FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
POWER CONVERTER, MOTOR DRIVER, AND REFRIGERATION CYCLE
APPLIED EQUIPMENT;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED
AND EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-
3, MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 1008310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
DESCRIPTION
TITLE OF THE INVENTION:
POWER CONVERTER, MOTOR DRIVER, AND REFRIGERATION CYCLE
APPLIED EQUIPMENT5
Field
[0001] The present disclosure relates to a power
converter that converts an alternating-current power into
desired power, a motor driver, and a refrigeration cycle10
applied equipment.
Background
[0002] Conventionally, there is a power converter that
converts an alternating-current power supplied from an15
alternating-current power supply into a desired
alternating-current power and supplies the alternating-
current power to a load such as an air conditioner. For
example, Patent Literature 1 discloses a technology in
which a power converter that is a control device of an air20
conditioner rectifies an alternating-current power supplied
from an alternating-current power supply with a diode stack
that is a rectifier, converts power smoothed by a smoothing
capacitor into a desired alternating-current power with an
inverter including a plurality of switching elements, and25
outputs the alternating-current power to a compressor motor
that is a load.
Citation List
Patent Literature30
[0003] Patent Literature 1: Japanese Patent Application
Laid-open No. 07-71805
3
Summary of Invention
Problem to be solved by the Invention
[0004] However, according to the above conventional
technology, since a large current flows into the smoothing
capacitor, there has been a problem in that aged5
deterioration of the smoothing capacitor is accelerated.
In view of such a problem, a method for suppressing a
ripple change of a capacitor voltage by increasing a
capacity of the smoothing capacitor or using the smoothing
capacitor with a large degradation tolerance due to the10
ripple can be considered. However, cost of a capacitor
component increases, and in addition, a size of the device
increases.
[0005] The present disclosure has been made in view of
the above, and an object is to obtain a power converter15
that can suppress an increase in size of a device while
suppressing deterioration of a smoothing capacitor.
Means to Solve the Problem
[0006] To solve the above problems and to achieve the20
object, a power converter according to the present
disclosure is a power converter to be installed in a
refrigeration cycle applied equipment and includes: a
rectifier; a capacitor connected to output ends of the
rectifier; an inverter connected across the capacitor; and25
a controller. The rectifier is configured to rectify a
first alternating-current power supplied from an
alternating-current power supply. The inverter is
configured: to convert power output from the rectifier and
the capacitor into a second alternating-current power; and30
to output the second alternating-current power to a load
including a motor. The controller is configured to control
an operation of the inverter such that the second
4
alternating-current power containing pulsation according to
pulsation of power flowing from the rectifier into the
capacitor is output from the inverter to the load and
suppresses the current flowing to the capacitor. The power
converter is configured to operate so that a pulsation5
width of a pulsating current generated by the second
alternating-current power is different, depending on
whether or not an operation of the refrigeration cycle
applied equipment is a cooling operation or a heating
operation, in a state where a predetermined power is10
received from the alternating-current power supply.
Effects of the Invention
[0007] A power converter according to the present
disclosure achieves an effect of suppressing an increase in15
a size of a device while suppressing deterioration in a
smoothing capacitor.
Brief Description of Drawings
[0008] FIG. 1 is a diagram illustrating a configuration20
example of a power converter according to a first
embodiment.
FIG. 2 is a diagram illustrating an example of each
current and a capacitor voltage of a capacitor of a
smoother in a case where a current output from a rectifier25
is smoothed by the smoother and current flowing to an
inverter is made constant.
FIG. 3 is a diagram illustrating an example of each
current and a capacitor voltage of the capacitor of the
smoother when a controller of the power converter according30
to the first embodiment controls an operation of the
inverter and reduces current flowing to the smoother.
FIG. 4 is a flowchart illustrating an operation of the
5
controller included in the power converter according to the
first embodiment.
FIG. 5 is a diagram illustrating an example of a
hardware configuration that implements the controller
included in the power converter according to the first5
embodiment.
FIG. 6 is a diagram illustrating a configuration
example of a refrigeration cycle applied equipment
according to a second embodiment.
10
Description of Embodiments
[0009] Hereinafter, a power converter, a motor driver,
and a refrigeration cycle applied equipment according to
embodiments of the present disclosure will be described in
detail with reference to the drawings.15
[0010] First Embodiment.
