KR101445960B1 - Motor control device and air conditioner - Google Patents

Abstract

SUMMARY OF THE INVENTION It is an object of the present invention to provide an inverter circuit and a method of controlling the same so as not to increase the number of circuit components and complicate circuit operation control when switching elements having different characteristics are disposed on the upper arm and the lower arm of the inverter circuit, The reverse recovery current is suppressed. The motor control apparatus 100 includes a motor 4 that rotates with AC power and an inverter circuit 2A that converts DC power to AC power and controls drive of the motor 4 by AC power. The inverter circuit 2A is connected to the upper and lower arms between the bus lines PL and NL to which the DC power is supplied, and the n-th and m-th switching elements 11 to 16, Pair. The three switching elements 11 to 16 are connected to the power line of the motor 4 so that all pairs of switching elements have different characteristics and the switching speed of the IGBT 11 of the n- Is set to be slower than the switching speed of the MOSFET (12) of the m-th switching element by a predetermined value.

Description

TECHNICAL FIELD [0001] The present invention relates to a motor control device and an air conditioner,

The present invention relates to a motor control device and an air conditioner that perform drive control of a motor by using an inverter circuit.

In equipment such as electric car and car and air conditioner equipped motor as load, resource saving and energy saving are strongly demanded from request of global environment conservation in recent years. In order to meet such a demand, various techniques for improving the loss of a three-phase inverter circuit (simply referred to as an inverter circuit) for converting DC power into three-phase AC power have been proposed.

In general, IGBTs (IGBTs) are used for six switching elements (simply referred to as elements) in an inverter circuit. However, in order to improve the steady-state loss of the inverter circuit during normal operation of the inverter circuit, a technique of using a metal-oxide-semiconductor field-effect transistor (MOSFET) Has been proposed.

As a MOSFET having a small normal loss, there is a super-junction MOSFET (hereinafter referred to as SJ-MOS). This SJ-MOS has a characteristic that a reverse recovery current generated in the parasitic diode of the SJ-MOS is large. This is larger than the reverse recovery current of the FRD (Fast-Recovery-Diode) used in the reflux diode connected in anti-parallel to the IGBT in general. Normally, when the reflux diode of the lower arm side switching element performs the switching operation during the reflux mode, the upper arm side switching element performs the switching operation, so that the voltage is biased as opposed to the forward direction of the reflux diode. As a result, a reverse recovery current is generated in the reflux diode and a short-circuit current is generated in the upper and lower arms.

For example, when an IGBT is arranged on the upper arm side of the inverter circuit and an SJ-MOS is arranged on the lower arm side, for example, an SJ-MOS, the parasitic diode on the lower arm side is connected to the IGBT of the upper arm When switched, a large short-circuit current flows in the upper and lower arms. This is due to the characteristic that the reverse recovery current generated in the parasitic diode of the SJ-MOS is large.

As a technique for suppressing a reverse recovery current, for example, as disclosed in Patent Document 1, when a MOSFET is disposed in an element of upper and lower arms in an inverter circuit, and a return current flows in a parasitic diode of a MOSFET A reverse voltage applying circuit for applying a reverse voltage lower than the voltage for driving the MOSFET to the reflux diode and suppressing the reverse recovery current is proposed before the other element of the pair is turned on.

Japanese Patent No. 4300209

However, in Patent Document 1, the number of circuit components such as semiconductor elements, capacitors, and resistors is increased in order to implement a reverse voltage application circuit, and control for operating a reverse voltage application circuit becomes complicated .

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an inverter circuit in which switching elements having different characteristics are arranged on the upper arm and the lower arm of the inverter circuit, And it is an object of the present invention to provide a motor control device and an air conditioner capable of suppressing a reverse recovery current generated when a device is switched.

According to an aspect of the present invention, there is provided an inverter circuit comprising: a motor rotating with AC power; an inverter circuit converting DC power into AC power and performing drive control of the motor with the converted AC power; The three pairs of switching elements are connected to the upper arm and the lower arm between the busbars of the unit to which the DC power is supplied, and the pair of switching elements constitute a pair of upper and lower pairs. The three pairs of switching elements are connected to the power line of the motor, The switching elements have different characteristics and the switching speed of one switching element is set to be slower than the switching speed of the other switching element.

According to the present invention, when switching elements having different characteristics are arranged on the upper arm and the lower arm of the inverter circuit, an increase in the number of switching elements occurring during switching of the one-side arm elements It is possible to provide a motor control device and an air conditioner that can suppress the recovery current.

