JP6279648B2 - Power converter - Google Patents

Description

  The present invention relates to a power conversion device having a semiconductor switching element formed of a wide band gap semiconductor and a power smoothing capacitor.

  In recent years, electric vehicles such as electric vehicles and hybrid vehicles have been developed as environmentally friendly vehicles. Such an automobile has a power converter for driving a driving motor and charging a high voltage battery. The power conversion device is always required to be downsized in order to improve the loadability in an automobile.

  The power converter includes a converter circuit that converts DC power or AC power into DC power, an inverter circuit that converts DC power into AC power, or a circuit that combines a plurality of them as a power conversion circuit. These circuits include a semiconductor switching element and a power smoothing capacitor.

  In general, it is known that the carrier frequency of a semiconductor switching element should be increased in miniaturization of a power converter. This is because by increasing the carrier frequency, the current ripple generated by the switching operation of the semiconductor switching element is reduced, so that a smaller-capacity power smoothing capacitor or magnetic component can be employed.

  However, when the carrier frequency of the semiconductor switching element is simply increased, the switching loss generated in the semiconductor switching element increases. Therefore, it is necessary to suppress the switching loss by increasing the switching speed. However, when the switching speed is increased, the switching surge generated by the parasitic impedance of the circuit is increased and a burden is imposed on the semiconductor switching element. Therefore, an increase in carrier frequency is limited.

  As the carrier frequency increases, the voltage ripple generated in the power smoothing capacitor increases due to the influence of the internal parasitic inductance of the power smoothing capacitor. For this reason, it is necessary to increase the capacity for high voltage tolerance and voltage ripple. Further, since spike surge is generated, a filter circuit for suppressing spike surge is required separately. Therefore, the capacitor and the power conversion circuit are increased in size.

In the power conversion device described in Patent Document 1, a method is disclosed in which the switching surge is suppressed and the carrier frequency is increased by reducing the impedance of the bus bar from the power smoothing capacitor to the semiconductor switching element.
Patent Document 2 discloses a low inductance capacitor in which the smoothing function is not impaired even at a high carrier frequency by suppressing the internal inductance of the capacitor.

Japanese Patent Laying-Open No. 2015-136223 JP 2006-319027 A

  There is a demand for further miniaturization of power conversion devices for electric vehicles, and in order to reduce the size of components such as power smoothing capacitors and magnetic parts, it is essential to increase the carrier frequency of semiconductor switching elements. However, an IGBT (Insulated Gate Bipolar Transistor), which is a semiconductor switching element used in a power conversion device for an electric vehicle on the premise of a high breakdown voltage and a large capacity, has a large switching loss and has a limit in increasing a carrier frequency. Therefore, in recent years, application of high-speed switching and ultra-high carrier frequency of a semiconductor switching element formed of a wide band gap semiconductor having a wide band gap such as a silicon carbide (SiC) semiconductor element has been studied.

  However, in the power conversion device disclosed in Patent Document 1, the effect of suppressing the circuit impedance is limited to the bus bar between the DC / DC converter and the power smoothing capacitor, and the internal parasitic inductance of the power smoothing capacitor is taken into consideration. Absent. Therefore, in high-speed switching, a large surge voltage is generated in the semiconductor switching element due to the internal parasitic inductance of the power smoothing capacitor. Therefore, the switching speed must be suppressed, and the performance of the wide bandgap semiconductor switching element cannot be fully exhibited. . There is also a problem that the internal smoothing inductance of the power smoothing capacitor increases the voltage ripple of the power smoothing capacitor and the occurrence of spike surges hinders the miniaturization of the power smoothing capacitor and the power conversion circuit accompanying the increase in the carrier frequency. .

  Moreover, in patent document 2, since the internal parasitic inductance of a power smoothing capacitor is reduced, an increase in the size of the power smoothing capacitor due to an increase in voltage ripple or a spike surge can be suppressed. However, since the capacitance required for the power smoothing capacitor in the power converter is determined by the current ripple flowing in the power smoothing capacitor, simply reducing the internal parasitic inductance of the power smoothing capacitor does not directly contribute to the miniaturization of the power smoothing capacitor. There is a problem.

