JP5785780B2 - Power conversion device, and air conditioner and washing machine using the same - Google Patents

Description

  The present invention relates to a power conversion device that detects an alternating current flowing in an electric motor based on a direct current bus current, and an air conditioner and a washing machine using the same.

  Electric motor drive devices used in air conditioners and washing machines have strong demands for downsizing, reducing the number of parts, high efficiency, and high output, and many technologies have been developed to meet these requirements.

  As one of methods for increasing the suppliable voltage of the power conversion device and reducing the pulsation of current and torque, for example, in Non-Patent Document 1 and Non-Patent Document 2, non-periodic pulses based on the phase of output AC power are used. PHM (Pulse Harmonic Modulation) control that performs pulse control has been proposed. By using the PHM control, the supplyable voltage can be increased, and the high-efficiency operation range can be expanded particularly in the high-speed rotation range.

  Further, as one of the methods not using a phase current sensor, for example, as disclosed in Patent Document 1, the DC bus current and power conversion of a power conversion circuit that drives an electric motor by pulse width modulation control (PWM control) A current detection method has been proposed in which the instantaneous phase current of the motor is detected based on the switching state of the circuit and the phase current of the motor is reproduced.

  The current detection method of Patent Document 1 uses a PWM signal that drives a power conversion circuit, and detects an AC current component of an electric motor that appears on a DC bus of the power conversion circuit by a combination of PWM signals.

  As another method, for example, as disclosed in Patent Document 2, the instantaneous phase current of the maximum voltage phase of the DC bus current of the power conversion circuit that drives the motor is detected near the middle of the PWM carrier signal, and the current is detected. A current detection method for detecting valid / reactive current to the motor based on the integral value of the value and the periodic function has also been proposed.

JP 2004-48886 A JP 2004-282969 A

2010 IEEJ Industrial Application Division Conference 1-134 "High-efficiency motor control by harmonic modulation type pulse-saving drive" Hitachi Group's Electrification Solutions Contributing to the Global Environment, Hitachi Review December 2010, P52-57

  The PHM control in Non-Patent Document 1 and Non-Patent Document 2 is based on the premise that AC motor phase current is directly detected, and there is no description of a method for detecting DC bus current. In the case of PHM control, it is difficult to apply the DC bus current detection method disclosed in Patent Document 1 or Patent Document 2.

  In addition, during the PHM control, the pulse waveform for controlling the power conversion circuit becomes aperiodic, and therefore, a section in which phase current information for two phases cannot be obtained from the DC bus current is generated. It becomes difficult to reproduce. In addition, when DC bus current detection is performed at regular intervals during PHM control, a section in which specific phase current information cannot be obtained continuously occurs, and current reproduction is difficult with the method of Patent Document 2.

  As described above, Non-Patent Documents 1 and 2 that disclose PHM control do not disclose any DC bus current detection method and no motor phase current estimation method based on DC bus current, and PWM control. In the techniques of Patent Documents 1 and 2 that presuppose the above, current reproduction by DC bus current detection is difficult during PHM control.

The subject is a power conversion device that detects an alternating current flowing in an electric motor, and converts a direct-current power into an alternating-current power by using a first pulse control circuit that outputs a non-periodic pulse and the non-periodic pulse. Alternatively, a power conversion circuit that converts AC power into DC power, a DC bus current detection circuit that detects a DC bus current of the current conversion circuit, and a DC bus current detected by the DC bus current detection circuit are A control circuit that performs sampling and vector control based on a periodic pulse and creates a command voltage to the pulse control circuit, and the control circuit includes first current reproduction means, and the DC bus current The detection circuit detects the linear bus current a plurality of times in each of the first period and the second period, and the first current reproduction means detects the moment when detection is performed by the non-periodic pulse waveform. The AC voltage phase of the power conversion circuit is determined as any one of the phase voltage phases, and the integrated values of the current detection values in the first period and the second period, and the first period and the second period, This is solved by the power conversion device that estimates the reactive current and the effective current based on the respective integration values of the sine function calculation value and the cosine function calculation value of the phase voltage phase .

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to reproduce the alternating current which flows into the power converter circuit which carries out pulse control by the non-periodic pulse waveform based on the phase of output alternating current power by DC bus current detection.

