JP2013135525A - Inverter driver, and air conditioner, refrigerator, and chiller with inverter driver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inverter driver capable of reducing recovery loss while suppressing increase in cost, and to provide an air conditioner, a refrigerator, and a chiller with the inverter driver.SOLUTION: A half-bridge circuit is configured by connecting the primary winding of a transformer 8 between the joints of upper and lower switching elements 11 and 13 for driving transformer connected in series in the voltage application direction, and the neutrals of upper and lower capacitors 15 and 16 connected in series in the voltage application direction. A commutation circuit 62 connected in parallel with reflux diodes 5 and 7, connected in reverse parallel with switching elements 4 and 6 for conversion, is provided for each phase by connecting auxiliary diodes 9 and 10 having excellent high speed and reverse recovery characteristics in series with the secondary windings of the transformer 8 having polarities different from each other, and the neutrals of the upper and lower capacitors 15 and 16 are interconnected between respective phases.

Description

  The present invention relates to an inverter drive device and a refrigeration air conditioner, a refrigerator, and a refrigerator equipped with the inverter drive device.

  Power devices such as IGBTs and MOSFETs are used in a variety of fields from consumer equipment to industrial equipment. Various device improvements and improvements are made from the standpoints of higher device breakdown voltage, higher switching speed, higher efficiency, and lower noise. Development has been underway. Typical examples are SiC (silicon carbide), GaN (gallium nitride), SJ (Super Junction) MOSFETs, and the like.

  SJ-structured MOSFETs have the advantage of low on-resistance and high breakdown voltage due to their element structure, but have a characteristic that reverse recovery time is slow due to parasitic diodes (hereinafter referred to as “freewheeling diodes”) associated with the elements. Have.

  When such a MOSFET having a long reverse recovery time is applied to an inverter as a switching element, for example, the switching element on the upper side (or lower side) of the arm is turned off and the switching element on the lower side (or upper side) of the arm is turned on. There is a problem that an equivalent short-circuit current flows in the loop path with the main circuit side, leading to loss deterioration (hereinafter, this loss is referred to as “recovery loss”).

  In addition, when a relatively high voltage is applied to the switching element, even when an IGBT or the like is used as the switching element, the increase in recovery loss becomes significant due to the characteristics of the return diode.

  Conventionally, as a technique for reducing the recovery loss, for example, a transformer and a transformer drive circuit are used to supply current to the primary winding of the transformer while controlling from the transformer drive circuit. A technique is disclosed in which a current generated during reverse recovery is suppressed by flowing a current from a winding to a switching element for conversion, which is a MOSFET having a super junction structure, to the reflux means side, thereby reducing recovery loss ( For example, Patent Document 1).

JP 2011-036079 A

  The transformer driving device in the above prior art operates with power supplied from a voltage source different from the power source of the inverter device, and the upper and lower switching units connected in series along the voltage application direction of the voltage source. The primary winding of the transformer is connected between the connection point of the element and the neutral point of each of the upper and lower capacitors connected in series along the voltage application direction of the voltage source. In the above prior art, this transformer driving device is provided for each phase, and a considerable amount of ripple current is generated in consideration of the excitation current required for driving the primary winding of the transformer. For this reason, each of the upper and lower capacitors constituting the transformer drive device has a large capacitance value and ripple resistance so that it can withstand the ripple current due to switching of the upper and lower switching elements for each phase. There is a problem that the cost is high.

  The present invention has been made in view of the above, and an inverter drive device capable of reducing recovery loss while suppressing an increase in cost, and a refrigeration air conditioner, a refrigerator, and a refrigeration device including the inverter drive device The purpose is to provide a machine.

  In order to solve the above-described problems and achieve the object, an inverter drive device according to the present invention includes an upper conversion switching element and a lower conversion switching element connected in series along a voltage application direction of a first DC voltage source. Each of which has a plurality of arms each having a free-wheeling diode connected in antiparallel, and a commutation circuit that operates by a second DC voltage source and commutates a forward voltage flowing through each of the free-wheeling diodes. The commutation circuit includes a transformer having a primary side winding and two secondary side windings having different polarities, and is connected in series to each of the secondary side windings. An auxiliary diode connected in parallel to each of the freewheeling diodes, and upper and lower transformer driving switching elements connected in series along the voltage application direction of the second DC voltage source; Each of the upper and lower capacitors connected in series along the voltage application direction of the second DC voltage source, and the neutral point of each of the upper and lower capacitors is the primary winding. And connected to the connection point of each of the upper and lower transformer driving switching elements and interconnected with each of the commutation circuits provided for each of the plurality of arms. Features.

