magnetic core in a coil shape. In this figure, a first reactor 21 is shown as the reactor 20. One end of the first reactor 21 is connected to the positive electrode of the power supply 10.

[0022] The converter device 100 is a DC / DC converter that can boost the voltage from the power supply 10 by repeatedly accumulating / discharging the energy of the reactor 20. The converter device 100 includes a parallel circuit 110, a capacitor 120, and a control circuit 130.

[0023] The parallel circuit 110 has a plurality of legs connected in parallel between the terminals of the capacitor 120. In each leg, the upper arm and the lower arm are connected at the midpoint. And in each leg, the upper arm end, which is one end not on the midpoint side of the upper arm, is connected to the positive electrode of the capacitor 120, and the lower arm end, which is one end not on the midpoint side of the lower arm, is connected to the negative electrode of the capacitor 120 and the negative electrode of the power supply 10.

[0024] In this figure, an example is shown where the parallel circuit 110 has two legs, the first leg 111 and the second leg 112. However, it is not limited to this. The parallel circuit 110 may have more than two legs.

[0025] The first leg 111 may include a first rectifier element 210 connected to the positive terminal of the capacitor 120 and a first semiconductor switch 310 connected in series with the anode side of the first rectifier element 210. In the above description, the case in which the first leg 111 includes the first rectifier element 210 as the upper arm was shown as an example, but it is not limited to this. The first leg 111 may include various components (not limited to passive elements, but also active elements such as switches) that can allow current to flow in only one direction from the midpoint to the end of the upper arm as the upper arm.

[0026] The first connection point U, which is the midpoint of the first leg 111, is connected to the other end of the first reactor 21. In other words, the first connection point U, which is the midpoint of the first leg 111 among the multiple legs, is connected to the power supply 10 via the first reactor 21.

[0027] The second leg 112 may include a second rectifier element 220 connected to the negative terminal of the capacitor 120 and a second semiconductor switch 320 connected in series with the cathode side of the second rectifier element 220.

[0028] In the above explanation, the case in which the second leg 112 includes the second rectifier element 220 as the lower arm was shown as an example, but it is not limited to this. The second leg 112 may include various components (not limited to passive elements, but also active elements such as switches) that can allow current to flow in only one direction from the end of the lower arm to the midpoint.

[0029] In this figure, an example is shown where the second connection point W, which is the midpoint of the second leg 112, is connected to the DC bus. In this case, the second connection point W functions as a power output terminal, and DC power is distributed from the second connection point W to the DC bus. The ground wire of the DC bus may be connected to the negative terminal of the power supply 10, the lower arm end of each leg, and the negative terminal of the capacitor 120. This connection configuration, in which the second connection point W, which is the midpoint of the second leg 112 among multiple legs, is used as a power output terminal, will be called the first connection configuration.

[0030] Capacitor 120 is a smoothing capacitor that smooths the voltage across its terminals. The positive terminal of capacitor 120 is connected to the upper arm end of each leg, and the negative terminal of capacitor 120 is connected to the negative terminal of power supply 10 and the lower arm end of each leg. In this figure, the case where capacitor 120 is built into the converter device 100 is shown as an example, but it is not limited to this. Capacitor 120 may also be mounted externally outside the converter device 100.

[0031] The control circuit 130 controls the parallel circuit 110. The control circuit 130 operates in a first mode when the converter device 100 is connected in a first connection configuration, and controls the parallel circuit 110 so that the converter device 100 provides a power output cutoff function.

[0032] The first rectifier element 210 and the second rectifier element 220, together with the third rectifier element 230 described later, are collectively referred to as "rectifier element 200". Rectifier element 200 is an element that allows current to flow in only one direction. In this figure, the case where the rectifier element 200 is a single diode is shown as an example.

[0033] In the first rectifier element 210, the anode is connected to the first connection point U, which is the midpoint of the first leg 111, and the cathode is connected to the end of the upper arm, allowing current to flow in only one direction from the midpoint of the first leg 111 to the end of the upper arm. In the second rectifier element 220, the anode is connected to the end of the lower arm, and the cathode is connected to the second connection point W, which is the midpoint of the second leg 112, allowing current to flow in only one direction from the end of the lower arm to the midpoint of the second leg 112.

