WO2018073875A1

WO2018073875A1 - Power conversion device, motor drive device, and air conditioner

Info

Publication number: WO2018073875A1
Application number: PCT/JP2016/080747
Authority: WO
Inventors: 崇山川; 成雄梅原; 啓介植村
Original assignee: 三菱電機株式会社
Priority date: 2016-10-17
Filing date: 2016-10-17
Publication date: 2018-04-26
Also published as: JPWO2018073875A1

Abstract

This power conversion device (100) is provided with the following: a reactor (2); a first arm (33) that comprises a switching element (311) and a switching element (312) that are connected in series and that have a connection point connected to the reactor (2); a second arm (34) that is connected in parallel to the first arm (33) and that comprises a switching element (313) and a switching element (314) that are connected in series and that have a connection point connected to the reactor (2); a second circuit (32) that is connected in parallel to the second arm (34) and that comprises a switching element (321) and a switching element (322) that are connected in series and that have a connection point connected to an alternating current power source; and a smoothing capacitor (4) that is connected in parallel to the second circuit (32).

Description

Power conversion device, motor drive device, and air conditioner

The present invention relates to a power conversion device that converts AC power into DC power and supplies the load to a load, a motor driving device including the power conversion device, and an air conditioner.

The power source current that is a current supplied from the power source includes a harmonic current that is a harmonic component that is a frequency component of a frequency higher than the frequency of the fundamental wave. In order to suppress obstacles caused by harmonic currents, there are international regulations for electronic devices that generate harmonic currents. In order to comply with this regulation, the converter takes measures to suppress the harmonic current contained in the power supply current by chopping with AC (Alternating Current) or DC (Direct Current).

In particular, full-bridge converters in which rectifier circuits are configured with switch elements are being actively studied as loss reduction techniques using AC chopping techniques. For example, Patent Document 1 discloses a technique for realizing a low loss by controlling a power supply current by one arm of a full bridge circuit and switching a switching element of the other arm of the full bridge circuit in accordance with the power supply polarity. Is disclosed.

JP 2014-099946 A

However, in the technique described in Patent Document 1, the switching element of the arm that performs switching for controlling the power supply current has a higher switching frequency than the switching element of the other arm that performs switching according to the power supply polarity. Become. For this reason, the loss of the switching element of the arm that performs switching for power supply control is larger than that of the switching element of the other arm that performs switching according to the voltage polarity of the power supply. Therefore, the technique described in Patent Document 1 has a problem in that unevenness of heat generation occurs and it is difficult to increase the output.

The present invention has been made in view of the above, and an object of the present invention is to obtain a power conversion device that can suppress unevenness in heat generation and achieve high output.

In order to solve the above-described problems and achieve the object, a power converter according to the present invention is a power converter that converts AC power supplied from an AC power source into DC power, each connected to the AC power source. First and second wirings, and a reactor disposed on the first wiring. Moreover, the power converter device concerning this invention is provided with the 1st switching element, the 2nd switching element, and the 3rd wiring provided with the 1st connection point, The 1st switching element and the 2nd switching The elements are connected in series by a third wiring, the first connection point is connected to the reactor by the first wiring, the first arm is connected in parallel with the first arm, and the third switching element , A fourth switching element and a fourth wiring having a second connection point, wherein the third switching element and the fourth switching element are connected in series by the fourth wiring, and the second connection point Comprises a second arm connected to the reactor by a first wiring. Furthermore, the power conversion device according to the present invention includes a fifth switching element, a sixth switching element, and a fifth wiring having a third connection point, which are connected in parallel with the second arm. The fifth switching element and the sixth switching element are connected in series by the fifth wiring, and the third connection point is a third arm connected to the AC power source by the second wiring, the third arm, A capacitor connected in parallel.

The power conversion device according to the present invention has the effect of suppressing the bias of heat generation and realizing high output.

The figure which shows the structural example of the power converter device concerning Embodiment 1. FIG. The figure which shows the current pathway in the power converter device of Embodiment 1 when the absolute value of power supply current is larger than a current threshold value. The figure which shows the current pathway in the power converter device of Embodiment 1 when the absolute value of power supply current is larger than a current threshold value. The figure which shows the current pathway in the power converter device of Embodiment 1 when the absolute value of power supply current is larger than a current threshold value. The figure which shows the current pathway in the power converter device of Embodiment 1 when the absolute value of power supply current is larger than a current threshold value. The figure which shows an example of the capacitor | condenser short circuit through the alternating current power supply and reactor of Embodiment 1 The figure which shows an example of the capacitor | condenser short circuit through the alternating current power supply and reactor of Embodiment 1 The figure which shows the example of the current pathway in the power converter device of Embodiment 1 when the absolute value of power supply current is less than a threshold value The figure which shows the example of the current pathway in the power converter device of Embodiment 1 when the absolute value of power supply current is less than a threshold value The figure which shows the example of the current pathway in the power converter device of Embodiment 1 when the absolute value of power supply current is less than a threshold value The figure which shows the example of the current pathway in the power converter device of Embodiment 1 when the absolute value of power supply current is less than a threshold value The figure which shows the structural example of the control apparatus of Embodiment 1. The figure which shows an example of the power supply voltage phase estimation value (theta) s ^ and sine wave value sin (theta) s ^ calculated by the power supply voltage Vs of Embodiment 1, and a power supply voltage detection part The figure which shows the structural example of the 1st pulse generation part of Embodiment 1. FIG. The figure which shows an example of the carrier wave of Embodiment 1, and a reference | standard PWM signal The figure which shows an example of the reference | standard PWM signal Scom of Embodiment 1, inversion PWM signal Scom ', 1st PWM signal Sig1, and 2nd PWM signal Sig2. A flowchart showing an example of a selection processing procedure in the pulse selector unit of the first embodiment. Schematic diagram showing the relationship between current and loss in the switching element of the first embodiment The flowchart which shows an example of the process sequence in the synchronous drive pulse generation part of Embodiment 1. The flowchart which shows an example of the control procedure of the switching element based on the power supply current in the synchronous drive pulse generation part of Embodiment 1 The figure which shows an example of each drive signal for 1 period of the power supply voltage in the power converter device of Embodiment 1. The figure which shows another example of each drive signal for 1 period of the power supply voltage in the power converter device of Embodiment 1. FIG. The figure which shows an example of each drive signal in the case of implementing the simple switching control of Embodiment 1 The figure which shows an example of each drive signal of the passive state of Embodiment 1 FIG. 3 is a diagram illustrating a configuration example of a control circuit according to the first embodiment. The figure which shows the structural example of the drive device of Embodiment 2. FIG. The figure which shows the structural example of the air conditioner of Embodiment 3.

