JP2008043048A - Inverter controller for driving motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inverter controller for driving a motor which satisfies even the harmonic regulation of a power supply current while being achieved in the reduction of a size, weight and cost. <P>SOLUTION: The inverter controller for driving a motor is equipped with a rectifying circuit 7 which is constituted of an extremely small capacity reactor 11 connected to a diode bridge 7a and its AC input side or the DC output side, an inverter 2, and an extremely small capacity capacitor 12 connected between the bus lines of the inverter 2. The control unit 6 for controlling the motor 3 and the inverter 2 is provided with a phase current converting section 20 which reproduces the current value of each phase of the motor 3 based on the bus line current of the inverter 2 when the voltage value to applied to the inverter 2 exceeds a setting value and with a PWM signal generating part 9 which generates the PWM signal to control the inverter 2 from the current value of each phase obtained by the phase current converting section 20 and the voltage value to be applied to the inverter 2. The inverter controller though reduced in size, weight and cost, can control the motor phase current correctly without incorrect recognition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an inverter control device for driving a motor.

  As a general motor drive inverter control device used in a general-purpose inverter or the like, the one shown in FIG. 10 is well known (see, for example, Non-Patent Document 1).

  In FIG. 10, a main circuit 115 of a conventional motor drive inverter control device is composed of a DC power supply device 113, an inverter 2 and a motor 3. The DC power supply device 113 is composed of an AC power supply 1 and a rectifier circuit. 7, a smoothing capacitor 112 that stores electric energy for the DC voltage source of the inverter 2, and a power factor improving reactor 111 of the AC power source 1.

  On the other hand, in the control calculation unit 116, the PWM signal generation unit 9 that generates each phase voltage command value of the motor 3 based on the speed command of the motor 3 given from the outside, and each phase generated by the PWM signal generation unit 9 The base driver 10 is configured to PWM control the inverter 2 based on the voltage command value.

  Here, when the AC power source 1 is 220 V (power frequency 50 Hz), the input of the inverter 2 is 1.5 kW, and the smoothing capacitor 112 is 1500 μF, the harmonic component of the power source current when the power factor improving reactor 111 is 5 mH and 20 mH. 11 shows the relationship between the power and the order with respect to the power supply frequency.

  FIG. 11 is shown together with the IEC (International Electrotechnical Commission) standard. When the power factor improving reactor 111 is 5 mH, the third harmonic component greatly exceeds that of the IEC standard. It can be seen that in the case of 20 mH, the IEC standard is cleared in the harmonic components up to the 40th order.

  Therefore, it is necessary to take measures such as further increasing the inductance value of the power factor improving reactor 111 in order to clear the IEC standard even when the load is high, increasing the size and weight of the motor drive inverter control device, In addition, there is a disadvantage that the cost is increased.

  Thus, for example, a DC power supply device as shown in FIG. 12 has been proposed as a DC power supply device that suppresses an increase in the inductance value of the power factor improving reactor 111 and achieves a reduction in power harmonic components and an increase in power factor. (For example, refer to Patent Document 1).

  In FIG. 12, the power supply voltage of the AC power supply 1 is applied to the AC input terminal of the full-wave rectifier circuit 120 formed by bridge-connecting the diodes D1 to D4, and the output is charged to the intermediate capacitor C via the reactor Lin. The electric charge of the intermediate capacitor C is discharged to the smoothing capacitor CD, and a DC voltage is supplied to the load resistor RL.

  In this case, the transistor Q1 is connected to the positive and negative DC current path connecting the load side of the reactor Lin and the intermediate capacitor C, and the transistor Q1 is driven by the base drive circuit G1.

Further, pulse generators I1 and I2 for applying a pulse voltage to the base drive circuit G1 and a dummy resistor Rdm are further provided. The pulse generators I1 and I2 each detect a zero cross point of the power supply voltage (see FIG. And a pulse current circuit (not shown) for supplying a pulse current to the dummy resistor Rdm until the instantaneous value of the power supply voltage becomes equal to the voltage across the intermediate capacitor C from the detection of the zero cross point.

  Here, the pulse generation circuit I1 generates a pulse voltage in the first half of the half cycle of the power supply voltage, and the pulse generation I2 generates a pulse voltage in the second half of the half cycle of the power supply voltage.