[0034] The first semiconductor switch 310 and the second semiconductor switch 320, together with the third to sixth semiconductor switches 330 and 360 described later, are collectively referred to as "semiconductor switches 300". The semiconductor switches 300 are switching elements that switch on / off in response to a drive signal from the control circuit 130. In this embodiment, the case where the semiconductor switch 300 is an IGBT (Insulated Gate Bipolar Transistor) is shown as an example. However, it is not limited to this. The semiconductor switches 300 may be various switching elements such as MOS-FETs. The semiconductor switches 300 may be provided with, for example, a transistor having three terminals: a collector, an emitter, and a gate, and a freewheeling diode connected in antiparallel between the emitter and collector of the transistor.

[0035] In the first semiconductor switch 310, the collector is connected to a first connection point U, which is the midpoint of the first leg 111, and the emitter is connected to the lower arm end. It switches between the midpoint of the first leg 111 and the lower arm end in response to a gate drive signal from the control circuit 130. In the second semiconductor switch 320, the collector is connected to the upper arm end, and the emitter is connected to a second connection point W, which is the midpoint of the second leg 112. It switches between the upper arm end and the midpoint of the second leg 112 in response to a gate drive signal from the control circuit 130.

[0036] When such a converter device 100 is connected in a first connection configuration in which the second connection point W, which is the midpoint of the second leg 112, is used as the power output terminal, the control circuit 130 operates in the first mode. This will be explained in detail.

[0037] In the first mode, when the control circuit 130 controls the first semiconductor switch 310 to the OFF state, energy from the power supply 10 is stored in the capacitor 120 via the first reactor 21 and the first rectifier element 210. When the control circuit 130 controls the first semiconductor switch 310 to the ON state, a closed circuit is formed by the power supply 10, the first reactor 21, and the first semiconductor switch 310, and energy from the power supply 10 is stored in the first reactor 21. At this time, the energy stored in the capacitor 120 is not released to the closed circuit side due to the rectifying action of the first rectifier element 210. Therefore, in the first mode, the control circuit 130 can increase the voltage across the terminals of the capacitor 120 by repeatedly controlling the first semiconductor switch 310 to store and release energy in the first reactor 21. In other words, the control circuit 130 can make the first leg 111 of the multiple legs function as a boost chopper.

[0038] Furthermore, in the first mode, when the control circuit 130 controls the second semiconductor switch 320 to turn on, the positive terminal of the capacitor 120 is connected to the second connection point W, which is the power output terminal. As a result, the converter device 100 can distribute DC power from the second connection point W to the DC bus.

[0039] When DC power distribution is performed in this manner, if the control circuit 130 controls the second semiconductor switch 320 to the OFF position, the connection between the positive terminal of the capacitor 120 and the second connection point W, which is the power output terminal, is interrupted. As a result, the converter device 100 can prevent current from flowing from the power supply 10 to the DC bus. In this way, in the first mode, the control circuit 130 can control the second semiconductor switch 320 to switch whether or not to connect the positive terminal of the capacitor 120 to the power output terminal. As a result, the control circuit 130 can make the second leg 112 of the multiple legs function as a power output interruption circuit.

[0040] In particular, suppose a short circuit occurs in the DC bus (power output terminal) for some reason. In this case, in the first mode, the control circuit 130 can control the second leg 112 (second semiconductor switch 320) to disconnect the connection between the positive terminal of the capacitor 120 and the power output terminal in response to the detection of a short circuit in the power output terminal. As a result, the control circuit 130 can make the second leg 112 of the multiple legs function as a short-circuit current protection circuit.

[0041] Thus, in a first mode in which the second connection point W, which is the midpoint of the second leg 112 among the multiple legs, is the power output terminal, the control circuit 130 controls the first leg 111 to boost the voltage across the terminals of the capacitor 120, and controls the second leg 112 to switch whether or not to connect the positive terminal of the capacitor 120 to the power output terminal. As a result, the converter device 100 can provide a power output cutoff function, in particular a short-circuit current protection function.

[0042] For example, when distributing DC power on a ship, the short-circuit current becomes very large as the capacity of the lithium-ion battery increases (for example, the short-circuit current of a 300kWh, 650V lithium-ion battery is 70kA), making it difficult to handle. Here, it is conceivable to have all of the legs function as boost choppers, for example, by having the second leg 112 function as a boost chopper in the same way as the first leg 111. However, in such a case, if a short circuit occurs in the DC bus, the power supply 10 will also be short-circuited through the rectifier element 200 and the freewheeling diode of the semiconductor switch 300. Such a short circuit in the power supply 10 can lead to a serious accident if the short-circuit current is large. Therefore, it is desirable to devise a way to reduce the short-circuit current when a short circuit occurs in the DC bus.

