EXTRACTED FROM WIPO SITE
FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
POWER CONVERTER
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED
AND EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 100-8310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

DESCRIPTION
Field
[0001] The present invention relates to a power
converter that converts alternating current (AC) power into direct current (DC) power.
Background
[0002] An electric motor (hereinafter, simply “motor”)
driver that uses an inverter employs a converter that converts AC power supplied from a power system into DC power. Such converter is often provided by a step-up chopper capable of controlling power to be input to the
inverter for purposes of drive range extension, loss reduction, power factor improvement, and the like. A stepup chopper is a circuit including a rectification circuit,
a reactor, a switching element, a reverse blocking diode, a capacitor, and the like connected to a power system. The
switching element and the capacitor are connected in parallel with the rectification circuit, and both ends of
each of the switching element and the capacitor are connected to the respective ends of the rectification
circuit. The reactor is connected to connect the positive output terminal of the rectification circuit and the
switching element. The reverse blocking diode is connected to allow current to flow from the reactor to the positive
terminal of the capacitor.
[0003] The switching element performs power supply short-circuiting operation to short-circuit the output path of the rectification circuit upon transition to a conductive state. This power supply short-circuiting
operation increases the current flowing in the reactor, thereby the reactor charges energy. Opening the switching
element under this condition decreases the current flowing to the reactor, and accordingly generates a voltage across
the reactor based on a relationship of V=5 Ldi/dt. When the voltage at the reactor exceeds the terminal voltage of the
capacitor, the reverse blocking diode transitions to a conductive state, thereby causing a current to flow from
the reactor to the capacitor, and the capacitor is thus charged. When the reactor completely discharges the energy,
the reactor voltage decreases. When the reactor voltage falls below the capacitor terminal voltage, the reverse blocking diode is reversed. Reversing of the reverse blocking diode suppresses a current from flowing back from
the capacitor to the reactor, thereby the voltage of the capacitor is maintained. Iteration of this process causes
the capacitor to be charged, and thus causes the capacitor terminal voltage to exceed the supply voltage. The converter can control the input voltage of the inverter in this manner.
[0004] Reduction of the loss in the converter itself is essential to reduce the loss in a motor driver. In particular, since the switching element that performs power
supply short-circuiting operation generates a switching loss in a step-up chopper, reduction of the switching loss
is required. The switching loss depends on the switching characteristic of the switching element. Thus, use of a
switching element employing a wide bandgap semiconductor having a good switching characteristic, such as silicon
(Si), gallium nitride (GaN), gallium oxide (Ga2O3), and diamond enables the switching loss to be reduced.
[0005] Improvement in a switching characteristic may result in an increase in noise in the switching element.
Noise is likely to be generated by, among others, ringing generated in the switching element itself by the switching operation, ringing caused by a recovery current generated upon reversing of the reverse blocking diode, and the like.
Patent Literature 1 discloses a technology 5 in which a snubber circuit consisting of diodes and a capacitor is provided in parallel with a switching element, and the snubber circuit absorbs the recovery current upon reversing
of the reverse blocking diode to reduce noise.
Citation List Patent Literature
[0006] Patent Literature 1: Japanese Patent Application
Laid-open No. H09-285126

Summary
Technical Problem
[0007] However, the technology described in Patent Literature 1 listed above allows charge and discharge currents to flow through the snubber circuit also during
switching in normal operation of the switching element. This presents a problem of occurrence of loss in the snubber circuit.
[0008] The present invention has been made in view of the foregoing, and it is an object of the present invention to provide a power converter capable of reducing noise generation concurrently with loss reduction.
