JP6602466B2 - Motor drive device - Google Patents

Description

  The present invention relates to a motor drive device including a converter circuit that converts an AC voltage input from an AC power source into a DC voltage.

  In general, a motor drive system includes an AC power supply, a motor drive device, and a motor. The motor drive device is composed of a converter circuit and an inverter circuit. (For example, refer to Patent Document 1.)

  The converter circuit includes a rectifier circuit including four diodes, a switch circuit including four diodes and two bidirectional switching elements, and two capacitors connected in series. And a capacitor circuit. The inverter circuit is composed of six switching elements.

  The converter circuit described above operates as follows. The AC power input from the AC power source to the converter circuit is full-wave rectified by the rectifier circuit and charged into the capacitor circuit, thereby being converted into DC power. When a positive voltage is applied from the AC power supply, if the switching element of the switch circuit is complementarily controlled so that when one is on and the other is off, both capacitors of the capacitor circuit are Each is charged to the input voltage. Even when a negative voltage is applied from the AC power supply, both capacitors of the capacitor circuit are input to each other when the switching elements of the switch circuit are complementarily controlled so that one of them is on and the other is off. It is charged to become voltage.

  With the above operation, the DC voltage output from the converter circuit becomes a sum voltage obtained by adding the voltages accumulated in the capacitors connected in series in the capacitor circuit, and is twice the input voltage.

JP 2005-110491 A

  However, in the converter circuit of Patent Document 1, when the switch circuit is used to control the voltage of the AC power supply from the full-wave rectified voltage to the double voltage rectified voltage, four diodes are used in any charge / discharge path. There was a circuit loss due to the fact that either one of them was always conducted.

  Furthermore, even in a situation where the two switching elements are simultaneously turned on in order to short-circuit the switch circuit of Patent Document 1, a circuit loss has occurred due to conduction of the two diodes.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a motor drive device that can avoid circuit loss due to a diode in a converter circuit.

In order to solve the above-described problems and achieve the object, the present invention boosts the AC voltage between the first terminal and the second terminal of the AC power supply and outputs the boosted voltage to the first output terminal and the second output terminal. A converter circuit; and an inverter circuit having three sets of two switching elements connected in series between the first output terminal and the second output terminal in parallel. The converter circuit includes a reactor having one end connected in series to the first terminal, a first diode and a second diode connected in series between the first output terminal and the second output terminal, a first output terminal, and a second output terminal. A third diode and a fourth diode are connected in series with the output terminal and connected in parallel to the first diode and the second diode, and the connection point between the first diode and the second diode is the other end of the reactor. A rectifier circuit in which a connection point between the third diode and the fourth diode is connected to the second output terminal, a first capacitor connected in series between the first output terminal and the second output terminal, and The second capacitor, the first switching element and the second switching element connected in series, the parallel connection to the first switching element and the second switching element, and the serial connection A third switching element and a fourth switching element; and a fifth switching element and a sixth switching element connected in parallel to and connected in series to the first switching element and the second switching element. A connection point of the element is connected to a connection point of the first capacitor and the second capacitor, a connection point of the first switching element and the second switching element is connected to a connection point of the first diode and the second diode; A connection point between the third switching element and the fourth switching element is connected to a connection point between the third diode and the fourth diode, and the first to sixth switching elements each have a switching circuit having an anti-parallel diode; The period during which power of one polarity of positive and negative polarity is output from the AC power supply is A first state in which only the third switching element and the fifth switching element among the first to sixth switching elements are turned on, and the fourth switching element and the fourth switching element among the first to sixth switching elements; The first capacitor is charged by the second state in which only the six switching elements are turned on, and the second switching element and only the sixth switching element among the first to sixth switching elements are turned on. The second capacitor is charged according to the state and the fourth state in which only the first switching element and the fifth switching element among the first to sixth switching elements are turned on. During the period in which power of the other polarity is output, the first state, the second state, The second capacitor is charged by, and the first capacitor is charged by the third state and the fourth state.

  The motor drive device according to the present invention has an effect that circuit loss due to a diode in the converter circuit can be avoided.

