AC-DC converter, rotary machine drive device, refrigeration cycle application device, and method for controlling AC-DC converter

Abstract

The AC-DC converter includes a control unit that controls a switching element of a rectifier circuit that rectifies a power supply voltage. The control unit includes a voltage control unit that generates a first current command value using a voltage deviation, and a current control unit (64a) that generates a second voltage command value (70) using a current deviation (69) that is the difference between a second current command value obtained by making the first current command value follow a sine wave and the power supply current. The current control unit (64a) includes a PS controller that includes a proportional controller (641) and a sine wave tracking controller (642). The sine wave tracking controller (642) has a feedback loop including two integrators (6423, 6424). When one of the two integrators (6423, 6424) exceeds a predetermined threshold, the integral operation of the one integrator is stopped, while the integral operation of the other integrator continues without stopping.

Description

[Technical Field]

[0001] The present disclosure relates to an AC / DC converter that converts AC power into desired DC power, a rotating machine drive device and a refrigeration cycle device that include the AC / DC converter, and a method for controlling the AC / DC converter. [Background technology]

[0002] When obtaining DC voltage from an AC power supply, it is common to use a power factor correction circuit. A power factor correction circuit has the function of controlling the bus voltage to a constant value and the function of controlling the power supply current so as to comply with harmonic standards. The "simple switching method" (also called the "partial switching method"), which is one type of control method for a power factor correction circuit, is a method in which switching is performed at least once per half cycle of the power supply voltage, which is the voltage of the AC power supply, and has the characteristic of being able to control the bus voltage to be lower than the peak value of the power supply voltage. Patent Document 1 listed below discloses a technology for improving the power factor using the simple switching method.

[0003] In the simple switching method, when the bus voltage is lower than the power supply voltage, the circuit operation switches from boost chopper operation to capacitor-input passive operation. When the peak value of the power supply voltage is higher than the bus voltage, such a passive operation period always exists.

[0004] Proportional Integral (PI) controllers are widely used as current controllers in power factor correction circuits. However, when feedback control is performed using a PI controller in a power factor correction circuit, passive operation becomes a disturbance to the current control, resulting in a problem of control instability. This phenomenon of control instability is called "windup." Non-Patent Document 1 listed below describes a technique for stabilizing the operation of a PI controller in power factor correction control. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-125545 [Non-patent literature]

[0006] [Non-Patent Document 1] R. Pena-Alzola, MABianchi and M. Ordonez, “Control Design of a PFC With Harmonic Mitigation Function for Small Hybrid AC / DC Buildings”, IEEE Transactions on Power Electronics, vol. 31, no. 9, pp. 6607-6620, September 2016. Summary of the Invention [Problem to be solved by the invention]

[0007] When the circuit operation switches from boost chopper operation to passive operation, the power supply current becomes distorted. To address this issue, it has been proposed to perform current feedback control using a controller called a PS (Proportional Sinusoidal) controller, which has high tracking performance for sine wave commands. However, when simple switching control is performed using a PS controller, the S controller of the PS controller experiences windup in a certain range, causing instability.

[0008] The present disclosure has been made in view of the above, and has an object to provide an AC / DC converter that can prevent windup from occurring even when a PS controller is used for current feedback control. [Means for solving the problem]

[0009] To solve the above-mentioned problems and achieve the object, an AC-DC converter according to the present disclosure includes a rectifier circuit having at least one switching element that rectifies a power supply voltage applied from an AC power supply, a capacitor connected to a DC bus that smooths the output voltage of the rectifier circuit, a reactor located closer to the AC power supply than the capacitor, and a control unit that generates a switching signal for controlling the switching element. The switching element is located closer to the AC power supply than the capacitor. The control unit includes a voltage control unit that generates a first current command value using a voltage deviation that is the difference between a first voltage command value, which is a command value for a bus voltage that is the voltage of the DC bus, and the bus voltage, a current control unit that generates a second voltage command value using a current deviation that is the difference between a second current command value obtained by making the first current command value follow a sine wave and a power supply current flowing through the AC power supply, and a switching signal generation unit that generates a switching signal using the second voltage command value. The current control unit includes a proportional sine wave controller that includes a proportional controller and a sine wave tracking controller. The sine wave tracking controller has a feedback loop including two integrators, and when one of the two integrators exceeds a predetermined threshold, the integral calculation of that integrator is stopped, while the integral calculation of the other integrator continues without stopping. [Effects of the Invention]