It is a block diagram which shows the whole block diagram of the power converter device of Example 1. FIG. It is the figure which showed the relationship between the alternating voltage which flows into an electric motor, and an electric current. It is the figure which showed the relationship between alternating current and voltage, and effective current and reactive current. It is an example of a waveform which shows sampling of direct-current bus current in patent documents 1. It is an example of a waveform which shows sampling of direct-current bus current in patent documents 2. 4 is a waveform example showing sampling of a DC bus current in Example 1. FIG. 3 is a flowchart illustrating a process flow of a current reproduction unit according to the first embodiment. It is an example of a waveform which shows the case where the sampling of DC bus current in Example 1 is made into a fixed interval. It is a flowchart in the case of reproducing current by sampling the DC bus current in Example 1 at a constant interval. It is a flowchart in the case of reproducing current only in the effective current in Example 1. It is a block diagram which shows the whole block diagram of the power converter device of Example 2. FIG. It is the figure which showed the relationship between alternating current and a voltage, and d-axis current and q-axis current. FIG. 10 is a flowchart showing a flow of current reproduction processing in the second embodiment. It is an example of a waveform which shows the sampling of the direct current bus current in Example 2. It is a block diagram which shows the whole block diagram of the power converter device of Example 3. FIG. It is a whole block diagram of the air conditioner of Example 4. It is the schematic of the efficiency with respect to the motor rotation speed of the electric motor for compressors of Example 4. FIG. It is a whole block diagram of the washing machine of Example 5. It is the schematic of the operating point of the electric motor for washing machines of Example 5.

  Examples of the present invention will be described below.

From Figure 1 with reference to FIG. 7, the power conversion device of Example 1 that current reproduction active current Ia and reactive current Ir from the DC bus current I _DC of the power conversion circuit 4 for driving a non-periodic pulse.

In FIG. 1, the DC power supplied from the DC power source 2 is converted into AC power by the power converter 1 and output to the AC motor 3. Incidentally, the AC motor 3 performs electric, even if for converting AC power to DC power by the power conversion apparatus 1, the active current Ia and the reactive current in the manner shown in the present embodiment from the DC bus current I _DC of the power conversion circuit 4 It is possible to reproduce current of Ir.

As shown in FIG. 1, the power conversion device 1 controls the power conversion circuit 4 that converts DC power into AC power, and a non-periodic pulse such as a PHM control system based on the phase of AC power. performing a pulse control unit 5, a DC bus current detecting circuit 6 for detecting a DC bus current I _DC of the power conversion circuit 4, a vector control based on the DC bus current I _DC and the like detected by the DC bus current detection circuit 6 It is comprised by the control apparatus 7. Further, the power conversion circuit 4 generates a gate signal to the IGBT of the main circuit based on the power conversion main circuit 41 composed of an IGBT and a switching element such as a diode, and the non-periodic pulse signal 5A from the pulse control unit 5. The gate driver 42 is configured to be configured.

The control device 7 estimates the alternating current flowing through the alternating current motor 3 based on the direct current bus current I _DC detected by the direct current bus current detection circuit 6, the pulse signal information 5B, and the applied voltage command information 9A as the reproduced current Ic. It comprises a current reproduction unit 8 for output and a vector control unit 9 for performing a vector control calculation using the reproduction current Ic and calculating an applied voltage command value V ^* .

  2 is a diagram showing three-phase AC voltages Vu, Vv, and Vw output from the power conversion circuit 4, and these voltages are expressed by (Equation 1). With these voltages, three-phase alternating currents Iu, Iv, and Iw shown in the lower diagram of FIG. These currents are expressed by (Expression 2).

Here, θ _v : voltage phase with reference to U phase, φ: voltage / current phase difference.

Next, the relationship between each voltage / current and each phase will be described with reference to FIG. The U axis in FIG. 3 represents the U phase coil direction of the stator of the AC motor 3. U-phase voltage Vu and U-phase current Iu are components in the U-axis direction of motor voltage V ₁ and motor current I ₁ , respectively. The reactive current Ir is a component orthogonal to the motor voltage V ₁ , and the effective current Ia is a component parallel to the motor voltage V ₁ . Although not shown in FIG. 3, the same applies to Vv, Iv, Vw, and Iw.

  Here, in order to clarify the problem, problems of the conventional current detection method will be described before describing the current detection method of the present embodiment. In the current detection methods of Patent Literature 1 and Patent Literature 2, pulse width modulation control (PWM control) is performed by the pulse control unit 5 to perform DC bus current detection.

For example, in the current detection method of Patent Document 1, as shown in FIG. 4, a DC pulse current I is used to control the power conversion circuit 4 by outputting a periodic pulse waveform (GPu, GPv, GPw) using a PWM carrier signal. _A periodic current flows through _DC . Therefore, as shown by white circles in FIG. 4, the DC bus current detection circuit 6, that the intermediate phase voltage Vv ^* and the PWM carrier signal is sampled DC-bus current I _DC before and after the intersection, a voltage maximum phase and the minimum Instantaneous phase currents (Iu, -Iw) for two phases can be acquired. The three-phase AC currents Iu, Iv, and Iw flowing through the AC motor 3 are reproduced based on the instantaneous phase currents for these two phases.