1 is a circuit diagram showing a configuration of a motor control device according to a first embodiment of the present invention;
2 is a block diagram showing a configuration example of a motor control unit of the motor control apparatus according to the first embodiment;
3 is a diagram showing a configuration of a gate circuit of an IGBT and a MOSFET which are first and second switching elements of a motor control apparatus according to the first embodiment;
4 shows the collector current Ic at the ordinate and time t at the abscissa, and the collector current Ic when the lower arm element is in the reflux mode and the upper arm element is turned on, Fig.
Fig. 5 is a diagram showing collector current Ic on the vertical axis and time t on the horizontal axis, and collector current Ic when the lower arm element is in the reflux mode and the upper arm element is turned on, for each magnitude of the gate resistance value of the lower arm element.
6 shows the collector current Ic on the vertical axis and the time t on the horizontal axis and the waveform of the collector current Ic when the upper arm element is turned on and the collector emitter voltage of the upper arm element when the lower arm element is in the reflux mode, Fig.
7 is a diagram showing a configuration of a gate circuit of an IGBT and a MOSFET which are the first and second switching elements of the motor control apparatus according to the first embodiment. The gate circuit of the MOSFET uses two resistors and one diode Drawings constructed.
8 is a waveform diagram showing a drive signal of a drive control signal for driving and controlling the upper arm element and a drive signal of a drive control signal for driving and controlling the lower arm element;
9 is a circuit diagram showing a configuration of a motor control device according to a second embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

≪ First Embodiment >

1 is a circuit diagram showing a configuration of a motor control device 100 according to a first embodiment of the present invention. This motor control apparatus 100 will be described by taking as an example the case where drive control of the three-phase synchronous motor 4 is performed using the three-phase inverter circuit 2A.

The motor control apparatus 100 includes a DC power supply 1 and a three-phase inverter circuit (simply referred to as an inverter circuit) (2A) for performing drive control of the three-phase synchronous motor 4 by PWM (Pulse Width Modulation) A current detection unit 5, a DC voltage detection unit 6, a motor control unit 7, and an inverter driving unit 8. [ The DC power supply 1 may be a battery in this example, but a converter circuit (not shown) capable of controlling the output DC voltage may be employed.

The inverter circuit 2A converts the DC power supplied from the DC power supply 1 into the U phase / DC power based on the drive control signal ds which is the pulse width modulated wave signal (PWM signal) Phase synchronous motor (simply referred to as a motor) 4 with the converted three-phase alternating-current power, and the first to sixth (Also referred to simply as elements) 11, 12, 13, 14, 15, and 16, respectively.

These switching elements 11 to 16 are connected to upper and lower arms between a DC bus line PL connected to the positive electrode side of the DC power supply 1 and a DC bus line NL connected to the negative electrode side. IGBTs are connected as the first, third and fifth switching elements (nth switching elements) 11, 13 and 15 to the upper arm and second, fourth and sixth switching elements MOSFETs 12, 14, and 16 are connected to a low power consumption MOSFET. That is, elements having different characteristics are connected to the upper arm and the lower arm.

The switching elements 11, 13 and 15 of the upper arm are also referred to as IGBTs 11 and 13 or 15 or the upper arm elements 11 and 13 and 15 and the switching elements 12, ) Are also referred to as MOSFETs 12, 14, 16 or lower arm elements 12, 14, 16.

The first IGBT 11 and the second MOSFET 12 are connected in series between the direct current buses PL and NL through the first connection point Nd1 and between the collector emitters of the first IGBT 11 and the second direct- The parasitic diode 22 is connected in anti-parallel between the drain of the second MOSFET 12 and the parasitic diode 22 is connected in parallel. The first connection point Nd1 is connected to the U phase power line of the motor 4. [

The third IGBT 13 and the fourth MOSFET 14 are connected in series between the direct current buses PL and NL through the second connection point Nd2 and between the collector emitters of the third IGBT 13 and the fourth direct- The parasitic diode 24 is connected in antiparallel with the drain of the fourth MOSFET 14. The parasitic diode 24 is connected in parallel to the parasitic diode 23, The second connection point Nd2 is connected to the V phase power line of the motor 4. [

The fifth IGBT 15 and the sixth MOSFET 16 are connected in series between the direct current buses PL and NL via the third connection point Nd3 and between the collector emitters of the fifth IGBT 15 and the sixth direct- A parasitic diode 26 is connected in anti-parallel between the drain of the sixth MOSFET 16 and the parasitic diode 26 is connected in parallel. The third connection point Nd3 is connected to the W phase power line of the motor 4. [

The gate circuits 31, 32, 33, 34, 35, and 36 are connected to the gates of the first to sixth switching elements 11 to 16, respectively.