[0043] In contrast, according to the converter device 100 of this embodiment, at least one of the multiple legs functions as a boost chopper, while at least one of the multiple legs functions as a power output cutoff circuit. This prevents current from flowing from the power supply 10 to the DC bus as needed. As a result, according to the converter device 100 of this embodiment, even if a short circuit occurs in the DC bus, for example, the connection between the positive terminal of the capacitor 120 and the power output terminal can be cut off in response to the detection of the short circuit, thereby reducing the short-circuit current.

[0044] Figure 2 shows an example of a connection diagram in which the converter device 100 according to the first modification is connected in the first connection configuration. In Figure 2, the same reference numerals are used for components having the same function and configuration as in Figure 1, and explanations are omitted below except for differences. In Figure 1, the case where the rectifier element 200 is a standalone diode was shown as an example. However, in this figure, the case where the rectifier element 200 is configured as part of a semiconductor switch 300 is shown.

[0045] In the first modification, the first leg 111 includes a third semiconductor switch 330 as an upper arm. The third semiconductor switch 330, like the first semiconductor switch 310 and the second semiconductor switch 320, includes a transistor having three terminals: a collector, an emitter, and a gate, and a freewheeling diode connected in antiparallel between the emitter and collector of the transistor. In the first modification, such a freewheeling diode may be substituted for the first rectifier element 210. In the third semiconductor switch 330, the collector is connected to the end of the upper arm, and the emitter is connected to a first connection point U, which is the midpoint of the first leg 111, and switches between the end of the upper arm and the midpoint of the first leg 111 in response to a gate drive signal from the control circuit 130. Thus, the first rectifier element 210 may be a first freewheeling diode connected in antiparallel to the transistor constituting the third semiconductor switch 330.

[0046] Furthermore, in the first modified example, the second leg 112 includes a fourth semiconductor switch 340 as a lower arm. The fourth semiconductor switch 340, like the first semiconductor switch 310 and the second semiconductor switch 320, is provided with a transistor having three terminals: a collector, an emitter, and a gate, and a freewheeling diode connected in antiparallel between the emitter and collector of the transistor. In the first modified example, such a freewheeling diode may be substituted as a second rectifier element 220. In the fourth semiconductor switch 340, the collector is connected to a second connection point W, which is the midpoint of the second leg 112, and the emitter is connected to the end of the lower arm, and it switches between the midpoint of the second leg 112 and the end of the lower arm in response to a gate drive signal from the control circuit 130. Thus, the second rectifier element 220 may be a second freewheeling diode connected in antiparallel to the transistor constituting the fourth semiconductor switch 340.

[0047] Therefore, in the first modification, the first leg 111 and the second leg 112 may each constitute an inverter circuit. That is, the parallel circuit 110 may be a two-phase inverter circuit. The control circuit 130 may then control the parallel circuit 110 so that one of the two phases functions as a boost chopper and the remaining phase functions as a power output cutoff circuit.

[0048] Here, the power supply 10 may be a secondary battery, as described above. That is, the power supply 10 may be capable of discharging and charging. When the power supply 10 is discharged, i.e., when the converter device 100 performs DC power distribution, the control circuit 130 may control the first semiconductor switch 310 and the second semiconductor switch 320 as described above, and also control the third semiconductor switch 330 and the fourth semiconductor switch 340 to the OFF position. On the other hand, when charging the power supply 10, the control circuit 130 may control the second semiconductor switch 320 and the third semiconductor switch 330 to the ON position, and control the first semiconductor switch 310 and the fourth semiconductor switch 340 to the OFF position. The control circuit 130 can also charge the power supply 10, which is a secondary battery, by controlling the parallel circuit 110 in this way, for example. In this way, the converter device 100 can also provide a charge / discharge control function for the secondary battery.

[0049] Figure 3 shows an example of a connection diagram in which the converter device 100 according to the first modification is connected in the second connection configuration. In Figure 3, the same reference numerals are used for components having the same function and configuration as in Figure 2, and explanations are omitted below except for differences. Figure 2 shows the case where the converter device 100 is connected in the first connection configuration. However, this figure shows the case where the converter device 100 is connected in the second connection configuration.