[0010] The AC-DC converter according to the present disclosure has the advantage of being able to prevent windup from occurring even when a PS controller is used for current feedback control. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing a configuration example of a rotary machine driving device according to a first embodiment; [Figure 2] 1 is a circuit diagram showing a configuration example of an AC-DC converter according to a first embodiment; [Figure 3] FIG. 1 is a block diagram showing a configuration example of a control unit according to a first embodiment. [Figure 4] FIG. 1 is a block diagram showing a configuration example of a switching signal generating unit according to a first embodiment; [Figure 5]FIG. 1 is a block diagram showing a configuration example of a voltage control unit according to a first embodiment; [Figure 6] FIG. 1 is a block diagram showing a configuration example of a current control unit according to a first embodiment; [Figure 7] A comparative example of the operating waveform in the light load region when anti-windup control is not applied. [Figure 8] A comparative example of the operating waveform in the heavy load region when anti-windup control is not applied. [Figure 9] FIG. 10 is a diagram showing an example of an operating waveform in a light load region when anti-windup control is applied to the AC-DC converter according to the first embodiment. [Figure 10] FIG. 10 is a diagram showing an example of an operating waveform in a heavy load region when anti-windup control is applied to the AC-DC converter according to the first embodiment. [Figure 11] FIG. 1 is a flowchart illustrating an algorithm according to a control method of the first embodiment. [Figure 12] FIG. 10 is a block diagram showing a configuration example of a current control unit of an AC-DC converter according to a second embodiment. [Figure 13] FIG. 10 is a diagram showing an example of an operating waveform in a light load region when anti-windup control is applied to the AC-DC converter according to the second embodiment. [Figure 14] FIG. 10 is a diagram showing an example of an operating waveform in a heavy load region when anti-windup control is applied to the AC-DC converter according to the second embodiment. [Figure 15] FIG. 10 is a flowchart illustrating an algorithm according to a control method of the second embodiment. [Figure 16] FIG. 10 is a diagram showing a configuration example of a control unit according to a third embodiment; [Figure 17] FIG. 10 is a diagram showing an example of an operating waveform in a light load region when anti-windup control is applied to the AC-DC converter according to the third embodiment. [Figure 18] FIG. 10 is a flowchart illustrating an algorithm according to a control method of the third embodiment. [Figure 19] FIG. 10 is a diagram showing a configuration example of an AC-DC converter according to a fourth embodiment. [Figure 20] FIG. 10 is a diagram showing a configuration example of an AC-DC converter according to a fifth embodiment. [Figure 21] FIG. 13 is a diagram showing a configuration example of a refrigeration cycle application device according to a sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An AC-DC converter, a rotary machine drive device, a refrigeration cycle device, and a method for controlling an AC-DC converter according to embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0013] Embodiment 1 1 is a block diagram showing an example of the configuration of a rotating machine driving device 8 according to embodiment 1. The rotating machine driving device 8 is connected to an AC power source 1 and a load 4 including a motor 41. The rotating machine driving device 8 includes an AC-DC converter 2 and a DC-AC converter 3. When the rotating machine driving device 8 is used in an air conditioner, the load 4 is a compressor or a fan, and the motor 41 is a compressor motor or a fan motor.

[0014] 2 is a circuit diagram showing a configuration example of the AC-DC converter 2 according to the first embodiment. The AC-DC converter 2 according to the first embodiment mainly includes a control unit 6, a rectifier circuit 20, a reactor 212, and a capacitor 216. The AC-DC converter 2 also includes a current detection unit 211 and voltage detection units 217a and 217b as means for detecting voltage or current. In this document, when the voltage detection units 217a and 217b are distinguished from each other without reference numerals, the voltage detection unit 217b will be referred to as a "first voltage detection unit" and the voltage detection unit 217a will be referred to as a "second voltage detection unit."

[0015] The rectifier circuit 20 includes single-phase diode bridge cells 213a and 213b, each of which has four diodes bridge-connected, and a switching element 215 connected in parallel across the single-phase diode bridge cell 213b. The single-phase diode bridge cells 213a and 213b are connected in parallel to each other across the AC power supply 1. The rectifier circuit 20 shown in FIG. 2 is called a "simple switching circuit." The single-phase diode bridge cell 213b and the switching element 215 form a switching cell 225. The switching element 215 performs a switching operation at least once per half cycle of the power supply voltage.

[0016] The capacitor 216 is connected between the DC bus 9a and the DC bus 9b. The reactor 212 is arranged closer to the AC power supply 1 than the capacitor 216. The rectifier circuit 20 receives the power supply voltage applied from the AC power supply 1 via the reactor 212 and rectifies the received power supply voltage. The capacitor 216 smoothes the output voltage of the rectifier circuit 20.

[0017] The voltage detection unit 217b detects the bus voltage, which is the voltage of the DC buses 9a and 9b to which the capacitor 216 is connected. The voltage detection unit 217a detects the power supply voltage. The current detection unit 211 detects the power supply current flowing through the AC power supply 1, i.e., the power supply current flowing between the AC power supply 1 and the rectifier circuit 20.

[0018] The control unit 6 receives the detection values ​​of the voltage detection units 217a and 217b and the current detection unit 211. The control unit 6 generates a switching signal for controlling the on / off of the switching element 215 based on the detection values.

[0019] An example of the switching element 215 is an IGBT (Insulated Gate Bipolar Transistor) shown in the figure, but is not limited to an IGBT. Any element capable of switching operation may be used as the switching element 215. Another example of the switching element 215 is a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor).

[0020] 2 is configured as a closed loop using the detected values ​​of the voltage detection units 217a, 217b and the current detection unit 211, but may be configured as an open loop using a target value, an estimated value, etc. When the AC-DC conversion device 2 is configured as an open loop, it is also possible to control the switching element 215 without using the detected values ​​of the voltage detection units 217a, 217b and the current detection unit 211.

[0021] 3 is a block diagram showing an example configuration of the control unit 6 according to embodiment 1. The control unit 6 includes subtractors 61a and 61b, a voltage control unit 63, an integrator 62, a current control unit 64, and a switching signal generation unit 65.

[0022] Subtractor 61a generates voltage deviation 66, which is the difference between first voltage command value 71 and bus voltage detection value 81 detected by voltage detection unit 217b. First voltage command value 71 is a command value for the bus voltage. Voltage control unit 63 generates first current command value 67 using voltage deviation 66. Note that voltage deviation 66 does not necessarily have to use bus voltage detection value 81, and a target value for the bus voltage, an estimated value for the bus voltage, or the like may be used.

[0023] The integrator 62 multiplies the first current command value 67 by an arbitrary excitation signal 82 to generate a second current command value 68. An example of the excitation signal 82 is a sine wave synchronized with the phase of the power supply voltage, but it does not necessarily have to be synchronized.