1 is an overall circuit diagram of a motor drive device according to a first embodiment of the present invention. The figure which shows the state of the switching element for every state of the switch circuit concerning Embodiment 1 FIG. 2 is an overall circuit diagram of a motor drive device according to a second embodiment of the present invention. The figure which shows the state of the switching element for every state of the switch circuit concerning Embodiment 2

  Hereinafter, a motor drive device according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is an overall circuit diagram of a motor drive device 100 according to the first embodiment of the present invention. The motor driving device 100 drives the motor 7 with AC power output from the AC power supply 1 as an input. The motor drive device 100 includes a converter circuit 8 and an inverter circuit 6. The inverter circuit 6 drives the motor 7. A specific example of the motor 7 is a motor built in a compressor used in home appliances.

  The converter circuit 8 is a booster circuit that takes the AC power supply 1 as an input, converts the input voltage into a positive voltage equal to or higher than the amplitude value, and outputs the positive voltage. The converter circuit 8 includes a reactor circuit 2 for improving the power factor of the AC power source 1, a rectifier circuit 3 for rectifying the voltage, a switch circuit 4 for switching the connection between the capacitor circuit 5 and the AC power source 1, and an AC And a capacitor circuit 5 that can output up to twice the output voltage of the power supply 1. The inverter circuit 6 is connected to the capacitor circuit 5 and drives the motor 7.

  The AC power source 1 includes a first terminal 41 and a second terminal 42, and generates an AC voltage between the first terminal 41 and the second terminal 42.

  Reactor circuit 2 includes reactors 9 and 10. Reactors 9 and 10 each have a first end and a second end. The first end of the reactor 9 is connected to the first terminal 41, and the first end of the reactor 10 is connected to the second terminal 42.

  The rectifier circuit 3 includes diodes 11 and 12 connected in series to the first output terminal 51 and the second output terminal 52, and diodes 13 and 14 connected in series to the first output terminal 51 and the second output terminal 52. In parallel.

  The switch circuit 4 includes switching elements 15 and 16 connected in series, switching elements 17 and 18 connected in series, and switching elements 19 and 20 connected in series. Switching elements 15 to 20 are bidirectional switching elements.

  The capacitor circuit 5 includes a first capacitor 21 and a second capacitor 22 connected in series to the first output terminal 51 and the second output terminal 52, and a third capacitor connected to the first output terminal 51 and the second output terminal 52. 23. Therefore, the first output terminal 51 and the second output terminal 52 and the third capacitor 23 are connected in parallel. The capacitor circuit 5 smoothes the output of the rectifier circuit 3. In FIG. 1, the first capacitor 21, the second capacitor 22, and the third capacitor 23 are described as electrolytic capacitors, but other capacitors may be used. The first capacitor 21 and the second capacitor 22 for voltage doubler rectification are not limited to two and can be provided between the first output terminal 51 and the second output terminal 52. The third capacitor 23 may be omitted.

  A second end of the reactor 9 is connected to a connection point 71 that is a connection point of the diodes 11 and 12 and a connection point 73 that is a connection point of the switching elements 15 and 16. The second end of the reactor 10 is connected to a connection point 72 that is a connection point of the diodes 13 and 14 and a connection point 74 that is a connection point of the switching elements 17 and 18. Further, a connection point 75 that is a connection point of the switching elements 19 and 20 and a connection point 76 that is a connection point of the first capacitor 21 and the second capacitor 22 are connected.

  The second end portion of the reactor 9 is finally connected to the first terminal 41 via the main body and the first end portion of the reactor 9, and the second end portion of the reactor 10 is connected to the reactor 10. Is finally connected to the second terminal 42 via the main body and the first end. Here, a bidirectional switching element capable of short-circuiting between the connection point 76 and the first terminal 41 is defined as a first switching element, and a bidirectional switching element capable of short-circuiting between the connection point 76 and the second terminal 42 is defined as a first switching element. If two switching elements are used, the connection status described above can be said as follows.