FIG. 1 is a diagram illustrating a configuration
example of a power converter 1 according to a first
embodiment. The power converter 1 is connected to a
commercial power supply 110 and a compressor 315. The20
commercial power supply 110 is an example of an
alternating-current power supply. The power converter 1
converts a first alternating-current power of a power
supply voltage Vs supplied from the commercial power supply
110 into a second alternating-current power having a25
desired amplitude and phase and supplies the second
alternating-current power to the compressor 315. The power
converter 1 includes: a voltage-current detector 501; a
reactor 120; a rectifier 130; a voltage detector 502; a
smoother 200; an inverter 310; current detectors 313a and30
313b; a temperature detector 504; and a controller 400.
Note that a motor driver 2 is constituted by: the power
converter 1; and a motor 314 included in the compressor
6
315. Furthermore, the power converter 1 is configured to
be installed in a refrigeration cycle applied equipment to
be described later.
[0011] The voltage-current detector 501 detects a
voltage value and a current value of the first alternating-5
current power of the power supply voltage Vs supplied from
the commercial power supply 110 and outputs the detected
voltage value and current value to the controller 400. The
reactor 120 is connected between the voltage-current
detector 501 and the rectifier 130.10
[0012] The rectifier 130: includes a bridge circuit
including rectifier elements 131 to 134; and rectifies and
outputs the first alternating-current power of the power
supply voltage Vs supplied from the commercial power supply
110. The rectifier 130 performs full-wave rectification.15
[0013] The voltage detector 502 detects a voltage value
of power rectified by the rectifier 130 and outputs the
detected voltage value to the controller 400.
[0014] The smoother 200 is connected to output ends of
the rectifier 130 via the voltage detector 502. The20
smoother 200 includes a capacitor 210 as a smoothing
element and smooths the power rectified by the rectifier
130.
[0015] The capacitor 210 is, for example, an
electrolytic capacitor, a film capacitor, or the like. The25
capacitor 210 has a capacity for smoothing the power
rectified by the rectifier 130. A voltage generated in the
capacitor 210 by smoothing does not have a full-wave
rectification waveform shape of the commercial power supply
110 and has a waveform shape in which a voltage ripple30
according to a frequency of the commercial power supply 110
is superimposed on a DC component and does not largely
pulsate. The frequency of the voltage ripple is a twice
7
component of a frequency of the power supply voltage Vs in
a case where the commercial power supply 110 has a single
phase, and has a 6-fold component as a main component in a
case where the commercial power supply 110 has three
phases. In a case where the power input from the5
commercial power supply 110 and power output from the
inverter 310 do not change, an amplitude of the voltage
ripple is determined on the basis of the capacity of the
capacitor 210. The amplitude of the voltage ripple
pulsates, for example, within a range in which a maximum10
value of the voltage ripple generated in the capacitor 210
is less than a twice of a minimum value.
[0016] The inverter 310 is connected across the smoother
200, that is, the capacitor 210. The inverter 310 includes
switching elements 311a to 311f and freewheeling diodes15
312a to 312f. The inverter 310 turns on/off the switching
elements 311a to 311f by controlling the controller 400,
converts the power output from the rectifier 130 and the
smoother 200 into the second alternating-current power
having a desired amplitude and phase, and outputs the20
second alternating-current power to the compressor 315.
[0017] Each of the current detectors 313a and 313b:
detects a current value of one phase of three-phase
currents output from the inverter 310; and outputs the
detected current value to the controller 400. Note that,25
by acquiring the current values of two phases of the three-
phase current values output from the inverter 310, the
controller 400 can calculate a current value of one
remaining phase output from the inverter 310.
[0018] The temperature detector 504 detects a30
temperature of the capacitor 210 and an ambient temperature
of the capacitor 210 and outputs the detected temperature
value to the controller 400. Note that, in a case of a
8
general power converter, a temperature detector is provided
on a control board or a circuit board. Therefore, a
detection value of the temperature detector provided on the
board may be substituted, without providing the temperature
detector 504.5
[0019] The compressor 315 is a load having the motor 314
for driving the compressor. The motor 314 rotates
according to the amplitude and the phase of the second
alternating-current power supplied from the inverter 310
and performs a compression operation. For example, in a10
case where the compressor 315 is a sealed compressor used
for an air conditioner or the like, a load torque of the
compressor 315 can be often regarded as a constant torque
load.