  According to the present invention, there is an effect that recovery loss can be reduced while suppressing an increase in cost.

FIG. 1 is a diagram of a configuration example of the inverter drive device according to the first embodiment. FIG. 2 is a diagram showing a configuration for one phase of the inverter driving apparatus shown in FIG. FIG. 3 is a timing chart of the U-phase PWM signal, the transformer drive signal, and the primary winding voltage of the transformer of the inverter drive apparatus according to the first embodiment. FIG. 4 is a diagram illustrating a commutation operation of a forward current flowing through the free wheeling diode in the inverter driving device according to the first embodiment. FIG. 5 is a diagram showing the drain-source current Ids of the conversion switching element when the forward current flowing through the freewheeling diode is not commutated. FIG. 6 is a diagram showing the drain-source current Ids of the conversion switching element when the forward current flowing through the freewheeling diode is commutated. FIG. 7 is a diagram illustrating an example in which the intermediate tap of the secondary side winding is shared. FIG. 8 is a diagram illustrating a configuration example of the inverter driving device when the neutral points of the upper capacitor and the lower capacitor of each commutation circuit are not interconnected between the phases. FIG. 9 is a diagram of a configuration example of the refrigeration air conditioning apparatus according to the second embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an inverter driving device according to an embodiment of the present invention, a refrigeration air conditioner, a refrigerator, and a refrigerator provided with the same will be described with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

Embodiment 1 FIG.
FIG. 1 is a diagram of a configuration example of the inverter drive device according to the first embodiment. As shown in FIG. 1, the inverter drive apparatus according to the first embodiment includes an inverter 2 that is operated by a first DC voltage source 80 and drives an electric motor 1 that is a load. The inverter 2 includes an upper conversion switching element 4 and a lower side connected in series along the voltage application direction of the first DC voltage source 80 for each of the U phase, V phase, and W phase of the electric motor 1. Conversion diode 6, a free-wheeling diode 5 connected antiparallel to each upper conversion switching element 4, and a free-wheeling diode 7 connected antiparallel to the lower conversion switching element 6. Each arm is provided. In the present embodiment, electric motor 1 is a three-phase AC electric motor, and inverter 2 is configured to have an arm for each phase.

  In addition, the inverter drive device includes a commutation circuit 62 that operates from the second DC voltage source 17 for each phase and commutates forward currents flowing through the free-wheeling diodes 5 and 7.

  Each commutation circuit 62 includes a transformer 8 having a primary side winding and two secondary side windings of different polarities, and is connected in series to each secondary side winding to each of the free-wheeling diodes 5 and 7. The auxiliary diodes 9 and 10 connected in parallel and the transformer drive circuit 61 are provided.

  Each transformer driving circuit 61 includes an upper transformer driving switching element 11 and a lower transformer driving switching element 13 connected in series along the voltage application direction of the second DC voltage source 17, and an upper side. The freewheeling diode 12 connected in reverse parallel to the transformer driving switching element 11, the freewheeling diode 14 connected in reverse parallel to the lower transformer driving switching element 13, and the second DC voltage source 17 An upper capacitor 15 and a lower capacitor 16 connected in series along the voltage application direction are provided. In the present embodiment, the upper capacitor 15 and the lower capacitor 16 have the same capacitance value.

  Each commutation circuit 62 is connected between the connection point of the upper transformer driving switching element 11 and the lower transformer driving switching element 13 and the neutral point of the upper capacitor 15 and the lower capacitor 16. The primary side winding of the transformer 8 is connected to the half bridge circuit.

  Further, the neutral points of the upper capacitor 15 and the lower capacitor 16 of each commutation circuit 62 are interconnected between the respective phases, and a recovery current commutation unit 60 is configured.

  Further, the inverter driving device includes a current detection unit 3 including current detection elements 3a and 3b and current detection circuits 31a and 31b, a voltage detection unit 20 including a voltage detection circuit 21, an inverter 2 and a recovery current commutation unit 60. And a control unit 70 that drives and controls each switching element. In addition, the control unit 70 includes a control circuit 71 configured by, for example, a CPU (Central Processing Unit), an A / D converter, and the like and each conversion switching element 4 and 6 for driving each conversion switching element 4 and 6 of each phase of the inverter 2 Gate drive circuits 41 to 46 for generating gate drive signals and gate drives for driving the transformer drive switching elements 11 and 13 on the upper and lower sides of each phase of the recovery current commutation unit 60. Each of the commutation circuit gate drive circuits 51 to 56 generates a signal.