Hereinafter, a power conversion device, a motor drive device, and an air conditioner according to an embodiment of the present invention will be described in detail based on the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of the power conversion device according to the first embodiment of the present invention. The power conversion apparatus 100 according to the first embodiment converts AC power supplied from a single-phase AC power source (hereinafter simply referred to as AC power source) 1 into DC power and outputs the DC power. As shown in FIG. 1, the power conversion device 100 includes a reactor 2, a bridge circuit 3, a smoothing capacitor 4, a power supply voltage detection unit 5, a power supply current detection unit 6, a bus voltage detection unit 7, and a control device 10. .

The bridge circuit 3 includes a first circuit 31 and a second circuit 32. The first circuit 31 includes a first arm 33 and a second arm 34 connected in parallel to each other. The first arm 33 includes a switching element 311 and a switching element 312 connected in series. The second arm 34 includes a switching element 313 and a switching element 314 connected in series. The second circuit 32 which is the third arm includes a switching element 321 and a switching element 322 connected in series. The second circuit 32 is connected to the first circuit 31 in parallel.

Specifically, the power conversion apparatus 100 includes a first wiring 501 and a second wiring 502 that are connected to the AC power source 1, and a reactor 2 that is disposed on the first wiring 501. The first arm 33 includes a switching element 311 that is a first switching element, a switching element 312 that is a second switching element, and a third wiring 503 including a first connection point 506. Switching element 311 and switching element 312 are connected in series by third wiring 503, and first connection point 506 is connected to reactor 2 by first wiring 501. The second arm 34 is connected in parallel to the first arm 33 and includes a switching element 313 that is a third switching element, a switching element 314 that is a fourth switching element, and a second connection point 507. 4th wiring 504 is provided. The switching element 313 and the switching element 314 are connected in series by the fourth wiring 504, and the second connection point 507 is connected to the reactor 2 by the first wiring 501.

The second circuit 32 that is the third arm is connected in parallel to the second arm 34, the switching element 321 that is the fifth switching element, the switching element 322 that is the sixth switching element, and the third The switching element 321 and the switching element 322 are connected in series by the fifth wiring 505. The third connection point 508 is connected to the AC power source 1 by the second wiring 502. The smoothing capacitor 4 that is a capacitor is connected in parallel with the second circuit 32 that is the third arm. A first connection point 506 that is a connection point between the switching element 311 and the switching element 312 and a second connection point 507 that is a connection point between the switching element 313 and the switching element 314 are connected by a first wiring 501. The Therefore, the first connection point 506 and the second connection point 507 have the same potential, that is, the potential difference is zero.

The switching elements 311 to 314, 321, and 322 are configured by MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). As an example, switching elements 311 to 314, 321, and 322 may be MOSFETs formed of a wide band gap semiconductor such as GaN (gallium nitride), SiC (silicon carbide: silicon carbide), diamond, or the like. In addition, the use of a wide band gap semiconductor has high voltage resistance and high allowable current density, so that the module can be miniaturized. Since the wide band gap semiconductor has high heat resistance, it is possible to reduce the size of the radiating fin of the radiating portion.

The control device 10 generates drive pulses for operating the switching elements of the bridge circuit 3 based on signals output from the power supply voltage detection unit 5, the power supply current detection unit 6, and the bus voltage detection unit 7, respectively. The power supply voltage detection unit 5 detects a power supply voltage Vs that is a voltage of electric power output from the AC power supply 1 and outputs an electric signal indicating the detection result to the control device 10. The power supply current detection unit 6 detects a power supply current Is that is a current of power output from the AC power supply 1, and outputs an electric signal indicating the detection result to the control device 10. The bus voltage detector 7 detects the bus voltage Vdc, which is a voltage obtained by smoothing the output voltage of the bridge circuit 3 with the smoothing capacitor 4, and outputs the detected voltage to the control device 10.

Next, the basic operation of the power conversion device 100 of the present embodiment will be described. Hereinafter, among the switching elements, the switching

elements

311, 313 and 321 which are switching elements connected to the positive side of the AC power supply 1, that is, the positive terminal of the AC power supply 1 are also referred to as upper switching elements. In addition, among the switching elements, switching

elements

312, 314, and 322 that are switching elements connected to the negative side of the AC power supply 1, that is, the negative terminal of the AC power supply 1 are also referred to as lower switching elements.

In the first arm 33 and the second arm 34 constituting the first circuit 31 in the power conversion device 100 of the present embodiment, the upper switching element and the lower switching element operate in a complementary manner. That is, when one of the upper switching element and the lower switching element is on, the other is off. Moreover, the 1st arm 33 and the 2nd arm 34 of the power converter device 100 of this Embodiment implement switching operation simultaneously. The drive signal for driving the switching element 311 of the first arm 33 and the drive signal for driving the switching element 313 are the same, and the switching element 311 and the switching element 313 are simultaneously turned on and simultaneously turned off. The drive signal for driving the switching element 312 of the first arm 33 and the drive signal for driving the switching element 314 are the same, and the switching element 312 and the switching element 314 are simultaneously turned on and simultaneously turned off. As will be described later, each switching element constituting the first arm 33 and the second arm 34 is driven by a PWM (Pulse Width Modulation) signal generated by the control device 10. The on / off operation of the switching elements 311 to 314 in accordance with the PWM signal is hereinafter also referred to as a switching operation.

The switching elements constituting the second circuit 32 that is the third arm are turned on or off by a drive signal generated by the control device 10. Basically, the power supply voltage polarity, which is the voltage polarity of the power supplied from the AC power supply 1, is turned on or off. Specifically, when the power supply voltage polarity is positive, the switching element 322 is on and the switching element 321 is off, and when the power supply voltage polarity is negative, the switching element 321 is on and switching. Element 322 is off. However, as will be described later, in this embodiment, in order to prevent a capacitor short circuit via the AC power supply 1 and the reactor 2, the absolute value of the power supply current, which is the current of the power supplied from the AC power supply 1, is set to a threshold value (hereinafter, In the following case (referred to as current threshold), both the switching element 322 and the switching element 321 are turned off.

2 to 5 are diagrams showing current paths in the power conversion device 100 of the present embodiment when the absolute value of the power supply current is larger than the current threshold value. FIG. 2 shows a state in which the power supply voltage polarity is positive, the switching element 311, the switching element 313, and the switching element 322 are on, and the other switching elements are off. In this state, current flows in the order of AC power source 1, reactor 2, switching element 311 and switching element 313, smoothing capacitor 4, switching element 322, and AC power source 1.

FIG. 3 shows a state where the power supply voltage polarity is negative, the switching element 312, the switching element 314 and the switching element 321 are on, and the other switching elements are off. In this state, current flows in the order of the AC power supply 1, the switching element 321, the smoothing capacitor 4, the switching element 312 and the switching element 314, the reactor 2, and the AC power supply 1.