The current detecting section 5 is arranged in proximity to the negative DC bus line NL in accordance with a line current sensor or the like arranged in parallel with the electric wire and detects the circuit current Io flowing from the DC power supply 1 to the inverter circuit 2A. And outputs the detected circuit current Io to the motor control section 7. [

The DC voltage detection unit 6 detects the DC voltage Vd of the DC power supply 1 and outputs it to the motor control unit 7.

The motor control unit 7 reproduces the three-phase alternating currents Iu, Iv and Iw (Iu, Iv and Iw are not shown) flowing in the motor 4 based on the circuit current Io, Phase AC command voltages Vu, Vv, Vw (Vw) applied to the motor 4 based on the three-phase alternating currents Iu, Iv, Iw, the DC voltage Vd and the externally input motor rotational speed command value ir (Note that Vu, Vv, and Vw are not shown), calculates the amplitude value Vs (where Vs is not shown) of the sinusoidal voltage applied to the motor 4, (8).

2, the motor control unit 7 includes a CPU (Central Processing Unit) 101a, a ROM (Read Only Memory) 101b, a RAM (Random Access Memory) 101c, a storage device HDD: Hard Disk Drive, etc.) 101d, and these components 101a to 101d are connected to the bus 102. [ In such a configuration, for example, the CPU 101a executes the program 101f written in the ROM 101b to realize the control such as the calculation of the motor control unit 7 described above.

The inverter driving unit 8 shown in Fig. 1 receives the three-phase AC command voltages Vu, Vv, Vw (not shown) and the amplitude value Vs (not shown) of the predetermined sinusoidal voltage, which are the calculation results in the motor control unit 7 And the drive control signal ds for performing the switching control (PWM control) of the first to sixth switching elements 11 to 16 to the gate circuits 31 to 36 of the inverter circuit 2A Output.

3 is a diagram showing the configurations of the gate circuits 31 and 32 of the IGBT 11 and the MOSFET 12 which are the first and second switching elements. The gate circuit 31 shown in Fig. 3 represents the gate circuits 31, 33 and 35 of the first, third and fifth switching elements 11, 13 and 15, ) Represent the gate circuits 32, 34, and 36 of the second, fourth, and sixth switching elements 12, 14, and 16, respectively. Hereinafter, the inverter circuit 2A will be described on behalf of the gate circuits 31 and 32 shown in Fig.

The gate circuit 31 includes a gate resistor R1 connected between the gate of the IGBT 11 and the inverter drive unit 8, a diode D1 whose anode is connected to the gate thereof, And a gate resistor R2 connected between the inverter driving unit 8 and the inverter driving unit 8. The gate circuit 32 includes a gate resistor R3 connected between the gate of the MOSFET 12 and the inverter driver 8.

The gate resistor R1 is used when the IGBT 11 is turned on. That is, as indicated by the arrow Yon, the current flows from the inverter driving unit 8 to the gate of the IGBT 11 while regulating the current to a predetermined resistance value. As a result, charges are charged in the gate and the IGBT 11 is turned on.

The diode D1 draws out the electric charge accumulated in the gate when the IGBT 11 is turned off, and the gate resistor R2 removes the drawn electric charge. That is, when the IGBT 11 is turned off, the charge stored in the gate is pulled out from the diode D1 as indicated by the arrow Yoff and passes through the gate resistor R2, whereby the charge is removed, (11) is completely turned off.

3, the gate circuit 32 is composed only of the gate resistor R3, but a plurality of resistors and diodes may be combined as in the gate circuit 31. [ The gate circuits 31 and 32 are not limited to the number of gate resistors or the number of diodes.

4 shows the collector current Ic when the vertical axis is the collector current Ic and the horizontal axis is the time t and the upper arm element 11 is turned on when the lower arm element 12 is in the reflux mode and the collector current Ic when the upper arm element 11 is turned on (The resistance value of the gate resistor R1) R1N.

In Fig. 4, the magnitude of the gate resistance value R1N is represented by R1N among R1N and R1N. These sizes are sizes for the gate resistance value of the MOSFET 12 of the lower arm at the time of off (the resistance value of the gate resistor R3) R3N. That is, as the gate resistance value R1N of the IGBT 11 of the upper arm becomes larger with respect to the gate resistance value R3N when the MOSFET 12 of the lower arm is turned off, R1N is expressed as R1N, which is larger than R1N.