[0050] In the second connection configuration, the second connection point W, which is the midpoint of the second leg 112, is connected to the positive terminal of the power supply 10 via the second reactor 22. Also, the positive terminal of the capacitor 120 is connected to the DC bus. In this case, the positive terminal of the capacitor 120 functions as a power supply output terminal, and DC power is distributed from the positive terminal of the capacitor 120 to the DC bus. Thus, the connection configuration in which the second connection point W, which is the midpoint of the second leg 112 among the multiple legs, is connected to the power supply 10 via the second reactor 22, and the positive terminal of the capacitor 120 is used as a power supply output terminal, will be called the second connection configuration.

[0051] When the converter device 100 is connected in the second connection configuration, the control circuit 130 operates in the second mode. This will be explained in detail.

[0052] In the second mode, when the control circuit 130 controls the first semiconductor switch 310 to the off side, energy from the power supply 10 is stored in the capacitor 120 via the first reactor 21 and the first rectifier element 210. Similarly, when the control circuit 130 controls the fourth semiconductor switch 340 to the off side, energy from the power supply 10 is stored in the capacitor 120 via the second reactor 22 and the freewheeling diode of the second semiconductor switch 320. Furthermore, when the control circuit 130 controls the first semiconductor switch 310 to the on side, the power supply 10, the first reactor 21, and the first semiconductor switch 310 form a closed circuit, and energy from the power supply 10 is stored in the first reactor 21. At this time, the energy stored in the capacitor 120 is not released to the closed circuit side due to the rectifying action of the first rectifier element 210. Similarly, when the control circuit 130 controls the fourth semiconductor switch 340 to turn on, the power supply 10, the second reactor 22, and the fourth semiconductor switch 340 form a closed circuit, and energy from the power supply 10 is stored in the second reactor 22. At this time, the energy stored in the capacitor 120 is not released to the closed circuit side due to the rectifying action of the freewheeling diode of the second semiconductor switch 320.

[0053] Therefore, in the second mode in which the second connection point W is connected to the power supply 10 via the second reactor 22 and the positive terminal of the capacitor 120 is the power supply output terminal, the control circuit 130 can boost the voltage across the terminals of the capacitor 120 by controlling the first semiconductor switch 310 and the fourth semiconductor switch 340 to repeatedly store and release energy in the first reactor 21 and the second reactor 22. In other words, the control circuit 130 can make both the first leg 111 and the second leg 112 function as boost choppers.

[0054] Thus, the converter device 100 according to the first modification can be connected in a first connection configuration as shown in Figure 2, and can also be connected in a second connection configuration as shown in Figure 3. When the converter device 100 is connected in the first connection configuration, the control circuit 130 operates in the first mode, and when the converter device 100 is connected in the second connection configuration, the control circuit 130 can operate in the second mode.

[0055] Thus, the control circuit 130 may switch operating modes depending on the connection configuration of the converter device 100. Preferably, the control circuit 130 can switch between the first mode and the second mode in response to an external signal. As a result, the converter device 100 according to the first embodiment can operate in two ways: with or without providing a power output cutoff function, so it can be used in different ways depending on the application and purpose.

[0056] Figure 4 shows an example of a connection diagram in which the converter device 100 according to the second modified example is connected in the first connection configuration. In Figure 4, the same reference numerals are used for components having the same function and configuration as in Figure 1, and explanations are omitted below except for differences. In Figure 1, the case in which the parallel circuit 110 has two legs, a first leg 111 and a second leg 112, is shown as an example. However, in this figure, the case in which the parallel circuit 110 has three legs, a first leg 111, a second leg 112, and a third leg 113.

[0057] In this figure, in addition to the first reactor 21, a third reactor 23 is shown as reactor 20. One end of the third reactor 23 is connected to the positive terminal of the power supply 10.

[0058] The third leg 113 may include a third rectifier element 230 connected to the positive terminal of the capacitor 120 and a fifth semiconductor switch 350 connected in series with the anode side of the third rectifier element 230. In the above description, the case in which the third leg 113 includes the third rectifier element 230 as the upper arm was shown as an example, but it is not limited to this. The third leg 113 may include various components (not limited to passive elements, but also active elements such as switches) that can allow current to flow in only one direction from the midpoint to the end of the upper arm as the upper arm.