FIG. 4 shows a state in which the power supply voltage polarity is positive, the switching element 312, the switching element 314 and the switching element 322 are on, and the other switching elements are off. In this state, current flows in the order of the AC power source 1, the reactor 2, the switching element 312, the switching element 314, the switching element 322, and the AC power source 1, and a power supply short-circuit path that does not pass through the smoothing capacitor 4 is formed. As described above, in this embodiment, the power supply short-circuit path can be formed not through the freewheeling diode but via the switching element 312 and the switching element 314 that are in the on state.

FIG. 5 shows a state where the power supply voltage polarity is negative, the switching element 311, the switching element 313, and the switching element 321 are on, and the other switching elements are off. In this state, current flows in the order of the AC power source 1, the switching element 321, the switching element 311, the switching element 313, the reactor 2, and the AC power source 1, and a power supply short-circuit path that does not pass through the smoothing capacitor 4 is formed. Thus, in the present embodiment, the power supply short-circuit path can be formed via the switching element 311 and the switching element 313 rather than via the free wheel diode.

The control device 10 can control the power supply current Is and the bus voltage Vdc by controlling the switching of the current paths described above.

However, for example, when the switching element 311, the switching element 313, and the switching element 322 are turned on when the power supply current is not flowing, a capacitor short circuit occurs via the AC power supply 1 and the reactor 2. As a result, current flows in a direction opposite to the original direction, which may cause problems such as power factor deterioration, increase in harmonic components, element destruction due to overcurrent, and increase in loss.

6 and 7 are diagrams showing an example of capacitor short-circuiting via the AC power supply 1 and the reactor 2. FIG. 6 shows a state where the power supply voltage polarity is positive and the power supply current is not flowing. Since the power supply voltage polarity is positive, originally, as shown in FIG. 2, the AC power source 1, the reactor 2, the switching element 311 and the switching element 313, the smoothing capacitor 4, the switching element 322, and the AC power source 1 Should flow. However, if the switching element 311, the switching element 313, and the switching element 322 are turned on when the power supply current is not flowing, the current flows in the opposite direction as shown in FIG. become.

FIG. 7 shows a state where the power supply voltage polarity is negative and the power supply current is not flowing. Since the power supply voltage polarity is negative, originally, as shown in FIG. 3, the AC power supply 1, the switching element 321, the smoothing capacitor 4, the switching element 312 and the switching element 314, the reactor 2, and the AC power supply 1 Should flow. However, if the switching element 312, the switching element 314, and the switching element 321 are turned on when the power supply current is not flowing, as shown in FIG. become.

In the present embodiment, in order to prevent the capacitor short circuit described above, when the power supply current is equal to or higher than the threshold value, the switching element 321 and the switching element 322 are allowed to be turned on, and when the power supply current is lower than the threshold value, The switching element 321 and the switching element 322 are turned off. Thereby, it is possible to prevent a capacitor short circuit through the AC power source 1 and the reactor 2, and it is possible to obtain a highly reliable power conversion device.

8 to 11 are diagrams showing examples of current paths in the power conversion device 100 of the present embodiment when the absolute value of the power supply current is less than the threshold value. FIG. 8 shows a state in which the power supply voltage polarity is positive, the switching

elements

311 and 322 are on, and the other switching elements are off. In this case, the parasitic diode of the switching element 322 functions as a free-wheeling diode. As shown in FIG. 8, the AC power supply 1, the reactor 2, the switching element 311 and the switching element 313, the smoothing capacitor 4, the free-wheeling diode of the switching element 322, and the AC A current flows in the order of the power source 1. The absolute value of the power supply current may be a value that does not cause malfunction, and the lower the value, the longer the synchronous rectification period, and the more effective the conduction loss can be reduced. When the current is small, the switching

elements

311 and 322 may be turned off. By doing so, loss due to the drive power source generated in the switching

elements

311 and 322 can be reduced.

FIG. 9 shows a state in which the power supply voltage polarity is negative, the switching

elements

312 and 314 are on, and the other switching elements are off. In this case, the parasitic diode of the switching element 321 functions as a freewheeling diode, and as shown in FIG. 9, the AC power supply 1, the freewheeling diode of the switching element 321, the smoothing capacitor 4, the switching element 312 and the switching element 314, the reactor 2, the alternating current A current flows in the order of the power source 1. The absolute value of the power supply current may be a value that does not cause malfunction, and the lower the value, the longer the synchronous rectification period, and the more effective the conduction loss can be reduced. When the current is small, the switching

elements

312 and 314 may be turned off. By doing so, it is possible to reduce the loss due to the drive power generated in the switching

elements

312 and 314.

FIG. 10 shows a state in which the power supply voltage polarity is positive, the switching

elements

312 and 314 are on, and the other switching elements are off. In this state, as shown in FIG. 10, current flows in the order of the AC power supply 1, the reactor 2, the switching element 312 and the switching element 314, the return diode of the switching element 322, and the AC power supply 1. In this case, since a short circuit current flows, the switching element 322 may be controlled to be turned on at the same time even if the absolute value of the power supply current is less than the threshold value. In that case, the conduction loss of the switching element 322 can be reduced.

FIG. 11 shows a state in which the power supply voltage polarity is negative, the switching

elements

311 and 313 are on, and the other switching elements are off. In this state, as shown in FIG. 11, the current flows in the order of the AC power supply 1, the return diode of the switching element 321, the switching element 311 and the switching element 313, the reactor 2, and the AC power supply 1. In this case, since a short-circuit current flows, the switching element 321 may be controlled to be turned on at the same time even if the absolute value of the power supply current is less than the threshold value. In that case, the conduction loss of the switching element 321 can be reduced.

Next, the control device 10 of the present embodiment will be described. FIG. 12 is a diagram illustrating a configuration example of the control device 10 according to the present embodiment. As shown in FIG. 12, the control device 10 includes a power supply current command value control unit 21, an on-duty control unit 22, a power supply voltage phase calculation unit 23, a first pulse generation unit 24, and a second pulse generation. The unit 25 is provided.

The power supply current command value control unit 21 calculates the power supply current effective value command value Is_rms ^* from the signal output from the bus voltage detection unit 7, that is, the bus voltage Vdc and the bus voltage command value Vdc ^* . Bus voltage command value Vdc ^* may be set in advance or may be input from the outside of power converter 100. The power supply current command value control unit 21 calculates the power supply current effective value command value Is_rms ^* by, for example, proportional-integral control using a difference between the bus voltage Vdc and the bus voltage command value Vdc ^* .