  The present invention has been made in order to solve the above-described problems, and uses a semiconductor switching element formed of a wide band gap semiconductor as a switching element in a power conversion device. To provide a power conversion device that achieves ultra-high carrier frequency by a wide band gap semiconductor switching element by reducing parasitic inductance and achieves miniaturization of a magnetic smoothing capacitor and magnetic components constituting a circuit by increasing the carrier frequency. It is the purpose.

The power conversion device of the present invention includes a semiconductor switching element, a power conversion circuit that performs power conversion by switching control of the semiconductor switching element, and a plurality of power smoothing capacitors that are connected to the front stage or the rear stage of the power conversion circuit, The power conversion circuit is composed of a plurality of circuits among an inverter circuit, a DC / DC converter circuit, and an AC / DC converter circuit, and the plurality of power smoothing capacitors are power conversion devices connected between the plurality of circuits. The semiconductor switching element is formed of a wide bandgap semiconductor, and the plurality of power smoothing capacitors are arranged adjacent to each other. Each of the power smoothing capacitors includes a first electrode, a second electrode, and a first electrode. A first wiring connected to the electrode and a second wiring connected to the second electrode; There are one or more connection forms in which the first wiring and the second wiring intersect once.

  According to the present invention, in a power conversion circuit having a power conversion circuit including a wide bandgap semiconductor switching element and a power smoothing capacitor, the power smoothing capacitor has a predetermined configuration and the internal parasitic inductance of the power smoothing capacitor is reduced. Therefore, the switching surge at the time of high-speed switching is suppressed, and an ultra-high carrier frequency can be achieved. As a result, the current ripple generated by the switching operation can be reduced, and the size of the magnetic components constituting the power smoothing capacitor and the circuit can be reduced. Thereby, a small power converter is obtained.

It is a circuit diagram which shows the structure of the power converter device which concerns on Embodiment 1 of this invention. In the power converter device concerning Embodiment 1 of this invention, it is explanatory drawing which shows a current pathway when the semiconductor switching elements 101-102 are on-off. It is explanatory drawing explaining each current waveform in the power converter device which concerns on Embodiment 1 of this invention. It is an equivalent circuit diagram of the power smoothing capacitor in the power converter device according to Embodiment 1 of the present invention. It is explanatory drawing explaining the voltage ripple of the electric power smoothing capacitor in the power converter device which concerns on Embodiment 1 of this invention. It is explanatory drawing explaining the structure of the electric power smoothing capacitor in the power converter device which concerns on Embodiment 1 of this invention. In the power smoothing capacitor of the power conversion device according to Embodiment 1 of the present invention, it is an explanatory diagram showing an equivalent circuit of the power smoothing capacitor when the currents flowing in adjacent power smoothing capacitors are in the same direction. In the power smoothing capacitor of the power converter according to Embodiment 1 of the present invention, it is an explanatory diagram showing an equivalent circuit of the power smoothing capacitor when the current flowing in the adjacent power smoothing capacitors is in the reverse direction. It is a circuit diagram which shows the structure of the power converter device which concerns on Embodiment 2 of this invention.

Embodiment 1 FIG.
Hereinafter, preferred embodiments of the power conversion device according to Embodiment 1 of the present invention will be described with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals and redundant description is given. Omitted.
FIG. 1 is a configuration circuit diagram showing a power conversion apparatus according to the first embodiment. Referring to FIG. 1, a power converter 1000 has a power smoothing capacitor 2a connected in parallel to a DC input power source 1, and a DC / DC converter circuit 100 of a one-stone chopper system as a power conversion circuit at the subsequent stage of the power smoothing capacitor 2a. Is connected. A load 3 is connected to the subsequent stage of the DC / DC converter circuit 100 via a power smoothing capacitor 2b.