Solution to Problem
[0009] To solve the problem and achieve the object described above, the present invention is directed to a power converter connected between a supply source of a first DC power and a supply destination of a second direct current power obtained by performing power conversion on
the first DC power. The power converter includes: a switching element; a reactor connected to one end of the switching element; and a first diode having an anode
connected to a first connection point and 5 having a cathode connected to one end of the reactor, the one end of the switching element and another end of the reactor being connected to each other at the first connection point. The
power converter also includes: a first capacitor connected in parallel with the supply source and having one end connected to a second connection point, the one end of the reactor and the cathode of the first diode being connected
to each other at the second connection point; and a second diode having an anode connected to the first connection point and having a cathode connected to the supply destination.
Advantageous Effects of Invention
[0010] A power converter according to the present
invention provides an advantage in being capable of reducing loss and noise generation.
Brief Description of Drawings
[0011] FIG. 1 is a block diagram illustrating an example configuration of a motor driver according to a first
embodiment.
FIG. 2 is a diagram illustrating an example of return path of recovery current in a power converter of a comparative example not including a snubber circuit.
30 FIG. 3 is a diagram illustrating an example of return path of recovery current in the power converter according to the first embodiment.
FIG. 4 is a block diagram illustrating an example
configuration of a motor driver according to a second embodiment.
FIG. 5 is a block diagram illustrating an example
configuration of a motor driver according to a third embodiment.
FIG. 6 is a block diagram illustrating an example
configuration of a motor driver according to a fourth embodiment.
FIG. 7 is a block diagram illustrating an example
configuration of an air conditioner according to a fifth embodiment.
Description of Embodiments
[0012] A power converter according to embodiments of the present invention will be described in detail below with
reference to the drawings. Note that these embodiments are not intended to limit the scope of this invention.
[0013] First Embodiment.
FIG. 1 is a block diagram illustrating an example
configuration of a motor driver 100 according to a first embodiment of the present invention. The motor driver 100
includes a rectification circuit 30, a power converter 40,
and an inverter 50. The rectification circuit 30 and the power converter 40 together constitute a converter 70. The
motor driver 100 is connected to an AC power supply 20 and to a motor 60.
[0014] The rectification circuit 30 includes a diode bridge consisting of four rectification elements 31, and converts AC power supplied from the AC power supply 20 into
30 DC power. The configuration of the rectification circuit
illustrated in FIG. 1 is merely by way of example, and the configuration of the rectification circuit 30 is not
limited thereto. Note that the power supplied to the motor driver 100 is not limited to AC power, but may also be DC power. The power converter 40 may use the rectification
circuit 30 or a DC power supply, as the supply source of the DC power. When DC power is supplied to the motor
driver 100 from a DC power supply, 5 the rectification circuit 30 is not needed. The power converter 40 converts
the magnitude of the DC power output from the rectification circuit 30, and supplies DC power resulting from the power
conversion to the inverter 50. The DC power supplied from the rectification circuit 30 to the power converter 40 may be referred to herein as first DC power. In addition, the
DC power supplied by the power converter 40 to the inverter
50, i.e., the DC power resulting from the power conversion performed by the power converter 40 on the first DC power
may be referred to herein as second DC power. A detailed configuration of the power converter 40 will be described ater. The inverter 50 converts the DC power into AC power,
and supplies the AC power to the motor 60 to drive the otor 60. From a viewpoint of the power converter 40, the
inverter 50 is a supply destination of the second DC power. he motor 60 is driven by the AC power supplied from the
inverter 50. The motor 60 is, for example, a motor to be nstalled in a compressor for use in an air-conditioning nd refrigeration apparatus such as an air conditioner and
a refrigerator.
[0015] A configuration of the power converter 40 will ow be described. As illustrated in FIG. 1, the power onverter 40 includes: two first capacitors 1; two first iodes 2; two reactors 3; two switching elements 4; two
second diodes 5; a second capacitor 6; a voltage detection nit 7; a current detection unit 8; and a controller 9. ach set of the reactors 3, the switching elements 4, and
the second diodes 5 constitutes a chopper circuit. In ddition, each set of the first capacitors 1 and the first
diodes 2 constitutes a snubber circuit. That is, the power onverter 40 includes: two chopper circuits; and two
snubber circuits corresponding to the respective chopper
circuits.