[0020] Note that, in the power converter 1, arrangement15
of each component illustrated in FIG. 1 is an example, and
the arrangement of each component is not limited to the
example illustrated in FIG. 1. For example, the reactor
120 may be disposed at a subsequent stage of the rectifier
130. In the following description, the voltage-current20
detector 501, the voltage detector 502, and the current
detectors 313a and 313b may be collectively referred to as
a detector. Furthermore, the voltage value and the current
value detected by the voltage-current detector 501, the
voltage value detected by the voltage detector 502, and the25
current values detected by the current detectors 313a and
313b may be referred to as a detection value.
[0021] The controller 400 acquires the voltage value and
the current value of the first alternating-current power
from the voltage-current detector 501 and acquires the30
voltage value of the power rectified by the rectifier 130
from the voltage detector 502. Furthermore, the controller
400 acquires a current value of the second alternating-
9
current power having the desired amplitude and phase
converted by the inverter 310 from the current detectors
313a and 313b and acquires the temperature or the
temperature value of the ambient temperature of the
capacitor 210 from the temperature detector 504. The5
controller 400 controls an operation of the inverter 310,
specifically, on/off of the switching elements 311a to 311f
included in the inverter 310, using the detection value
detected by each detector. Note that the controller 400
does not need to use all the detection values acquired from10
each detector and can perform control using some detection
values.
[0022] In the first embodiment, the controller 400
controls current flowing into the capacitor 210 of the
smoother 200, by a pulsating current generated by the15
second alternating-current power. Specifically, the
controller 400 controls the operation of the inverter 310
such that the second alternating-current power containing
pulsation according to pulsation of the power flowing into
the capacitor 210 of the smoother 200 from the rectifier20
130 is output from the inverter 310 to the compressor 315
that is a load. Here, the pulsation according to the
pulsation of the power flowing into the capacitor 210 of
the smoother 200 is pulsation that varies, for example,
depending on a frequency of the pulsation of the power25
flowing into the capacitor 210 of the smoother 200 or the
like. As a result, the controller 400 controls the current
flowing to the capacitor 210 of the smoother 200.
[0023] Next, an operation of the controller 400 included
in the power converter 1 will be described. Note that, in30
the power converter 1 according to the first embodiment,
the loads generated by the inverter 310 and the compressor
315 can be regarded as a constant load. Therefore, here,
10
the following description is made as assuming that a
constant current load is connected to the smoother 200 in a
case of viewing current output from the smoother 200, in
the power converter 1.
[0024] Here, as illustrated in FIG. 1, current flowing5
from the rectifier 130 is referred to as current I1,
current flowing into the inverter 310 is referred to as
current I2, and current flowing from the smoother 200 is
referred to as current I3. The current I2 is current
obtained by combining the currents I1 and I3. The current10
I3 can be expressed as a difference between the currents I2
and I1, that is, current obtained by the current I2 - the
current I1. In the current I3, a discharging direction of
the smoother 200 is set as a positive direction, and a
charging direction of the smoother 200 is set as a negative15
direction. That is, the current may flow into and from the
smoother 200.
[0025] FIG. 2 is a diagram illustrating an example of
each of the currents I1 to I3 and a capacitor voltage Vdc
of the capacitor 210 of the smoother 200 in a case where20
the current output from the rectifier 130 is smoothed by
the smoother 200 and the current I2 flowing to the inverter
310 is made constant. From the top, the current I1, the
current I2, the current I3, and the capacitor voltage Vdc
of the capacitor 210 generated according to the current I325
are illustrated. A vertical axis of the currents I1 to I3
indicates a current value, and a vertical axis of the
capacitor voltage Vdc indicates a voltage value. All the
horizontal axes indicate a time t. Note that, although
carrier components of the inverter 310 are actually30
superimposed on the currents I2 and I3, the carrier
components are omitted here. The same applies to the
following.
11
[0026] As illustrated in FIG. 2, in the power converter
1, if the current I1 flowing from the rectifier 130 is
sufficiently smoothed by the smoother 200, the current I2
flowing to the inverter 310 has a constant current value.
However, the large current I3 flows into the capacitor 2105
of the smoother 200, and this causes deterioration in the
capacitor 210. Therefore, in the first embodiment, in the
power converter 1, the controller 400 controls the current
I2 flowing to the inverter 310, that is, the operation of
the inverter 310, so as to reduce the current I3 flowing to10
the smoother 200.
[0027] FIG. 3 is a diagram illustrating an example of
each of the currents I1 to I3 and the capacitor voltage Vdc
of the capacitor 210 of the smoother 200 when the
controller 400 of the power converter 1 according to the15
first embodiment controls the operation of the inverter 310
and reduces the current I3 flowing to the smoother 200.