The on-duty control unit 22 uses the power supply current effective value command value Is_rms ^* calculated by the power supply current command value control unit 21 and a sin θ ^ s described later calculated by the power supply voltage phase calculation unit 23 to supply the instantaneous power supply current value. The command value Is ^* is calculated. Furthermore, the on-duty control unit 22 calculates the reference on-duty duty of the switching

elements

311 and 312 using the power source current instantaneous value command value Is ^* and the signal output from the power source current detecting unit 6, that is, the power source current Is. . The reference duty of the switching

elements

313 and 314 is the same as the reference on-duty duty of the switching

elements

311 and 312. The reference on-duty duty is calculated, for example, by proportional-integral control based on the difference between the power supply current instantaneous value command value Is ^* and the power supply current Is.

The power supply voltage phase calculation unit 23 uses the signal output from the power supply voltage detection unit 5, that is, the power supply voltage Vs, to calculate the power supply voltage phase estimation value θ ^ s and the sine wave value sinθ ^ s. FIG. 13 is a diagram illustrating an example of the power supply voltage Vs and the power supply voltage phase estimation value θs ^ and the sine wave value sinθs ^ calculated by the power supply voltage detection unit 5. The first stage of FIG. 13 shows the power supply voltage Vs, the second stage of FIG. 13 shows the power supply voltage phase estimation value θs ^, and the third stage of FIG. 13 shows the sine wave value sinθs ^. It is shown. For example, the power supply voltage phase calculation unit 23 linearly increases θs ^, detects the timing at which the power supply voltage Vs switches from negative polarity to positive polarity, and resets θs ^ to 0 at this timing. As a result, under ideal conditions with no control delay, no detection delay, etc., θs ^ becomes 360 °, that is, 0 ° at the timing when the power supply voltage Vs switches from negative polarity to positive polarity. The power supply voltage phase calculation unit 23 calculates sin θs ^ based on the calculated power supply voltage phase estimation value θs ^. When the reset of the power supply voltage phase estimation value θs ^ is realized by using an interrupt function or the like of a microcomputer, a zero cross detection circuit is used by using a zero cross detection circuit that detects the timing at which the power supply voltage Vs switches from negative polarity to positive polarity. Is used as an interrupt signal to reset the power supply voltage phase estimation value θs ^. Note that the method of calculating the power supply voltage phase estimation value θs ^ is not limited to the above-described example, and any method may be used.

FIG. 14 is a diagram illustrating a configuration example of the first pulse generation unit 24. The first pulse generation unit 24 includes a carrier generation unit 241, a reference PWM generation unit 242, a dead time generation unit 243, and a pulse selector unit 244.

The carrier generation unit 241 generates a carrier wave used for generating the reference PWM signal Scom. The reference PWM signal Scom is a signal that serves as a reference for the PWM signal used to drive the switching elements 311 to 314. As described above, in the present embodiment, complementary PWM control is assumed, and the reference PWM signal is used to drive one switching element of the first arm 33, and the other switching element will be described later. In addition, a PWM signal complementary to the reference PWM signal is used.

The reference PWM generation unit 242 generates a reference PWM signal Scom by comparing the magnitude relationship between the reference on-duty and the carrier wave, that is, the carrier signal. FIG. 15 is a diagram illustrating an example of the carrier wave carry and the reference PWM signal. As illustrated in FIG. 15, the carrier generation unit 241 sets the reference PWM signal Scom as a value indicating ON when duty> carry, and sets the reference PWM signal Scom as a value indicating OFF when duty ≦ carry. Thus, the reference PWM signal Scom is generated. In the case of FIG. 15, the high level indicates on and the low level indicates off. However, the high level indicates off and the reference PWM signal Scom is generated with the low level indicating on. Good.

The dead time generator 243 generates and outputs two complementary signals, the first PWM signal Sig1 and the second PWM signal Sig2, based on the reference PWM signal Scom. Specifically, the dead time generation unit 243 generates an inverted PWM signal Scom ′ that is a signal obtained by inverting the reference PWM signal Scom. Thereafter, the dead time generation unit 243 generates a first PWM signal Sig1 and a second PWM signal Sig2 by providing a dead time for the reference PWM signal Scom and the inverted PWM signal Scom '. In other words, the dead time generation unit 243 sets the first PWM signal Sig1 and the second PWM so that both the first PWM signal Sig1 and the second PWM signal Sig2 have values indicating OFF during the dead time period. A signal Sig2 is generated. For example, the dead time generation unit 243 makes the first PWM signal Sig1 the same as the reference PWM signal Scom. In addition, the dead time generation unit 243 generates the second PWM signal Sig2 by changing the inverted PWM signal Scom 'from a value indicating ON to a value indicating OFF during the dead time.

When the inverted PWM signal Scom ′ is generated by inverting the reference PWM signal Scom and the two switching elements constituting the same arm are driven by the reference PWM signal Scom and the inverted PWM signal Scom ′, respectively, ideally the same There is no period during which the two switching elements constituting the arm are turned on simultaneously. However, in general, there is a delay in the transition from the on state to the off state and from the off state to the on state. Therefore, due to this delay, two switching elements constituting the same arm may be turned on simultaneously, and the two switching elements constituting the same arm may be short-circuited. As described above, the dead time (td) is a period provided so that the two switching elements constituting the same arm are not turned on at the same time even if there is a delay in the state transition. During the dead time, the two PWM signals that drive the two switching elements constituting the same arm are both set to values indicating OFF.

FIG. 16 is a diagram illustrating an example of the reference PWM signal Scom, the inverted PWM signal Scom ′, the first PWM signal Sig1, and the second PWM signal Sig2. The first stage of FIG. 16 shows the reference PWM signal Scom, the second stage of FIG. 16 shows the inverted PWM signal Scom ′, and the third stage of FIG. 16 shows the first PWM signal Sig1. The second PWM signal Sig2 is shown in the fourth stage of FIG. In the example shown in FIG. 16, during the dead time (td) in which the inverted PWM signal Scom 'has a value indicating ON, the second PWM signal Sig2 has a value indicating OFF. Note that the above-described dead time generation method is an example, and the dead time generation method is not limited to the above-described example, and any method may be used.

The pulse selector unit 244 selects either the switching element 311 or the switching element 312 to transmit the first PWM signal Sig1 and the second PWM signal Sig2 output from the dead time generation unit 243. FIG. 17 is a flowchart illustrating an example of a selection processing procedure in the pulse selector unit 244. First, the pulse selector 244 determines whether the polarity of the power supply voltage Vs is positive, that is, whether Vs> 0 (step S1). When the polarity of the power supply voltage Vs is positive (step S1, Yes), the pulse selector unit 244 transmits the first PWM signal Sig1 as pulse_312 to the switching element 312 and the second PWM signal Sig2 as pulse_311. (Step S2). This is because when the power supply voltage Vs is positive, the path shown in FIG. 4 and the path shown in FIG. 2 are switched by turning off or on the switching element 312, that is, the bus voltage Vdc is switched by the switching operation of the switching element 312. This is because the power supply current Is is controlled.