[0016] The voltage detection unit 7 detects the voltage value of the DC power output from the rectification circuit
. The current detection unit 8 detects a current flowing
through a ground line 12 of the power converter 40. The controller 9 controls switching of each of the switching
elements 4 using the voltage value detected by the voltage detection unit 7 and using the current value detected by
the current detection unit 8. Note that the controller may control switching of each of the switching elements using a rotational speed detected by a detection unit (not
illustrated) that detects the rotational speed of the motor
60. The controller 9 may also control switching of each of the switching elements 4 based on user operation in a case
in which the motor driver 100 is installed in an air conditioning and refrigeration apparatus as described above.
[0017] In the power converter 40, the switching elementsof the respective chopper circuits operate complementarily to each other. The switching elements 4
operate at different timings in the respective chopper circuits, but operate similarly to each other. Accordingly,
the following description of a configuration and an operation of the power converter 40 will be given taking an
example that includes one chopper circuit and one snubber circuit.
[0018] In the power converter 40, the switching element is connected between the reactor 3 and the second diode .
The reactor 3 has one end, the second diode 5 has an anode,
and the switching element 4 has one end, connected to one another at a connection point, which is referred to herein
as first connection point 10. The switching element 4 has another end connected to the ground line 12. The above
first connection point is further connected with an
anode of the first diode 2. The first 5 diode 2 has a cathode connected to another end of the reactor 3. As illustrated in FIG. 1, the reactor 3 and the first diode 2
are connected in parallel with each other. The another end of the reactor 3 and the cathode of the first diode 2 are
connected to each other at a connection point, which is referred to herein as second connection point 11. The above second connection point 11 is further connected with
one end of the first capacitor 1. The second connection point 11 is also connected with the rectification circuit
. The first capacitor 1 has another end connected to the
ground line 12. The first capacitor 1 is connected in parallel with the rectification circuit 30. In the power converter 40, the second diode 5 has a cathode connected to
one end of the second capacitor 6. The cathode of the
second diode 5 is also connected with the inverter 50. The
second capacitor 6 has another end connected to the ground
line 12. The second capacitor 6 is connected in parallel
with the inverter 50.
[0019] The chopper circuits illustrated in FIG. 1 are
each configured as a typical step-up chopper circuit. FIG.
1 illustrates an example in which the power converter 40 includes two chopper circuits, and the two chopper circuits
are connected in parallel with each other, but this is by way of example, and the configuration thereof is not limited thereto. The power converter 40 may be configured
to include a single chopper circuit, or configured to include three or more chopper circuits. In a case in which
multiple chopper circuits are included, the power converter
40 is configured such that the chopper circuits are connected in parallel with each other. This means that, in
the power converter 40, the second connection points 11 of the chopper circuits are connected to each other.
[0020] In the power converter 40, a 5 DC current output from the rectification circuit flows through the reactor and through the second diode to charge the second
capacitor 6. The power charged in the second capacitor 6
will be the input power to the inverter 50.
[0021] In the power converter 40, turning on of the switching element 4 causes the output terminals of the rectification circuit 30 to be short-circuited through the
reactor 3 and the switching element 4, thereby allowing a current to flow through the reactor 3 and the switching
element 4.
[0022] In the power converter 40, turning on of the switching element 4 causes the current flowing through the
second diode to be reversed from the forward direction to the reverse direction. The forward direction is a direction from the reactor 3 to the second capacitor 6,
while the reverse direction is a direction from the second capacitor 6 to the reactor 3. The second diode 5 blocks a flow of current in the reverse direction, but during a
transient condition immediately after the reversing, a
current flows in the reverse direction. This current
flowing in the reverse direction is called recovery current.
The time period from when a recovery current started
flowing in the reverse direction until the recovery current
is blocked is called a reverse recovery time.