  When the transistor Q1 is turned on and a current is forced to flow through the reactor Lin, a backflow prevention diode D5 is connected so that the charge of the intermediate capacitor C is not discharged through the transistor Q1, and further, the intermediate capacitor C A backflow prevention diode D6 and a reactor Ldc for enhancing the smoothing effect are connected in series to a path for discharging the electric charge of the current to the smoothing capacitor CD.

With the above configuration, the transistor Q1 is turned on in part or all of the phase interval in which the instantaneous value of the power supply voltage does not exceed the voltage across the intermediate capacitor C. Component reduction and higher power factor can be achieved.
JP-A-9-266684 Inverter Drive Handbook Editorial Committee, “Inverter Drive Handbook”, published by Nikkan Kogyo Shimbun, first edition in 1995

  However, in the configuration of the conventional DC power supply of the inverter control device for driving a motor, the smoothing capacitor CD having a large capacity and the reactor Lin (Patent Document 1 describes a simulation result at 1500 μF and 6.2 mH). The intermediate capacitor C, the transistor Q1, the base drive circuit G1, the pulse generation circuits I1 and I2, the dummy resistor Rdm, and the backflow prevention diodes D5 and D6 are enhanced. By providing the reactor Ldc, there has been a problem of incurring an increase in cost associated with an increase in the size of the inverter control device for driving the motor and an increase in the number of components.

  The present invention solves such a conventional problem, and an object of the present invention is to provide a small, light, and low-cost motor drive inverter control device that suppresses harmonic components of a power supply current.

In order to solve the above-described conventional problems, an inverter control apparatus for driving a motor according to the present invention includes a rectifier circuit that receives an AC power supply, an inverter that converts DC power obtained by the rectifier circuit into AC power, A motor driven by an inverter, a control unit for controlling the operation of the inverter, a bus current detector for detecting a current flowing in the bus of the inverter, a very small capacitor connected between the buses of the inverter, An inverter input voltage detection unit that detects an applied voltage value of the inverter, and the rectifier circuit includes a diode bridge and a very small capacity reactor connected to an AC input side or a DC output side of the diode bridge. The controller detects the bus current detector when the applied voltage value of the inverter is greater than or equal to an arbitrary set value. A phase current converter that reproduces the current value of each phase of the motor based on the current value, and a current value of each phase of the motor obtained by the phase current converter and the inverter input voltage detector A PWM signal generator that generates a PWM signal for controlling the inverter from the applied voltage value is provided. By using a small-capacitance capacitor and reactor, the motor phase current can be accurately measured while being small, lightweight, and low cost. It is possible to realize a high-performance motor drive inverter control device that can be controlled without erroneous recognition.

  The motor drive inverter control device of the present invention can realize a small, light, and low cost motor drive inverter control device by using a small-capacity reactor and a small-capacitance capacitor, and uses an expensive current sensor or the like. Since the motor phase current can be accurately recognized without the need, sensorless vector control of the brushless motor is possible, and the system can be reduced in noise and vibration by energizing the motor current in a sine wave form.

  A first aspect of the present invention is a rectifier circuit using an AC power supply as input, an inverter for converting DC power obtained by the rectifier circuit into AC power, a motor driven by the inverter, and a control for controlling the operation of the inverter. A bus current detector that detects a current flowing in the bus of the inverter, a very small capacitor connected between the buses of the inverter, and an inverter input voltage detector that detects an applied voltage value of the inverter The rectifier circuit includes a diode bridge and a very small capacity reactor connected to an AC input side or a DC output side of the diode bridge, and an applied voltage value of the inverter is arbitrarily set in the control unit. Phase current converter that reproduces the current value of each phase of the motor based on the current value detected by the bus current detector when the value is equal to or greater than the set value A PWM signal generation unit that generates a PWM signal for controlling the inverter from the current value of each phase of the motor obtained by the phase current conversion unit and the applied voltage value obtained by the inverter input voltage detection unit; Realizing a high-performance inverter controller for driving a motor that can control the motor phase current accurately and without misrecognition while using a small-capacity capacitor and reactor. Can do.

  In a second aspect of the invention, in particular, in the phase current converter of the first aspect of the invention, the current value of each phase of the motor when the applied voltage value to the inverter is less than an arbitrary set value, It is estimated from the amount of time series change of the current value of each phase of the motor when it is above the set value. The applied voltage value to the inverter is very small so that the motor phase current cannot be detected by the bus current detector. Even in such a case, the motor phase current can be reproduced and high-quality driving can be maintained.