[0059] The third connection point V, which is the midpoint of the third leg 113, is connected to the other end of the third reactor 23. In other words, the third connection point V, which is the midpoint of the third leg 113 among the multiple legs, is connected to the power supply 10 via the third reactor 23.

[0060] In the third rectifier element 230, the anode is connected to the third connection point V, which is the midpoint of the third leg 113, and the cathode is connected to the end of the upper arm, allowing current to flow in only one direction, from the midpoint of the third leg 113 to the end of the upper arm.

[0061] In the fifth semiconductor switch 350, the collector is connected to the third connection point V, which is the midpoint of the third leg 113, and the emitter is connected to the lower arm end. It switches between the midpoint of the third leg 113 and the lower arm end in response to the gate drive signal from the control circuit 130.

[0062] In the first mode, when the control circuit 130 controls the first semiconductor switch 310 to the OFF state, energy from the power supply 10 is stored in the capacitor 120 via the first reactor 21 and the first rectifier element 210. Similarly, when the control circuit 130 controls the fifth semiconductor switch 350 to the OFF state, energy from the power supply 10 is stored in the capacitor 120 via the third reactor 23 and the third rectifier element 230. Furthermore, when the control circuit 130 controls the first semiconductor switch 310 to the ON state, the power supply 10, the first reactor 21, and the first semiconductor switch 310 form a closed circuit, and energy from the power supply 10 is stored in the first reactor 21. At this time, the energy stored in the capacitor 120 is not released to the closed circuit side due to the rectifying action of the first rectifier element 210. Similarly, when the control circuit 130 controls the fifth semiconductor switch 350 to turn on, the power supply 10, the third reactor 23, and the fifth semiconductor switch 350 form a closed circuit, and energy from the power supply 10 is stored in the third reactor 23. At this time, the energy stored in the capacitor 120 is not released to the closed circuit side due to the rectifying action of the third rectifier element 230.

[0063] Therefore, in the first mode, the control circuit 130 can boost the voltage across the terminals of the capacitor 120 by controlling the first semiconductor switch 310 and the fifth semiconductor switch 350 to repeatedly store and release energy in the first reactor 21 and the third reactor 23. In other words, the control circuit 130 can make the first leg 111 and the third leg 113 of the multiple legs function as a boost chopper.

[0064] The second leg 112 is the same as in the embodiment described above. In this way, in the first mode, the control circuit 130 controls the first leg 111 and the third leg 113 to boost the voltage across the terminals of the capacitor 120, and controls the second leg 112 to switch whether or not to connect the positive terminal of the capacitor 120 to the power supply output terminal. As a result, the converter device 100 according to the second modified example can provide a power supply output cutoff function, in particular a short-circuit current protection function, even when the two legs are used as a boost chopper.

[0065] Figure 5 shows an example of a connection diagram in which the converter device 100 according to the third modified example is connected in the first connection configuration. In Figure 5, the same reference numerals are used for components having the same function and configuration as in Figures 2 and 4, and explanations are omitted below except for differences. In Figure 4, the case where the rectifier element 200 is a standalone diode was shown as an example. However, in this figure, the case where the rectifier element 200 is configured as part of a semiconductor switch 300 is shown.

[0066] In the third modification, the third leg 113 includes a sixth semiconductor switch 360 as the upper arm. The sixth semiconductor switch 360, like the first semiconductor switches 310 to the fifth semiconductor switches 350, includes a transistor having three terminals: a collector, an emitter, and a gate, and a freewheeling diode connected in antiparallel between the emitter and collector of the transistor. In the third modification, such a freewheeling diode may be substituted as the third rectifier element 230. In the sixth semiconductor switch 360, the collector is connected to the end of the upper arm, and the emitter is connected to a first connection point V, which is the midpoint of the third leg 113, and switches between the end of the upper arm and the midpoint of the third leg 113 in response to a gate drive signal from the control circuit 130. Thus, the third rectifier element 230 may be a third freewheeling diode connected in antiparallel to the transistor constituting the sixth semiconductor switch 360.

[0067] Therefore, in the third modification, the first leg 111, the second leg 112, and the third leg 113 may each constitute an inverter circuit. That is, the parallel circuit 110 may be a three-phase inverter circuit. The control circuit 130 may then control the parallel circuit 110 to make two of the three phases function as a boost chopper and the remaining phase function as a power output cutoff circuit.