When the polarity of the power supply voltage Vs is negative (No in step S1), the pulse selector unit 244 transmits the first PWM signal Sig1 to the switching element 311 as pulse_311 and the switching element 312 as the second PWM signal Sig2 as pulse_312. (Step S3). As described in FIG. 4, when the power supply voltage Vs is negative, the path shown in FIG. 5 and the path shown in FIG. 3 are switched by turning off or on of the switching element 311, that is, the switching element 311. This is because the bus voltage Vdc and the power supply current Is are controlled by the switching operation. The pulse selector unit 244 repeats the above operation every time Vs is input.

As described above, the first pulse generation unit 24 generates pulse_311 that is a drive signal drive signal for the switching element 311 and pulse_312 that is a drive signal for the switching element 312. As described above, the switching element 313 performs the switching operation at the same time as the switching element 311 and the switching element 314 performs the switching operation at the same time. Therefore, the pulse selector unit 244 outputs the same signal as the pulse_311 as the pulse_313 that is the drive signal of the switching element 313, and outputs the same signal as the pulse_312 as the pulse_314 that is the drive signal of the switching element 314. Therefore, there is no problem even if only pulse_311 and pulse_312 are generated and output as actual control signals and input as drive signals to the respective elements. In that case, it is possible to suppress processing related to pulse_313 and pulse_314.

As described above, since the switching element 311 and the switching element 312 are controlled in a complementary relationship, the process of generating the inverted PWM signal Scom ′ from the reference PWM signal Scom can be realized using a simple signal inversion process. it can. In addition, it is possible to easily realize the output relationship of the drive pulses in one carrier and to prevent the upper and lower arms from being short-circuited regardless of the power source polarity. Stable control can be realized with simple processing.

Further, since synchronous rectification control by switching elements 311 to 314 of two arms connected in series can be realized, as shown in FIG. 18, in a region where switching element loss is lower than parasitic diode loss, that is, current is small. Loss can be reduced, and a highly efficient system can be obtained. FIG. 18 is a schematic diagram showing the relationship between current and loss in the switching element. Further, as shown in FIG. 18, in the region where the switching element loss is higher than the parasitic diode loss, that is, the current is high, it is possible to suppress the increase in loss due to the synchronous rectification control by stopping the complementary operation. That is, by performing control so that the synchronous rectification control is performed according to the power supply current Is, a highly efficient system can be obtained in the entire load region.

Here, the control parameter used for the calculation in the power supply current command value control unit 21 and the on-duty control unit 22 has an optimum value according to the operation state of the circuit. The operation state of the circuit is represented by at least one value among the power supply voltage Vs, the power supply current Is, and the bus voltage Vdc. For example, it is desirable that the proportional control gain in the on-duty control unit 22 changes in inverse proportion to the bus voltage. Therefore, the power supply current command value control unit 21 and the on-duty control unit 22 have at least one value among the power supply voltage Vs, the power supply current Is, and the bus voltage Vdc for realizing such a desired circuit operation. A calculation formula or a table for calculating the corresponding control parameter may be held, and the control parameter may be adjusted according to the operation state of the circuit. Thereby, controllability can be improved.

Further, in the above-described example, proportional-integral control is given as the calculation method in the power supply current command value control unit 21 and the on-duty control unit 22, but the present invention is not limited by these control calculation methods, Other calculation methods may be used such as adding a term for proportional-integral-derivative control. Further, the calculation method in the power supply current command value control unit 21 and the on-duty control unit 22 may not be the same method.

Returning to the description of FIG. 12, the second pulse generator 25 is based on the signal output from the power supply voltage detector 5, that is, the power supply voltage Vs and the signal output from the power supply current detector 6, that is, the power supply current Is. Pulse_321 that is a drive signal for the switching element 321 and pulse_322 that is a drive signal for the switching element 322 are generated and output, respectively.

FIG. 19 is a flowchart illustrating an example of a processing procedure in the second pulse generation unit 25. As a basic operation, the second pulse generator 25 controls the on / off state of the switching element 321 and the switching element 322 according to the polarity of the power supply voltage. As shown in FIG. 19, the second pulse generation unit 25 determines whether the polarity of the power supply voltage Vs is positive, that is, whether Vs> 0 (step S11). When the polarity of the power supply voltage Vs is positive (step S11, Yes), the second pulse generation unit 25 generates and outputs pulse_321 and pulse_322 so that the switching element 321 is turned off and the switching element 322 is turned on. (Step S12). When the polarity of the power supply voltage Vs is negative (No in step S11), the second pulse generation unit 25 generates and outputs pulse_321 and pulse_322 so that the switching element 321 is turned on and the switching element 322 is turned off. (Step S13). Thereby, synchronous rectification control is possible and a highly efficient system can be realized as described above.

However, as described above, when the switching element 311 and the switching element 322 are turned on while the power supply current is not flowing, a capacitor short circuit occurs via the AC power supply 1 and the reactor 2. For this reason, in the present embodiment, the ON or OFF state of the switching element 321 and the switching element 322 is further controlled based on the power supply current Is. FIG. 20 is a flowchart illustrating an example of a switching element control procedure based on the power supply current in the second pulse generation unit 25. As shown in FIG. 20, it is determined whether or not the power supply current is larger than the current threshold value β (step S21). When the power supply current is larger than the current threshold β (step S21, Yes), the second pulse generator 25 permits the switching element 321 and the switching element 322 to be turned on (step S22). When the switching element 321 and the switching element 322 are turned on, the on and off states are controlled by the polarity of the power supply voltage shown in FIG.

When the power supply current is equal to or less than the current threshold β (No in step S21), the second pulse generation unit 25 does not allow the switching element 321 and the switching element 322 to be turned on (step S23). When the switching element 321 and the switching element 322 are not turned on, the switching element 321 and the switching element 322 are controlled to be turned off regardless of the polarity of the power supply voltage shown in FIG.

With the above control, the switching element 321 and the switching element 322 are turned on when a current greater than or equal to the current threshold is flowing in the forward direction with respect to the freewheeling diode of the switching element. Thereby, it is possible to prevent a capacitor short circuit through the AC power supply 1 and the reactor 2. The second pulse generation unit 25 controls the switching element 321 and the switching element 322 using the polarity of the power supply current, that is, the direction in which the current flows, without performing the on / off control based on the polarity of the power supply voltage. Also good.

Further, instead of the processing shown in FIG. 20, it may be determined whether to allow the switching element 321 and the switching element 322 to be turned on based on the state of the switching control. Since no current flows through the switching element when switching is not performed, the timing at which such a state occurs is predicted so that the switching element 321 and the switching element 322 are not allowed to be turned on. In this case, the synchronous rectification effect may not be obtained in passive full-wave rectification (in a state where no short-circuit path is used), but it is possible to simply construct control without depending on detection of current or voltage.