  The DC / DC converter circuit 100 includes a semiconductor switching element 101, which is a pair of switching elements, a semiconductor switching element 102, and a reactor 110. A source terminal of the semiconductor switching element 101 and a drain terminal of the semiconductor switching element 102 are one terminal of the reactor 110. The other terminal of the reactor 110 is connected to the positive electrode of the power smoothing capacitor 2a. The drain terminal of the semiconductor switching element 101 is connected to the positive electrode of the power smoothing capacitor 2b, and the source terminal of the semiconductor switching element 102 is connected to the negative electrodes of the power smoothing capacitor 2a and the power smoothing capacitor 2b. The semiconductor switching elements 101 to 102 are semiconductor switching elements formed of wide band gap semiconductors.

Hereinafter, the operation principle of the power conversion device according to Embodiment 1 of the present invention will be described. The power conversion apparatus 1000 according to the first embodiment has two operation modes shown in FIGS. 2A and 2B in accordance with the state of each semiconductor switching element.
In FIG. 2, the input voltage of the DC / DC converter circuit 100 is Vin, the output voltage of the DC / DC converter circuit 100 is Vout, the winding current of the reactor 110 is i _L , the current flowing through the power smoothing capacitor 2a is ic1, and the power smoothing is performed. the current flowing through the capacitor 2b ic2, a current flowing in the load 3 and _{i lOAD.}

  In Mode 1 shown in FIG. 2A, the semiconductor switching element 102 is on and the semiconductor switching element 101 is off. In Mode 2 shown in FIG. 2B, in contrast to Mode 1, the semiconductor switching element 101 is on and the semiconductor switching element 102 is off. Mode 1 and Mode 2 are alternately repeated.

Here, if the inductance value of the reactor 110 in FIG. 2 is _L , the following relational expression (1) is established for the current i _L of the winding of the reactor 110 in Mode 1 and Mode 2.

Actually, the power conversion apparatus 1000 and the DC input power supply 1 and the power conversion apparatus 1000 and the load 3 are connected by a harness or the like having a parasitic inductance component. For this reason, the high frequency impedance is large, and the current ripple generated in the power conversion circuit of the DC / DC converter circuit 100 flows to the power smoothing capacitors 2a and 2b.
From the above, the current waveform of each part in the power converter according to Embodiment 1 is shown in FIG. Here, the switching period of the semiconductor switching element is Tsw, and the duty ratio of Mode 1 is D.

From FIG. 3, _assuming that the current ripple of the reactor 110 is _{Δi Lpp} and the current ripple of the power smoothing capacitor 2a is _{Δi c1pp} , each current ripple value and the maximum value i _{Lmax of the} current flowing through the reactor 110 are expressed by the following equation (2). It is expressed. Here, i _Love is the average value of the current flowing through the reactor 110.

Here, assuming that each power smoothing capacitor 2a, 2b is an ideal capacitor, the capacitance of the power smoothing capacitor 2a is C1, and the capacitance of the power smoothing capacitor 2b is C2. _Further , voltage ripples generated in the power smoothing capacitors 2a and 2b are _assumed to be ΔV _c1pp and ΔV _c2pp . Since all current ripples flow through the power smoothing capacitors 2a and 2b, the voltage ripples ΔV _c1pp and ΔV _c2pp are _expressed by the following equation (3).

Equation (2), the equation (3), the current ripple of the reactor 110 △ _{i Lpp} and the power smoothing capacitor 2a, voltage ripple △ _{V ClpP} occur 2b, under the condition that _{△ V} c2pp becomes less than the allowable value, the reactor 110 In order to reduce the inductance value L and the capacitances C1 and C2 of the power smoothing capacitors 2a and 2b, it is effective to shorten the switching period Tsw of the semiconductor switching elements 101 and 102, that is, to increase the carrier frequency. .