  The current detection elements 3a and 3b are elements for detecting currents supplied to the U phase and the W phase of the electric motor 1, respectively. Current signals (Iu, Iw) detected by the current detection elements 3a, 3b are input to the control circuit 71 via the current detection circuits 31a, 31b. The control circuit 71 converts it into a current value based on the current signal (Iu, Iw) and uses it as data. In the present embodiment, a current transformer or the like is used as the current detection elements 3a and 3b to detect the current supplied to the electric motor 1, but this detection method is used as a method for detecting the electric current supplied to the electric motor 1. It is not limited. For example, a method of detecting a current supplied to the motor 1 using a direct current flowing through a resistor inserted in a direct current bus path (one shunt current detection method), each of the lower conversion switching elements 6 and the first direct current A method of inserting a resistor between the negative side of the voltage source 80, detecting a current flowing through the resistor, and detecting a current flowing through the electric motor 1 (three-shunt current detection method) may be used. .

  Further, the voltage detection means 20 in the present embodiment is configured by a voltage dividing circuit composed of a resistor, a capacitor and the like, an amplifier and the like. The voltage signal (Vdc) detected by the voltage detection means 20 is input to the control circuit 71. The control circuit 71 converts it into a DC bus voltage value based on the voltage signal (Vdc) and uses it as data.

  The control circuit 71 performs various vector control calculations based on the obtained current value data and voltage value data, and drives each PWM (Pulse Width Modulation): (Pulse Width Modulation) A signal that is a source of a duty signal (hereinafter referred to as “PWM signal”) Up, Vp, Wp, Un, Vn, Wn is generated.

  Further, in the present embodiment, the control circuit 71 drives the upper and lower transformer driving switching elements 11 and 13 of each phase that supplies power to the primary winding of the transformer 8 at a predetermined timing. The signal which becomes the origin of each transformer drive signal Upa, Vpa, Wpa, Una, Vna, Wna for performing is generated.

  Each of the inverter gate drive circuits 41 to 46 is based on a signal output from the control circuit 71, and each PWM signal Up, Vp, Wp, which is each gate drive signal of each conversion switching element 4, 6 of each phase. Un, Vn, and Wn are generated.

  Each of the commutation circuit gate drive circuits 51 to 56 is a gate drive signal of each of the upper and lower transformer drive switching elements 11 and 13 of each phase based on a signal output from the control circuit 71. Each transformer drive signal Upa, Vpa, Wpa, Una, Vna, Wna is generated. Here, for example, a logic is configured using each PWM signal Up, Vp, Wp, Un, Vn, Wn, and each transformer drive signal Upa, Vpa, Wpa, Una, Vna is used in a desired section using a logic circuit. , Wna may be output.

  In the present embodiment, for example, MOSFETs having a SJ (Super Junction) structure are used as the conversion switching elements 4 and 6. SJ-structure MOSFETs have the advantages of low on-resistance and high breakdown voltage, but on the other hand, the reverse recovery time (recovery time) of the free-wheeling diodes 5 and 7 that are parasitic diodes is long. . Therefore, in the present embodiment, as the auxiliary diodes 9 and 10, diodes having higher reverse recovery characteristics than the free-wheeling diodes 5 and 7, such as Schottky barrier diodes, are used. Recovery loss is reduced by commutating the flowing forward current to the auxiliary diodes 9 and 10.

  In the present embodiment, the voltage value of the second DC voltage source is set to a voltage value of about several tenths of the voltage value of the first DC voltage source. For example, the voltage value of the first DC voltage source is generally a high voltage of about 230V, but the voltage value of the second DC voltage source is a low voltage value of about 15V, for example. At this time, the voltage value of the second DC voltage source 17 is the power supply voltage value of each of the inverter gate drive circuits 41 to 46 and each of the commutation gate drive circuits 51 to 56 or the power supply voltage value of the control circuit 71. If configured to have the same voltage value, a reduction in recovery loss can be realized without adding a new power supply.