Further, in the current detection method of Patent Document 2, as shown in FIG. 5, a DC pulse current I is used to control the power conversion circuit 4 by outputting a periodic pulse waveform (GPu, GPv, GPw) using a PWM carrier signal. _A periodic current flows through _DC . Therefore, as shown by a white circle in FIG. 5, the DC bus current detection circuit 6 is to sample the DC-bus current I _DC near the midpoint of the PWM carrier signal to obtain repeat the phase current Iu of the voltage maximum phase The effective current Ia and the reactive current Ir flowing in the AC motor 3 are reproduced based on the phase current Iu.

However, in the above-described PHM control, as shown in FIG. 6, since the non-periodic pulse waveform (GPu, GPv, GPw) that does not use the PWM carrier signal is output and the power conversion circuit 4 is controlled, the non-periodic DC bus is used. Current _IDC will flow.

Thus, when using the PHM control, to become the aperiodic DC bus current I _DC flows in the current detection method of Patent Document 1 a section that can be detected continuously the instantaneous phase currents of two phases decreases Therefore, current reproduction of the three-phase alternating currents Iu, Iv, Iw becomes difficult. Further, in the current detection method of Patent Document 2, since the section in which the phase current of the specific phase can be continuously detected decreases, it becomes difficult to reproduce the effective current Ia and the reactive current Ir.

  Hereinafter, the operation of the current reproduction unit 8 of the present embodiment that solves the above-described problem that current reproduction becomes difficult during PHM control will be described with reference to FIGS.

FIG. 7 is a block diagram showing the configuration of the current reproduction unit 8. As shown here, the current reproduction unit 8, the DC-bus current I _DC on the basis of the switch signal information SW pulse signal information 5B an A / D converter 81 for converting A / D, applying command switch signal information SW A phase current discriminating unit 82 for discriminating the phase voltage phase θ _vp of the acquired DC bus current value from the voltage phase information θ _v of the voltage information 9A; a sine function calculator 83a for outputting the value of the sine function of the phase voltage phase θ _vp ; , and the cosine function calculator 83b to output the value of the cosine function of the phase voltage phase theta _vp, an integrator 84a for integrating the DC-bus current I _DC, an integrator 84b for integrating a sine function operation value, a cosine function operation value Are integrated with each other, and an active current Ia and a reactive current Ir are calculated from each integrated value. Details of each part will be described below.

When the AC motor 3 rotates, the voltage phase information θ _v also advances. At this time, the DC-bus current I _DC, flows aperiodic current as shown in FIG. The A / D converter 81, as shown in FIG. 7, on the basis of the switch signal information SW, acquires the aperiodic DC bus current I _DC. In the following, the values detected at the respective timings _{I DC (1), I DC} (2), ..., DC (m), ..., denoted I _DC (k). Further, the voltage phase information θ _v at the time of detecting I _DC (n) is represented by θ _v (n), and the switch signal information SW is represented by SW (n). Note that the period Q1 shown in FIG. 6 is referred to as a first period, the period Q2 is referred to as a second period, I _DC (1),..., I _DC (m) are detected during the first period, and I _DC (m) is detected during the second period. _{Assume that DC} (m + 1),..., I _DC (k) is detected. The phase current discriminating unit 82 outputs the phase voltage phase θ _vp (n) based on the switch signal information SW (n) and the voltage phase information θ _v (n). The phase voltage phase θ _vp (n) of the U phase is obtained by ( _Equation 3). Similarly, the phase voltage phase θ _vp (n) of the V phase is obtained by ( _Equation 4), and the phase voltage phase θ _vp (n) of the W phase is obtained by ( _Equation 5).

The sine function calculator 83a and the cosine function calculator 83b shown in FIG. 7 indicate the values of the sine function sin (θ _vp (n)) and cosine function cos (θ _vp (n)) with θ _vp (n) as arguments. Output. Further, the integrators 84a to 84c divide the integration of I _DC (n), sin (θ _vp (n)), cos (θ _vp (n)) into two periods of a first period Q1 and a second period Q2. Do it. That is, in the first period Q1, I _DC (1),..., I _DC (m) and θ _vp (1),... Θ _vp (m) are integrated, and in the second period Q2, I _DC (m + 1). , ..., I _DC (k) and θ _vp (m + 1), ..., θ _vp (k) are integrated.

Based on the integrated values of I _DC (n) and θ _vp (n) in the first period Q1 and the second period Q2, the current estimation unit 85 _calculates the reactive current Ir in (Equation 6) and (Equation 7). The effective current Ia is estimated and output as a reproduction current Ic.