When the IGBT 11 of the upper arm is turned on by the switching operation in the reflux mode in which the MOSFET 12 of the lower arm shown in Fig. 3 flows in the forward direction to the parasitic diode 22, A reverse bias voltage is applied to the parasitic diode 22 of FIG. Thereby, a reverse reverse current flows in the parasitic diode 22. As a result, the collector current Ic1, Ic2, Ic3 of the size as shown in Fig. 4 flows in the IGBT 11. Fig.

The collector current Ic1 flows when the gate resistance value R1N of the IGBT 11 of the upper arm is small (R1N small) and the collector current Ic2 flows when the gate resistance R1N is middle (among R1N) Ic3 flows when the gate resistance R1N is large (R1N large). The maximum values (maximum peak values) of the collector current Ic1, Ic2, and Ic3 are represented by arrows h1, h2, and h3, respectively.

As described above, as the collector current Ic becomes larger as indicated by Ic3, Ic2, and Ic1, a large reverse recovery current flows into the parasitic diode 22 of the MOSFET 12 of the lower arm. As a result, a short circuit current flows between the collector of the IGBT 11 of the upper arm and the source of the lower arm element 12. If this short-circuit current becomes excessive, problems such as an increase in noise and a breakdown of the device occur.

Therefore, in the present embodiment, the gate resistance value R1N of the upper arm at the time of turning on the IGBT 11 of the upper arm is extremely large (R1N versus the gate resistance value R3N when the MOSFET 12 of the lower arm is off) The reverse recovery current flowing through the parasitic diode 22 is reduced by suppressing the collector current (arrow h3) as indicated by Ic3 in FIG.

Here, IGBTs are used for all six elements in a general inverter circuit, and the magnitude of the gate resistance value is set to the same value for all six elements. However, when a pair of switching elements having different characteristics such as an IGBT and a MOSFET are arranged on the upper and lower arms and a device having a large reverse recovery current of a parasitic diode such as an SJ-MOS having a small normal loss is employed, There is a problem that the reverse recovery current generated in the diode becomes excessive.

When the IGBT 11 of the upper arm performs the switching operation and the short-circuit current flows to the upper and lower arms while the MOSFET 12 of the lower arm is in the reflux mode, the return current existing between the drain gates of the MOSFET 12 of the lower arm And the short-circuit current is also classified into the gate of the MOSFET 12. In this classification, a so-called self-turn-on phenomenon occurs in which the gate of the MOSFET 12, which should be in the off state, is turned on.

As the gate resistance value R3N of the MOSFET 12 is larger, the self-turn-on phenomenon becomes longer as the reverse recovery time becomes longer. As the degree of the self-turn-on phenomenon increases, the reverse recovery current generated in the parasitic diode 22 is adversely affected. As a result, there arises a problem that the switching loss increases and the heat generation of the device increases. However, if the gate resistance value R3N of the MOSFET 12 is excessively reduced in order to prevent the increase of the switching loss, the di / dt at the time of the disappearance of the reverse recovery current becomes large, and the noise becomes large.

Therefore, in the first embodiment, the degree of the self-turn-on phenomenon is reduced by making the gate resistance R3N of the MOSFET 12 of the lower arm equal to or smaller than a predetermined resistance value (predetermined resistance value). Note that the predetermined resistance value is a resistance value in which the self-turn-on phenomenon is such that the heat generation of the device due to the switching loss caused by the self-turn-on phenomenon is not affected by the device and the noise is not excessively increased.

5 shows the collector current Ic when the vertical axis is the collector current Ic and the horizontal axis is the time t and the upper arm element 11 is turned on when the lower arm element 12 is in the reflux mode, And the resistance value R3N. In Fig. 5, the magnitude of the gate resistance value R3N is represented by R3N among R3N, R3N, and these magnitudes are sizes for a predetermined resistance value (predetermined resistance value). That is, as the gate resistance value R3N of the lower arm element 12 increases, R3N and R3N become larger as R3N.

Ic4, Ic5 and Ic6 all have the same maximum peak value, but the collector current Ic5, T1, which is the longest collector current Ic4 as shown by the arrow width T3, And the collector current Ic6 that is shown in Fig. T1, T2, and T3 are reverse recovery times of the parasitic diode 22 for each collector current Ic4, Ic5, Ic6.

The collector current Ic4 flows when the gate resistance value R3N of the MOSFET 12 of the lower arm is large (R3N versus) and the collector current Ic5 flows when the gate resistance R3N is middle (among the R3N) Ic6 flows when the gate resistance R3N is small (R3N small).