  Next, the commutation operation of the forward current flowing through the free-wheeling diodes 5 and 7 of the inverter driving device according to the present embodiment will be described with reference to FIGS. FIG. 2 is a diagram showing a configuration for one phase of the inverter driving apparatus shown in FIG. FIG. 3 is a timing chart of the U-phase PWM signal, transformer drive signal, and transformer primary winding voltage of the inverter drive apparatus according to the first embodiment. FIG. 4 is a diagram illustrating a commutation operation of the forward current flowing through the free wheel diode in the inverter driving apparatus according to the first embodiment. In FIG. 4, a line indicated by a broken line arrow indicates a path through which the load current flows, and a line indicated by a solid line arrow indicates the direction of the current flowing through the primary side winding of the transformer 8. In the example shown in FIG. 4, an operation example in the section A shown in FIG. 3 is shown. FIG. 5 is a diagram showing the drain-source current Ids of the conversion switching element when the forward current flowing through the freewheeling diode is not commutated. FIG. 6 is a diagram showing the drain-source current Ids of the switching element for conversion when the forward current flowing through the freewheeling diode is commutated. Here, although the commutation operation in the U phase will be described, the same commutation operation is also performed for the V phase and the W phase.

  As described above, since the capacitance values of the upper capacitor 15 and the lower capacitor 16 are the same, as shown in FIG. 2, the upper capacitor 15 is driven by the DC voltage Vcc2 applied by the second DC voltage source 17. The both-ends voltage V15 of 15 and the both-ends voltage V16 of the lower capacitor 16 are Vcc2 / 2, respectively.

  In the present embodiment, the polarity of the lower secondary winding is reversed with respect to the polarity of the primary winding and the upper secondary winding of the transformer 8. Thus, when the upper transformer driving switching element 11 is controlled to be turned on, Va = Vcc2 / 2 is applied to the primary winding of the transformer 8, and the primary winding is connected to the upper secondary winding. A reverse voltage corresponding to the winding ratio with the upper secondary winding is applied. When the lower transformer driving switching element 13 is controlled to be on, Va = −Vcc2 / 2 is applied to the primary winding of the transformer 8 and the primary winding is applied to the lower secondary winding. A reverse voltage according to the winding ratio between the line and the upper secondary winding is applied.

  In the present embodiment, the upper transformer drive switching element 11 is controlled to be turned on for a predetermined period from when the upper conversion switching element 4 is turned off to when the lower conversion switching element 6 is turned on. The forward current flowing through the return diode 5 of the conversion switching element 11 is commutated to the auxiliary diode 9, and a predetermined period from when the lower conversion switching element 6 is turned off to when the upper conversion switching element 4 is turned on. During the period, the lower transformer driving switching element 13 is controlled to be turned on, and the forward current flowing through the freewheeling diode 7 of the lower conversion switching element 6 is commutated to the auxiliary diode 10.

  That is, for example, as shown in FIG. 3, the transformer drive signal Upa is controlled from off (L) to on (H) in accordance with the timing at which the PWM signal Up is controlled from on (H) to off (L). The transformer drive signal Upa is controlled from on (H) to off (L) in accordance with the timing at which the PWM signal Un is controlled from off (L) to on (H). Also, for example, the transformer drive signal Una is controlled from off (L) to on (H) in accordance with the timing for controlling the PWM signal Un from on (H) to off (L), and the PWM signal Up is turned off ( The transformer drive signal Una is controlled from on (H) to off (L) in accordance with the timing of control from L) to on (H).

  First, an operation when the commutation operation according to the present embodiment is not performed will be described. When the commutation operation according to the present embodiment is not performed, a load current (forward current) flows from the electric motor 1 via the freewheeling diode 5 as shown in FIG. 4A in the section A shown in FIG. .

  At this time, when the lower conversion switching element 6 is controlled to be turned on, a large voltage is applied to the freewheeling diode 5 by the first DC voltage source 80, and the drain-source current Ids of the conversion switching element 6 is As shown in FIG. 5, a large recovery current is generated by the freewheeling diode 5. That is, a large recovery loss occurs and the switching loss increases.

  Next, an operation when the commutation operation according to the present embodiment is performed will be described. Here, the commutation operation at the ON timing of the lower conversion switching element 6 will be described.

  When the upper conversion switching element 4 is controlled to be turned off and the upper transformer driving switching element 11 is controlled to be turned on, as shown in FIG. An exciting current flows in the direction of the solid line arrow, and Va = Vcc2 / 2 is applied to both ends of the primary winding. At this time, a reverse voltage corresponding to the turn ratio between the primary side winding and the secondary side winding is generated in the upper secondary side winding of the transformer 8, and the upper secondary side winding and the auxiliary diode 9. As the current starts to flow, the freewheeling diode 5 shifts to the reverse recovery operation, and the forward current flowing through the freewheeling diode 5 decreases. At this time, since the freewheeling diode 5 performs the reverse recovery operation by the low voltage generated in the secondary winding of the transformer 8, the recovery loss due to the freewheeling diode 5 can be suppressed.