  In the third aspect of the invention, in particular, the phase current conversion unit of the first or second aspect of the invention performs a filter calculation of the current value of each phase of the motor. Even if the set value determination is incorrect, the motor phase current can be reproduced and high-quality driving can be maintained.

  According to a fourth aspect of the invention, in particular, the reactor and the resonance frequency of the small-capacity reactor of any one of the first to third aspects and the small-capacitance capacitor are set to be higher than 40 times the frequency of the AC power supply. The capacitor combination is determined, and the harmonic component of the power supply current can be suppressed and the IEC standard can be reliably cleared.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a system configuration diagram of an inverter control device for driving a motor according to the first embodiment of the present invention.

The inverter control apparatus for driving a motor in the present embodiment includes a diode bridge 7 that converts AC power from an AC power source 1 into DC power, a rectifier circuit 7 that includes a reactor 11 having a small capacity of 2 mH or less, and a small capacity that is 100 μF or less. Capacitor 12 and brushless motor 3
An inverter 2 that generates and outputs a drive voltage to be supplied to and a control unit 6 that controls the inverter 2 are provided.

  The motor 3 includes a stator 4 to which three-phase windings 4u, 4v, 4w Y-connected around a neutral point are attached, and a rotor 5 to which a magnet is attached. The U-phase terminal 8u is connected to the non-connected end of the U-phase winding 4u, the V-phase terminal 8v is connected to the non-connected end of the V-phase winding 4v, and the W-phase terminal 8w is connected to the non-connected end of the W-phase winding 4w. ing.

  The inverter 2 has a half-bridge circuit composed of a pair of switching elements for three phases for the U phase, the V phase, and the W phase. A pair of switching elements of the half-bridge circuit are connected in series between the high-voltage side end and the low-voltage side end of the capacitor 12, and a DC voltage is applied to the half-bridge circuit.

  The U-phase half-bridge circuit includes a high-voltage side (upper arm) switching element 13u and a low-voltage side (lower arm) switching element 13x, and the V-phase half-bridge circuit includes a high-voltage side switching element 13v and a low-voltage side switching element 13v. The W-phase half-bridge circuit includes a high-voltage side switching element 13w and a low-voltage side switching element 13z.

  In addition, free wheel diodes 14u, 14v, 14w, 14x, 14y, and 14z are connected in parallel with the switching elements (13u to 13z).

  Terminals 8u, 8v, and 8w of the motor 3 are connected to an interconnection point between the switching element 13u and the switching element 13x in the inverter 2, an interconnection point between the switching element 13v and the switching element 13y, and an interconnection point between the switching element 13w and the switching element 13z. Each is connected.

  The DC voltage applied to the inverter 2 is converted into a three-phase AC voltage by the switching operation of the switching elements 13u to 13z in the inverter 2, and the motor 3 is thereby driven.

  The bus 2 of the inverter 2 is provided with a bus current detector 15 for detecting a current flowing through the bus.

  The control unit 6 includes a PWM signal generation unit 9, a base driver 10, a phase current conversion unit 20, a motor phase estimation unit 17, a rotor speed detection unit 18, and a current command calculation unit 19.

  The phase current converter 20 observes the inverter bus current flowing through the bus current detector 15 and converts the inverter bus current into the phase current of the motor 3. The phase current converter 20 actually detects the current only for a predetermined period from when the inverter bus current changes.

  The motor phase estimation unit 17 outputs the phase current of the motor 3 converted by the phase current conversion unit 20, the output voltage calculated by the PWM signal generation unit 9, and the inverter 2 detected by the inverter input voltage detection unit 16. The phase of the motor 3 is estimated from the information on the applied voltage.

  Further, the rotor speed detection unit 18 estimates the speed of the motor 3 from the estimated phase.

In the current command calculation unit 19, the current command execution value to be energized so that the rotor speed becomes the target speed based on deviation information between the estimated speed of the rotor 5 of the motor 3 and the target speed given from the outside. Is derived using PI calculation or the like, and the PWM signal generation unit 9 generates a PWM signal for driving the motor 3.

  The PWM signal is output to the base driver 10, and the switching elements 13u, 13v, 13w, 13x, 13y, and 13z are driven according to the PWM signal to generate a sinusoidal alternating current.

  Thus, in the present embodiment, the sine wave drive of the motor 3 is realized by flowing a sine wave phase current.