  The basic principle of the current estimation method performed by the current estimation unit 85 will be described below.

  When (Equation 6) and (Equation 7) are used, the U-phase current Iu of (Equation 2) is expressed by (Equation 8).

  Similarly, the V-phase current Iv and the W-phase current Iw are expressed by (Equation 9) and (Equation 10), respectively.

Here, as shown in FIG. 7, each phase current of the U-phase current Iu (Equation 8), the V-phase current Iv (Equation 9), and the W-phase current Iw (Equation 10) is sent from the A / D converter 81. Is output. The sine function calculator 83a outputs a sine function sin (θ _vp (n)), and the cosine function calculator 83b outputs a cosine function cos (θ _vp (n)). As described above, the integrators 84a to 84c output integrated values of I _DC (n), sin (θ _vp (n)), and cos (θ _vp (n)).

The integral of I _DC in the first period is obtained by (Equation 11), and the integral of the second period is obtained by (Equation 12).

  Here, when (Equation 11) and (Equation 12) are arranged, (Equation 13) is obtained.

  Therefore, the current estimation unit 85 can estimate the reactive current Ir and the effective current Ia by using (Equation 13).

  As described above, the current reproducing unit 8 can detect the effective current Ia and the reactive current Ir from the DC bus current detection circuit 6 even when the pulse control unit 5 outputs a non-periodic pulse waveform such as PHM control. It becomes. That is, when the configuration of the present embodiment is used, the phase current sensor can be omitted, so that the power conversion device can be downsized and the number of parts can be reduced. At the same time, since current reproduction is possible even in the case of field weakening control using PHM control, the suppliable voltage of the power conversion circuit can be improved, and the reactive current Ir in the field weakening control method can be reduced. It is possible to achieve output.

  Next, a first modification of the first embodiment will be described with reference to FIGS. 8 and 9. The present modification is a power conversion device that performs A / D conversion in the A / D conversion unit 81 at regular intervals. The power conversion device of this modification uses a current reproduction unit 8A shown in FIG. 9 instead of the current reproduction unit 8 in the power conversion device of the first embodiment. The current reproduction unit 8A is obtained by adding a switch state determination unit 86 in front of the integrators 84a to 84c of the current reproduction unit 8. In addition, description is abbreviate | omitted about the point which is common in the power converter device of Example 1. FIG.

  When the control device 7 is realized by an integrated circuit such as a microcomputer, the A / D conversion in the A / D conversion unit 81 is at regular intervals in order to limit the timer setting of the A / D conversion unit of the microcomputer and reduce the calculation load. It is preferable.

Here, FIG. 8 shows an example of a waveform when the A / D conversion of the A / D converter 81 is set at a constant interval. In FIG. 1, when the upper switches Sup, Svp, Swp of the power conversion main circuit 41 are all on, or when the lower switches Sun, Svn, Swn are all on, occurs, as in the three sampling points indicated by the "all Aishita on" in FIG. 8, a state in which the DC bus current I _DC does not flow through the DC bus current detection circuit 6. Therefore, when the A / D converter with a constant interval, the DC bus current I _DC is sometimes A / D converter 81 in a section that does not flow to perform A / D converter, the integrator output error-current reproducibility There arises a problem that a decrease in the frequency of the image occurs.

Therefore, in the switch state determination unit 86 of the present modification shown in FIG. 9, the presence / absence of output is switched based on the switch signal information SW. That is, the switch signal information SW is a combination of DC-bus current I _DC does not flow, upper switch Sup, Svp, when all the phases of Swp is on or below the switch Sun, Svn, all the phases are turned on Swn The output values of the A / D converter 81, the sine function calculator 83a, and the cosine sine function calculator 83b are not output to the integrators 84a to 84c. Are output to the integrators 84a to 84c.

  Thus, even when the A / D conversion is performed at a constant interval, the current estimation unit 85 can output the effective current Ia and the reactive current Ir as the reproduction current Ic based on the integrators 84a to 84c. In other words, the effective current Ia and the reactive current Ir can be output as the reproduction current Ic even when the microcomputer is restricted or the calculation load of the A / D converter is reduced.

  Next, a second modification of the first embodiment will be described with reference to FIG. This modification is a power conversion device that can reproduce the effective current Ia even when the reactive current Ir is small (when the voltage / current phase φ is small). The power conversion device of this modification uses a current reproduction unit 8B whose process flow is shown in FIG. 10 instead of the current reproduction unit 8 described in FIG. As a result, it is possible to detect only the effective current Ia and reduce the calculation load of the microcomputer. In addition, description is abbreviate | omitted about the point which is common in the power converter device of Example 1. FIG.