From the top, the current I1, the current I2, the current
I3, and the capacitor voltage Vdc of the capacitor 210
generated according to the current I3 are illustrated. A20
vertical axis of the currents I1 to I3 indicates a current
value, and a vertical axis of the capacitor voltage Vdc
indicates a voltage value. All the horizontal axes
indicate a time t. The controller 400 of the power
converter 1 controls the operation of the inverter 310 such25
that the current I2 as illustrated in FIG. 3 flows to the
inverter 310. With this control, as compared with the
example in FIG. 2, the current flowing from the rectifier
130 into the smoother 200 is reduced, and as a result, the
current I3 flowing to the smoother 200 is reduced.30
Specifically, the controller 400 controls the operation of
the inverter 310 such that the current I2 including the
pulsating current having the frequency component of the
12
current I1 as a main component flows to the inverter 310.
[0028] The frequency component of the current I1 is
determined by a frequency of an alternating-current
supplied from the commercial power supply 110 and a
configuration of the rectifier 130. Therefore, the5
controller 400 can set the frequency component of the
pulsating current superimposed on the current I2 as a
component having a predetermined amplitude and phase. The
frequency component of the pulsating current superimposed
on the current I2 has a waveform similar to the frequency10
component of the current I1. The controller 400 can reduce
the current I3 flowing to the smoother 200 and reduce a
pulsating voltage generated in the capacitor voltage Vdc as
the frequency component of the pulsating current
superimposed on the current I2 approaches the frequency15
component of the current I1.
[0029] Controlling the pulsation of the current flowing
to the inverter 310 by controlling the operation of the
inverter 310 by the controller 400 is equivalent to
controlling the pulsating current generated by the second20
alternating-current power output from the inverter 310 to
the compressor 315. The controller 400 controls the
operation of the inverter 310 so that a pulsation amount,
that is, a pulsation width of the pulsating current
generated by the second alternating-current power output25
from the inverter 310 becomes smaller than that of the
pulsating current generated by the power output from the
rectifier 130.
[0030] The controller 400 controls the pulsation width
of the pulsating current generated by the second30
alternating-current power output from the inverter 310, so
that the pulsation of the current flowing into and from the
capacitor 210 becomes smaller than the pulsation of the
13
current generated in the capacitor 210 when the pulsation
according to the pulsation of the power flowing to the
capacitor 210 is not included in the second alternating-
current power output from the inverter 310. Alternatively,
the controller 400 controls the pulsation width of the5
pulsating current generated by the second alternating-
current power output from the inverter 310 so that
pulsation of the voltage of the capacitor voltage Vdc, that
is, the pulsation of the voltage generated in the capacitor
210 becomes smaller than the pulsation of the voltage10
generated in the capacitor 210 when pulsation power
according to the pulsation of the power flowing into the
capacitor 210 is not included in the second alternating-
current power output from the inverter 310. Note that,
when the pulsation according to the pulsation of the power15
flowing into the capacitor 210 is not included in the
second alternating-current power output from the inverter
310 means the control illustrated in FIG. 2. Furthermore,
the pulsation width is a difference between a maximum value
and a minimum value of the pulsating current.20
[0031] The control described above is referred to as
“power supply pulsation compensation control”. That is,
the power supply pulsation compensation control is control
for suppressing a ripple current that may flow to the
capacitor 210 of the smoother 200 due to power supply25
pulsation. According to the power supply pulsation
compensation control, most of the ripple current due to the
power supply pulsation is supplied to the load avoiding the
capacitor 210. Therefore, by using the power supply
pulsation compensation control, it is possible to reduce30
stress of the capacitor 210 and suppress the deterioration
of the capacitor 210.
[0032] Note that the alternating-current supplied from
14
the commercial power supply 110 is not particularly limited
and may have a single phase or three phases. It is
sufficient for the controller 400 to determine the
frequency component of the pulsating current superimposed
on the current I2, according to the first alternating-5
current power supplied from the commercial power supply
110. Specifically, the controller 400 controls the
pulsation waveform of the current I2 flowing to the
inverter 310: to a frequency component that is twice of the
frequency of the first alternating-current power in a case10
where the first alternating-current power supplied from the
commercial power supply 110 has a single phase; or to a
shape obtained adding the direct current to the pulsation
waveform having a frequency component that is six times of
the frequency of the first alternating-current power as a15
main component in a case where the first alternating-
current power supplied from the commercial power supply 110
has three phases. The pulsation waveform is, for example,
a shape of an absolute value of a sine wave or a shape of a
sine wave. In this case, the controller 400 may add at20
least one frequency component among integral-multiple
components of a frequency of the sine wave to the pulsation
waveform, as a predefined amplitude. Furthermore, the
pulsation waveform may be a shape of a rectangular wave or
a shape of a triangular shape. In this case, the25
controller 400 may set the amplitude and the phase of the
pulsation waveform to be predetermined values.