  The state where the reverse voltage is generated in the upper secondary winding of the transformer 8 is maintained for a predetermined time, whereby the diode 5 completes the reverse recovery operation, and the load current is as shown in FIG. Then, the secondary secondary winding and the auxiliary diode 9 flow. That is, the load current (forward current) flowing through the return diode 5 is commutated to the auxiliary diode 9.

  When the lower conversion switching element 6 is turned on and the upper transformer driving switching element 11 is turned off after a predetermined time has elapsed, the auxiliary diode 9 shifts to the reverse recovery operation, and FIG. ), A recovery current is generated by the auxiliary diode 9. As described above, in the present embodiment, the auxiliary diodes 9 and 10 are diodes having higher reverse recovery characteristics than the free-wheeling diodes 5 and 7 such as Schottky barrier diodes. As shown in FIG. 6, the recovery current generated in the drain-source current Ids of the switching element 6 is smaller than the recovery current (see FIG. 5) due to the freewheeling diode 5.

  Thereafter, as the reverse recovery operation of the auxiliary diode 9 is completed, the load current flows through the lower conversion switching element 6 as shown in FIG.

  Thus, in the commutation operation at the on timing of the lower conversion switching element 6, the recovery current can be reduced by commutating the forward current flowing through the freewheeling diode 5 to the auxiliary diode 9.

  In the commutation operation at the ON timing of the upper conversion switching element 4, the transformer drive signal Una shown in FIG. 3 is applied to the lower transformer drive switching element 13, and the lower conversion switching element described above is applied. Similarly to the commutation operation at the ON timing 6, recovery loss can be reduced by commutating the forward current flowing through the freewheeling diode 7 to the auxiliary diode 10.

  Further, in the present embodiment, the intermediate taps of the secondary side windings are not made common, but two independent output terminals are provided for the secondary side windings, and the auxiliary diodes 9 and 10 are switched for each conversion. It is provided between the positive terminal of the elements 4 and 6 and each secondary winding. FIG. 7 is a diagram illustrating an example in which the intermediate tap of the secondary side winding is shared. As shown in FIG. 7, when the intermediate tap of the secondary side winding is shared, an auxiliary diode 10 is provided between the negative side terminal of the lower conversion switching element 6 and the secondary side winding. Become. Even if such a configuration is used, there is no problem under normal use conditions, but depending on the use conditions and environmental conditions, as shown in FIG. 7, when the stray capacitance generated in the secondary winding becomes a size that cannot be ignored. There is. In this case, an excessive voltage is applied at the moment when the upper conversion switching element 4 is controlled from OFF to ON, and a large current indicated by a broken-line arrow in the figure flows. And reinforcement of insulation are required.

  In the present embodiment, the auxiliary diode 10 provided between the positive terminal of the conversion switching element 6 and the secondary winding cuts off the current path shown in FIG. Further, it is not necessary to increase the withstand voltage of the windings or to strengthen the insulation, and it is possible to enhance the reliability.

  Next, the intention of interconnecting the neutral points of the upper capacitor 15 and the lower capacitor 16 of each commutation circuit 62 between the phases will be described with reference to FIGS. FIG. 8 is a diagram illustrating a configuration example of the inverter driving device when the neutral points of the upper capacitor and the lower capacitor of each commutation circuit are not interconnected between the phases. Since each component is the same as that of the inverter driving apparatus according to the first embodiment shown in FIG. 1, the description thereof is omitted here.

  In the commutation circuit 62 of the inverter drive device according to the present embodiment, the upper and lower capacitors 15 and 16 are charged and discharged by switching of the upper and lower transformer driving switching elements 11 and 13. Often done. At this time, considering the exciting current required for driving the primary side winding of the transformer 8, a considerable amount of ripple current is generated.

  As shown in FIG. 8, when the neutral points of the upper capacitors and the lower capacitors 15 and 16 of each commutation circuit 62 are not interconnected between the phases, the upper and lower transformer driving switching elements 11 are connected. , 13 to withstand the ripple current caused by switching, it is necessary to increase the capacities and ripple tolerances of the upper and lower capacitors 15 and 16 for each phase, which increases the cost.