Further, instead of the processing shown in FIG. 20, it may be determined whether to allow switching element 321 and switching element 322 to be turned on based on the difference between the power supply voltage and the bus voltage. For example, when power supply voltage−bus voltage> 0, switching element 321 and switching element 322 are turned on, and when power supply voltage−bus voltage ≦ 0, switching element 321 and switching element 322 are not allowed to be turned on. Like that.

In this embodiment, control is performed so that the on-timing phase of the switching element 313 is synchronized with the on-timing of the switching element 311 in the switching cycle of the switching elements 311 to 314. As a result, the current flowing through each switching element is halved when only the switching element 311 and the switching element 312 are used, and the loss generated in each switching element 311 to 314 is reduced. Thereby, it is possible to suppress the bias of element loss, that is, the bias of heat generation in the bridge circuit constituted by the switching elements. In this embodiment, the synchronization control is performed using two arms connected in parallel. However, the synchronization control may be performed using three arms connected in parallel. For example, when the power conversion device according to the present embodiment is configured by connecting n arms (n is an integer of 2 or more) in parallel, the current of each switching element is a single arm. Of 1 / n. For this reason, the bias of loss can be suppressed by selecting n, which is the number of parallel connections of each switching element, based on the switching frequency, element characteristics, and characteristics of the gate drive circuit. Note that the bias of the element loss does not need to be completely suppressed, and the number of parallel connections of the switching elements may be appropriately selected based on the driving conditions and the like.

In the example described above, the second pulse generation unit 25 selects the switching element to be turned on from the switching element 321 and the switching element 322 based on the power supply voltage polarity, and prevents a capacitor short circuit based on the power supply current. Therefore, the switching element 321 and the switching element 322 were controlled. However, the present invention is not limited to this example, and the first pulse generator 24 controls whether or not to allow the switching elements 311 to 314 to be turned on to prevent a capacitor short circuit based on the power supply current, The pulse generating unit 25 may perform switching according to the power supply polarity without performing control for preventing the capacitor short circuit for the switching element 321 and the switching element 322. That is, for example, when the power supply voltage is positive, the first pulse generation unit 24 does not allow the

switching elements

311 and 313 to be turned on when the power supply current is equal to or smaller than the current threshold β, and the power supply current is larger than the current threshold β. In this case, the switching

elements

311 and 313 are allowed to be turned on. When the power supply voltage is negative, the first pulse generator 24 does not allow the

switching elements

312 and 314 to be turned on when the power supply current is less than or equal to the current threshold value β, and when the power supply current is greater than the current threshold value β, the switching

element

312 and 314 are allowed to be turned on.

In the above-described example, switching in each arm for each power cycle is realized using a method for generating a complementary PWM signal, but the method for generating a PWM signal is not limited to this example. For example, the control device 10 may generate a drive signal pulse_312 for the switching element 312 when the power supply voltage is positive, and may generate a drive signal pulse_311 for the switching element 311 when the power supply voltage is negative (described later). (See FIG. 22). In this case, the control device 10 may generate a PWM signal for driving the switching elements 311 to 314 from the relationship among the power supply current Is, the power supply voltage Vs, and the bus voltage Vdc. By doing so, the switching elements 311 to 314 can be turned off before the timing when the power supply current becomes zero. In this case, even if the control of the switching

elements

321 and 322 is controlled based on the power supply voltage polarity. Capacitor short-circuiting via an AC power supply can be prevented.

FIG. 21 is a diagram illustrating an example of each drive signal for one cycle of the power supply voltage in the power conversion apparatus 100 of the present embodiment. FIG. 21 shows an example of each drive signal when a PWM signal is generated by the processing used in FIG. The first stage of FIG. 21 shows the power supply voltage Vs, the second stage of FIG. 21 shows the primary current Is that is the power supply current, and the third stage of FIG. The carrier signal is shown, and the driving signals for the switching

elements

311, 312, 321, and 322 are shown in the fourth to seventh stages in FIG. 21, respectively. In FIG. 21, the timer set value α is shown in a staircase pattern, but the timer set value is a period in which the vertical axis of one stage is the same value. As shown in FIG. 21, the pulse width is determined for each timer set value α by comparison with the carrier signal. In FIG. 21, the dead time is omitted. As shown in FIG. 21, the switching element 321 and the switching element 322 are turned on or off according to the polarity of the power supply voltage, and are turned off when the absolute value of the power supply current is less than or equal to the current threshold value. . In addition, by providing a filter or hysteresis in the current detection circuit or in the microcomputer after detection, excessive ON / OFF switching of switching near the threshold can be suppressed. It is possible to suppress the increase.

FIG. 22 is a diagram illustrating another example of each drive signal for one cycle of the power supply voltage in the power conversion apparatus 100 of the present embodiment. FIG. 22 shows an example of each drive signal when the drive signal pulse_312 of the switching element 312 is generated when the power supply voltage is positive, and when the drive signal pulse_311 of the switching element 311 is generated when the power supply voltage is negative. ing.

FIG. 21 shows an example in which the switching element is controlled using the carrier signal. However, the present invention is also applicable to the case where simple switching control is performed in which switching is performed once to a plurality of times during a half cycle of the power supply cycle. The operation of the embodiment can be applied. FIG. 23 is a diagram illustrating an example of each drive signal when the simple switching control is performed. The first stage of FIG. 23 shows the power supply voltage Vs, the second stage of FIG. 23 shows the primary current Is as the power supply current, and the third stage of FIG. 23 shows the primary current absolute value | Is | (bus current) is shown, the power supply polarity signal is shown in the fourth stage of FIG. 23, the power supply current signal is shown in the fifth stage of FIG. 23, and the sixth to ninth stages of FIG. The drive signals of the switching

elements

311, 312, 321, 322 are shown in FIG. FIG. 23 shows an example in which the power supply voltage itself is not measured, the power supply polarity signal is generated by detecting the zero cross of the power supply voltage, and the power supply current signal is generated by detecting the zero cross of the power supply current. ing. Also in this case, when the power supply current is equal to or less than the current threshold, the switching element 311 and the switching element 321 are not turned on at the same time, and the switching element 312 and the switching element 322 are not turned on at the same time. Can be prevented.

Further, even in a passive state where no switching operation is performed, a short circuit of the capacitor can be prevented by preventing the switching element 321 and the switching element 322 from being turned on when the power supply current is equal to or lower than the current threshold. FIG. 24 is a diagram illustrating an example of each drive signal in a passive state. The first stage of FIG. 24 shows the power supply voltage Vs, the second stage of FIG. 24 shows the primary current Is as the power supply current, and the third stage of FIG. 24 shows the primary current absolute value | Is | (bus current) is shown, the power supply polarity signal is shown in the fourth stage of FIG. 24, the power supply current signal is shown in the fifth stage of FIG. 24, and the sixth to ninth stages of FIG. The drive signals of the switching

elements

311, 312, 321, 322 are shown in FIG. Also in this case, when the power supply current is equal to or less than the current threshold, the switching element 311 and the switching element 321 are not turned on at the same time, and the switching element 312 and the switching element 322 are not turned on at the same time. Can be prevented.