[0024] The subtractor 61b generates a current deviation 69, which is the difference between the second current command value 68 and a detection value 83 of the power supply current detected by the current detection unit 211. Note that the current deviation 69 does not necessarily have to use the detection value 83 of the power supply current, and a target value of the power supply current, an estimated value of the power supply current, or the like may also be used.

[0025] The current control unit 64 generates a second voltage command value 70 using the current deviation 69. The output of the current control unit 64 is in the dimension of voltage. To distinguish it from the first voltage command value 71, the output of the current control unit 64 is called the "second voltage command value 70." The switching signal generation unit 65 generates a switching signal 84 using the second voltage command value 70.

[0026] FIG. 4 is a block diagram showing an example of the configuration of the switching signal generating unit 65 according to the first embodiment. The switching signal generating unit 65 includes a scaling unit 651, a limiter 652, a carrier generating unit 653, and a carrier comparing unit 654. The scaling unit 651 converts the second voltage command value 70 into a dimensionless value and outputs a pre-limiting duty 655. Note that if dimensionlessization has already been performed in the control gain design of the current control unit 64, the scaling unit 651 is unnecessary. The pre-limiting duty 655 is input to the limiter 652, which performs limiting processing for carrier comparison. The minimum and maximum values ​​of the limiting processing correspond to the minimum and maximum values ​​of the carrier generated by the carrier generating unit 653, respectively. The post-limiting duty 656 output from the limiter 652 is input to the carrier comparing unit 654. The carrier comparator 654 compares the magnitude relationship between the post-limit duty 656 and the carrier output from the carrier generator 653, and generates a switching signal 84 based on the comparison result. Note that the configuration in Fig. 4 is an example and is not limited to this configuration. Any configuration may be used as long as the switching signal 84 is generated based on the output of the current controller 64.

[0027] Fig. 5 is a block diagram showing a configuration example of voltage control unit 63 according to embodiment 1. Voltage control unit 63 includes a voltage controller 636 and a limiter 634. Voltage controller 636 can be configured, for example, as a PI controller. Fig. 5 shows an example in which the PI controller is configured with a proportional controller 631, an integrator 632, and an adder 633.

[0028] The transfer function G when the voltage controller 636 is configured as a PI controller AVR(s)can be expressed by the following equation (1).

[0029]

number

[0030] Here, the transfer function G AVR(s) "AVR" in the above is an abbreviation for "Automatic Voltage Regulator." Also, in the above equation (1), K pAVR is the proportional gain and K iAVR is the integral gain and s is the Laplace operator. In a PI controller, the proportional gain K pAVR and integral gain K iAVR can be determined arbitrarily. Note that the proportional gain K pAVR can be set to zero and configured as an I controller, or the integral gain K iAVR may be set to zero to configure a P controller. Also, a D (Differential) controller may be added to configure a PID controller. Furthermore, feedforward control may be applied to the voltage control unit 63.

[0031] When the input exceeds an upper limit, the limiter 634 sets the output of the limiter 634 to the upper limit, and when the input exceeds a lower limit, the limiter 634 sets the output of the limiter 634 to the lower limit. By applying the limiter 634 to the subsequent stage of the voltage controller 636, it is possible to prevent the first current command value 67 from being an excessively large output. ref * When expressed as: the first current command value 67, which is the output of the limiter 634, is limited to a value in the range expressed by the following formula (2) by the upper and lower limit values ​​set in the limiter 634.

[0032]

number

[0033] In the above formula (2), the upper limit i MaxAn example of the current value is a current value at which the switching element 215 does not break down, but is not limited to a value that depends on the failure of the switching element 215. In addition, in the above formula (2), the lower limit is set to zero because the rectifier circuit 20 shown in FIG. 2, which is a simple switching circuit, is a circuit in which regenerative operation is impossible due to the single-phase diode bridge cell 213a. Note that the lower limit does not need to be zero, but is a value that exceeds zero and is equal to or less than i Max In the case of a regenerative circuit that is a simple switching circuit, the lower limit value may be set to a positive value less than i Max -i with a minus sign Max , or may be set to a negative value greater than .gamma. and less than zero.

[0034] When the limiter 634 limits the output of the voltage controller 636, the limiter 634 outputs a saturation determination signal 635 to the integrator 632. This causes the integrator 632 to stop its integration operation.

[0035] FIG. 6 is a block diagram showing an example of the configuration of a current control unit 64a according to the first embodiment. In FIG. 6, the configuration example according to the first embodiment of the current control unit 64 shown in FIG. 3 is shown as the current control unit 64a. The current control unit 64a has a proportional controller 641, a sine wave tracking controller 642, and an adder 643, and constitutes a PS controller. When the current control unit 64a is constituted by a PS controller, the transfer function G ACR(s) can be expressed by the following equation (3).

[0036]

number

[0037] Here, the transfer function G ACR(s) "ACR" in the above is an abbreviation for "Automatic Current Regulator." Also, in the above equation (3), K pACR is the proportional gain and K sACR is the S control gain, and ω nis the angular frequency and s is the Laplace operator. In the PS controller, the proportional gain K pACR , S control gain K sACR and angular frequency ω n can be determined arbitrarily.

[0038] The PS controller is a controller in which an S controller, which is a Laplace transform expression of a sine wave function or a cosine wave function, is inserted in parallel with a P controller. The S controller operates at an angular frequency ω n This controller has improved tracking performance for a sinusoidal input of angular frequency ω n The reason why the tracking performance improves for pulsating inputs can be explained by the internal model principle. The internal model principle states that if the controller's denominator has the same factors as the denominator polynomial of the command value expressed in Laplace transform, the command value can be tracked without deviation. Note that the current control unit 64a may be configured as a PIS controller by inserting an I controller in parallel with a PS controller. Also, feedforward control may be applied to the current control unit 64a.