[0033] The controller 400 may: calculate the pulsation
amount of the pulsating current generated by the second
alternating-current power output from the inverter 310,30
using the voltage applied to the capacitor 210 or the
current flowing to the capacitor 210; or may calculate the
pulsation amount of the pulsating current generated by the
15
second alternating-current power output from the inverter
310, using a voltage or current of the first alternating-
current power supplied from the commercial power supply
110.
[0034] Next, an operation of the controller 400 in a5
case where the power converter 1 is installed in the
refrigeration cycle applied equipment will be described
with reference to the flowchart. FIG. 4 is a flowchart
illustrating the operation of the controller 400 included
in the power converter 1 according to the first embodiment.10
[0035] The controller 400 acquires a required detection
value from each detector of the power converter 1 (step
S11). The controller 400 confirms whether an operation of
the refrigeration cycle applied equipment is a cooling
operation or a heating operation (step S12). The15
controller 400 appropriately controls the pulsation width
of the pulsating current generated by the second
alternating-current power, according to whether the
operation is the cooling operation or the heating operation
(step S13).20
[0036] Note that the flowchart in FIG. 4 includes
various operation modes. First, a first operation mode in
the first embodiment will be described. The first
operation mode is an operation mode in which the pulsation
width of the pulsating current generated by the second25
alternating-current power is different, depending on
whether or not the operation of the refrigeration cycle
applied equipment is the cooling operation or the heating
operation, in a state where predetermined power is received
from the commercial power supply 110. Note that, here, to30
operate a heat pump device of the refrigeration cycle
applied equipment in a cooling cycle is referred to as the
“cooling operation”, and to operate the heat pump device of
16
the refrigeration cycle applied equipment in a heating
cycle is referred to as the “heating operation”.
[0037] For example, it is considered to control the
operation of the inverter 310 so that the pulsation width
of the pulsating current generated by the second5
alternating-current power output from the inverter 310 to
the motor 314 at the time of cooling operation becomes
larger than that at the time of heating operation. In
general, at the time of the cooling operation, the ambient
temperature of the refrigeration cycle applied equipment is10
higher, and life degradation of the capacitor 210 is
accelerated. Therefore, if control is performed so that
the pulsation width of the pulsating current at the time of
cooling operation becomes larger than that at the time of
heating operation, conversely, control is performed so that15
the pulsation width of the pulsating current at the time of
heating operation becomes smaller than that at the time of
cooling operation, it is possible to make the power supply
pulsation compensation control strongly work at the time of
cooling operation when an outside temperature is high. As20
a result, under a cooling condition in which a temperature
environment is severe, it is possible to effectively reduce
a capacitor current, and it is possible to suppress self-
heating of the capacitor 210. As a result, the capacitor
210 with a low heat-resistant temperature can be applied.25
[0038] For example, it is considered to control the
operation of the inverter 310 so that the pulsation width
of the pulsating current generated by the second
alternating-current power output from the inverter 310 to
the motor 314 at the time of heating operation becomes30
larger than that at the time of cooling operation. In a
case where the refrigeration cycle applied equipment is an
air conditioner, in a cold district, there is a possibility
17
that the air conditioner operates the heating operation at
an extremely low temperature. The extremely low
temperature is, for example, equal to or lower than -20°C.
It is generally known that a capacitance of the capacitor
is lowered as the temperature is lowered. When the5
capacitance of the capacitor 210 is significantly lowered,
it is difficult to stably operate an air conditioning
operation. Therefore, control is performed so that the
pulsation width of the pulsating current at the time of
heating operation becomes larger than that at the time of10
cooling operation. With this control, at the time of
heating operation with a low outside temperature, it is
possible to heat the capacitor 210. As a result, even in a
case where the refrigeration cycle applied equipment is
placed in an extremely low temperature environment, the15
refrigeration cycle applied equipment can be stably
operated.