That is, as the gate resistance value R3N decreases from R3N to R3N to R3N, the reverse recovery time becomes shorter to T3, T2, and T1. It is known that as the reverse recovery time increases to T1, T2, and T3, the switching loss of the switching device increases. Therefore, when the gate resistance value R3N is the smallest (R3N small), the collector current Ic6 flows in the shortest reverse recovery time T1, and the switching loss becomes the smallest in this case. In the case of noise, R3N is the worst case.

6 shows the relationship between collector currents Ic11 and Ic12 when the vertical axis is collector current Ic and the horizontal axis is time t and when the lower arm element 12 is in the reflux mode and the upper arm element 11 is turned on, And the waveform Vce1 of the collector-emitter voltage Vce of the voltage Vce in accordance with the ratio of the time constant.

The ratio of the time constants is the on time constant of the upper arm element 11 with respect to the time constant when the lower arm element 12 is turned on and the time constant of the lower arm element 12 with respect to the time constant of the lower arm element 12, The collector current Ic11 flows when the time constant of the transistor 11 is the same (1 time), and the collector current Ic12 flows when the time constant of the transistor 11 is three times. Further, in the case of 1x and 3x, the voltage waveform between the collector emitter of the upper arm element 11 becomes like the waveform indicated by Vce1. The time constant of each of the elements 11 and 12 to be described later is a time constant when each of the elements 11 and 12 is on and even if it is expressed simply as a time constant, it indicates a time constant of on time.

The maximum peak value of the collector current Ic11 is denoted by h11, the reverse recovery time is denoted by T11, the maximum peak value of the collector current Ic12 is denoted by h12, and the reverse recovery time is denoted by T12. That is, the maximum peak value h11 of the collector current Ic11 is higher than the maximum peak value h12 of the collector current Ic12 by a value indicated by the arrow Y1, and the reverse recovery time T11 of the collector current Ic11 is at least 3 It can be seen that it is longer than twice.

From these relationships, when the time constant of the IGBT 11 of the upper arm is three times the time constant of the MOSFET 12 of the lower arm, the maximum peak value changes from h11 to h12 And the reverse recovery time is significantly shortened from T11 to T12 (approximately three times or more shortened), which is improved.

However, the time constant Rg · Cg of the IGBT 11 of the upper arm in the case of three times is set to Rg · Cg = 400 ran. This setting will be described. As shown in Fig. 3, there is a capacitance component C1 between the gate collectors of the IGBT 11 of the upper arm and a capacitance component C2 between the gate sources of the MOSFET 12 of the lower arm. Therefore, in the IGBT 11 of the upper arm, the time constant is determined by the gate resistance value R1N and the capacitance value C1N (not shown) of the capacitance component C1, and in the MOSFET 12 of the lower arm, The time constant is determined by the capacitance value C2N (not shown) of the component C2.

The gate resistance value R1N of the IGBT 11 of the upper arm is made to be three times the gate resistance value R3N of the MOSFET 12 of the lower arm so that the time constant of the IGBT 11 Is three times the time constant of the MOSFET (12).

As described above, by setting the time constant of the IGBT 11 of the upper arm to three times or more the MOSFET 12 of the lower arm, it is possible to prevent the MOSFET 12 from performing the switching operation when the IGBT 11 performs the switching operation during the reflux mode The reverse recovery current of the parasitic diode 22 of the MOSFET 12 can be suppressed. This suppression makes it possible to suppress the short-circuit current flowing in the upper and lower arms.

In other words, by making the switching speed of the IGBT 11 of the upper arm extremely lower than the switching speed of the MOSFET 12 of the lower arm, when the IGBT 11 performs the switching operation during the reflux mode of the MOSFET 12 The reverse recovery current with respect to the MOSFET 12 to be generated can be suppressed, the short-circuit current can be suppressed, and the switching loss can be suppressed.

However, the time constant of the upper arm element 11 is set to be three times the time constant of the lower arm element 12. However, the time constant of the lower arm element 12 may be set to be 3 times as long as the desired peak value to be suppressed and the reverse recovery time 4 times, 5 times, ... The reverse recovery current can be suppressed, the short-circuit current can be suppressed, and the switching loss can be suppressed.

As described above, if the reverse recovery current can be suppressed and the switching loss can be suppressed, the SJ-MOS can be used for the MOSFET 12 of the lower arm. As described above, the SJ-MOS has a small normal loss, but a large reverse recovery current. However, as described above, since the time constant of the IGBT 11 of the upper arm can be increased and the reverse recovery current can be suppressed, it is possible to introduce the effect of reducing the normal loss by using the SJ-MOS.