  That is, the switching elements 15 and 19 as the first switching elements are connected in series between the connection point 76 and the first terminal 41, and the switching element as the second switching element is connected between the connection point 76 and the second terminal 42. 18 and 20 are connected in series. And the switching element 17 which is a 3rd switching element is connected between the connection point 77 which is a connection point of two 1st switching elements, and the 2nd terminal 42. FIG. Furthermore, the switching element 16 that is the fourth switching element is connected between the connection point 78 that is a connection point between the two second switching elements and the first terminal 41.

  Further, unlike the above, the first switching element may be switching elements 16 and 20, the second switching element may be switching elements 17 and 19, the third switching element may be switching element 18, and the fourth switching element may be switching element 15. The situation described above can be said as follows. That is, the switching elements 16 and 20 as the first switching elements are connected in series between the connection point 76 and the first terminal 41, and the switching element as the second switching element is connected between the connection point 76 and the second terminal 42. 17 and 19 are connected in series. Then, the switching element 18 that is the third switching element is connected between the connection point 78 that is the connection point between the two first switching elements and the second terminal 42. Further, the switching element 15, which is the fourth switching element, is connected between the connection point 77, which is a connection point between the two second switching elements, and the first terminal 41.

  The inverter circuit 6 is connected in series between the switching elements 24 and 25 connected in series between the first output terminal 51 and the second output terminal 52, and between the first output terminal 51 and the second output terminal 52. Switching elements 26 and 27 and switching elements 28 and 29 connected in series between the first output terminal 51 and the second output terminal 52 are provided in parallel. Switching elements 24 to 29 are bidirectional switching elements. A connection point between the switching elements 24 and 25, a connection point between the switching elements 26 and 27, and a connection point between the switching elements 28 and 29 are connected to the motor 7, respectively.

  In FIG. 1, the reactor circuit 2 is configured by two reactors 9 and 10, but may be configured by one of the reactors 9 and 10. When the reactor 9 is not present, the first terminal 41 is directly connected to the connection point 71 and the connection point 73. When the reactor 10 is not present, the second terminal 42 is directly connected to the connection point 72 and the connection point 74. That is, the connection point 71 and the connection point 72 of the rectifier circuit 3 are connected to the first terminal 41 and the second terminal 42, respectively, but at least one of the first terminal 41 and the second terminal 42 and the rectifier circuit 3 There is a reactor in between.

  Specific examples of the switching elements used in the switch circuit 4 and the inverter circuit 6 are elements such as IGBTs (Insulated Gate Bipolar Transistors) and MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors).

  Next, the operation of the motor driving apparatus 100 according to the first embodiment will be described. Since the operation state of the motor drive device 100 differs depending on the states of the switching elements 15 to 20 of the switch circuit 4, the operation will be described for each state below. FIG. 2 is a diagram illustrating states of the switching elements 15 to 20 for each state of the switch circuit 4 according to the first embodiment. The states of the switch circuit 4 are (State 1), (State 2-1), (State 2-2) and (State 3) described below. The output of the AC power supply 1 is such that the voltage at which the voltage at the first terminal 41 is higher than that at the second terminal 42 is a positive voltage, and the voltage at which the voltage at the second terminal 42 is higher than that of the first terminal 41 is negative. The voltage will be described.

(State 1)
First, a description will be given of a case where all of the switching elements 15 to 20 are turned off (state 1). In the converter circuit 8 configured as described above, when the output of the AC power supply 1 is input, the output is rectified by the rectifier circuit 3, and the capacitors 21 to 23 are connected to the second output voltage of the capacitors 21 to 23 by the output of the rectifier circuit 3. The capacitor circuit 5 is charged so as to be higher than the voltage at the terminal 52. That is, when a positive voltage is output from the AC power supply 1, the capacitor circuit is formed by the current flowing through the path of the AC power supply 1 → reactor 9 → diode 11 → capacitor circuit 5 → diode 14 → reactor 10 → AC power supply 1. 5 is charged. On the contrary, when a negative voltage is output from the AC power source 1, the capacitor flows due to the current flowing through the path of the AC power source 1 → reactor 10 → diode 13 → capacitor circuit 5 → diode 12 → reactor 9 → AC power source 1. The circuit 5 is charged.

  Next, (state 2) in which the capacitors 21 and 22 are charged alternately will be further divided into two states (state 2-1) and (state 2-2).