  Next, how the phase current of the motor 3 appears in the current flowing through the inverter bus will be described with reference to FIGS.

  FIG. 2 is a diagram showing the state of the phase current flowing through each phase winding of the motor 3 and the direction of the current flowing through each phase winding in each section of the electrical angle every 60 °.

  In FIG. 2, in the section where the electrical angle is 0 to 60 °, the U-phase winding 4u and the W-phase winding 4w are connected to the neutral point from the unconnected ends 8u and 8w, and the V-phase winding 4v is Current flows from the sex point toward the non-connection end 8v. In the section of electrical angle of 60 to 120 °, the U-phase winding 4u is directed from the non-connection end 8u toward the neutral point, and the V-phase winding 4v and the W-phase winding 4w are not neutral from the neutral point. Current flows toward the connection ends 8v and 8w. Hereinafter, it is shown that the state of the phase current flowing through the windings of each phase changes every electrical angle of 60 °.

  For example, consider a case in FIG. 2 where the PWM signal for the half carrier period generated by the PWM signal generator 9 when the electrical angle is 30 ° changes as shown in FIG.

  In FIG. 3, the signal “U” indicates the upper arm switching element 13 u, the signal “V” indicates the upper arm switching element 13 v, and the signal “W” indicates the upper arm switching element 13 w. "X" indicates a switching element 13x for the lower arm, "Y" indicates a switching element 13y for the lower arm, and "Z" indicates a signal for operating the switching element 13z for the lower arm.

  These signals operate active high. In this case, at the timing (1), no current appears on the inverter bus as shown in FIG. 4A, and at the timing (2), the current flows through the W-phase winding 4w as shown in FIG. 4B. (W-phase current) appears, and at timing (3), a current (V-phase current) flowing through the V-phase winding 4v appears as shown in FIG. 4 (c).

  As another example, let us consider a case where the PWM signal having a half carrier period generated by the PWM signal generation unit 9 when the electrical angle is 30 ° in FIG. 2 changes as shown in FIG. In this case, as shown in FIG. 6 (a), no current appears in the inverter bus at timing (1), and as shown in FIG. 6 (b), current flowing in the U-phase winding 4u at timing (2) ( U-phase current) appears, and current flowing through the V-phase winding 4v appears at timing (3) as shown in FIG. 6 (c).

  As described above, it can be seen that the phase current of the brushless motor 3 appears on the inverter bus in accordance with the states of the switching elements 13u, 13v, 13w, 13x, 13y, and 13z of the inverter 2.

  Specifically, when any one of the switching elements 13u, 13v, 13w of the upper arm is turned on, the motor current of the turned-on phase or the switching elements 13x, 13y, 13z of the lower arm When any one of them is turned on, the relationship that the motor current of the turned-on phase appears on the inverter bus is established.

  If the current for two phases can be determined at close timings within the carrier period as described above, it is obvious that the currents iu, iv, and iw for the three phases can be obtained from the relationship of the following equations.

iu + iv + iw = 0 (Formula 1)
Timing (4) and timing (5) are dead time periods for preventing the inverter upper and lower arms from being short-circuited due to the operation delay of the switching elements (13u to 13z), and the current flowing through the inverter bus during this period Is indefinite depending on the direction in which each phase current flows.

  FIG. 7 shows a first operation result of the motor drive inverter control apparatus according to the present embodiment. The inverter applied voltage, the actual U phase current, and the U converted by the phase current conversion unit 20 when the motor 3 is driven. The phase current and the waveform of the inverter bus current flowing through the bus current detector 15 are shown.

  Since the capacitor 12 in the present embodiment has a very small capacity, the inverter applied voltage pulsates greatly at a frequency twice the power supply frequency fs (= 50 Hz) when a current flows through the motor 3. The U-phase current converted by the phase current converter 20 is obtained based on the relationship between the state of the switching element of the inverter 2 and the phase current appearing on the inverter bus, but the voltage applied to the inverter drops greatly. It can be seen that at the timing (T1 in the figure), the actual U-phase current is erroneously recognized as a different value.

  FIG. 8 shows the operating state of the switching elements 13u, 13v and 13w of the inverter 2 and the waveform of the inverter bus current flowing through the bus current detector 15 at this time.

  "U" is the upper arm switching element 13u, "V" is the upper arm switching element 13v, and "W" is the upper arm switching element 13w. .