In the above example, the capacitance values C1N and C2N of the upper and lower arms are substantially the same, and the gate resistance R1N of the IGBT 11 of the upper arm is tripled. However, when the capacitance values C1N and C2N of the upper and lower arms are different, the gate resistance values R1N and R3N of the upper and lower arms are varied in accordance with these different capacitance values. As a result, the gate resistance value R1N of the IGBT 11 of the upper arm is 3 times or more. Further, it is not limited to three times or more, and even if the number is smaller than that, it is possible to suppress the reverse recovery current so that the short-circuit current flowing in the upper and lower arms can be suppressed.

However, the gate resistance values R1, R3 may be variable resistors, and the gate resistance values R1N, R3N may be variably controlled so as to obtain a desired current value while measuring the reverse recovery current.

7, when the gate resistors R3 and R4 and the diode D2 are used as the gate circuit of the lower arm, the gate resistance of the off- , The gate resistance value R1N of the IGBT 11 of the upper arm is set to be three times or more, that is, the time constant of the IGBT 11 is set to be three times or more of the time constant of the MOSFET 12.

The gate resistance Rl of the upper arm gate circuit 31 is set to be in the range of 300 to 540 Ω and the gate resistance R3 of the lower arm gate circuit 32 or the gate The gate resistance R4 of the circuit 32a may be set in the range of 56 to 200 OMEGA.

8 is a waveform diagram showing the drive signal 11DV of the drive control signal ds for driving and controlling the upper arm element 11 and the drive signal 12DV of the drive control signal ds for driving and controlling the lower arm element 12 .

The configuration of the first embodiment is such that the switching speed of the upper arm element 11 is extremely reduced to three times or more as described above. As a result, as shown in Fig. 8, the on-timing of the IGBT 11 of the upper arm is delayed by the delay time? T before the speed is lowered. The gate voltage indicated by the curve 11G1 is a case where the gate resistance R1N is small (R1N small). The gate voltage indicated by the curve 11G2 is extremely larger (R1N versus) than when the gate resistance R1N is small (R1N small). In this manner, by making the ratio (R1N), the rise time of the gate voltage 11G2 is delayed by? T.

The dead time td until the upper arm element 11 is turned on becomes longer by? T than the design value after the lower arm element 12 is turned off. Therefore, in the first embodiment, the value td-t obtained by subtracting the delay amount? T of the actual dead time from the design dead time td is employed as the dead time. Thereby, the inverter circuit 2A can be driven without deteriorating the deformation of the current waveform.

≪ Effects of First Embodiment >

As described above, the motor control device 100 of the first embodiment includes the inverter circuit 2A that converts DC power to AC power and controls drive of the motor 4 with this AC power. The inverter circuit 2A is connected to the upper arm and the lower arm between the bus lines PL and NL to which the DC power is supplied, and the n-th and m-th switching elements 11 to 16, Three pairs. The three pairs of the n-th and m-th switching elements 11 to 16 are connected to the power line of the motor 4 and the n-th and m-th switching elements (for example, 11 and 12) And the switching speed of the nth switching element 11 is set to be slower than the switching speed of the mth switching element 12. [ The switching speed of the IGBT 11 is set to be slower than the switching speed of the MOSFET 12 by a predetermined value or less Respectively.

According to this configuration, by making the switching speed of the IGBT 11 of the upper arm slower than the switching speed of the MOSFET 12 of the lower arm by a predetermined value or more, the IGBT 11 performs the switching operation It is possible to suppress the reverse recovery current with respect to the MOSFET 12 that occurs when the MOSFET 12 is operated. As a result, a short-circuit current flowing in the upper and lower arms can be suppressed. That is, for suppressing the reverse recovery current, the switching speed of one IGBT 11, which is a pair of the inverter circuits 2A, may be made slower than a predetermined value more than the other MOSFET 12. Therefore, the reverse recovery current generated at the time of switching the one-side arm element 11 can be suppressed so as not to increase the number of circuit components and complicate the circuit operation control.

The ON time constants of the pair of IGBTs 11 are set to be larger than the time constants of the other MOSFETs 12 by a predetermined value or more. More specifically, the time constant of the IGBT 11 is set to be three times larger than the time constant of the MOSFET 12. In addition, the time constant of the IGBT 11 was set to 400. Or more.