[0039] According to the first operation mode described
above, since an operation condition according to an
operation request of the refrigeration cycle applied20
equipment can be set, an appropriate protection operation
of the capacitor 210 can be realized. Note that, according
to the first operation mode, there is a case where the
pulsation width of the pulsating current generated by the
second alternating-current power becomes zero during at25
least one of the cooling operation and the heating
operation in a state where predetermined power is received
from the commercial power supply 110. Furthermore,
according to the first operation mode, in a state where the
predetermined power is received from the commercial power30
supply 110, there is a case where the pulsation width of
the pulsating current generated by the second alternating-
current power during both of the cooling operation and the
18
heating operation is not zero. It is considered that
control according to the first operation mode may be useful
or not useful, depending on functions of a product, a use
place of the product, or a cost effectiveness. Therefore,
it is desirable to determine whether or not to adopt the5
control according to the first operation mode, in
consideration of the functions of the product, the use
place of the product, or the cost effectiveness.
[0040] Next, a second operation mode in the first
embodiment will be described. The second operation mode is10
an operation mode in which the pulsation width of the
pulsating current generated by the second alternating-
current power is increased or the phase of the pulsating
current is changed to heat the capacitor 210 when the
temperature or the ambient temperature of the capacitor 21015
is equal to or less than a threshold in a case where the
operation of the refrigeration cycle applied equipment is
the heating operation. For example, in a case where the
refrigeration cycle applied equipment is the air
conditioner, there is a problem in that, if the power20
supply pulsation compensation control is performed by the
control similar to that of the cooling operation performed
when the outside temperature is high at the time when the
outside temperature is low and when the outside temperature
is high, the heating of the capacitor 210 is not25
sufficiently accelerated at the time of heating operation
performed when the outside temperature is low. Therefore,
when the temperature of the capacitor 210 or the ambient
temperature of the capacitor 210 is equal to or lower than
the threshold, the pulsation width of the pulsating current30
generated by the second alternating-current power is
increased or the phase of the pulsating current is changed
to actively heat the capacitor 210. This control
19
accelerates the heat generation of the capacitor 210. As a
result, even in a case where the refrigeration cycle
applied equipment is placed in an extremely low temperature
environment, the refrigeration cycle applied equipment can
be stably operated.5
[0041] Note that the phase of the pulsating current in a
case where the phase of the pulsating current is changed to
heat the capacitor 210 can be an opposite phase of the
phase of the pulsating current in a case where the
pulsation of the current flowing to the capacitor 210 is10
suppressed. The opposite phase is to reverse the phase of
the pulsating current by 180°. By using such a method, the
power supply pulsation compensation control with respect to
the capacitor 210 and the heat control of the capacitor 210
can be easily and quickly switched.15
[0042] Next, a third operation mode in the first
embodiment will be described. The third operation mode is
an operation mode in which the pulsation width of the
pulsating current generated by the second alternating-
current power is reduced so as to alleviate the heat20
generation of the capacitor 210 when the temperature or the
ambient temperature of the capacitor 210 is equal to or
higher than a first threshold; and the pulsation width of
the pulsating current generated by the second alternating-
current power is increased so as to accelerate the heat25
generation of the capacitor 210 when the temperature or the
ambient temperature of the capacitor 210 is equal to or
lower than a second threshold smaller than the first
threshold. Furthermore, similarly to the second operation
mode, the phase of the pulsating current may be changed,30
instead of decreasing or increasing the pulsation width of
the pulsating current generated by the second alternating-
current power. Note that, when the temperature or the
20
ambient temperature of the capacitor 210 is higher than the
second threshold and lower than the first threshold, normal
power supply pulsation compensation control is performed.
[0043] According to the third operation mode, it is
possible to control the temperature of the capacitor 2105
according to a temperature condition. As a result, since
it is possible to reduce the stress of the capacitor 210
and prevent the deterioration of the capacitor 210, the
refrigeration cycle applied equipment can be stably
operated.10
[0044] Note that, similarly to the control according to
the first operation mode, it is considered that the control
according to the second and third operation modes may be
useful or not useful, depending on the functions of the
product, the use place of the product, or the cost15
effectiveness. Therefore, it is desirable to determine
whether or not to adopt the control according to the second
and third operation modes, in consideration of the
functions of the product, the use place of the product, or
the cost effectiveness.20
[0045] Next, a hardware configuration of the controller
400 included in the power converter 1 will be described.
FIG. 5 is a diagram illustrating an example of a hardware
configuration that implements the controller 400 included
in the power converter 1 according to the first embodiment.25
The controller 400 is implemented by a processor 91 and a
memory 92.