(State 2-1)
As shown in the column of (State 2-1) in FIG. 2, among the switching elements 15 to 20, only the switching elements 17 and 19 are turned on or only the switching elements 18 and 20 are turned on. This is to turn on only the two second switching elements. Thereby, reactor 10 and connection point 76 are connected. In (state 2-1), when a positive voltage is output from the AC power source 1, the current is passed through the path of the AC power source 1 → reactor 9 → diode 11 → capacitor 21 → switch circuit 4 → reactor 10 → AC power source 1. The capacitor 21 is charged. On the other hand, when a negative voltage is output from the AC power source 1, current flows through the path of the AC power source 1 → reactor 10 → switch circuit 4 → capacitor 22 → diode 12 → reactor 9 → AC power source 1. As a result, the capacitor 22 is charged.

(State 2-2)
As shown in the column of (State 2-2) in FIG. 2, among the switching elements 15 to 20, only the switching elements 15 and 19 are turned on or only the switching elements 16 and 20 are turned on. This is to turn on only the two first switching elements. Thereby, the reactor 9 and the connection point 76 are connected. In (State 2-2), when a positive voltage is output from the AC power source 1, the current flows through the path of the AC power source 1 → reactor 9 → switch circuit 4 → capacitor 22 → diode 14 → reactor 10 → AC power source 1. The capacitor 22 is charged. On the other hand, when a negative voltage is output from the AC power source 1, a current flows through the path of the AC power source 1 → reactor 10 → diode 13 → capacitor 21 → switch circuit 4 → reactor 9 → AC power source 1. As a result, the capacitor 21 is charged.

(State 3)
When only the switching elements 15 and 17 among the switching elements 15 to 20 are turned on when the output voltage of the AC power supply 1 is about 0 volts, the AC power supply 1 → reactor 9 → switching element 15 → switching element 17 When the current flows through the path of the reactor 10 → the AC power source 1, the AC power source 1 is short-circuited. Further, when the output voltage of the AC power supply 1 is a voltage of about 0 volts, if only the switching elements 16 and 18 are turned on among the switching elements 15 to 20, the AC power supply 1 → the reactor 10 → the switching element 18 → switching. When a current flows through the path of the element 16 → the reactor 9 → the AC power supply 1, the AC power supply 1 is in a short circuit state.

  When charging the capacitor circuit 5 in the above (State 2-1) and (State 2-2), the charging effect is the same even if the selection of the switching element to be turned on among the switching elements 15 to 20 is changed. is there. In (State 2-1) and (State 2-2), if the switching element to be turned on is determined, the capacitors 21 and 22 are alternately charged. A voltage about twice the maximum value of the output voltage is obtained.

  The overall operation of the motor driving apparatus 100 according to the first embodiment will be described below. As can be seen from the above, if the capacitor circuit 5 is charged in (state 1), the capacitor circuit 5 is charged so that the voltage is about the maximum voltage value output from the AC power supply 1. Further, if the capacitor circuit 5 is charged in (State 2), that is, (State 2-1) and (State 2-2), the capacitor is set to a voltage about twice the maximum voltage value output from the AC power supply 1. The circuit 5 is charged. In (State 3), the capacitor circuit 5 is not charged.

  Therefore, if the capacitor circuit 5 is charged in each of the states (state 1) to (state 3) according to the power required by the motor 7, a voltage of about 0 volts, the maximum voltage output from the AC power source 1 is obtained. A three-stage output voltage is obtained, such as a voltage of about the value and a voltage of about twice the maximum voltage value output from the AC power supply 1.

  Based on the output of the AC power supply 1, by controlling the switching from (State 1) to (State 3) at a frequency higher than the frequency of the AC power supply 1, it is possible to prevent a rapid current flow and suppress the harmonic current. can do. That is, it is possible to smoothly change the output of the AC power supply 1 to boost the voltage and output it to the motor 7.

  According to the converter circuit 8 according to the first embodiment, (State 2) and (State 3) can be realized by conducting two switching elements without using a diode, and by conducting the diode in the current path. Since circuit loss can be avoided, a highly efficient converter circuit with low switching loss can be realized. In addition, since the converter circuit 8 is composed only of switching elements, the creation or selection of the module of the converter circuit 8 is simplified.