[0039] The sine wave tracking controller 642 is configured to have a feedback loop including two integrators. Specifically, the sine wave tracking controller 642 includes a subtractor 6421, a frequency gain setter 6422, integrators 6423 and 6424, a limiter 6425, and a sine wave tracking control gain setter 6427.

[0040] A current deviation 69 is input to one input terminal of the subtractor 6421, and the output of a frequency gain setter 6422 is input to the other input terminal of the subtractor 6421. The output of the limiter 6425 is integrated by an integrator 6424 and then input to the frequency gain setter 6422. A frequency gain is given in the frequency gain setter 6422, and the output is fed back to the subtractor 6421. The frequency gain set by the frequency gain setter 6422 is calculated by ω n 2 The sine wave tracking control gain set by the sine wave tracking control gain setter 6427 corresponds to the S control gain K sACRIn the following explanation, the sine wave tracking control gain set by the sine wave tracking control gain setter 6427 is referred to as "K c " is expressed as

[0041] Limiter 6425 is connected downstream of integrator 6423, and when the output of integrator 6423 exceeds an arbitrarily set upper limit value, it limits the output of limiter 6425 to that upper limit value, and when the output of integrator 6423 falls below an arbitrarily set lower limit value, it sets the output of limiter 6425 to that lower limit value. Furthermore, when the output of integrator 6423 exceeds the upper limit value or falls below the lower limit value, limiter 6425 outputs saturation determination signal 6426 to integrator 6423. This causes the integration calculation of integrator 6423 to stop.

[0042] An example of the upper and lower limit values ​​set in the limiter 6425 is as follows: the output of the integrator 6423 is y, the bus voltage is V dc Then, the sinusoidal wave tracking control gain K c Using this, it can be expressed as the following equation (4).

[0043]

number

[0044] As described above, the output of the current control unit 64 is in the dimension of voltage, and the normalization unit 651 of the switching signal generation unit 65 performs normalization processing to convert the second voltage command value 70, which is the output of the current control unit 64, into a dimensionless value. This normalization processing generally involves converting the bus voltage V dc Therefore, the bus voltage V dc When using the above, the maximum value that the output of the current control unit 64 can take is the bus voltage V dc This becomes:

[0045] 6, a sine wave tracking control gain setter 6427 is provided between the output terminal of the current control unit 64a and the output terminal of the integrator 6423. Therefore, the sine wave tracking control gain Kc Considering this, the maximum and minimum values ​​of the output of the limiter 6425 are determined by the sine wave tracking control gain K c in the denominator. However, the above equation (4) is just an example, and the present invention is not limited to this example. The limiter 6425 may be configured to suppress the occurrence of windup in current feedback control in cooperation with other controllers. In other words, the limiter 6425 may limit the output of the integrator 6423 so as to suppress the occurrence of windup, and upper and lower limit values ​​other than those in the above equation (4) may be used.

[0046] 6 illustrates a configuration in which limiter 6425 is provided on the output side of integrator 6423, but instead of this configuration, limiter 6425 may be provided on the output side of integrator 6424. Alternatively, instead of the configuration in FIG. 6, limiter 6425 may be provided on the output side of proportional controller 641, or limiter 6425 may be provided on the output side of current control unit 64a, i.e., the output side of adder 643. When limiter 6425 is provided on the output side of integrator 6424, if the output of integrator 6424 exceeds an upper limit value or falls below a lower limit value, limiter 6425 outputs saturation determination signal 6426 to integrator 6424. This causes integrator 6424 to stop its integral calculation.

[0047] Next, the operating characteristics when anti-windup control, which is a control for suppressing windup, is applied to the PS controller used in the current control unit 64a will be clarified by comparing them with the operating characteristics when anti-windup control is not applied to the PS controller.

[0048] Fig. 7 is a diagram showing, as a comparative example, the operating waveforms in the light load region when anti-windup control is not applied, and Fig. 8 is a diagram showing, as a comparative example, the operating waveforms in the heavy load region when anti-windup control is not applied.

[0049] 7 and 8 show, as operational waveforms when anti-windup control is not applied, waveforms of the bus voltage command value, the bus voltage, and the absolute value of the power supply voltage in the upper part, waveforms of the current command value, the power supply current, and the actual phase of the power supply current in the middle part, and waveforms of the duty before and after limiting in the lower part. The horizontal axis represents time.

[0050] The bus voltage command value corresponds to the first voltage command value 71 described above, and the current command value corresponds to the second current command value 68 described above. The duty before limiting is calculated by multiplying the second voltage command value 70, which is the output of the current control unit 64, by the bus voltage V dc The duty after limiting is a value that is limited to a range of 0 to 1. In other words, the duty after limiting is limited to 1 in the section where the duty value before limiting exceeds 1.

[0051] Here, we will explain the meaning of the terms "light load" and "heavy load." As mentioned above, in the simple switching method, when the circuit operation switches from boost chopper operation to passive operation and the passive operation becomes a disturbance to the current control, the control becomes unstable and windup may occur. In terms of the operating waveform, the passive operation region is the region where the absolute value of the power supply voltage is greater than the bus voltage command value. In Figure 8, the passive operation region in a half cycle of the power supply voltage is indicated by the symbol A.

[0052] When the control system includes a voltage PI controller and a current PS controller, the voltage PI controller operates to generate a current command value according to the load power supplied to the load 4 and the bus voltage command value, and the current PS controller operates to compensate for the current deficiency that occurs in the passive operating region so as to be able to follow the fundamental wave current command value.