  Normally, at the timing when only “U” is turned on (T2 in the figure), the U-phase current appears in the bus current detector 15, but at the timing when the inverter applied voltage drops significantly (T1 in the figure). It can be seen that no U-phase current appears in the bus current detector 15 even when only “U” is on.

  This is normally the state as shown in FIG. 6B, and a U-phase current should appear in the bus current detector 15. However, when the inverter applied voltage drops to near zero, the switching of the inverter 2 is performed. Even if an ON signal is given to the element, it does not actually conduct, so it is impossible to specify which phase the inverter bus current flowing through the bus current detector 15 is.

  For this reason, at the timing when the voltage applied to the inverter has dropped significantly, it was erroneously recognized as a value different from the actual phase current.

  Therefore, the phase current converter 20 in the present embodiment obtains from the bus current detector 15 only when the applied voltage value of the inverter 2 is equal to or larger than an arbitrary set value in order to eliminate the above-described erroneous recognition of the motor phase current. The current value of each phase of the motor 3 is reproduced based on the generated bus current.

Specifically, FIG. 9 shows an operation result when an arbitrary set value is set to 20 V, for example.
At the timing when the applied voltage value of the inverter 2 is less than 20 V (T1 in the figure), the reproduction of the current value of each phase of the motor 3 based on the current value obtained from the bus current detector 15 is canceled. The generation of a large error from the actual U-phase current as shown in FIG.

  As described above, according to the present embodiment, sensorless sine wave driving without using an expensive current sensor can be applied to a motor driving inverter control device using a small capacity capacitor 12 and a small capacity reactor 11. Is possible.

  In addition, about the electric current value of each phase of the motor 3 when the applied voltage value of the inverter 2 is less than 20V, the phase current conversion unit 20 determines the current value of each phase of the motor 3 when the applied voltage value of the inverter 2 is 20V or more. You may make it estimate | require from the time series variation | change_quantity of an electric current value.

Specifically, the previous U-phase current value of the motor 3 detected when the applied voltage value of the inverter 2 is 20 V or more is Iu (n-1), and the previous current value is Iu (n-2). If the applied voltage value of the inverter 2 is less than 20 V this time, the estimated current value Iu of the U phase is
Iu = Iu (n−1) × 2−Iu (n−2)
To ask for.

  According to this method, since the calculation is made by adding the amount of change from the previous detection value to the latest value when the applied voltage value of the inverter 2 is secured at an arbitrary set value or more, it is stored. Even if the amount of data to be stored is small and a large amount of memory such as a microcomputer is not secured, an estimated value that takes into account the time series changes up to that point can be obtained.

  Conversely, if a large amount of memory such as a microcomputer can be secured, high-precision estimation calculation can be realized by approximate expression calculation.

  Thus, even when the applied voltage value of the inverter 2 is very small and the phase current of the motor 3 does not appear in the bus current detector 15, the estimation calculation that takes into account the time-series change up to that time. By reproducing with high accuracy, it became possible to maintain high-quality sensorless sine wave drive.

  Further, in addition to the above-described embodiment, the phase current conversion unit 20 may perform a filter calculation of the current value of each phase of the brushless motor 3.

The specific equation is
Iu [f] (n) = K * Iu + (1-K) * Iu [f] (n-1)
It was. Here, K represents a filter coefficient, and a value between 0 and 1 is selected.

  By performing this filter operation, for example, when it is not possible to specify which phase the inverter bus current flowing through the bus current detector 15 is, a noise component is generated in the applied voltage value of the inverter 2, Even if it is erroneously determined that it is an arbitrary set value or more, high-quality driving can be maintained without greatly misrecognizing the motor phase current.

  Next, a specific method for determining the specifications of the small-capacitance capacitor 12 and the small-capacity reactor 11 described in the above embodiment will be described below.

In the inverter control device for driving a motor in the present embodiment, the resonance frequency f _LC (LC resonance frequency) between the capacitor 12 and the reactor 11 is changed to AC in order to suppress the harmonic component of the power supply current and clear the IEC standard. The combination of the capacitor 12 and the reactor 11 is determined so as to be larger than 40 times the frequency fs of the power source.

Here, when the capacitance of the capacitor 12 is C [F] and the inductance value of the reactor 11 is L [H], the LC resonance frequency f _LC is expressed by the following equation.