  Furthermore, the converter circuit 8 according to the first embodiment can be shared with the inverter circuit 6 by using a module having the same configuration of the inverter circuit 6 and the switching element. Thereby, the manufacturing process can be simplified. In addition, since a general-purpose module used in the inverter circuit 6 can be used, an inexpensive module can be selected, and the range of module selection can be expanded. Furthermore, since the switch circuit 4 is configured using all switching elements, synchronous rectification using only the switching elements can be realized.

Embodiment 2. FIG.
FIG. 3 is an overall circuit diagram of the motor drive device 200 according to the second embodiment of the present invention. The motor drive device 200 has the same configuration as the motor drive device 100 according to the first embodiment except that the configuration of the switch circuit is different.

  The motor driving device 200 includes a converter circuit 8 ′ and an inverter circuit 6. The converter circuit 8 ′ includes a reactor circuit 2, a rectifier circuit 3, a switch circuit 4 ′, and a capacitor circuit 5. The switch circuit 4 'is composed of switching elements 30 to 33 which are four bidirectional switching elements.

  The switching circuit 4 ′ includes switching elements 30 and 32 which are first switching elements connected in series between the connection point 71 and the connection point 76, and second switching connected in series between the connection point 72 and the connection point 76. Switching elements 31 and 33 which are elements. Since the connection point 71 is finally connected to the first terminal 41 and the connection point 72 is finally connected to the second terminal 42, the first switching element is the same as in the first embodiment. The first terminal 41 and the connection point 76 are connected, and the second switching element connects the second terminal 42 and the connection point 76.

  For the switching elements 30 to 33, field effect transistors such as MOSFETs are used. The switching elements 30 and 32 have their source terminals connected to each other, the drain terminal of the switching element 30 is connected to the connection point 71, and the drain terminal of the switching element 32 is connected to the connection point 76. The switching elements 31 and 33 also have their source terminals connected to each other, the drain terminal of the switching element 31 is connected to the connection point 72, and the drain terminal of the switching element 33 is connected to the connection point 76. By connecting the source terminals to each other, there is no possibility of conduction when both switching elements are off.

  Next, the operation of the motor driving apparatus 200 according to the second embodiment will be described. Since the operation state of the motor driving device 200 varies depending on the states of the switching elements 30 to 33 of the switch circuit 4 ′, the operation will be described for each state below. FIG. 4 is a diagram illustrating states of the switching elements 30 to 33 for each state of the switch circuit 4 ′ according to the second embodiment. The states of the switch circuit 4 'are (State 1), (State 2-1), (State 2-2), and (State 3) described below.

(State 1)
First, the switching element 30 to 33 are all turned off (state 1) will be described. In the converter circuit 8 ′ thus configured, when the output of the AC power supply 1 is input, the output is rectified by the rectifier circuit 3, and the capacitors 21 to 23 are connected to the second output terminal 51 by the output of the rectifier circuit 3. The capacitor circuit 5 is charged so as to be higher than the voltage at the output terminal 52. That is, when a positive voltage is output from the AC power supply 1, the capacitor circuit is formed by the current flowing through the path of the AC power supply 1 → reactor 9 → diode 11 → capacitor circuit 5 → diode 14 → reactor 10 → AC power supply 1. 5 is charged. On the contrary, when a negative voltage is output from the AC power source 1, the capacitor flows due to the current flowing through the path of the AC power source 1 → reactor 10 → diode 13 → capacitor circuit 5 → diode 12 → reactor 9 → AC power source 1. The circuit 5 is charged.

  Next, (state 2) in which the capacitors 21 and 22 are charged alternately will be further divided into two states (state 2-1) and (state 2-2).

(State 2-1)
As shown in the column of (State 2-1) in FIG. 4, only the switching elements 31 and 33, which are the second switching elements, are turned on among the switching elements 30 to 33. Thereby, reactor 10 and connection point 76 are connected. In (state 2-1), when a positive voltage is output from the AC power source 1, the current is passed through the path of the AC power source 1 → reactor 9 → diode 11 → capacitor 21 → switch circuit 4 → reactor 10 → AC power source 1. The capacitor 21 is charged. On the other hand, when a negative voltage is output from the AC power source 1, current flows through the path of the AC power source 1 → reactor 10 → switch circuit 4 → capacitor 22 → diode 12 → reactor 9 → AC power source 1. As a result, the capacitor 22 is charged.