In this embodiment, the control is performed by the method of detecting the power supply current. However, there is no problem even if the bus current between the circuit 3 and the capacitor 4 is detected. At this time, since the current in the short-circuit path cannot be detected, the synchronous rectification control period may be limited (shortened) when the synchronous rectification control is performed with the current threshold. Therefore, when performing synchronous rectification control by detecting the bus current, as described above, the switching element 321 or the switching element 322 depending on the polarity even if the absolute value of the power supply current is less than the threshold value during the short-circuit current operation. It may be controlled to turn on. In that case, since a synchronous rectification operation can be performed over a wide period, the conduction loss of the switching element 321 or the switching element 322 can be reduced.

Note that this embodiment is particularly suitable when a general-purpose IPM (intelligent power module) is used. In general-purpose IPM, a switching element having substantially the same characteristics is mounted on an internal switching element. For this reason, when a switching element that performs a switching operation by PWM and a switching element that performs a switching element according to the polarity of the power supply voltage coexist, the switching frequency of the switching element that performs a switching operation by PWM depends on the polarity of the power supply voltage. Higher than the switching frequency of the switching element. For this reason, the element loss of the switching element that performs the switching operation by PWM becomes larger than the loss of the switching element corresponding to the polarity of the power supply voltage. However, in this embodiment, since a plurality of switching elements that perform the switching operation by PWM are connected in parallel, the current flowing through the switching elements that perform the switching operation by PWM can be suppressed, and the loss between each element can be reduced. The bias can be suppressed. In particular, the yield of large chips such as SiC is poor, and in the case of an element that can be reduced in cost by using a small chip, it is possible to adopt a small chip compared to the case of four elements. Therefore, it is preferable because it can be realized at a relatively low cost.

Also, by using the IPM, the drive circuit of the switching element can be taken into the IPM, and the board area can be reduced. Moreover, cost can be suppressed by using a general general-purpose IPM.

In addition, as another example in which a plurality of arms are connected in parallel to perform a switching operation, there is an interleave method in which switching elements connected in parallel are controlled by shifting the phase by 180 °. In the present embodiment, a synchronous control system that switches switching elements connected in parallel at the same time is adopted instead of the interleave system. In the interleave method, the reactor can be downsized and the reactor loss can be reduced. However, if the reactor is often used in a passive state such as an air conditioner, it is not necessary to reduce the size of the reactor, and the configuration and operation of the present embodiment are more effective in suppressing harmonics and power source power factor. It is effective in terms of

In the present embodiment, one reactor 2 is connected between the AC power source 1 and the first arm 33. However, the reactor is also inserted between the AC power source 1 and the second arm 34. There is no problem. In this case, the capacity per reactor can be reduced.

In the present embodiment, the power supply voltage is detected. However, even if the method detects only the zero-cross information of the power supply voltage, it is only necessary to know the polarity of the power supply voltage, so that the operation described above can be performed. In that case, there is no problem even if the control is performed such that the off operation is performed for a certain period based on the estimated value of the power supply voltage phase in order to suppress erroneous polarity determination near the zero cross.

In the present embodiment, the switching element drive permission determination is performed by determining the threshold of the power supply current, but switching is performed by the power supply voltage, the input voltage of the first circuit 31 and the bus voltage, or the voltage across the switching element. There is no problem even if it is estimated and controlled that a current flows through the return diode of the element. Note that when estimating with the power supply voltage or the input voltage of the first circuit 31 and the bus voltage, there are many factors in the determination, so it is necessary to pay attention to the estimation error. When determining with the voltage across the switching element, A detection circuit is required for each switching element to be determined.

Here, the hardware configuration of the control device 10 of the present embodiment will be described. The control device 10 is realized by a processing circuit. This processing circuit may be a processing circuit that is dedicated hardware, or may be a control circuit including a processor. Further, it may be constituted by a plurality of processing circuits. In the case of dedicated hardware, the processing circuit is, for example, a single circuit, a composite circuit, a programmed processor, a processor programmed in parallel, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or these Is a combination.

When the processing circuit for realizing the control device 10 is realized by a control circuit including a processor, this control circuit is, for example, a control circuit 200 having a configuration shown in FIG. FIG. 25 is a diagram illustrating a configuration example of the control circuit 200 of the present embodiment. The control circuit 200 includes a processor 201 and a memory 202. The processor is a CPU (Central Processing Unit, central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, DSP (Digital Signal Processor)) or the like. The memory corresponds to, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, or a magnetic disk.

When the processing circuit that implements the control device 10 is the control circuit 200 including a processor, the processor 201 reads out and executes a program describing the processing of the control device 10 stored in the memory 202. The memory 202 is also used as a temporary memory in each process executed by the processor 201.

As described above, in the present embodiment, in a power conversion device including an arm that performs switching for controlling the power supply current and an arm that corresponds to the polarity of the power supply voltage, switching for controlling the power supply current is performed. The arms were connected in parallel. Thereby, the bias of element loss can be suppressed.

Embodiment 2. FIG.
FIG. 26 is a diagram illustrating a configuration example of the driving apparatus according to the second embodiment. The driving device 101 according to the second embodiment is a motor driving device and drives a motor 42 that is a load. The drive device 101 according to the second embodiment includes the power conversion device 100 described in the first embodiment, the inverter 41, the motor current detection unit 44, and the inverter control unit 43. The inverter 41 drives the motor 42 by converting the DC power supplied from the power converter 100 into AC power and applying it to the motor 42. Hereinafter, an example in which the load driven by the driving device is the motor 42 will be described. The motor driven by the inverter 41 is not limited to the load.

The inverter 41 may have any configuration. For example, a switching element including an IGBT (Insulated Gate Bipolar Transistor) has a three-phase bridge configuration or a two-phase bridge configuration. A wide band gap element may be used as the switching element.

The motor current detector 44 detects the current flowing through the motor 42. The inverter control unit 43 uses the current detected by the motor current detection unit 44 to generate a PWM signal for driving the switching element in the inverter 41 so that the motor 42 rotates at a desired rotational speed. Applied to the inverter 41.

The inverter control unit 43 is realized by a processing circuit similarly to the control device 10. Further, the control device 10 and the inverter control unit 43 may be realized by an integrated processing circuit.

When the power conversion device 100 described in the first embodiment is used in the drive device 101 that drives the motor 42 as shown in FIG. 26, the required bus voltage Vds varies depending on the operating state of the motor 42. There is a special feature.