[0023] The switching element 4 is herein assumed to be
an element having a good switching characteristic employing
a wide bandgap semiconductor such as silicon, gallium
nitride, gallium oxide, and diamond. In this case, a high
recovery current may flow depending on the recovery
characteristic of the second diode 5. A recovery current
may cause ringing to occur between the second diode 5 and
the switching element 4 by resonance due to a capacitive
component and an inductive component such 5 as the switching
element 4 and a wire, which generates noise in some cases.
[0024] In the present embodiment, to reduce noise
generation, the power converter 40 includes snubber
circuits each including the first capacitor 1 and the first
diode 2. The power converter 40 suppresses the recovery
current from flowing toward the switching element 4 by
providing a path that allows the recovery current, having
flowed through the second diode 5, to flow toward the AC
power supply 20 through the first diode 2. In addition,
the power converter 40 may include a capacitive element
(not illustrated), such as a bead inductor, in a section
between the first connection point 10 and the switching
element 4. The bead inductor acts as an impedance
component against the recovery current or against ringing
caused by the recovery current, thereby facilitating the
power converter 40 to direct the recovery current toward
the first diode 2. In addition, the power converter 40
allows the recovery current, having flowed through the
first diode 2, to be absorbed by the first capacitor 1, or
to be directed through the first capacitor 1 to the ground
line 12, thus to suppress occurrence of ringing caused by
the recovery current.
[0025] Moreover, the power converter 40 directs the
recovery current toward the AC power supply 20, and can
30 thus reduce the portion including elements, loads, and the
like on the ground line 12 along the return path of the
recovery current. This enables the power converter 40 to
reduce variation in the ground potential, and thus to
stabilize the operation of the elements, loads, and the
like. An example of advantages of the power converter 40
will be described below with reference to the drawings.
[0026] FIG. 2 is a diagram illustrating an example of
return path of the recovery current in a 5 power converter of
a comparative example not including the snubber circuits.
The power converter of a comparative example illustrated in
FIG. 2 is assumed to be one in which the snubber circuits
are removed from the power converter 40. Note that, for
the purpose of facilitating an understanding of the return path of the recovery current, FIG. 2 illustrates only a portion related to the return path of the recovery current
in the power converter of the comparative example. In FIG.
2, a parasitic capacitor 13 is an unintended capacitive component that occurs in the switching element 4. In the power converter of the comparative example, turning on of the switching element 4 causes the recovery current flowing from one end of the second capacitor 6 through the second
diode 5 to flow through the parasitic capacitor 13 in the switching element 4 into the ground line 12. As
illustrated in FIG. 2, the return path of the recovery
current partly passes through the ground line 12 in a
section between another end of the switching element 4 and
the rectification circuit 30. This may reduce detection
accuracy in the voltage detection unit 7 and in the current
detection unit 8 that are connected to the ground line 12.
[0027] FIG. 3 is a diagram illustrating an example of
return path of the recovery current in the power converter
according to the first embodiment. For the purpose of
facilitating an understanding of the return path of the
recovery current, FIG. 3 illustrates only a portion related
to the return path of the recovery current in the power
converter 40. In the power converter 40, turning on of the
switching element 4 causes the recovery current flowing
from one end of the second capacitor 6 through the second
diode 5 to flow through the first diode 2 into the first
capacitor 1. The recovery current is absorbed in the first
capacitor 1 or flows through the first 5 capacitor 1 to the
ground line 12. As illustrated in FIG. 3, the return path
of the recovery current partly passes through the ground
line 12, but the length of that portion can be reduced as
compared to the length of the portion in the power
converter of the comparative example illustrated in FIG. 2.
The power converter 40 thus provides an advantage in being
capable of reducing the decrease in detection accuracy of
the voltage detection unit 7 and of the current detection
unit 8 as compared to the decrease in the power converter
of the comparative example illustrated in FIG. 2.