As shown in FIG. 10, current reproduction unit 8B is a DC-bus current I _DC on the basis of the switch signal information SW and A / D conversion unit 8B1 to convert A / D, an integrator for integrating the DC-bus current I _DC 8B4 And a current estimation unit 8B5 that calculates the effective current Ia from the integrated value.

In A / D conversion unit 8B1, like the A / D converter 81 of FIG. 7, for a predetermined period of time to obtain the aperiodic DC bus current I _DC on the basis of the switch signal information SW, at respective timings The detected values are I _DC (1), I _DC (2), ..., I _DC (m). The integrator 8B4 performs integration of the DC bus current I _DC (n) for a predetermined period.

The current estimation unit 8B5 estimates the effective current Ia from (Equation 14) using the integrated value of the DC bus current I _DC (n) output from the integrator 8B4, and outputs it as the reproduction current Ic.

  As described above, by using the current reproduction unit 8B, even when the voltage / current phase φ is small, the effective current Ia can be detected with a configuration in which the calculation load is reduced.

  A power conversion apparatus according to a second embodiment that reproduces current using DC power will be described with reference to FIGS. 11 to 14.

FIG. 11 is a configuration diagram of the power conversion device 1A of the present embodiment. As shown in FIG. 11, the power conversion device 1 </ b> A is obtained by adding a DC voltage detector 10 to the power conversion device 1 of the first embodiment and replacing the current reproduction unit 8 with a current reproduction unit 8 c. The DC voltage detector 10 detects the DC voltage E _d of the DC power supply and outputs it as a detected DC voltage E _D to the current reproduction unit 8C. In addition, since the other structure is the same as the power converter device 1 of Example 1, description is abbreviate | omitted.

  The operation of the current reproduction unit 8C according to the present embodiment will be described with reference to FIGS.

As shown in FIG. 13, current reproduction unit 8C is DC-bus current I _DC to the filter processing unit 8C1 which filtered outputs an average DC-bus current I _{DC_FL,} the average DC-bus current I _{DC_FL} the A / D conversion A / D conversion unit 8C2 and a current estimation unit 8C3 that calculates the q-axis current Iq flowing through the power conversion circuit 4. The current estimating portion 8C3, the average DC-bus current I _{DC_FL} and applying command voltage information 9A applying command voltage Vd of ^*, and thereby calculates the q-axis current Iq from Vq ^* and the detected DC voltage E _D. In the A / D conversion unit 8C2, the average DC bus current I _{DC_FL} is sampled at regular intervals as shown by white circles in FIG.

  Next, details of the current estimation unit 8C3 will be described. As described above, the AC voltage / current represented by (Equation 1) and (Equation 2) flows through the power conversion circuit 4. 12 and (Equation 15), (Equation 16) when the respective voltages / currents and phases are set to the motor voltage (Vd, Vq) / current (Id, Iq) on the rotation (dq) coordinate axis of the motor. ). Here, the d-axis is the main magnetic flux direction of the AC motor 3, the q-axis is the direction orthogonal to the d-axis, and the q-axis current Iq is a current that contributes to the torque.

Here, if the DC power input to the power conversion circuit 4 and the power output from the power conversion circuit 4 to the AC motor 3 are equal, the average DC bus current I _{DC_FL} , the applied command voltages Vd ^* , Vq ^* , and the detected DC by using the voltage E _D is (number 17) is represented.

  When the d-axis current Id, which is an invalid current, is sufficiently small, the q-axis current Iq contributing to the torque can be obtained from (Equation 18) by setting the d-axis current Id in (Equation 17) to zero.

As described above, the current reproduction unit 8C estimates the q-axis current Iq using ( _Equation 18) based on the average DC bus current I _{DC_FL} , the applied command voltages Vd ^* , Vq ^*, and the detected DC voltage E _D. Output as the reproduction current Ic.

  As described above, by using the current reproduction unit 8C of the present embodiment, when the d-axis current Id, which is an invalid current, is sufficiently small, the integrator / inverse matrix calculation is not used, and the calculation load is reduced. The q-axis current Iq which is a torque current can be detected with the configuration.

  In addition, when the power conversion circuit 4 is in a steady state, the d-axis current Id is controlled according to the command value. Therefore, even when the d-axis current is large when the command value of the d-axis current Id is taken into consideration (Equation 19 ) To detect the q-axis current Iq which is a torque current.

  A power conversion device according to a third embodiment that switches between a pulse control method and a current reproduction method will be described with reference to FIG.