[0053] The present inventors have discovered that the behavior of the controller when windup occurs in the passive operation region varies depending on the magnitude of the load power. Based on this finding, in this paper, the passive operation region is divided into a "light load region" and a "heavy load region." The light load region is a region where the load power is relatively small, and windup can occur mainly because the actual load power supplied to the load 4 by passive operation is greater than the power command value (a converted value obtained from the current command value and the voltage command value) in the controller. The heavy load region is a region where the load power is relatively large, and windup can occur mainly because the PS controller cannot track the current command value due to a current phase delay during passive operation.

[0054] As described above, windup can occur in the light load region because the actual load power supplied to the load 4 by passive operation is greater than the power command value in the controller. In this region, the fundamental current generated by passive operation is greater than the current command value. In this case, the voltage PI controller outputs a negative current command value to satisfy the operating conditions determined by the bus voltage command value and the load power. Meanwhile, the rectifier circuit 20 is unable to perform regenerative operation and cannot pass a negative current, so the actual current cannot track the current command value. As a result, the integration process of the voltage PI controller diverges, and control by the S controller of the current PS controller becomes unstable, resulting in windup.

[0055] Looking at the operating waveforms in Figure 7, the polarity of the current command value and the power supply current begins to reverse from the point indicated by symbol B in the middle, and from this point onwards the power supply current cannot follow the current command value, and the current command value diverges. Furthermore, because the current command value diverges, the duty before the limit also diverges.

[0056] As mentioned above, Figure 8 shows the operating waveforms in the heavy load region without anti-windup control. Windup in the heavy load region occurs in the S-controller of the current PS controller. Simple switching control in the heavy load region widens the diode conduction angle with one or two switching operations, resulting in passive operation for most of the half-cycle of the power supply voltage. In the heavy load region, a larger power needs to be supplied to the load 4 than in the light load region. Therefore, in some cases, the load power cannot be met unless the simple switching pulse width is widened and a lagging power factor is achieved. In this case, if the current command value is controlled to achieve a fundamental power factor of 1, the relationship between the S-controller operation and power becomes contradictory, resulting in windup. The middle part of Figure 8 shows how the actual phase of the power supply current (dash-dotted line) always lags behind the current command value (dashed line), which is synchronized with the power supply voltage. The bottom part of Figure 8 also shows how the pre-limit duty cycle increases to a value close to 100, causing control to become unstable.

[0057] 9 is a diagram showing an example of operating waveforms in a light load region when anti-windup control is applied to the AC-DC converter 2 according to Embodiment 1. The types and display formats of the operating waveforms are the same as those in FIG.

[0058] By using the control unit 6 according to the first embodiment described above, it is possible to prevent the divergence of the current command value, as shown in the middle part of Fig. 9. Furthermore, by using the control unit 6 according to the first embodiment, it is possible to suppress an excessive increase in the duty, as shown in the bottom part of Fig. 9.

[0059] Furthermore, in the control unit 6 according to the first embodiment, when one of the two integrators 6423, 6424 exceeds a predetermined threshold, the integral calculation of that one integrator is stopped, while the integral calculation of the other integrator is continued without being stopped. That is, the control method according to the first embodiment does not stop the operations of both of the two integrators 6423, 6424, and therefore has the effect of suppressing an excessive increase in current in the light load region while performing sine wave tracking control.

[0060] Furthermore, focusing on the power supply current shown in the middle part of Fig. 9, the power supply current includes a first current component resulting from the voltage difference between the power supply voltage and the bus voltage and the rectification operation of rectifier circuit 20, and a second current component resulting from switching of switching element 215. In Fig. 9, the portion surrounded by the dashed-dotted ellipse is the first current component, and the portion surrounded by the broken-dashed ellipse is the second current component. Looking at the waveform in Fig. 9, the current amplitude of the second current component is smaller than the current amplitude of the first current component.

[0061] From the viewpoint of reducing the harmonic components contained in the power supply current, it is preferable to make the current amplitude of the second current component smaller than the current amplitude of the first current component. Therefore, it can be said that by using the anti-windup control according to the first embodiment, it is possible to suppress the occurrence of windup while enhancing the effect of reducing the harmonic components contained in the power supply current.

[0062] Fig. 10 is a diagram showing an example of operating waveforms in the heavy load region when anti-windup control is applied to the AC-DC converter 2 according to embodiment 1. Fig. 10 does not show the waveform of the actual phase of the power supply current, but the other operating waveforms and display format are the same as Fig. 8. By applying the anti-windup control according to embodiment 1 to the windup that occurs under heavy load, an excessive increase in duty can be suppressed.

[0063] The control method of the first embodiment is characterized in that the current control unit 64a includes an S controller, and the S controller has a feedback loop including two integrators 6423 and 6424. When the calculation value of one of the two integrators 6423 and 6424 exceeds a predetermined threshold, the integration calculation of that one integrator is stopped, while the integration calculation of the other integrator continues without stopping. The anti-windup method, which stops the integration calculation when the calculation value of the integration calculation exceeds a threshold, is considered to be relatively widely used, but the method of regarding the S controller as a feedback loop consisting of two integrators and stopping the integration calculation of only one integrator when the calculation value of one integrator exceeds a predetermined threshold, is considered to be a novel method that has not been used before.

[0064] 11 is a flowchart illustrating an algorithm according to the control method of the first embodiment. Current control unit 64a calculates a P control term using current deviation 69 (step S11). This calculation corresponds to the processing of proportional controller 641 in FIG. 6. The P control term refers to a calculated value obtained by the processing of proportional controller 641.