[0028] Due to the need for the recovery current that
occurs transiently to pass through, the power converter 40
also desirably uses, as the first diode 2, a highly
responsive element employing a wide bandgap semiconductor
such as silicon, gallium nitride, gallium oxide, and
diamond. In addition, the first diode 2 desirably has a
response characteristic equivalent to or faster than the
response characteristic of the second diode 5. One typicaL response characteristic is a reverse recovery time. This enables the snubber circuit including the first diode 2 to also respond to a rapid change in the recovery current, and rapid noise generation caused by the recovery current to
thus be suppressed.
[0029] The switching element 4 and the first diode 2
formed of a wide bandgap semiconductor as described above
are characterized in a low resistance in a conductive state,
and are thus capable of reducing loss. In addition, the
switching element 4 and the first diode 2 formed of a wide

bandgap semiconductor as described above are highly
voltage-proof, and thus has a high allowable current
density. This enables size reduction of the switching
element 4 and of the first diode 2, and use of such
switching element 4 and such first diode 5 2 having a reduced
size enables size reduction of a semiconductor module
including therein these elements. Moreover, the switching
element 4 and the first diode 2 formed of a wide bandgap
semiconductor as described above are highly heat resistant.
This enables size reduction of a heat-dissipating component,
thereby allowing further size reduction of the
semiconductor module. Furthermore, the switching element 4
and the first diode 2 formed of a wide bandgap
semiconductor as described above has a low power loss.
This can achieve a higher efficiency of elements, and thus,
a higher efficiency of the semiconductor module.
[0030] As described above, according to the present
embodiment, the power converter 40 includes a snubber
circuit including the first diode 2 and the first capacitor
1, in which the first diode 2 is connected in parallel with
the reactor 3 such that the first diode 2 has a polarity to
become conductive when a current flows from the switching
element 4 side toward the AC power supply 20 thus to allow
the recovery current flowing from the second diode 5 to
flow into the snubber circuit. The power converter 40 can
suppress the recovery current from flowing into the
switching element 4, and can thus suppresses occurrence of
ringing caused by the recovery current, thereby allowing
noise to be reduced or eliminated. In addition, since
current does not flow into the snubber circuit except
during a transient condition in which the recovery current
flows, the power converter 40 can reduce the loss.
[0031] Second Embodiment.
In the first embodiment, the power converter 40
includes as many first capacitors 1 as the number of the
chopper circuits. In a second embodiment, the power
converter includes fewer first capacitors 1 than the number
of the chopper circuits. Differences 5 from the first
embodiment will be described below.
[0032] FIG. 4 is a block diagram illustrating an example
configuration of a motor driver 100a according to the
second embodiment. The motor driver 100a includes a power
converter 40a in place of the power converter 40 of the
motor driver 100 of the first embodiment illustrated in FIG.
1. The rectification circuit 30 and the power converter
40a together constitute a converter 70a.
[0033] The power converter 40a is obtained by removing
one of the first capacitors 1 from the power converter 40
of the first embodiment illustrated in FIG. 1. As
illustrated in FIG. 1, the power converter 40 has the
second connection points 11 of the respective chopper
circuits connected to each other. That is, it can be said
that, in the power converter 40 of the first embodiment,
two of the first capacitors 1 are connected in parallel
with each other between the connection point at which the
second connection points 11 are connected to each other,
and the ground line 12. A set of capacitors connected in
parallel with each other can be replaced with a single
capacitor having a capacity equal to the sum of the
capacities of the respective capacitors. Accordingly, the
second embodiment integrates the first capacitors 1 into
one first capacitor 1. In the second embodiment, a single
first capacitor 1 is connected between the connection point
at which the second connection points 11 are connected to
each other, and the ground line 12.
[0034] Note that, similarly to the power converter 40 of
the first embodiment, the number of the chopper circuits in
the power converter 40a is not limited to two, but may also
be one or three or more. In this case, the power converter
a may include, for example, two first capacitors 1 for
four chopper circuits, or two first capacitors 5 1 for eight
chopper circuits.