Here, the loss that occurs when the semiconductor switching elements 101 and 102 are turned on is the steady loss Pdc, and the loss that occurs in one switching operation of the semiconductor switching elements 101 and 102 (the sum of the turn-on loss and the turn-off loss) is the switching loss. Let Esw. The loss E generated in the semiconductor switching elements 101 and 102 is expressed by Expression (4). Note that the carrier frequency of the semiconductor switching elements 101 and 102 is fsw.
E = Esw / fsw + Pdc (4)

  From equation (4), the loss E generated in the semiconductor switching elements 101 and 102 increases as the carrier frequency increases. However, if the loss E becomes too large, the semiconductor switching elements 101 and 102 are damaged by heat generation. Therefore, the loss E must be suppressed. The steady loss Pdc is difficult to suppress because it is a value determined by the on-resistance which is a characteristic of the semiconductor switching elements 101 and 102 and the effective value of the current flowing through the semiconductor switching elements 101 and 102. Therefore, it is necessary to suppress the switching loss Esw. The switching loss Esw is a value obtained by integrating the product of the current flowing through the semiconductor switching elements 101 and 102 and the applied voltage at the time of switching (turn-on and turn-off). Here, the speed of change of the current and voltage at the time of switching is the switching speed. It is.

  In order to suppress the switching loss Esw, it is necessary to reduce the current or applied voltage flowing through the semiconductor switching elements 101 and 102 or increase the switching speed. However, the current flowing through the semiconductor switching elements 101 and 102 and the applied voltage depend on the power conversion circuit of the DC / DC converter 100 and are difficult to adjust. The switching speed can be increased within the performance range of the semiconductor switching element. Therefore, as the semiconductor switching elements 101 and 102 are increased in carrier frequency, it is necessary to increase the switching speed and suppress the switching loss.

However, since the actual power smoothing capacitors 2a and 2b have the internal parasitic inductance 10 as in the power smoothing capacitor 2 shown in FIG. 4, and there is a parasitic impedance in the circuit, the switching of the semiconductor switching elements 101 and 102 is performed. A surge voltage is generated in the semiconductor switching elements 101 and 102 during operation.
The current flowing through the semiconductor switching element 101 and 102 i, the switching time Ts, _{Lc ESL} internal parasitic inductance of the power smoothing capacitor 2, the circuit parasitic impedances as _{L ESL,} surge voltage generated in the semiconductor switching elements 101,102 △ Vsrg Is represented by equation (5).

式（５）より、スイッチング時間が短くなるほどサージ電圧が大きくなるため、サージ電圧が半導体スイッチング素子１０１、１０２の耐圧を超えないように、半導体スイッチング素子１０１、１０２のスイッチング速度を遅くする必要がある。そのため半導体スイッチング素子１０１、１０２に発生するスイッチング損失が増大し、高キャリア周波化に制限がかかるという課題がある。

From equation (5), since the surge voltage increases as the switching time becomes shorter, it is necessary to slow down the switching speed of the semiconductor switching elements 101, 102 so that the surge voltage does not exceed the breakdown voltage of the semiconductor switching elements 101, 102. . Therefore, there is a problem that the switching loss generated in the semiconductor switching elements 101 and 102 increases, and there is a limitation on the increase in the carrier frequency.

In addition, the voltage increment ΔV _ESL generated in the power smoothing capacitor 2 due to the internal parasitic inductance in the power smoothing capacitor 2 is shown in Equation (6). Here, dic / dT is a time change amount of the current flowing through the power smoothing capacitor. FIG. 5 shows voltage ripples of the power smoothing capacitors 2a and 2b with and without the internal parasitic inductance in the power smoothing capacitors 2a and 2b in the first embodiment.