Generally, the higher the rotation speed of the motor 42, the higher the output voltage from the inverter 41 needs to be. The upper limit of the output voltage from the inverter 41 is limited by the input voltage to the inverter 41, that is, the bus voltage Vds that is the output of the power converter 100. A region where the output voltage from the inverter 41 saturates beyond the upper limit limited by the bus voltage Vds is called an overmodulation region.

In such a driving device 101, it is not necessary to boost the bus voltage Vds in a range where the motor 42 is in a low rotation speed, that is, in a range where the motor 42 does not reach the overmodulation region. On the other hand, when the motor 42 is at a high speed, the overmodulation region can be set to a higher speed side by boosting the bus voltage Vds. Thereby, the operation range of the motor 42 can be expanded to the high rotation side.

Further, if it is not necessary to expand the operating range of the motor 42, the number of windings of the stator of the motor 42 can be increased accordingly. At this time, in the low rotation speed region, the current is reduced as the motor voltage increases, and loss reduction in the inverter 41 is expected. In order to obtain the effects of both expanding the operating range of the motor 42 and improving the loss in the low rotation speed region, the degree of increase in the number of turns of the motor 42 may be appropriately designed.

The example in which the power conversion apparatus 100 according to the first embodiment configures the drive apparatus 101 has been described above. By using the power conversion device 100 of the first embodiment, it is possible to realize the drive device 101 that suppresses the bias of element loss.

Embodiment 3 FIG.
FIG. 27 is a diagram illustrating a configuration example of an air conditioner according to Embodiment 3 of the present invention. The air conditioner of the present embodiment includes the motor 42 and the drive device (electric motor drive device) 101 described in the second embodiment. In the air conditioner of the present embodiment, a compressor 81 incorporating the motor 42 of the second embodiment, a four-way valve 82, an outdoor heat exchanger 83, an expansion valve 84, and an indoor heat exchanger 85 are connected via a refrigerant pipe 86. It has a refrigeration cycle attached, that is, a refrigeration cycle apparatus, and constitutes a separate air conditioner. The motor 42 is controlled by the driving device 101.

A compressor 81 for compressing refrigerant and a motor 42 for operating the compressor 81 are provided inside the compressor 81, and the refrigerant circulates between the outdoor heat exchanger 83 and the indoor heat exchanger 85 from the compressor 81 for air conditioning and the like. The refrigeration cycle to perform is comprised. In addition, the structure shown in FIG. 27 is applicable not only to an air conditioner but also to equipment including a refrigeration cycle such as a refrigerator and a freezer.

Further, in the above-described embodiment, the example in which the motor 42 is used as the motor of the compressor and the motor 42 is driven by the driving device 101 has been described. However, the motor 42 is used as the motor of the blower in the air conditioner. You may drive with the drive device 101. FIG. Further, the motor 42 may be used as the motor for both the blower and the driving device 101, and the motor 42 may be driven by the driving device 101.

In addition, air conditioners are often operated under intermediate conditions that are less than half of the rated output, that is, low output conditions throughout the year, and the contribution to the annual power consumption (APF (Annual Performance Factor)) of the intermediate conditions is high. In an air conditioner, the number of rotations of the motor is low, and the bus voltage necessary for driving the motor tends to be low. For this reason, it is effective from the aspect of system efficiency that the power conversion device used in the air conditioner is operated passively, and the loss can be reduced in a wide range of operation modes from passive to high-frequency switching. The power conversion device 100 is useful. As described above, in the interleave method, the reactor can be miniaturized, but in an air conditioner, there are many operations under intermediate conditions, so there is no need for miniaturization of the reactor. The configuration and operation are more effective in terms of harmonic suppression and power factor.

The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

1 single-phase AC power supply, 2 reactors, 3 bridge circuit, 4 smoothing capacitor, 5 power supply voltage detection unit, 6 power supply current detection unit, 7 bus voltage detection unit, 10 control device, 21 power supply current command value control unit, 22 on-duty Control unit, 23 power supply voltage phase calculation unit, 24 first pulse generation unit, 25 second pulse generation unit, 41 inverter, 42 motor, 43 inverter control unit, 44 motor current detection unit, 81 compressor, 82 four-way valve , 83 outdoor heat exchanger, 84 expansion valve, 85 indoor heat exchanger, 86 refrigerant piping, 87 compression mechanism, 100 power conversion device, 101 drive device, 241 carrier generation unit, 242 reference PWM generation unit, 243 dead time generation unit 244 Pulse selector part.

Claims

A power conversion device that converts AC power supplied from an AC power source into DC power,
A first wiring and a second wiring each connected to the AC power source;
A reactor disposed on the first wiring;
A first switching element, a second switching element, and a third wiring having a first connection point, wherein the first switching element and the second switching element are connected in series by the third wiring. A first arm connected to the reactor by the first wiring; and
A third switching element; a fourth switching element; and a fourth wiring having a second connection point. The fourth switching element and the fourth switching element are connected in parallel to the first arm. Are connected in series by the fourth wiring, and the second connection point is a second arm connected to the reactor by the first wiring;
A fifth switching element; a sixth switching element; and a fifth wiring having a third connection point. The fifth switching element and the sixth switching element are connected in parallel to the second arm. Switching elements are connected in series by the fifth wiring, and the third connection point is a third arm connected to the AC power supply by the second wiring;
A capacitor connected in parallel with the third arm;
A power conversion device comprising:
The power conversion device according to claim 1, wherein a switching frequency of the first arm and the second arm is higher than a switching frequency of the third arm.
The power conversion device according to claim 1 or 2, wherein the first arm, the second arm, and the third arm are configured by an intelligent power module.
It has a current detector that detects the power supply current,
4. The power conversion device according to claim 1, wherein whether to turn on the fifth switching element and the sixth switching element is determined according to the power supply current. 5.
When the power supply current is less than or equal to a threshold, the fifth switching element and the sixth switching element are not allowed to be turned on, and when the power supply current is greater than the threshold, the fifth switching element and the fifth switching element The power conversion device according to claim 4, wherein the switching element is allowed to be turned on.
The drive signal for the first switching element and the drive signal for the third switching element are the same, and the drive signal for the third switching element and the drive signal for the fourth switching element are the same. Item 6. The power conversion device according to any one of Items 1 to 5.
A motor control device for driving a motor,
The power conversion device according to any one of claims 1 to 6,
An inverter that converts DC power output from the power converter into AC power and applies the AC power to the motor;
A motor drive device comprising:
A motor,
The motor driving device according to claim 7 for driving the motor;
Air conditioner equipped with.
The air conditioner according to claim 8, further comprising a blower including the motor.
The air conditioner according to claim 8, further comprising a compressor including the motor.