[0035] As described above, the power converter 40a of
the present embodiment includes fewer first capacitors 1
than the number of the chopper circuits. This can reduce
the circuit size as compared to the first embodiment.
[0036] Third Embodiment.
In a third embodiment, one of the first diodes 2 and
one of the reactors 3 are removed from the power converter
40a of the second embodiment. Differences from the second
embodiment will be described below.
[0037] FIG. 5 is a block diagram illustrating an example
configuration of a motor driver 100b according to the third
embodiment. The motor driver 100b includes a power
converter 40b in place of the power converter 40a of the
motor driver 100a of the second embodiment illustrated in
FIG. 4. The rectification circuit 30 and the power
converter 40b together constitute a converter 70b.
[0038] The power converter 40b is obtained by removing
one of the first diodes 2 and one of the reactors 3 from
the power converter 40a of the second embodiment
illustrated in FIG. 4. The third embodiment integrates the
first diodes 2 and the reactors 3 into one first diode 2
and one reactor 3, respectively. Unlike the first and
second embodiments, the chopper circuit of the power
converter 40b is configured to include the switching
element 4 and the second diode 5. In a case in which
multiple chopper circuits are included, the power converter
b is configured such that the chopper circuits are
connected in parallel with each other. In the power
converter 40b, one end of the reactor 3 and the anode of
the first diode 2 are connected to the connection point at
which one ends of the respective switching elements 4 are
connected 5 to each other.
[0039] Note that, similarly to the power converter 40 of
the first embodiment, the number of the chopper circuits in
the power converter 40b is not limited to two, but may also
be one or three or more. In this case, the power converter
40b may be configured such that, for example, two chopper
circuits including two switching elements 4 and two second
diodes 5 are included, and one first diode 2 and one
reactor 3 are connected to the respective chopper circuits.
[0040] As described above, the power converter 40b of
the present embodiment includes fewer first diodes 2 and
fewer reactors 3 than the number of the chopper circuits.
This can reduce the circuit size as compared to the first
and second embodiments.
[0041] Fourth Embodiment.
In a fourth embodiment, a capacitor for the snubber
circuits is added between the second diodes 5 and the
second capacitor 6. This configuration is applicable to
any one of the first to third embodiments. The following
description will be given for a case of application to the
first embodiment by way of example.
[0042] FIG. 6 is a block diagram illustrating an example
configuration of a motor driver 100c according to the
fourth embodiment. The motor driver 100c includes a power
converter 40c in place of the power converter 40 of the
motor driver 100 of the first embodiment illustrated in FIG.
1. The rectification circuit 30 and the power converter
40c together constitute a converter 70c.
[0043] The power converter 40c is obtained by adding a
third capacitor 14 to the power converter 40 of the first
embodiment illustrated in FIG. 1. Upon turning on of the
switching element 4, the third capacitor 14 absorbs part of
the recovery current flowing from the second capacitor 6
through the second diode 5, or allows part 5 of that recovery
current to flow to the ground line 12, and thus reduces the
amount of the recovery current flowing through the second
diode .
[0044] As described above, the power converter 40c of
the present embodiment additionally includes the third
capacitor 14 for the snubber circuits between the second
diodes 5 and the second capacitor 6. This can reduce the
amount of the recovery current flowing from the second
diodes 5 as compared to the first embodiment.
[0045] Fifth Embodiment.
In a fifth embodiment, a configuration will be
described in a case in which the motor driver is installed
in an air conditioner, which is an example of an airconditioning
and refrigeration apparatus. A case of use of
the motor driver 100 of the first embodiment will be
described below, though, any of the motor drivers 100 to
100c described in the first through fourth embodiments may
be used.