[0046] The processor 91 is, for example, a central
processing unit (CPU) (also referred to as central
processing unit, processing device, arithmetic device,30
microprocessor, microcomputer, processor, and digital
signal processor (DSP)) or a system large scale integration
(LSI). As the memory 92, a nonvolatile or volatile
21
semiconductor memory can be exemplified such as a random
access memory (RAM), a read only memory (ROM), a flash
memory, an erasable programmable read only memory (EPROM),
or an electrically erasable programmable read only memory
(EEPROM)(registered trademark). Furthermore, the memory 925
is not limited to these and may be a magnetic disk, an
optical disk, a compact disk, a mini disk, or a digital
versatile disc (DVD).
[0047] As described above, the power converter 1
according to the first embodiment controls the operation of10
the inverter 310 so that the second alternating-current
power containing the pulsation according to the pulsation
of the power flowing from the rectifier 130 into the
capacitor 210 is output from the inverter 310 to the motor
314 and performs control for suppressing the current15
flowing to the capacitor 210. With this control, it is
possible to reduce the stress of the capacitor 210 and
suppress the deterioration of the capacitor 210. As a
result, since it is possible to reduce the capacity of the
capacitor 210 and use the capacitor 210 with a small20
degradation tolerance due to a ripple, it is possible to
suppress an increase in a size of the power converter 1.
[0048] The power converter 1 operates so that the
pulsation width of the pulsating current generated by the
second alternating-current power is different, depending on25
whether or not the operation of the refrigeration cycle
applied equipment is the cooling operation or the heating
operation, in a state where predetermined power is received
from the commercial power supply 110. According to the
refrigeration cycle applied equipment in which the power30
converter 1 that operates in this way is installed, it is
possible to perform the cooling operation, the heating
operation, and an operation suitable for a temperature
22
environmental condition. As a result, the refrigeration
cycle applied equipment can be stably operated.
[0049] Second Embodiment.
In a second embodiment, a refrigeration cycle applied
equipment in which the power converter 1 according to the5
first embodiment is installed will be described. FIG. 6 is
a diagram illustrating a configuration example of a
refrigeration cycle applied equipment 900 according to the
second embodiment. The refrigeration cycle applied
equipment 900 according to the second embodiment includes10
the power converter 1 described in the first embodiment.
The refrigeration cycle applied equipment 900 according to
the second embodiment can be applied to a product including
a refrigeration cycle such as an air conditioner, a
refrigerator, a freezer, or a heat pump water heater. Note15
that, in FIG. 6, components having functions similar to
those of the first embodiment are denoted with the same
reference numerals as in the first embodiment.
[0050] In the refrigeration cycle applied equipment 900,
the compressor 315 including the motor 314 in the first20
embodiment, a four-way valve 902, an indoor heat exchanger
906, an expansion valve 908, and an outdoor heat exchanger
910 are attached via a refrigerant pipe 912.
[0051] In the compressor 315, a compression mechanism
904 that compresses a refrigerant and the motor 314 that25
operates the compression mechanism 904 are provided.
[0052] The refrigeration cycle applied equipment 900 can
perform a heating operation or a cooling operation by a
switching operation of the four-way valve 902. The
compression mechanism 904 is driven by the motor 314 that30
is variable speed controlled.
[0053] At the time of heating operation, as indicated by
a solid arrow, the refrigerant is pressurized and sent by
23
the compression mechanism 904, passes through the four-way
valve 902, the indoor heat exchanger 906, the expansion
valve 908, the outdoor heat exchanger 910, and the four-way
valve 902, and returns to the compression mechanism 904.
[0054] At the time of cooling operation, as indicated by5
a broken arrow, the refrigerant is pressurized and sent by
the compression mechanism 904, passes through the four-way
valve 902, the outdoor heat exchanger 910, the expansion
valve 908, the indoor heat exchanger 906, and the four-way
valve 902, and returns to the compression mechanism 904.10
[0055] At the time of heating operation, the indoor heat
exchanger 906 releases heat by acting as a condenser, and
the outdoor heat exchanger 910 absorbs heat by acting as an
evaporator. At the time of cooling operation, the outdoor
heat exchanger 910 releases heat by acting as a condenser,15
and the indoor heat exchanger 906 absorbs heat by acting as
an evaporator. The expansion valve 908 decompresses and
expands the refrigerant.