  As shown in FIG. 5, when internal parasitic inductance exists in the power smoothing capacitors 2a and 2b, the voltage ripple generated in the power smoothing capacitors 2a and 2b increases. In addition, the current flowing in the power smoothing capacitors 2a and 2b is changed by the switching operation of the semiconductor switching elements 101 and 102, and a spike surge is applied to the power smoothing capacitors 2a and 2b at the transition from Mode1 to Mode2 or at the transition from Mode2 to Mode1. Will occur. The voltage ripple and spike surge generated in the power smoothing capacitors 2a and 2b increase in proportion to the switching speed of the semiconductor switching elements 101 and 102.

  Therefore, as the switching speed is increased to increase the carrier frequency, the power smoothing capacitors 2a and 2b need to have a higher breakdown voltage, and the electrostatic capacity of the power smoothing capacitors 2a and 2b is reduced in order to reduce voltage ripple. It is necessary to increase the capacity. Since spike surges deteriorate EMC (Electro-Magnetic Compatibility), it is necessary to add a filter circuit for suppressing spike surges. However, there is a problem that an increase in breakdown voltage, an increase in capacitance, and the addition of a filter circuit lead to an increase in the size of each power smoothing capacitor 2a, 2b and power conversion circuit.

  These issues are related to higher carrier frequencies of the semiconductor switching elements 101 and 102, and particularly limit the possibility of high-speed switching and ultra-high carrier frequencies of semiconductor switching devices formed of wide band gap semiconductors. This greatly reduces the effect of miniaturization of the power smoothing capacitors 2a and 2b due to the ultra-high carrier frequency.

  With regard to such a problem, in power conversion device 1000 according to the first embodiment of the present invention, power smoothing capacitors 2a and 2b are configured as described below to reduce internal parasitic inductances of power smoothing capacitors 2a and 2b, and surge High-speed switching and ultra-high carrier frequency are performed in the wide band gap semiconductor switching elements 101 and 102 without imposing a burden on the semiconductor switching elements 101 and 102 due to voltage. Thereby, the current ripple generated by the switching operation of the semiconductor switching elements 101 and 102 is reduced, and the values of the capacitances C1 and C2 of the power smoothing capacitors 2a and 2b and the inductance value L of the reactor 110 are selected to be smaller. The power smoothing capacitors 2a and 2b and the reactor 110 are made small. In addition, by reducing the internal parasitic inductance of the power smoothing capacitors 2a and 2b and suppressing the increase in voltage ripple and spike surge of the power smoothing capacitors 2a and 2b, the power smoothing capacitors 2a and 2b have a higher carrier frequency. Miniaturization is not hindered.

  With reference to FIG. 6, a predetermined configuration of power smoothing capacitors 2a and 2b in the power conversion device according to the first embodiment of the present invention will be described. Each of the power smoothing capacitors 2a and 2b is arranged such that a plurality of power smoothing capacitors 301 to 304 are adjacent to each other, and each of the power smoothing capacitors 301 to 304 includes a first electrode 301a to 304a and a second electrode 301b to 304b, respectively. It has. The first electrodes 301a to 304a of each power smoothing capacitor 301 to 304 are connected to the first wiring 300a, the second electrodes 301b to 304b of each power smoothing capacitor 301 to 304 are connected to the second wiring 300b, Between the adjacent power smoothing capacitors 301 to 304, one or more connection forms in which the first wiring 300a and the second wiring 300b intersect once are provided.

  In the predetermined configuration of the power smoothing capacitors 2a and 2b shown in FIG. 6, the principle of reducing the internal inductance of the power smoothing capacitor will be described by taking two adjacent power smoothing capacitors as an example. The internal parasitic inductances of two adjacent power smoothing capacitors are equally Ls, and the equivalent circuit in the case where the mutual inductances generated by the mutual internal parasitic inductances are M and the directions of the currents flowing to each other is the same is reversed in FIG. FIG. 8 shows the case of the orientation. Further, in each case, an equivalent series inductance Leq obtained by totaling the internal parasitic inductances of the two power smoothing capacitors is shown in Expression (7).