  FIG. 15 is a configuration diagram of the power conversion device 1B of the present embodiment. As illustrated in FIG. 15, the power conversion device 1B is obtained by adding a pulse control unit 11, a pulse signal switching unit 12, a current reproduction unit 8D, and a current reproduction switching unit 13 to the power conversion device of the first embodiment. The pulse signal switching unit 12 switches the pulse control unit 5 that outputs a non-periodic pulse by PHM control and the pulse control unit 11 that outputs a periodic pulse by PWM control according to operating conditions. The current reproduction switching unit 13 switches between the current reproduction unit 8 described in the first embodiment and the current reproduction unit 8D using the current reproduction method of Patent Document 1 described in FIG. In addition, since the other structure is the same as the power converter device 1 of Example 1, description is abbreviate | omitted.

  In the power conversion device of the present embodiment, the pulse signal switching unit 12 determines the magnitude of the rotational speed of the AC motor 3 and a predetermined value. If the rotational speed is less than the predetermined value, the periodic pulse signal 11A from the pulse control unit 11 is determined. Is output to the gate driver 42 as a pulse signal 12A. On the other hand, when the rotational speed is equal to or greater than the predetermined value, the non-periodic pulse signal 5A from the pulse control unit 5 is output to the gate driver 42 as the pulse signal 12A.

  The current reproduction switching unit 13 determines the magnitude of the rotational speed of the AC motor 3 and a predetermined value, and when the rotational speed is less than the predetermined value, the three-phase currents Iu, Iv, and Iw output from the current reproducing unit 8D are reproduced. Output as Ic. On the other hand, when the rotation speed is equal to or greater than a predetermined value, the effective current Ia and the reactive current Ir output from the current reproduction unit 8 are output as the reproduction current Ic.

  In other words, when the rotational speed of the AC motor 3 is less than the predetermined value, the vector control unit 9 controls the pulse control unit 11 based on the reproduction current Ic from the current reproduction unit 8D. The pulse control unit 5 is controlled based on the reproduction current Ic from the unit 8.

Instead of switching the control of the vector control unit 9 on the basis of the rotational speed of the AC motor 3, the control of the vector control unit 9 based on the value of the DC bus current I _DC detected by the DC bus current detection circuit 6 It is good also as a structure to switch. That is, if the value of the DC bus current I _DC is less than the predetermined value, the vector control unit 9 controls the pulse control unit 11 based on the reproduction current Ic from the current reproduction unit 8D, when the above predetermined value, the current reproduction The pulse control unit 5 may be controlled based on the reproduction current Ic from the unit 8.

  As described above, the current can be detected from the DC bus current detection circuit 6 by switching between the pulse waveform and the current reproduction method, and the power converter can be downsized and the number of parts can be reduced by not using the phase current sensor. It becomes. At the same time, when the AC motor 3 is in the low speed rotation region, driving with a periodic pulse waveform by PWM control makes it possible to drive the microcomputer with a lower computational load than when driving with a non-periodic pulse waveform. . In addition, when the AC motor 3 is in a high-speed rotation range, driving with a non-periodic pulse waveform by PHM control can reduce current and torque pulsations, and further improve the suppliable voltage of the power conversion circuit, so that the field weakening control system It is possible to reduce the reactive current Ir at the time and achieve high efficiency.

  A fourth embodiment in which the power conversion apparatus 1 according to the first embodiment is applied to the compressor driving of the air conditioner 100 will be described with reference to FIGS. 16 and 17.

  As shown in FIG. 16, the air conditioner 100 according to the present embodiment includes an outdoor unit 101 that exchanges heat with the outside air, an indoor unit 102 that exchanges heat with the room, and a pipe 103 that connects the two. The outdoor unit 101 includes a compressor 104 that compresses a refrigerant, a compressor drive motor 105 that drives the compressor 104, an electric motor drive device 106 that controls the compressor, and a heat exchanger 107 that exchanges heat with the outside air using the compressed refrigerant. Is done. The power conversion device 1 according to the first embodiment is applied to the electric motor drive device 106. The indoor unit 102 includes a heat exchanger 108 that exchanges heat with the room, and a blower 109 that blows air into the room.

  Here, the efficiency of the compressor drive motor 105 will be described with reference to FIG. In FIG. 17, the horizontal axis indicates the rotation speed of the compressor drive motor 105, and the vertical axis indicates the efficiency. When PWM control is used, a large amount of reactive current Ir generated by field weakening control flows in a voltage saturation region that exceeds the voltage that can be output by the sine wave modulation method of the power conversion circuit. For this reason, as shown by the solid line in FIG. 17, a significant reduction in efficiency occurs in the high speed rotation region of the compressor drive motor 105.