  In the inverter driving apparatus according to the present embodiment, as shown in FIG. 1, the neutral points of the upper capacitor 15 and the lower capacitor 16 of each commutation circuit 62 are interconnected between the phases. Although the charging / discharging frequency of the upper and lower capacitors 15 and 16 is increased, the ripple current due to one switching is shared by the upper capacitor 15 and the lower capacitor 16 of each phase, and the upper capacitor per phase is increased. The peak value of the ripple current applied to the capacitor 15 and the lower capacitor 16 can be suppressed. Further, since the capacitance value is the parallel capacitance of the upper capacitor 15 and the lower capacitor 16 for three phases, it is advantageous for the ripple resistance and life.

  Therefore, as shown in FIG. 8, the upper capacitors and the lower capacitors 15, 16 than the case where the neutral points of the upper capacitors and the lower capacitors 15, 16 of each commutation circuit 62 are not interconnected between the respective phases. Capacity and ripple resistance can be reduced, and an increase in cost can be suppressed.

  As described above, according to the inverter driving apparatus of the first embodiment, the connection points of the upper and lower transformer driving switching elements connected in series along the voltage application direction and the voltage application direction. A half-bridge circuit is configured by connecting the primary winding of the transformer between the neutral points of the upper and lower capacitors connected in series. Each phase is provided with a commutation circuit in which auxiliary diodes each having high speed and excellent reverse recovery characteristics are connected in series and connected in parallel to a free-wheeling diode connected in reverse parallel to the conversion switching element. By connecting the neutral point of each capacitor on each side between each phase, the ripple current due to one switching is shared by the upper and lower capacitors of each phase, and the upper and lower Since the peak value of the ripple current applied to the lower capacitor can be suppressed, the capacity and ripple tolerance of the upper and lower capacitors can be reduced, reducing the recovery loss while suppressing the increase in cost. Can be planned.

  The voltage value of the second DC voltage source that is the power source of the transformer drive circuit is a low voltage value of about several tenths of the voltage value of the first DC voltage source that is the DC bus voltage of the inverter. Thus, during the commutation operation, the freewheeling diode performs a reverse recovery operation due to the low voltage generated in the secondary winding of the transformer, so that recovery loss due to the freewheeling diode can be suppressed.

  Further, the voltage value of the second DC voltage source is configured to be the same as the power supply voltage value of each inverter gate drive circuit and each commutation circuit gate drive circuit or the power supply voltage value of the control circuit. This makes it possible to reduce recovery loss without adding a new power supply.

  Moreover, the intermediate tap of each secondary side winding of the transformer is not made common, but two independent output terminals are provided for each secondary side winding, and each auxiliary diode is connected to the positive side terminal of each switching element for conversion. By providing it between each secondary winding, an excessive voltage is applied to the lower secondary winding via the stray capacitance at the moment when the upper switching element is controlled from OFF to ON. Since the path through which the current flows is cut off, the withstand voltage and the insulation are ensured, and it is not necessary to increase the withstand voltage of the windings and the insulation reinforcement, and the reliability can be enhanced.

  In Embodiment 1 described above, the motor is a three-phase AC motor, and an example in which an arm is provided for each phase has been described. However, the present invention is not limited to this, and for example, the motor is a single-phase AC motor. In some cases, a configuration having two arms may be used, or a configuration having four or more arms may be used.

  Further, in the first embodiment described above, a configuration has been described in which each of the upper and lower transformer driving switching elements and the upper and lower capacitors constituting each transformer drive circuit is provided. Depending on the current capacity and the ripple tolerance, a plurality may be connected in parallel.

Embodiment 2. FIG.
In the present embodiment, an example in which the inverter driving device described in the first embodiment is applied to a refrigeration air conditioner will be described. FIG. 9 is a diagram of a configuration example of the refrigeration air conditioning apparatus according to the second embodiment. As shown in FIG. 9, the refrigeration air conditioner according to the second embodiment includes a heat source side unit (outdoor unit) 100 and a load side unit (indoor unit) 200, which are connected by a refrigerant pipe, The refrigerant circuit (hereinafter referred to as “main refrigerant circuit”) is configured to circulate the refrigerant. In the example shown in FIG. 9, among the refrigerant pipes, a pipe through which a gaseous refrigerant (gas refrigerant) flows is referred to as a gas pipe 300, and a pipe through which a liquid refrigerant (liquid refrigerant or gas-liquid two-phase refrigerant may flow) flows. Is the liquid pipe 400.

  In the present embodiment, the heat source side unit 100 includes a compressor 101, an oil separator 102, a four-way valve 103, a heat source side heat exchanger 104, a heat source side fan 105, an accumulator (gas-liquid separator) 106, and a heat source side expansion device. (Expansion valve) 107, heat exchanger 108 between refrigerants, bypass expansion device 109, and heat source side control device 110 are provided.