[0056] Note that the configurations illustrated in the
above embodiments indicate an example and can be combined20
with another known technique. Furthermore, the
configurations illustrated in the embodiments can be
partially omitted or changed without departing from the
scope. Furthermore the operation described in the above
embodiments indicates an example, and the first to the25
third operation modes can be combined, and the first to the
third operation modes can be combined with another known
technique without departing from the scope.
Reference Signs List30
[0057] 1 power converter; 2 motor driver; 91
processor; 92 memory; 110 commercial power supply; 120
reactor; 130 rectifier; 131 to 134 rectifier element; 200
24
smoother; 210 capacitor; 310 inverter; 311a to 311f
switching element; 312a to 312f freewheeling diode; 313a,
313b current detector; 314 motor; 315 compressor; 400
controller; 501 voltage-current detector; 502 voltage
detector; 504 temperature detector; 900 refrigeration5
cycle applied equipment; 902 four-way valve; 904
compression mechanism; 906 indoor heat exchanger; 908
expansion valve; 910 outdoor heat exchanger; 912
refrigerant pipe.
10
25
We Claim
[Claim 1] A power converter to be installed in a
refrigeration cycle applied equipment, the power converter
comprising:
a rectifier configured to rectify a first alternating-5
current power supplied from an alternating-current power
supply;
a capacitor connected to output ends of the rectifier;
an inverter connected across the capacitor,
configured:10
to convert power output from the rectifier and
the capacitor into a second alternating-current power; and
to output the second alternating-current power to
a load comprising a motor; and
a controller configured:15
to control an operation of the inverter such that
the second alternating-current power containing pulsation
according to pulsation of power flowing into the capacitor
from the rectifier is output from the inverter to the load;
and20
to suppress current flowing to the capacitor,
wherein
in a state where predetermined power is received from
the alternating-current power supply, a pulsation width of
a pulsating current generated by the second alternating-25
current power is different depending on whether an
operation of the refrigeration cycle applied equipment is a
cooling operation or a heating operation.
[Claim 2] The power converter according to claim 1, wherein30
the controller is configured to control the operation
of the inverter such that the pulsation width of the
pulsating current generated by the second alternating-
26
current power output from the inverter at the time of
heating operation becomes smaller than that at the time of
cooling operation.
[Claim 3] The power converter according to claim 1, wherein5
the controller is configured to control the operation
of the inverter such that the pulsation width of the
pulsating current generated by the second alternating-
current power output from the inverter at the time of
heating operation becomes larger than that at the time of10
cooling operation.
[Claim 4] The power converter according to claim 3, wherein
in a case where the operation of the refrigeration
cycle applied equipment is the heating operation, the15
controller is configured to heat the capacitor when a
temperature of the capacitor or an ambient temperature of
the capacitor is equal to or lower than a threshold:
by increasing the pulsation width of the pulsating
current generated by the second alternating-current power;20
or
by changing a phase of the pulsating current .
[Claim 5] The power converter according to claim 4, wherein
the phase of the pulsating current in a case where the25
phase of the pulsating current is changed to heat the
capacitor is an opposite phase of the phase of the
pulsating current in a case where the pulsation of the
current flowing to the capacitor is suppressed.
30
[Claim 6] The power converter according to claim 3, wherein
when a temperature of the capacitor or an ambient
temperature of the capacitor is equal to or higher than a
27
first threshold, the controller is configured:
to reduce the pulsation width of the pulsating
current generated by the second alternating-current power
so as to alleviate heat generation of the capacitor; or
to change a phase of the pulsating current, and5
when the temperature of the capacitor or the ambient
temperature of the capacitor is equal to or lower than a
second threshold that is smaller than the first threshold,
the controller is configured:
to increase the pulsation width of the pulsating10
current generated by the second alternating-current power
so as to accelerate the heat generation of the capacitor;
or
to change the phase of the pulsating current.
15
[Claim 7] The power converter according to any one of
claims 1 to 6, wherein
at least one of the time of the cooling operation and
the time of the heating operation in a state where
predetermined power is received from the alternating-20
current power supply, the pulsation width of the pulsating
current generated by the second alternating-current power
is zero.
[Claim 8] The power converter according to any one of25
claims 1 to 6, wherein
in a state where predetermined power is received from
the alternating-current power supply, the pulsation width
of the pulsating current generated by the second
alternating-current power at the time of both of the30
cooling operation and the heating operation is not zero.
[Claim 9] A motor driver comprising:
28
the power converter according to any one of claims 1
to 8.
[Claim 10] A refrigeration cycle applied equipment
comprising:5
the power converter according to any one of claims 1
to 8.