According to this configuration, by setting the time constant of one IGBT 11 to be equal to or larger than a predetermined value or three times or more than the time constant of the other MOSFET 12, The reverse recovery current with respect to the MOSFET 12 which occurs when the IGBT 11 performs the switching operation during this reflux mode can be suppressed and thus the short-circuit current flowing in the upper and lower arms can be suppressed. That is, the time constant of one pair of IGBTs 11 may be set to be larger than a predetermined value more than the other MOSFET 12, so that the increase in the number of circuit components and the complication of circuit operation control , It is possible to suppress the reverse recovery current generated at the time of switching the one-side arm element 11.

In addition, the gate resistance value of one pair of IGBTs 11 is set to be larger than the gate resistance value of the other MOSFET 12 by a predetermined value or more. According to this configuration, since the collector current Ic flowing through the IGBT 11 is reduced, the reverse recovery current with respect to the MOSFET 12 is reduced, and a short-circuit current flowing in the upper and lower arms can be suppressed.

Further, the gate resistance value of the MOSFET 12 is set to be smaller than a predetermined value. According to this configuration, since the gate resistance value of the MOSFET 12 is set to be smaller than the predetermined value, the reverse recovery time with respect to the MOSFET 12 is shortened, and the degree of the self turn- do. This reduction can suppress the switching loss of the MOSFET 12 and can suppress the heat generation of the MOSFET 12. [ In addition, the influence of noise is not excessively large.

The gate resistor R1 of the IGBT 11 and the gate resistor R3 of the MOSFET are used as variable resistors to variably control their gate resistance values R1N and R3N. As a result, for example, the gate resistance values R1N and R3N can be variably controlled and set to a desired current value while measuring the reverse recovery current.

The dead time of the inverter circuit 2A is set to a value obtained by subtracting the time? T of the delay time of the switching speed of the IGBT 11 from the design dead time td.

According to this configuration, the following effects can be obtained. If the switching speed of the IGBT 11 is made slower than the switching speed of the MOSFET 12 by a predetermined value or more, the on timing of the IGBT 11 is delayed by the delay time? T as compared with the on timing of the design before the slowdown. As a result, the dead time td during turning on of the IGBT 11 after the MOSFET 12 is turned off becomes larger by Δt than the designed value. Therefore, by setting the value td -? T obtained by subtracting the time? T of the delay time of the switching speed of the IGBT 11 from the dead time td in the design as the dead time, the inverter circuit 2A, without deteriorating the deformation of the current waveform, Can be driven.

Further, the MOSFET 12 was made to be an SJ-MOS. According to this configuration, since the normal loss is smaller in the SJ-MOS, the motor 4 can be driven with high efficiency.

≪ Second Embodiment >

9 is a circuit diagram showing a configuration of the motor control device 200 according to the second embodiment of the present invention. The motor control device 200 of the second embodiment differs from the motor control device 100 of the embodiment only in the configuration of the inverter circuit 2B. Therefore, the description of other components will be omitted in due course.

The inverter circuit 2B of the second embodiment differs from the inverter circuit 2A of the first embodiment in that the constituent elements of the upper arm and the lower arm are inverted. 9, the MOSFETs 12, 14, 16, the parasitic diodes 22, 24, 26 and the gate circuits 32, 34, 36 are used for the upper arm, The IGBTs 11, 13 and 15, the reflux diodes 21, 23 and 25 and the gate circuits 31, 33 and 35 are used. The gate circuits 32, 34, and 36 of the lower arm may be configured using two resistors and one diode as the gate circuit 32a of FIG.

In the case of the inverter circuit 2B having this configuration, the time constant of the IGBT 11 on the lower arm with respect to the time constant when the MOSFET 12 of the upper arm is ON is three times or more. However, the ON time constants of the IGBT 11 of the lower arm are set to 4 times, 5 times, and 10 times, respectively, in accordance with the desired peak value to be suppressed and the reverse recovery time. The reverse recovery current can be suppressed and the short-circuit current can be suppressed.

In the second embodiment, contrary to the first embodiment, the delay time of the actual dead time? T is considered in consideration of the fact that the on speed of the IGBT 11 of the lower arm is slowed down. That is, the value of td -? T obtained by subtracting? T from the normal dead time td from the upper arm off to the dead time during the lower arm on is employed. Thereby, the drive of the inverter can be performed without deteriorating the deformation of the current waveform.

≪ Effects of Second Embodiment >

According to the motor control apparatus 200 according to the second embodiment, in the inverter circuit 2B, the constituent elements including the switching elements 11 and 12 of the upper and lower arms are vertically inverted. However, The same effects as those of the motor control apparatus 100 according to the first embodiment can be obtained.