  As the structure of the compressor 101, the electric motor 1 described in the first embodiment is used for the compressor. On the other hand, for operation control, the inverter drive device according to the first embodiment is provided, and the capacity of the compressor 101 (the amount of refrigerant sent out per unit time) is finely changed by arbitrarily changing the operation frequency. Shall be able to.

  The oil separator 102 separates lubricating oil mixed in the refrigerant discharged from the compressor 101. The separated lubricating oil is returned to the compressor 101. The four-way valve 103 switches the refrigerant flow between the cooling operation and the heating operation based on an instruction from the heat source side control device 110. The heat source side heat exchanger 104 performs heat exchange between the refrigerant and the outside air (outdoor air). For example, it functions as an evaporator during heating operation, performs heat exchange between the low-pressure refrigerant that has flowed in via the heat source side expansion device 107 and the outside air, and evaporates and vaporizes the refrigerant. Moreover, it functions as a condenser during the cooling operation, and performs heat exchange between the refrigerant compressed in the compressor 101 flowing in from the four-way valve 103 side and the outside air, and condenses and liquefies the refrigerant. The heat source side heat exchanger 104 is provided with a heat source side fan 105 in order to efficiently exchange heat between the refrigerant and the outside air. The heat source side fan 105 also includes the inverter drive device according to the first embodiment, and arbitrarily changes the operating frequency of the fan motor to finely change the rotational speed of the fan.

  The inter-refrigerant heat exchanger 108 exchanges heat between the refrigerant flowing in the main flow path of the refrigerant circuit and the refrigerant branched from the flow path and adjusted in flow rate by the bypass expansion device 109 (expansion valve). . In particular, when it is necessary to supercool the refrigerant during the cooling operation, the refrigerant is supercooled and supplied to the load side unit 200. The liquid flowing through the bypass throttle device 109 is returned to the accumulator 106 via the bypass pipe 107. The accumulator 106 is means for storing, for example, liquid excess refrigerant. The heat source side control device 110 is composed of, for example, a microcomputer. It can communicate with the load-side control device 204 by wire or wirelessly. For example, based on data detected by various detection means (sensors) in the refrigeration air conditioner, the operation frequency control of the compressor 101 by inverter circuit control, etc. The operation of the entire refrigerated air conditioner is controlled by controlling each means provided in the refrigerated air conditioner.

  On the other hand, the load side unit 200 includes a load side heat exchanger 201, a load side expansion device (expansion valve) 202, a load side fan 203, and a load side control device 204. The load side heat exchanger 201 performs heat exchange between the refrigerant and the outside air. For example, during heating operation, it functions as a condenser, performs heat exchange between the refrigerant flowing in from the gas pipe 300 and the outside air, condenses the refrigerant and liquefies (or gas-liquid two-phase), and moves to the liquid pipe 400 side. Spill. On the other hand, during cooling operation, it functions as an evaporator, performs heat exchange between the refrigerant that has been brought to a low pressure state by the load-side throttle device 202 and the outside air, causes the refrigerant to take off the heat of air, evaporates it, and vaporizes it. It flows out to the piping 300 side. In addition, the load side unit 200 is provided with a load side fan 203 for adjusting the flow of air for heat exchange. The operating speed of the load-side fan 203 is determined by, for example, user settings. The load side expansion device 202 is provided to adjust the pressure of the refrigerant in the load side heat exchanger 201 by changing the opening degree.

  The load-side control device 204 is also composed of a microcomputer or the like, and can communicate with the heat source-side control device 110, for example, by wire or wirelessly. Based on an instruction from the heat source side control device 110 and an instruction from a resident or the like, for example, each unit provided in the load side unit 200 is controlled so that the room has a predetermined temperature. In addition, a signal including data detected by the detection means provided in the load side unit 200 is transmitted.

  As described above, according to the refrigeration air conditioning apparatus of the second embodiment, it is possible to achieve a reduction in recovery loss and a reduction in cost in the inverter drive apparatus, so that the power consumption can be suppressed with high efficiency, and A low-cost refrigerated air conditioner can be obtained. Moreover, since high reliability can be obtained in the inverter drive device that drives the motor of the compressor that is particularly important among the components constituting the refrigeration air conditioner, high reliability is also obtained as a whole refrigeration air conditioner. be able to.