式（７）より、隣り合う２つのコンデンサにおいて、流れる電流の向きを逆向きとすることで、電力平滑コンデンサの内部等価インダクタンスが低減する。

From the equation (7), the internal equivalent inductance of the power smoothing capacitor is reduced by making the direction of the flowing current reverse in two adjacent capacitors.

In the predetermined configuration of the power smoothing capacitors 2a and 2b, the first wiring 300a and the second wiring 300b intersect each other between two adjacent ones of the power smoothing capacitors 301 to 304, so that the currents flowing through each other The directions are opposite to each other. Therefore, from the equation (7), the internal parasitic inductance is reduced.
In the predetermined configuration of the power smoothing capacitors 2a and 2b, there is at least one place where the first wiring 300a and the second wiring 300b intersect once between two of the adjacent power smoothing capacitors 301 to 304. Is effective, and the more the number, the more effective. Further, the first wiring 300a and the second wiring 300b may not be the base wiring but may be a bus bar. By using a bus bar, the wiring inductance can be further reduced.

In the predetermined configuration of the power smoothing capacitor of the power conversion device according to the first embodiment, it is assumed that the power smoothing capacitor includes four power smoothing capacitors 301 to 304 with reference to FIG. What is necessary is just to be comprised by one or more electric power smoothing capacitors.
In the power conversion apparatus 1000 according to the first embodiment, the power smoothing capacitors 2a and 2b have a predetermined configuration. However, only the power smoothing capacitor 2a is used according to the internal parasitic inductance of the power smoothing capacitor that is actually used. Alternatively, only the power smoothing capacitor 2b may have a predetermined configuration.

In the above-described power conversion device 1000 according to the first embodiment, the case where the power conversion circuit is the one-stone chopper type DC / DC converter circuit 100 is taken as an example, but the power conversion circuit is an LLC type converter or a phase shift type converter. Even in the case of the step-down converter circuit as described above, the same effect is obtained. Further, in a multi-phase converter circuit such as a two-phase interleaved converter circuit, for example, the frequency of the current ripple flowing in the power smoothing capacitor becomes a multiple of the number of phases of the carrier frequency of the semiconductor switching element, so that a greater effect can be obtained. Further, not only in the DC / DC converter circuit but also in the case where the power conversion circuit is an inverter circuit that converts a direct current input into an alternating current output or an AC / DC converter circuit that converts an alternating current input into a direct current output, Since the current ripple generated by the switching operation of the semiconductor switching element flows through the capacitor, the same effect is obtained.

Embodiment 2. FIG.
Next, a power converter according to Embodiment 2 of the present invention will be described with reference to FIG.
FIG. 9 is a configuration circuit diagram showing a power converter according to the second embodiment. In FIG. 9, the power conversion device 2000 is connected to the DC / DC converter circuit 100, which is the first power conversion circuit described in the first embodiment, and the inverter circuit, which is the second power conversion circuit, via the power smoothing capacitor 2b. 200 is connected, and the power smoothing capacitor 2b has the predetermined configuration.

  The DC / DC converter circuit 100 as the first power conversion circuit has the same circuit configuration as that of the first embodiment. The inverter circuit 200 that is a second power conversion circuit includes a semiconductor switching element 201 and a semiconductor switching element 204 that are a first switching element pair, and a semiconductor switching element 202 and a semiconductor switching element 205 that are a second switching element pair. The semiconductor switching element 203 and the semiconductor switching element 206, which are the third switching element pair, are provided, and each switching element pair is connected to the power smoothing capacitor 2b. The source terminal of the semiconductor switching element 201 and the drain terminal of the semiconductor switching element 204, the source terminal of the semiconductor switching element 202 and the drain terminal of the semiconductor switching element 205, the source terminal of the semiconductor switching element 203, and the drain terminal of the semiconductor switching element 206 are respectively Connected to load 3.

  The semiconductor switching elements 101 and 102 that constitute the DC / DC converter circuit 100 that is the first power conversion circuit are formed of a wide band gap semiconductor, and the semiconductor switching element 201 that constitutes the inverter circuit 200 that is the second power conversion circuit. ˜206 are made of silicon semiconductor.