[0065] The current control unit 64a calculates the first integral operation term of the S control term using the difference between the current deviation 69 and the second integral operation term of the S control term (step S12). This operation corresponds to the processing by the subtractor 6421 and the integrator 6423 in FIG. 6. The S control term refers to the overall operation value obtained by the processing by the sine wave tracking controller 642. The first integral operation term of the S control term refers to the operation value obtained by the processing by the integrator 6423, and the second integral operation term of the S control term refers to the operation value obtained by the processing by the integrator 6424 and the frequency gain setter 6422. The initial value of the second integral operation term is set to zero, and in the initial operation, the first integral operation term is calculated using only the current deviation 69.

[0066] The current control unit 64a compares the first integral term with an upper limit and a lower limit (step S13) and determines whether the first integral term exceeds the upper limit or the lower limit (step S14). These processes correspond to the processes of the limiter 6425 in FIG. 6. If the first integral term exceeds the upper limit or the lower limit (step S14, Yes), the current control unit 64a sets the first integral term to the upper limit or the lower limit (step S15). That is, if the first integral term exceeds the upper limit, the value of the first integral term is limited to the upper limit, and if the first integral term exceeds the lower limit, the value of the first integral term is limited to the lower limit.

[0067] After the process of step S15, or if the first integral term does not exceed the upper limit or the lower limit (step S14, No), the current control unit 64a calculates the second integral term using the first integral term (step S16). This calculation corresponds to the processing of the integrator 6423 and the frequency gain setter 6422 in FIG. 6.

[0068] The current control unit 64a calculates a second voltage command value by adding the P control term and the first integral calculation term (step S17). This calculation corresponds to the processing of the sine wave tracking control gain setter 6427 and the adder 643 in Fig. 6. After that, the process returns to step S11, and the processing of steps S11 to S17 is repeated.

[0069] As described above, the AC-DC converter according to the first embodiment includes a rectifier circuit having at least one switching element and rectifying a power supply voltage applied from an AC power supply, a capacitor smoothing the output voltage of the rectifier circuit, a reactor disposed closer to the AC power supply than the capacitor, and a control unit generating a switching signal for controlling the switching element. The control unit includes a voltage control unit generating a first current command value using a voltage deviation that is the difference between a bus voltage command value and the bus voltage, a current control unit generating a second voltage command value using a current deviation that is the difference between a second current command value obtained by making the first current command value follow a sine wave and the power supply current, and a switching signal generation unit generating a switching signal using the second voltage command value. The current control unit includes a PS controller including a proportional controller and a sine wave tracking controller. The sine wave tracking controller has a feedback loop including two integrators. When one of the two integrators exceeds a predetermined threshold, the integrating operation of the one integrator is stopped, while the integrating operation of the other integrator continues. According to the AC / DC converter of the first embodiment, it is possible to prevent the occurrence of windup even when a PS controller is used for current feedback control.

[0070] The power supply current includes a first current component resulting from the voltage difference between the power supply voltage and the bus voltage and the rectification operation of the rectifier circuit, and a second current component resulting from the switching of the switching elements. When the anti-windup control according to the first embodiment is used, the current amplitude of the second current component becomes smaller than the current amplitude of the first current component under power conditions in which the two integrators exceed their thresholds. Therefore, by using the AC-DC converter according to the first embodiment, it is possible to suppress the occurrence of windup while enhancing the effect of reducing harmonic components contained in the power supply current.

[0071] Furthermore, a control method for an AC-DC converter according to a first embodiment is a control method for an AC-DC converter that is applied to an AC-DC converter including: a rectifier circuit having at least one switching element and rectifying a power supply voltage applied from an AC power supply; a capacitor connected to a DC bus and smoothing an output voltage of the rectifier circuit; a reactor arranged closer to the AC power supply than the capacitor; and a control unit that generates a switching signal for controlling the switching element, the control unit including a proportional sine wave controller including a proportional controller and a sine wave tracking controller. The control method for an AC-DC converter according to the first embodiment can be a process including the following first to fifth steps. In the first step, a proportional control term is calculated using a current deviation. In the second step, a first integral term of the sine wave tracking control term is calculated using a difference between the current deviation and a second integral term of the sine wave tracking control term. In the third step, if the first integral term calculated in the second step exceeds a preset upper limit or lower limit, the value of the first integral term is set to the upper limit or lower limit. In the fourth step, a second integral term is calculated using the first integral term limited in the third step. In the fifth step, a voltage command value for controlling the switching element is generated by adding the proportional control term calculated in the first step and the first integral term calculated in the second step. By using a control method for an AC-DC converter including these first to fifth steps, it is possible to prevent windup from occurring even when a PS controller is used for current feedback control.

[0072] Furthermore, according to the AC-DC converter and the control method for the AC-DC converter of embodiment 1, even if a PS controller is used for current feedback control, it is possible to reliably suppress the occurrence of windup in both the light load region and the heavy load region. This makes it possible to effectively utilize the feature of the PS controller, namely, its high ability to follow sinusoidal wave commands, and suppress distortion of the power supply current, thereby reducing the harmonic components contained in the power supply current.

[0073] Embodiment 2 In the second embodiment, a method for configuring the sine wave tracking controller 642 described in the first embodiment with a discrete system controller will be described.