≪ Application example of first and second embodiments >

Any one of the motor control apparatuses 100 and 200 according to the first and second embodiments may be mounted on an air conditioner not shown and any one of the motor control apparatuses 100 and 200 may be mounted on an air conditioner And is applied to drive control of an outdoor fan motor (not shown).

The air conditioner can greatly improve the APF (Annual Performance Factor), which is an index showing the energy saving performance, by improving the efficiency in the low input region (middle rated region). The term " middle area " means an operation area in which the operation time of the air conditioner is the longest in the year, and the rated area is an area in which the operation is performed in accordance with the air conditioning load.

In the motor control apparatuses 100 and 200, a MOSFET using a MOSFET having a smaller loss than an IGBT in a low input region is used as a switching element. Therefore, by applying the motor control devices 100 and 200, an air conditioner having high efficiency and high energy saving performance can be realized.

In addition, it is possible to realize an air conditioner having high efficiency and high energy saving performance even if any one of the motor control devices 100 and 200 is applied to drive control of a compressor (not shown) of the air conditioner.

The present invention is not limited to the above-described embodiment, but includes various modifications. For example, the above-described embodiments have been described in detail in order to facilitate understanding of the present invention and are not necessarily limited to those having all the configurations described above. It is also possible to replace some of the configurations of the embodiments with those of the other embodiments, and the configurations of the other embodiments may be added to the configurations of the other embodiments. In addition, it is possible to add, delete, or substitute another configuration with respect to a part of the configuration of each embodiment.

The above-described components, functions, processing units (control units), processing means, and the like may be implemented in hardware by designing a part or all of them with, for example, an integrated circuit. Further, the above-described respective configurations, functions, and the like may be realized in software by analyzing and executing a program that realizes the respective functions of the processor. Information such as a program, a table, and a file that realize each function may be recorded in a memory, a recording device such as a hard disk or a solid state drive (SSD), an IC (Integrated Circuit) card, a SD (Secure Digital memory) Digital Versatile Disc) or the like.

In addition, the control lines and information lines indicate that they are considered to be necessary for explanation, and it is not necessarily the case that all control lines and information lines are shown on the product. In practice, it can be considered that almost all configurations are connected to each other.

1: DC power source
2A, 2B: Three-phase inverter circuit (inverter circuit)
4: 3 phase synchronous motor (motor)
5:
6: DC voltage detector
7: Motor control section
8:
21, 23, 25: reflux diode
22, 24, 26: parasitic diodes
11, 13, 15: IGBT (switching element)
12, 14, 16: MOSFET (switching element)
31, 33, 35: IGBT gate circuit
32, 34, 36, 32 (a): MOSFET gate circuit
100, 200: Motor control device
R1, R2, R3, R4: gate resistors
D1, D2: Diode
Io: Circuit current
PL: Definition DC bus
NL: negative DC bus
ds: drive control signal
ir: Motor speed command value

Claims (11)

delete delete And an inverter circuit for converting DC power into AC power and performing drive control of the motor with the converted AC power,
The inverter circuit includes:
And three pairs of the n-th and m-th switching elements connected to the upper arm and the lower arm between the busbars of the unit to which the DC power is supplied, the pair of upper and lower m- The nth and mth switching elements to be paired all have different characteristics and the switching speed of the nth switching element is set to be slower than the switching speed of the mth switching element,
The nth switching element is an IGBT, the mth switching element is a MOSFET,
Wherein the time constant of the IGBT is set larger than a predetermined value by a predetermined value greater than a time constant when the MOSFET is off. The method of claim 3,
Wherein the time constant when the IGBT is on is set to be three times larger than the time constant when the MOSFET is off. The method of claim 3,
And the time constant of the IGBT is 400 ㎱ or more. The method of claim 3,
Wherein a gate resistance value of the IGBT is set to be larger than a gate resistance value of the MOSFET by a predetermined value or more. The method according to claim 6,
Wherein a gate resistance value of the MOSFET is set to be smaller than a predetermined value. The method according to claim 6,
Wherein each of the resistors for defining the gate resistance value of the IGBT and the gate resistance value of the MOSFET is a variable resistor and the gate resistance value thereof is variably set. The method of claim 3,
Wherein the dead time of the inverter circuit is set to a value obtained by subtracting a delay time of the switching speed of the IGBT from a design dead time. The method of claim 3,
Characterized in that the MOSFET is a super-junction MOSFET. An air conditioner comprising the motor control device according to any one of claims 3 to 10.

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