[0068] Figure 6 shows an example of a connection diagram in which the converter device 100 according to the third modified example is connected in a second connection configuration. In Figure 6, the same reference numerals are used for components having the same function and configuration as in Figures 3 and 5. Thus, the converter device 100 according to the third modified example can be connected in a first connection configuration as shown in Figure 5, and can also be connected in a second connection configuration as shown in this figure. When the converter device 100 is connected in the first connection configuration, the control circuit 130 operates in the first mode, and when the converter device 100 is connected in the second connection configuration, the control circuit 130 can operate in the second mode.

[0069] Therefore, in a second mode in which the second connection point W is connected to the power supply 10 via the second reactor 22 and the positive terminal of the capacitor 120 is the power supply output terminal, the control circuit 130 can boost the voltage across the terminals of the capacitor 120 by controlling the first semiconductor switch 310, the fourth semiconductor switch 340, and the fifth semiconductor switch 350 to repeatedly store and release energy in the first reactor 21, the second reactor 22, and the third reactor 23. In other words, the control circuit 130 can make all of the first leg 111, the second leg 112, and the third leg 113 function as boost choppers.

[0070] Thus, the converter device 100 according to the third modified example can operate in two ways: with or without providing a power output cutoff function, allowing it to be used selectively depending on the application and purpose. In particular, in the converter device 100 according to the third embodiment, the parallel circuit 110 may be a three-phase inverter circuit. Such three-phase inverter circuits are widely used in motor control. Therefore, according to the converter device 100 according to the third embodiment, such a general-purpose circuit can be utilized and applied to various applications depending on the operating mode of the control circuit 130.

[0071] Figure 7 shows an example of a connection diagram in which the converter device 100 according to the fourth modification is connected in the first connection configuration. In Figure 7, the same reference numerals are used for components having the same function and configuration as in Figure 1, and explanations are omitted below except for differences. In Figure 1, an example was shown in which the converter device 100 does not have means for detecting a short circuit at the power output terminal. However, in this figure, a case is shown in which the converter device 100 does have means for detecting a short circuit at the power output terminal.

[0072] The converter device 100 according to the fourth modification further includes a sensor 710 in addition to the circuits and components of the converter device 100 according to the above-described embodiment. In this figure, the case in which the sensor 710 is added to the converter device 100 of Figure 1 is shown as an example, but the sensor 710 may also be added to the converter device 100 according to the first modification, the second modification, and the third modification. In other words, the fourth modification may be combined with any of the first modification, the second modification, and the third modification.

[0073] Sensor 710 is a sensor for detecting a short circuit at the power output terminal. Sensor 710 may be, for example, a current sensor that detects the current flowing through the power output terminal. This is preferable because it allows for immediate detection of a short circuit. However, it is not limited to this. Sensor 710 may also be a sensor that detects the voltage between the power output terminal and the ground line (i.e., the negative terminal of capacitor 120), or a sensor that detects the voltage across the semiconductor switch 300 provided on the upper arm.

[0074] The sensor 710 may supply the measured value (measured value) to the control circuit 130. In response, the control circuit 130 may detect a short circuit in the DC bus (power output terminal) if the measured value does not meet a predetermined standard (for example, if the current value exceeds a predetermined threshold). The control circuit 130 may then prevent current from flowing from the power supply 10 to the DC bus by controlling the second leg 112 (second semiconductor switch 320) to disconnect the connection between the positive terminal of the capacitor 120 and the power output terminal.

[0075] In the above explanation, an example was shown in which the sensor 710 supplies a measured value to the control circuit 130, and the control circuit 130 detects a short circuit by comparing the measured value with a reference. However, the sensor 710 may also supply a signal to the control circuit 130 indicating that a short circuit has been detected in the DC bus when the measured value does not meet the reference. Accordingly, the control circuit 130 may also control the second leg 112 to disconnect the connection between the positive terminal of the capacitor 120 and the power output terminal.

[0076] Thus, the converter device 100 according to the fourth modification further includes a sensor 710 for detecting a short circuit at the power output terminal. As a result, the converter device 100 according to the fourth modification can provide both a short-circuit detection function and a power output shutdown function in an integrated device.