  Therefore, in this embodiment, even when the power conversion device 1 of the first embodiment is applied to the air conditioner 100 and the non-periodic pulse signal 5A using the PHM control is output from the pulse controller 5, the DC bus current detection circuit 6 can be used to reproduce the current of the compressor drive motor 105. In other words, the suppliable voltage of the power conversion circuit 4 can be improved, and the reactive current Ir flowing through the compressor drive motor 105 can be reduced.

As described above, by increasing the suppliable voltage of the power conversion circuit 4, the reactive current Ir flowing during the field weakening control can be reduced even when the DC voltage _Ed is constant. For this reason, the loss due to the current is reduced, and it is possible to suppress a decrease in efficiency in a region where the rotation speed is higher than the rotation speed N3 where the efficiency reaches a peak, as shown by a dashed line in FIG.

  As described above, according to the fourth embodiment, since the current sensor of the compressor drive motor 105 can be eliminated, it is possible to reduce the size of the air conditioner, reduce the number of parts, and reduce the cost. In addition, the PHM control makes it possible to control the compressor 104 for the air conditioner at a high speed, to increase the flow rate of the refrigerant, and to increase the output of the air conditioner.

  A fifth embodiment in which the power conversion device 1 according to the first embodiment is applied to the stirring blade drive of the washing machine 200 will be described with reference to FIGS. 18 and 19.

  As shown in FIG. 18, the washing machine 200 of this embodiment includes a stirring blade 203 that stirs a washing tub, a stirring blade drive motor 202 that drives the stirring blade, a motor driving device 201 that controls the stirring blade, and a washing inner tub. 204 and an outer washing tub 205. The electric power conversion apparatus 1 of Example 1 is applied to the electric motor drive device 201.

  Here, the operating point of the stirring blade drive motor 202 will be described with reference to FIG. In FIG. 19, the horizontal axis indicates the rotation speed of the stirring blade drive motor 202, and the vertical axis indicates the torque characteristic.

  When PWM control is used, the stirring blade drive motor 202 operates at an operating point A that is an operating point of low-speed rotation and high torque during washing, and applies field-weakening control at an operating point B of high-speed rotation and low torque during dehydration. Is operating. In the future, in order to further increase the capacity of the washing machine and further shorten the dewatering time, the stirring blade drive motor 202 at the operating point C and the operating point D at a higher torque or rotational speed than the operating point B is used. Driving is necessary.

  Therefore, in this embodiment, even when the power conversion device 1 of the first embodiment is applied to the washing machine 200 and the non-periodic pulse signal using the PHM control is output from the pulse control unit 5, the DC bus current detection circuit 6 is used. The current of the stirring blade driving motor 202 can be reproduced using In other words, the supplyable voltage of the power conversion circuit 4 can be improved, and the reactive current Ir flowing through the stirring blade drive motor 202 can be reduced.

  Thus, by increasing the suppliable voltage of the power conversion circuit 4, it is possible to improve the outputtable torque during field-weakening operation. For this reason, the stirring blade drive motor 202 can be driven to the range shown by the dotted line in FIG. 19 and can be driven at the operating point C and the operating point D.

  As described above, according to the fifth embodiment, since the current sensor of the stirring blade driving motor 202 can be eliminated, it is possible to reduce the size of the washing machine, reduce the number of parts, and reduce the cost. Further, the PHM control enables the stirring blade driving motor 202 to be driven at the operating point C that outputs a larger torque at the same rotational speed as the operating point B, so that the capacity of the washing machine can be increased. Further, since it becomes possible to drive at high speed up to the operating point D with the same torque as the operating point B, it is possible to shorten the dehydrating time.

  In addition, although the example which applied the power converter device of Example 1 to the motor drive device for the stirring blade drive motor which rotates the stirring blade of a vertical washing machine was demonstrated above, the drum of a drum type washing machine is rotated. The same effect can be obtained even if the power conversion device of the first embodiment is applied to the motor drive device for the drum drive motor.

  In addition, this invention is not limited to description of above-described Examples 1-5, Various modifications are included. For example, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment.

  Each of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit. Each of the above-described configurations, functions, and the like may be realized by software by the processor interpreting and executing a program that realizes each function. Information such as programs, tables, and files that realize each function can be stored in a memory, a recording device such as a hard disk or an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, or a DVD.