  In addition, in Embodiment 2 mentioned above, although the example which applies an inverter drive device to a refrigeration air conditioning apparatus was demonstrated, it can utilize also for the cooling device, heat pump apparatus, etc. which are used for a refrigerator, a refrigerator, etc., for example. . Moreover, it can utilize also for the other apparatus which uses an electric motor, and it can utilize also for lighting equipment etc.

  The configurations described in the above embodiments are examples of the configurations of the present invention, and can be combined with other known techniques, and a part of the configurations is omitted without departing from the gist of the present invention. Needless to say, it is possible to change the configuration.

DESCRIPTION OF SYMBOLS 1 Electric motor 2 Inverter 3 Current detection means 3a, 3b Current detection element 4 Conversion switching element (upper side)
5 Freewheeling diode (upper side)
6 Switching element for conversion (lower side)
7 Freewheeling diode (lower side)
8 Transformer 9 Auxiliary diode (upper side)
10 Auxiliary diode (lower side)
11 Switching element for transformer drive (upper side)
12 Reflux diode (upper side)
13 Switching element for transformer drive (lower side)
14 Reflux diode (lower side)
15 Capacitor (upper side)
16 Capacitor (lower side)
17 Second DC voltage source (for transformer drive)
DESCRIPTION OF SYMBOLS 18 Commutation circuit 20 Voltage detection means 21 Voltage detection circuit 31a-31b Current detection circuit 41-46 Gate drive circuit for inverters 51-56 Gate drive circuit for commutation circuits 60 Recovery current commutation part 61 Transformer drive circuit 62 Commutation Circuit 70 Control unit 71 Control circuit 80 First DC voltage source (for inverter)
DESCRIPTION OF SYMBOLS 100 Heat source side unit 101 Compressor 102 Oil separator 103 Four-way valve 104 Heat source side heat exchanger 105 Heat source side fan 106 Accumulator 107 Heat source side throttle device 108 Heat exchanger between refrigerants 109 Bypass throttle device 110 Heat source side control device 200 Load side unit 201 Load side heat exchanger 202 Load side throttle device 203 Load side fan 204 Load side control device 300 Gas piping 400 Liquid piping

Claims (10)

An inverter driving device having a plurality of arms each having a freewheeling diode connected in antiparallel to each of the upper and lower conversion switching elements connected in series along the voltage application direction of the first DC voltage source. ,
Each of the plurality of arms includes a commutation circuit that operates by a second DC voltage source and commutates a forward voltage flowing through each of the return diodes.
The commutation circuit is
A transformer having a primary winding and two secondary windings of different polarities;
An auxiliary diode connected in series with each secondary winding and connected in parallel with each freewheeling diode;
Switching elements for driving the upper and lower transformers connected in series along the voltage application direction of the second DC voltage source;
Upper and lower capacitors connected in series along the voltage application direction of the second DC voltage source;
With
A neutral point of each of the upper and lower capacitors is connected to a connection point of each of the upper and lower transformer driving switching elements via the primary side winding, and for each of the plurality of arms. An inverter driving device interconnected with each of the commutation circuits provided in the circuit.   The commutation circuit is configured to turn on the upper transformer driving switching element for a predetermined period from when the upper conversion switching element is turned off until the lower conversion switching element is turned on. A forward current flowing through the return diode of the conversion switching element is commutated to the auxiliary diode, and a predetermined period from when the lower conversion switching element is turned off to when the upper conversion switching element is turned on, 2. The forward current flowing in the return diode of the lower conversion switching element is turned on by turning on the lower transformer driving switching element to commutate the auxiliary diode to the auxiliary diode. Inverter drive device.   3. The inverter drive device according to claim 1, wherein a voltage value of the second DC voltage source is smaller than a voltage value of the first DC voltage source.   The inverter drive device according to claim 1, wherein the auxiliary diode has a reverse recovery characteristic superior to that of the freewheeling diode.   The inverter driving apparatus according to claim 4, wherein the auxiliary diode is a Schottky barrier diode.   Each secondary winding has two output terminals, and each auxiliary diode is provided between a positive terminal of each conversion switching element and each secondary winding. The inverter drive device as described in any one of Claims 1-5 characterized by these.   The inverter driving apparatus according to claim 1, wherein the control unit that controls the commutation circuit is operated by the second DC voltage source.   A refrigeration air conditioner comprising the inverter drive device according to any one of claims 1 to 7.   The refrigerator provided with the inverter drive device as described in any one of Claims 1-7.   A refrigerator comprising the inverter driving device according to any one of claims 1 to 7.

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