[0074] FIG. 12 is a block diagram showing a configuration example of a current control unit 64b of the AC-DC converter 2 according to the second embodiment. In FIG. 12, a configuration example according to the second embodiment of the current control unit 64 shown in FIG. 3 is shown as the current control unit 64b. The current control unit 64b includes a current controller 646 and a limiter 644. The current controller 646 also includes a proportional controller 641, a sine wave tracking controller 642, and an adder 643. The current controller 646 may be configured as a PIS controller by inserting an I controller in parallel. Feedforward control may also be applied to the current control unit 64b.

[0075] The sine wave tracking controller 642 can be configured using a discrete difference equation obtained by discretizing the continuous system transfer function of the S controller expressed by the second term in the above equation (3). Comparing Fig. 12 with Fig. 6, the configuration of the controller is simplified. If the sine wave tracking controller 642 is not regarded as a feedback loop composed of individual integrators as in the configuration of Fig. 6, but rather anti-windup control is applied to the discretized difference equation, the configuration of the controller can be simplified as shown in Fig. 12.

[0076] An example of a discretization method is bilinear transformation. By using this bilinear transformation, the characteristics of the sine wave tracking controller 642 can be expressed by a difference equation including two delay elements, as shown in the following equation (5).

[0077]

number

[0078] In the above formula (5), Y [n] is the output of the current sample, Y [n-1] is the output one sample before, Y [n-2] is the output two samples ago, U [n] is the input of the current sample, U [n-2]is the input two samples ago, T is the sampling time, ω n(pre) is the angular frequency after prewarping. Note that the discretization method is not limited to the bilinear transformation, and other discretization methods such as backward Euler and forward Euler may be selected.

[0079] The limiter 644 limits the output of the current controller 646 so that it does not exceed a threshold defined by the limiter 644. ctrl Then, the output V of the current controller 646 ctrl is limited by the limiter 644 to a value in the range shown in the following equation (6).

[0080]

number

[0081] Output V of current controller 646 ctrl However, if the above equation (6) is not satisfied, the limiter 644 outputs a saturation determination signal 645 to the sine wave tracking controller 642, and Y [n-1] and Y [n-2] The accumulation of data in these Y [n-1] and Y [n-2] In Y, the previous value is retained. [n-1] and Y [n-2] The stopping of data accumulation in the output V of the current controller 646 corresponds to the process of stopping the integral calculation described in the first embodiment. ctrl If does not satisfy the above equation (6), Y [n-1] and Y [n-2] In this way, it is possible to prevent windup from occurring. [n-1] and Y [n-2] Instead of stopping the accumulation of data in U [n-2] You may stop storing data in Y. [n-1] and Y [n-2] , and U [n-2] The process of storing both data in the same directory may be stopped.

[0082] The functions of the current controller 646, including the sine wave tracking controller 642, can be realized using a processor and a semiconductor memory. The functions of the current controller 646 can be realized by causing the processor to operate software, firmware, or a combination of these. The software or firmware may be written as a program, stored in a semiconductor memory, and read and executed by the processor.

[0083] Examples of semiconductor memories include RAM (Random Access Memory), ROM (Read Only Memory), flash memory, etc. Further examples include EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), etc.

[0084] The functionality of the current controller 646 may also be implemented by a dedicated processing circuit, such as a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof.

[0085] 13 is a diagram showing an example of operating waveforms in a light load region when anti-windup control is applied to the AC-DC converter 2 according to embodiment 2. The types and display formats of the operating waveforms are the same as those in FIG.

[0086] By using the control unit 6 according to the second embodiment described above, it is possible to prevent the divergence of the current command value, as shown in the middle part of Fig. 13. Furthermore, by using the control unit 6 according to the second embodiment, it is possible to suppress an excessive increase in the duty, as shown in the bottom part of Fig. 13.

[0087] Fig. 14 is a diagram showing an example of an operating waveform in a heavy load region when anti-windup control is applied to the AC-DC converter 2 according to embodiment 2. The types and display formats of the operating waveforms are the same as those in Fig. 10. By applying the anti-windup control according to embodiment 2 to the windup that occurs under a heavy load, an excessive increase in duty can be suppressed.

[0088] 15 is a flowchart illustrating an algorithm according to the control method of the second embodiment. Current control unit 64b calculates a P control term P[n] using current deviation 69 (step S21). This calculation corresponds to the processing of proportional controller 641 in FIG. 12, and P control term P[n] refers to a calculated value obtained by the processing of proportional controller 641. Current control unit 64b also calculates an S control term S[n] using current deviation 69 (step S22). This calculation corresponds to the processing of sinusoidal wave tracking controller 642 in FIG. 12, and S control term S[n] refers to a calculated value obtained by the processing of sinusoidal wave tracking controller 642.

[0089] The current control unit 64b adds the P control term P[n] and the S control term S[n] to calculate the output (P[n]+S[n]) (step S23). This calculation corresponds to the processing of the adder 643 in FIG. 12, and the output (P[n]+S[n]) means the calculated value obtained by the processing of the adder 643.

[0090] The current control unit 64b compares the output (P[n]+S[n]) with the upper and lower limits (step S24) and determines whether the output (P[n]+S[n]) exceeds the upper or lower limit (step S25). These processes correspond to the processes of the limiter 644 in FIG. 12. If the output (P[n]+S[n]) exceeds the upper or lower limit (step S25, Yes), the current control unit 64b assigns S[n-1], the calculated value of the S control term from one sample before, to S[n-2], the calculated value of the S control term from two samples before (step S26), and assigns S[n], the calculated value of the S control term from the current sample, to S[n-1], the calculated value of the S control term from one sample before (step S27). That is, the value of the S control term two samples before is updated to the calculated value of the S control term one sample before, and the value of the S control term one sample before is updated to the calculated value of the S control term of the current sample. [n-1] and Y [n-2] This corresponds to the process of storing data in the buffer. After that, the process returns to step S21, and the processes of steps S21 to S27 are repeated. Also, in step S25, if the output (P[n]+S[n]) does not exceed either the upper limit or the lower limit (step S25, No), the process also returns to step S21, and the processes of steps S21 to S27 are repeated.