[0077] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications or improvements can be made to the above embodiments. It will be clear from the claims that such modified or improved forms may also be included in the technical scope of the present invention.

[0078] It should be noted that the execution order of operations, procedures, steps, and stages in the apparatus, systems, programs, and methods shown in the claims, specifications, and drawings is not explicitly stated as "before," "prior to," etc., and that these can be implemented in any order unless the output of a previous process is used in a later process. Even if the operation flow in the claims, specifications, and drawings is described using phrases such as "first," "next," etc. for convenience, it does not mean that it is essential to perform the operations in that order. [Explanation of Symbols]

[0079] 10 Power supply 20 Reactors 21 First Reactor 22 Second Reactor 23 The Third Reactor 100 Converter Device 110 parallel circuit 111 First Leg 112 Second Leg 113 Third Leg 120 Capacitors 130 Control circuits 200 rectifier element 210 First rectifier element 220 Second rectifier element 230 Third rectifier element 300 semiconductor switches 310 First semiconductor switch 320 Second semiconductor switch 330 Third semiconductor switch 340 Fourth semiconductor switch 350 Fifth semiconductor switch 360 The sixth semiconductor switch 710 Sensor

Claims

1. A parallel circuit having a plurality of legs connected in parallel between the terminals of a capacitor, wherein a first connection point, which is the midpoint of the first leg among the plurality of legs, is connected to a power supply via a first reactor, A control circuit for controlling the parallel circuit, Equipped with, In a first mode in which the second connection point, which is the midpoint of the second leg among the plurality of legs, is the power output terminal, the control circuit controls the first leg to boost the voltage between the terminals of the capacitor, and controls the second leg to switch whether or not to connect the positive electrode of the capacitor to the power output terminal. Converter device.

2. The first leg includes a first rectifier element connected to the positive terminal of the capacitor and a first semiconductor switch connected in series with the anode side of the first rectifier element. The converter device according to claim 1, wherein the control circuit controls the first semiconductor switch in the first mode to increase the voltage across the terminals of the capacitor.

3. The second leg includes a second rectifier element connected to the negative terminal of the capacitor and a second semiconductor switch connected in series with the cathode side of the second rectifier element. The converter device according to claim 2, wherein the control circuit controls the second semiconductor switch to switch whether or not to connect the positive electrode of the capacitor to the power output terminal in the first mode.

4. The first rectifier element is a first freewheeling diode connected in antiparallel to a transistor constituting a third semiconductor switch. The converter device according to claim 3, wherein the second rectifier element is a second freewheeling diode connected in antiparallel to a transistor constituting a fourth semiconductor switch.

5. The converter device according to claim 4, wherein the control circuit controls the first semiconductor switch and the fourth semiconductor switch to boost the voltage between the terminals of the capacitor in a second mode in which the second connection point is connected to the power supply via a second reactor and the positive terminal of the capacitor is the power supply output terminal.

6. The converter device according to claim 5, wherein the control circuit switches between the first mode and the second mode in response to an external signal.

7. In the parallel circuit, the third connection point, which is the midpoint of the third leg among the plurality of legs, is connected to the power supply via the third reactor. The converter device according to any one of claims 1 to 5, wherein the control circuit controls the first leg and the third leg in the first mode to increase the voltage between the terminals of the capacitor.

8. The converter device according to any one of claims 1 to 5, wherein the control circuit controls the second leg to disconnect the connection between the positive electrode of the capacitor and the power output terminal in the first mode when a short circuit of the power output terminal is detected.

9. The converter device according to claim 8, further comprising a sensor for detecting a short circuit at the power output terminal.

10. The converter device according to claim 9, wherein the sensor is a current sensor that detects the current flowing through the power output terminal.

11. The aforementioned power source is a secondary battery, The converter device according to any one of claims 1 to 5, wherein the control circuit controls the parallel circuit to charge the secondary battery.

12. A control method for a converter device comprising a parallel circuit having a plurality of legs connected in parallel between the terminals of a capacitor, wherein a first connection point, which is the midpoint of the first leg among the plurality of legs, is connected to a power supply via a first reactor, In a first mode in which the second connection point, which is the midpoint of the second leg among the plurality of legs, is used as the power output terminal, the first leg is controlled to increase the voltage between the terminals of the capacitor, and the second leg is controlled to switch whether or not to connect the positive electrode of the capacitor to the power output terminal. A control method for a converter device.

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