That is, the combination of the capacitor 12 and the reactor 11 is determined so as to satisfy f _LC > 40 fs (because the IEC standard defines the 40th harmonic in the harmonic component of the power supply current).

  As described above, by determining the combination of the capacitor 12 and the reactor 11, the harmonic component of the power supply current can be suppressed, and the IEC standard can be reliably cleared.

  As described above, the present invention described by taking the first embodiment as an example can be applied to a motor drive inverter control device that drives a motor using an inverter circuit.

  For example, it is a product such as an air conditioner equipped with an inverter circuit, a refrigerator, an electric washing machine, an electric dryer, an electric vacuum cleaner, a blower, and a heat pump water heater. For any product, by reducing the size and weight of the motor drive inverter device, the degree of freedom in product design is improved, and an inexpensive product can be provided.

  As described above, the inverter control apparatus for driving a motor according to the present invention can be reduced in size, weight, and cost by using a small-capacity reactor and a small-capacitance capacitor, and has a large ripple in the inverter applied voltage. Can be driven without using a position detection sensor, enabling stable current supply while maintaining high efficiency. For AV equipment (especially small equipment) that requires a small motor starter. Can also be widely used.

1 is a system configuration diagram of an inverter control device for driving a motor according to Embodiment 1 of the present invention. An example of a temporal change in a phase current state of a motor driven by the motor drive inverter control device, and a diagram showing a current state in each phase winding of the motor in each section of an electrical angle The figure showing an example of the PWM signal in the half carrier period in the inverter control device for motor drive (A)-(c) The figure showing the electric current state which flows into the motor and inverter at the time of the drive by the PWM signal The figure showing the other example of the PWM signal in the half carrier period in the inverter control apparatus for motor drive (A)-(c) The figure showing the electric current state which flows into the motor and inverter at the time of the drive by the PWM signal The figure which shows the 1st operation result of the inverter control apparatus for motor drive The figure showing the operation state of the switching element of the inverter control device for motor drive The figure which shows the 2nd operation result of the inverter control apparatus for motor drive System configuration diagram of conventional motor drive inverter control device A diagram showing the relationship between the harmonic component of the power supply current and the order with respect to the power supply frequency in the motor drive inverter device Circuit diagram of a conventional DC power supply for a motor drive inverter controller

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Inverter 3 Brushless motor 4 Stator 4u, 4v, 4w Winding 5 Rotor 6 Control part 7 Rectifier circuit 7a Diode bridge 8u, 8v, 8w Terminal 9 PWM signal generation part 10 Base driver 11 Reactor 12 Capacitor 13u, 13v, 13w, 13x, 13y, 13z Switching elements 14u, 14v, 14w, 14x, 14y, 14z Freewheel diode 15 Bus current detector 16 Inverter input voltage detector 17 Motor phase estimator 18 Rotor speed detector 19 Current command Arithmetic unit 20-phase current converter

Claims (4)

A rectifier circuit having an AC power supply as an input; an inverter that converts DC power obtained by the rectifier circuit into AC power; a motor driven by the inverter; a control unit that controls the operation of the inverter; A rectifier circuit comprising: a bus current detector for detecting a current flowing through the bus; an extremely small capacitor connected between the buses of the inverter; and an inverter input voltage detector for detecting an applied voltage value of the inverter. Is composed of a diode bridge and a very small-capacity reactor connected to the AC input side or DC output side of the diode bridge, and when the applied voltage value of the inverter is greater than or equal to an arbitrary set value, A phase current converter that reproduces a current value of each phase of the motor based on a current value detected by the bus current detector, and the phase current A motor drive provided with a PWM signal generation unit for generating a PWM signal for controlling the inverter from the current value of each phase of the motor obtained by the conversion unit and the applied voltage value obtained by the inverter input voltage detection unit Inverter control device. In the phase current converter, the current value of each phase of the motor when the applied voltage value to the inverter is less than an arbitrary set value, and the phase of the motor when the applied voltage value is greater than or equal to the set value The motor drive inverter control device according to claim 1, wherein the current value is estimated from a time-series change amount of the current value. The motor drive inverter control device according to claim 1 or 2, wherein the phase current conversion unit performs a filter calculation of a current value of each phase of the motor. The combination of the reactor and the capacitor is determined so that the resonance frequency of the small-capacity reactor and the small-capacitance capacitor is larger than 40 times the frequency of the AC power supply. An inverter control device for driving a motor according to item 1.