  In the second embodiment of the present invention, the DC / DC converter circuit 100 performs the same operation as the DC / DC converter circuit 100 that is the power conversion circuit in the first embodiment. The current ripple flowing through power smoothing capacitor 2a in the second embodiment is the same as the current ripple flowing through power smoothing capacitor 2a in the first embodiment shown in FIG.

  In the power conversion device 2000 according to the second embodiment, current ripples flowing through the power smoothing capacitor 2b are generated by the DC / DC converter circuit 100 that is the first power conversion circuit and the inverter circuit 200 that is the second power conversion circuit, respectively. This is the total current ripple to be generated. Therefore, a current ripple larger than the current ripple flowing in the power smoothing capacitor 2b in the first embodiment flows through the power smoothing capacitor 2b, and the capacitance required for the power smoothing capacitor 2b is the same as that in the power conversion device in the first embodiment. The capacitance of the power smoothing capacitor 2b becomes larger.

  However, when the capacitance increases in the power smoothing capacitor, the capacitor size increases and the internal parasitic inductance increases. As a result, the surge voltage generated in the semiconductor switching elements 101 to 102 and the semiconductor switching elements 201 to 206 increases, so that the carrier frequency of each semiconductor switching element is limited. Moreover, since the spike surge and voltage ripple which generate | occur | produce in the electric power smoothing capacitor 2b increase, the electric power smoothing capacitor 2b enlarges.

  Regarding this problem, in the power conversion device 2000 according to the second embodiment of the present invention, the power smoothing capacitor 2b connected to the plurality of power conversion circuits has the predetermined structure described in the first embodiment, so that power smoothing is performed. An increase in internal parasitic impedance due to an increase in capacitance due to the connection to the plurality of power conversion circuits of the capacitor 2b is suppressed. This suppresses the surge voltage generated in the semiconductor switching elements 101 to 102 and the semiconductor switching elements 201 to 206, thereby increasing the carrier frequency and reducing the size of the power smoothing capacitors 2a and 2b and the reactor 110. Further, by reducing the internal parasitic inductance of the power smoothing capacitor 2b and suppressing the increase of voltage ripple and spike surge, miniaturization of the power smoothing capacitor 2b and each power conversion circuit accompanying the increase in the carrier frequency is not hindered.

  In the power conversion device according to the second embodiment, the inverter circuit 200 that is the second power conversion circuit is connected to the DC / DC converter circuit 100 that is the first power conversion circuit via the power smoothing capacitor 2b. Although the number of connected power conversion circuits is not limited to this number, the larger the number of connected power conversion circuits, the larger the current ripple that flows through the power smoothing capacitor, so that a greater effect is exhibited.

  In the power conversion device according to the second embodiment, the first power conversion circuit is a one-stone chopper DC / DC converter circuit, and the second power conversion circuit is a three-phase inverter circuit. In the power conversion circuit, the form of the circuit is not limited to this, and can be freely combined within the scope of the present invention. For example, the same effect can be obtained when the first power conversion circuit is a gradation control type PFC (Power Factor Correction) AC / DC converter circuit and the second power conversion circuit is a step-down converter circuit of a phase shift type converter. It is done.

Embodiment 3 FIG.
In the power conversion device according to each of the above embodiments, the input power supply is a DC input power supply, but the present invention is not limited to this, and the input power supply may be a commercial power supply. Since the voltage fluctuation of the commercial power supply is about 20%, when the commercial power supply having an effective value of 100V is used as the input power supply, the input voltage becomes a high voltage of at least the effective value of 80V or more. Therefore, the power smoothing capacitor of the power converter is required to have a high breakdown voltage, so that the power smoothing capacitor is increased in size, and the internal parasitic inductance is increased accordingly. A DC power source such as a high voltage battery having an effective value of 80 V or more may be used as the input power source, and the same effect can be obtained.