(State 2-2)
As shown in the column of (State 2-2) in FIG. 4, among the switching elements 30 to 33, only the switching elements 30 and 32 that are the first switching elements are turned on. Thereby, the reactor 9 and the connection point 76 are connected. In (State 2-2), when a positive voltage is output from the AC power source 1, the current flows through the path of the AC power source 1 → reactor 9 → switch circuit 4 → capacitor 22 → diode 14 → reactor 10 → AC power source 1. The capacitor 22 is charged. On the other hand, when a negative voltage is output from the AC power source 1, a current flows through the path of the AC power source 1 → reactor 10 → diode 13 → capacitor 21 → switch circuit 4 → reactor 9 → AC power source 1. As a result, the capacitor 21 is charged.

(State 3)
When the output voltage of the AC power supply 1 is a voltage of about 0 volts, all the switching elements 30 to 33 are turned on. When a positive voltage is output from the AC power source 1, a current flows through the path of the AC power source 1 → reactor 9 → switching element 30 → switching element 32 → switching element 33 → switching element 31 → reactor 10 → AC power source 1. As a result, the AC power supply 1 is short-circuited. On the other hand, when a negative voltage is output from the AC power supply 1, a current flows through a path reverse to the above, and the AC power supply 1 is in a short circuit state.

  When charging the capacitor circuit 5 in the above (State 2-1) and (State 2-2), the charging effect is the same even if the selection of the switching element to be turned on among the switching elements 30 to 33 is changed. is there. In (State 2-1) and (State 2-2), if the switching element to be turned on is determined, the capacitors 21 and 22 are alternately charged. A voltage about twice the maximum value of the output voltage is obtained.

  The overall operation of the motor drive apparatus 200 according to the second embodiment is the same as the overall operation of the motor drive apparatus 100 according to the first embodiment, and the same effect as in the first embodiment is obtained.

  Furthermore, in the motor drive device 200, the number of switching elements provided in the switch circuit 4 ′ can be reduced from six to four compared to the switch circuit 4, so that the cost can be reduced compared to the motor drive device 100. Can be planned.

Embodiment 3 FIG.
The motor driving apparatus according to the third embodiment includes bidirectional switching elements formed of wide band gap semiconductors in the switching elements 15 to 20 of the switch circuit 4 and the switching elements 24 to 29 of the inverter circuit 6 according to the first embodiment. It is a motor drive device using. Alternatively, in the motor drive device according to the third embodiment, both the switching elements 30 to 33 of the switch circuit 4 ′ according to the second embodiment and the switching elements 24 to 29 of the inverter circuit 6 are formed of wide band gap semiconductors. This is a motor drive device using a directional switching element.

  Here, the wide band gap semiconductor refers to a semiconductor having a band gap larger than that of silicon, and a typical wide band gap semiconductor is SiC (silicon carbide), GaN (gallium nitride), or diamond.

  Since the switching element formed of such a wide band gap semiconductor has high voltage resistance and high allowable current density, the switching element can be reduced in size. By using these reduced switching elements, A semiconductor module incorporating these elements can be miniaturized.

  In addition, since the switching element formed of a wide band gap semiconductor has high heat resistance, it is possible to downsize the heat sink fins of the heat sink or to air-cool the water-cooled portion, thereby further reducing the size of the semiconductor module. .

  Furthermore, since the switching element formed of a wide band gap semiconductor has low power loss, the switching element can be highly efficient, and the semiconductor module can be highly efficient.

  Further, it is desirable that the switching elements of the switch circuits 4 and 4 ′ and the inverter circuit 6 are all formed of a wide band gap semiconductor, but only the switching elements of the switch circuits 4 and 4 ′ are formed of a wide band gap semiconductor. It doesn't matter.