  Further, the control lines and information lines indicate what is considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

DESCRIPTION OF SYMBOLS 1 Power converter 2 DC power source 3 AC motor 4 Power converter circuit 5 Pulse control part 6 DC bus current detection circuit 7 Controller 8 Current reproduction part 9 Vector control part 41 Power conversion main circuit 42 Gate driver

Claims (10)

A power conversion device for detecting an alternating current flowing in an electric motor,
A first pulse control circuit for outputting a non-periodic pulse;
Using the non-periodic pulse, a DC power is converted into AC power, or a power conversion circuit that converts AC power into DC power; and
A DC bus current detection circuit for detecting a DC bus current of the current conversion circuit;
A control circuit that samples the DC bus current detected by the DC bus current detection circuit based on the non-periodic pulse to perform vector control, and creates a command voltage to the pulse control circuit;
Comprising
The control circuit includes first current reproduction means,
The DC bus current detection circuit detects the linear bus current a plurality of times in each of the first period and the second period,
The first current reproduction means determines, based on the non-periodic pulse waveform, an alternating voltage phase of the power conversion circuit at the moment of detection as any phase voltage phase, and the first period and the second period Based on the respective integrated values of the current detection values in the period and the respective integrated values of the sine function calculation value and the cosine function calculation value of the phase voltage phase in the first period and the second period, and A power converter characterized by estimating an effective current. In the power converter device of Claim 1,
The control circuit includes a switch state determination circuit,
The DC bus current detection circuit detects the linear bus current a plurality of times at regular intervals in a predetermined first period and second period.
The switch state discriminating circuit discriminates an input of a current detection value, a sine function calculation value of the phase voltage phase and a cosine function calculation value to an integrator based on the non-periodic pulse waveform. A power conversion device for detecting an alternating current flowing in an electric motor,
A first pulse control circuit for outputting a non-periodic pulse;
Using the non-periodic pulse, a DC power is converted into AC power, or a power conversion circuit that converts AC power into DC power; and
A DC bus current detection circuit for detecting a DC bus current of the current conversion circuit;
A control circuit that samples the DC bus current detected by the DC bus current detection circuit based on the non-periodic pulse to perform vector control, and creates a command voltage to the pulse control circuit;
Comprising
The DC bus current detection circuit detects the linear bus current a plurality of times in a predetermined period;
The said control circuit estimates the effective current which flows into the said power converter device based on the integral value in the applicable period of a current detection value, The power converter device characterized by the above-mentioned. A power conversion device for detecting an alternating current flowing in an electric motor,
A first pulse control circuit for outputting a non-periodic pulse;
Using the non-periodic pulse, a DC power is converted into AC power, or a power conversion circuit that converts AC power into DC power; and
A DC bus current detection circuit for detecting a DC bus current of the current conversion circuit;
A control circuit that samples the DC bus current detected by the DC bus current detection circuit based on the non-periodic pulse to perform vector control, and creates a command voltage to the pulse control circuit;
Comprising
Based on the DC voltage of the power conversion circuit, the average DC bus current value obtained by filtering the DC bus current detected by the DC bus current detection circuit, and the applied command voltage, the torque current flowing through the power converter is estimated. The power converter characterized by doing. In the power converter device of Claim 1,
A second pulse control circuit for outputting a periodic pulse based on the PWM carrier signal;
A pulse signal switching circuit for switching between the first pulse control circuit and the second pulse control circuit,
The control circuit includes: a second current reproduction unit that reproduces a phase current flowing through the motor based on a PWM signal; a current detection switching circuit that switches between the first current reproduction unit and the second current reproduction unit; A power conversion device comprising: The power conversion device according to claim 5 ,
When the frequency of the AC power of the power converter is a predetermined value or more, the active current is estimated using the first pulse control circuit and the first current reproduction unit,
A power conversion device that estimates active power using the second pulse control circuit and the second current reproduction means when less than a predetermined value. The power conversion device according to claim 5 ,
When the average value of the DC bus current is equal to or greater than a predetermined value, the effective current is estimated using the first pulse control circuit and the first current reproduction means,
An effective current is estimated by using the second pulse control circuit and the second current reproduction means when it is less than a predetermined value. A compressor that compresses the refrigerant, a compressor drive motor that drives the compressor, an electric motor drive device that controls the compressor, an outdoor unit that includes a heat exchanger that exchanges heat with the outside air using the compressed refrigerant,
An indoor unit composed of a heat exchanger that exchanges heat with the room, and a blower that blows air into the room;
An air conditioner composed of a pipe connecting the outdoor unit and the indoor unit,
An air conditioner to which the power converter according to any one of claims 1 to 7 is applied to the electric motor drive device. A washing machine comprising: a stirring blade that stirs a washing tub; a stirring blade drive motor that drives the stirring blade; and an electric motor drive device that controls the stirring blade drive motor,
A washing machine, wherein the power converter according to any one of claims 1 to 7 is applied to the electric motor driving device. A washing machine comprising a drum, a drum drive motor that drives the drum, and a motor drive device that controls the drum drive motor,
A washing machine, wherein the power converter according to any one of claims 1 to 7 is applied to the electric motor driving device.

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