[0046] FIG. 7 is a block diagram illustrating an example
configuration of an air conditioner 200 according to the
fifth embodiment. The air conditioner 200 includes an
indoor unit 201 and an outdoor unit 202. The outdoor unit
202 includes an electrical component box 203, a reactor 204,
a compressor 205, and a separator 206. The motor 60 is
installed in the compressor 205. The converter 70 except
the reactor 3, and the inverter 50, of the motor driver 100
are housed in the electrical component box 203. The
reactor 204 is the reactor 3 described above, and is
attached to the separator 206. The reactor 204 may, in
general, be disposed in a different place from the place of
the other components of the converter 70 due to a large
size and need for heat dissipation. The reactor 204 and
the other components of the converter 5 70 may be directly
connected to each other by a wire or via wires and a
terminal block.
[0047] The configurations described in the foregoing
embodiments are merely examples of various aspects of the
present invention. These configurations may be combined
with a known other technology, and moreover, a part of such
configurations may be omitted and/or modified without
departing from the spirit of the present invention.
Reference Signs List
[0048] 1 first capacitor; 2 first diode; 3 reactor; 4
switching element; 5 second diode; 6 second capacitor; 7
voltage detection unit; 8 current detection unit; 9
controller; 10 first connection point; 11 second
connection point; 12 ground line; 13 parasitic capacitor;
14 third capacitor; 20 AC power supply; 30 rectification
circuit; 31 rectification element; 40, 40a, 40b, 40c
power converter; 50 inverter; 60 motor; 70, 70a, 70b, 70c
converter; 100, 100a, 100b, 100c motor driver; 200 air
conditioner; 201 indoor unit; 202 outdoor unit; 203
electrical component box; 204 reactor; 205 compressor;
206 separator.

We Claim :
1. A power converter connected between a supply source of
a first direct current power and a supply destination of a
second direct current power obtained by performing power
conversion on the first direct current 5 power, the power
converter comprising:
a switching element;
a reactor connected to one end of the switching
element;
a first diode having an anode connected to a first
connection point and having a cathode connected to one end
of the reactor, the one end of the switching element and
another end of the reactor being connected to each other at
the first connection point;
a first capacitor connected in parallel with the
supply source and having one end connected to a second
connection point, the one end of the reactor and the
cathode of the first diode being connected to each other at
the second connection point; and
a second diode having an anode connected to the first
connection point and having a cathode connected to the
supply destination.
2. The power converter according to claim 1, comprising:
a second capacitor connected in parallel with the
supply destination and having one end connected to the
cathode of the second diode.
3. The power converter according to claim 1 or 2, wherein
30 the first diode is formed of a wide bandgap
semiconductor.
4. The power converter according to claim 2, wherein
a recovery current flowing from the second capacitor
through the second diode flows through the first diode into
the first capacitor after turning on of the switching
element.
5. The power converter according to any one of claims 1
to 4, comprising:
a plurality of chopper circuits each including the
switching element, the reactor, and the second diode, the
chopper circuits being connected in parallel with each
other such that the second connection points of the
respective chopper circuits are connected to each other;
and
as many of the first diode as the chopper circuits,
the first diodes being connected in parallel with the
respective reactors of the respective chopper circuits.
6. The power converter according to claim 5, comprising:
as many of the first capacitor as the chopper circuits,
one end of each of the first capacitors being connected to
the second connection point of a corresponding one of the
chopper circuits.
7. The power converter according to claim 5, wherein the one end of the first capacitor is connected to a connection point at which the second connection points of
the respective chopper circuits are connected to each other.
8. The power converter according to any one of claims 1 to 4, comprising:
a plurality of chopper circuits each including the switching element and the second diode, the chopper circuits being connected in parallel with each other such that the one ends of the respective switching elements of
the respective chopper circu
and that the another
the first diode are connected to a connection point of the one ends of the respective 5 switching elements.
9. The power converter
to 8, wherein the switching element is formed of a wide bandgap semiconductor.
10. The power converter to 9, wherein the power converter converts alternating current power into direct curren
power.
11. The power converter
to 10, wherein the power converter
driver that drives an electric motor.
12. The power converter
to 11, wherein the power converter
conditioning and refrigeration apparatus.