  Since the operation of the motor driving apparatus according to the third embodiment is the same as that of the motor driving apparatus 100 according to the first embodiment or the motor driving apparatus 200 according to the second embodiment, the description thereof is omitted. Since a switching element formed of a wide bandgap semiconductor can increase the switching speed compared to other semiconductors, the motor drive device according to the third embodiment can further reduce the circuit loss of the entire device. Become.

  That is, by using a wide band gap semiconductor for the converter circuit 8 or 8 ', the loss does not increase even if the carrier frequency is increased. Therefore, by increasing the carrier frequency and controlling all the switching elements at high speed accordingly, the inductance values of the reactors 9 and 10 of the reactor circuit 2 are lowered, or the capacitances of the capacitors 21 to 23 of the capacitor circuit 5 are lowered. Accordingly, the entire circuit of the converter circuit 8 or 8 ′ can be reduced in size.

  In addition, since a switching element using a wide band gap semiconductor is expensive, the converter circuit 8 ′ according to the second embodiment is realized by using the wide band gap semiconductor. Since the number of switching elements is smaller than that realized by using a gap semiconductor, a significant cost reduction effect can be obtained.

  The configuration described in the above embodiment shows an example of the content of the present invention, and can be combined with another known technique, and can be combined with other configurations within the scope of the present invention. It is also possible to omit or change the part.

  1 AC power supply, 2 reactor circuit, 3 rectifier circuit, 4, 4 'switch circuit, 5 capacitor circuit, 6 inverter circuit, 7 motor, 8, 8' converter circuit, 9, 10 reactor, 11, 12, 13, 14 diode 15, 16, 17, 18, 19, 20, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33 switching element, 21 first capacitor, 22 second capacitor, 23 third capacitor, 41 1st terminal, 42 2nd terminal, 51 1st output terminal, 52 2nd output terminal, 71, 72, 73, 74, 75, 76, 77, 78 Connection point.

Claims (2)

A converter circuit that boosts the AC voltage between the first terminal and the second terminal of the AC power source and outputs the boosted voltage to the first output terminal and the second output terminal;
An inverter circuit having three sets of two switching elements connected in series between the first output terminal and the second output terminal in parallel;
In a motor drive device comprising:
The converter circuit is
A reactor having one end connected in series to the first terminal;
A first diode and a second diode connected in series between the first output terminal and the second output terminal; a first diode connected in series between the first output terminal and the second output terminal; A third diode and a fourth diode connected in parallel to the diode and the second diode, and a connection point between the first diode and the second diode is connected to the other end of the reactor, and the third diode And a rectifier circuit in which a connection point of the fourth diode is connected to the second output terminal;
A first capacitor and a second capacitor connected in series between the first output terminal and the second output terminal;
A first switching element and a second switching element connected in series, a third switching element and a fourth switching element connected in parallel to the first switching element and the second switching element, and the first switching element And a fifth switching element and a sixth switching element connected in parallel to each other and the second switching element, and a connection point between the fifth switching element and the sixth switching element is the first capacitor. And a connection point between the first capacitor and the second capacitor, a connection point between the first switching element and the second switching element is connected to a connection point between the first diode and the second diode, and the third switching element. The connection point between the element and the fourth switching element is the front end of the third diode. Connected to the connection point of the fourth diode, the sixth switching element from said first switching element, a switching circuit, each of which has an anti-parallel diode,
With
Only the third switching element and the fifth switching element among the first switching element to the sixth switching element are on during a period in which power of one polarity of positive and negative polarity is output from the AC power supply. The first capacitor is charged by the first state of the first switching element and the second state of turning on only the fourth switching element and the sixth switching element among the first to sixth switching elements. A third state in which only the second switching element and the sixth switching element among the first switching element to the sixth switching element are turned on; and the first switching element to the sixth switching element. Only the first switching element and the fifth switching element are turned on. Wherein the second capacitor is charged by the fourth condition,
The second capacitor is charged by the first state and the second state during a period in which power of the other polarity of positive and negative polarity is output from the AC power source, and the third state, The first capacitor is charged according to four states,
The motor drive device characterized by the above-mentioned. The motor driving apparatus according to claim 1, wherein the first to sixth switching elements are formed of a wide band gap semiconductor.

Images