  Since a high withstand voltage is required for the power smoothing capacitor of the power conversion device according to each of the above embodiments, a film capacitor is suitable. A film capacitor is easy to increase in size because of its small electrostatic capacity per volume, and the effect of the invention is further enhanced because of its large internal parasitic inductance. Further, when the capacitance required for the power smoothing capacitor is large, an electrolytic capacitor may be used as the power smoothing capacitor. Since the large-capacity electrolytic capacitor has a large internal parasitic inductance, the effect of the invention can be obtained. Furthermore, when the capacitance required for the power smoothing capacitor is small, a ceramic capacitor may be used as the power smoothing capacitor, and the same effect is achieved.

  In the power conversion circuit of the power conversion device according to the first embodiment and the first power conversion circuit of the power conversion device according to the second embodiment, as the wide band gap semiconductor forming each semiconductor switching element, Silicon carbide, gallium nitride, and diamond are suitable. A power semiconductor switching element made of a wide band gap semiconductor can be used in a high voltage region where unipolar operation is difficult with a silicon semiconductor, and is suitable for high-speed switching and ultrahigh carrier frequency operation. In the second power conversion circuit of the power conversion device according to the second embodiment, each semiconductor switching element is formed of a silicon semiconductor. However, the present invention is not limited to this, and semiconductor switching formed of a wide band gap semiconductor. An element may be sufficient. By using a semiconductor switching element formed of a wide band gap semiconductor to increase the carrier frequency, the current ripple flowing in the power smoothing capacitor 2b is reduced, and the power smoothing capacitor 2b can be further downsized.

The power smoothing capacitor of the power conversion device according to each embodiment of the present invention may be configured as a module that is housed in the case and in which resin is injected into the case. By using a module, it is possible to suppress the concentration of heat generation in the miniaturization of the power smoothing capacitor.
Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments, and various design changes can be made. Within the scope of the present invention, each embodiment is described. These embodiments can be freely combined, and each embodiment can be modified or omitted as appropriate.

1: DC input power supply, 2, 2a, 2b: power smoothing capacitor, 3: load,
10: Internal parasitic inductance, 100: DC / DC converter circuit,
101-102: Semiconductor switching element, 110: Reactor,
200: inverter circuit, 201-206: semiconductor switching element,
300a: first wiring, 300b: second wiring, 301 to 304: capacitor,
301a to 304b: capacitor electrode, 1000, 2000: power conversion device

Claims (7)

A power conversion circuit that includes a semiconductor switching element and performs power conversion by switching control of the semiconductor switching element; and a plurality of power smoothing capacitors connected to a front stage or a rear stage of the power conversion circuit , the power conversion circuit Is composed of a plurality of circuits among an inverter circuit, a DC / DC converter circuit, and an AC / DC converter circuit, and the plurality of power smoothing capacitors are power converters connected between the plurality of circuits ,
The semiconductor switching element is formed of a wide bandgap semiconductor, and the plurality of power smoothing capacitors are disposed adjacent to each other, each of the power smoothing capacitors including a first electrode, a second electrode, and the first electrode A first wiring connected to the second electrode and a second wiring connected to the second electrode, and the first wiring and the second wiring between the adjacent power smoothing capacitors A power conversion device characterized by having at least one connection form that crosses once. The power converter according to claim 1 , wherein the plurality of power smoothing capacitors are film capacitors. The power converter according to claim 1 , wherein the plurality of power smoothing capacitors are electrolytic capacitors. The power converter according to claim 1 , wherein the plurality of power smoothing capacitors are ceramic capacitors. Input voltage of the power converter circuit, the power conversion device as claimed in any one of claims 1 to 4, characterized in that it is an effective value 80V above. The power converter according to any one of claims 1 to 5 , wherein the wide band gap semiconductor is a semiconductor using silicon carbide, gallium nitride, or diamond. The power converter according to any one of claims 1 to 6 , wherein the plurality of power smoothing capacitors are configured as a module.

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