[0091] As described above, the AC-DC converter according to the second embodiment includes a rectifier circuit having at least one switching element and rectifying a power supply voltage applied from an AC power supply, a capacitor that smoothes the output voltage of the rectifier circuit, a reactor that is located closer to the AC power supply than the capacitor, and a control unit that generates a switching signal for controlling the switching element. The control unit includes a voltage control unit that generates a first current command value using a voltage deviation that is the difference between the bus voltage and a first voltage command value that is a command value for the bus voltage, a current control unit that generates a second voltage command value using a current deviation that is the difference between the power supply current and a second current command value that causes the first current command value to follow a sine wave, and a switching signal generation unit that generates a switching signal using the second voltage command value. The current control unit includes a PS controller that includes a proportional controller and a sine wave tracking controller. The sine wave tracking controller is expressed by a difference equation including two delay elements obtained by discretizing a transfer function obtained by Laplace transforming a sine function or a cosine function. When the sum of the calculated value of the proportional controller and the calculated value of the sine wave tracking controller or the output of the sine wave tracking controller exceeds a predetermined threshold, the sine wave tracking controller stops updating its input value, output value, or both the input and output values. In the AC-DC converter according to the second embodiment, the sine wave tracking controller is not regarded as a feedback loop composed of individual integrators, and anti-windup control is applied to the discretized difference equation. The AC-DC converter according to the second embodiment can achieve the same effects as those of the first embodiment while simplifying the configuration of the controller.

[0092] Furthermore, a control method for an AC-DC converter according to a second embodiment is applied to an AC-DC converter including a rectifier circuit having at least one switching element and rectifying a power supply voltage applied from an AC power supply, a capacitor connected to a DC bus and smoothing the output voltage of the rectifier circuit, a reactor arranged closer to the AC power supply than the capacitor, and a control unit that generates a switching signal for controlling the switching element, wherein the control unit includes a proportional sine wave controller including a proportional controller and a sine wave tracking controller, and the sine wave tracking controller is expressed by a difference equation including two delay elements obtained by discretizing a transfer function obtained by Laplace transforming a sine function or a cosine function. The control method for an AC-DC converter according to the second embodiment can be a process including the following first to fifth steps. In the first step, a proportional control term is calculated using a current deviation that is the difference between a current command value and a power supply current flowing through the AC power supply. In the second step, a sine wave tracking control term is calculated using the current deviation. In the third step, the proportional control term calculated in the first step and the sine wave tracking control term calculated in the second step are added together to calculate an added output. In the fourth step, if the added output calculated in the third step exceeds a preset upper or lower limit, the value of the S control term two samples earlier is updated to the calculated value of the S control term one sample earlier. In the fifth step, if the added output calculated in the third step exceeds a preset upper or lower limit, the value of the S control term one sample earlier is updated to the calculated value of the S control term of the current sample. By using a control method for an AC-DC converter including these first to fifth steps, it is possible to obtain the same effects as in embodiment 1 while simplifying the configuration of the controller.

[0093] Embodiment 3 In the third embodiment, a control method for anti-windup in the light load region will be described, which is different from the control methods described in the first or second embodiment. Fig. 16 is a diagram showing an example of the configuration of a control unit 6 according to the third embodiment. Note that components having the same or equivalent functions as those of the control unit 6 described in the first embodiment are denoted by the same reference numerals, and overlapping descriptions will be omitted as appropriate.

[0094] The control unit 6 according to the third embodiment further includes a bus voltage command value manipulation unit 90 in addition to the configuration shown in Fig. 3. The bus voltage command value manipulation unit 90 is configured to have a function of increasing the first voltage command value 71, which is a command value for the bus voltage. To achieve this function, the bus voltage command value manipulation unit 90 includes an adder 72, phase calculators 74a and 74b, a subtractor 75, an integral input determination unit 76, an integrator 77, and a limiter 78. With these components, the bus voltage command value manipulation unit 90 has a limit function for preventing an excessive increase in the command value for the bus voltage, an integration stop function for stopping the calculation of the integrator 77 when the limit function is activated, and a correction function for correcting the output of the integrator 77 to a specified set value.

[0095] A voltage command value manipulated variable 79, which is the output of the bus voltage command value manipulator 90 and is a controlled variable for increasing the bus voltage command value, is input to the voltage control unit 63 via an adder 72 and a subtractor 61a. The configuration of the voltage control unit 63 may be the same as that of the first embodiment shown in Fig. 5, and the operation of the voltage control unit 63 will be described with reference to Fig. 5.

[0096] In the voltage control unit 63 shown in Fig. 5, when the input exceeds an upper limit value, the limiter 634 sets the output of the limiter 634 to the upper limit value, and when the input exceeds a lower limit value, the limiter 634 sets the output of the limiter 634 to the lower limit value. By applying the limiter 634 to the stage subsequent to the voltage controller 636, it is possible to prevent the first current command value 67 from being an excessively large output. In the limiter 634 of the third embodiment, the upper limit value of the limiter 634 is set to i Max The lower limit of the limiter 634 is set to -i Max and the first current command value 67 is set to i ref * When expressed as: the first current command value 67 which is the output of the limiter 634 is limited to a value in the range expressed by the following equation (7).

[0097]

number

[0098] In the above equation (7), the case where the absolute values ​​of the upper limit value and the lower limit value of the limiter 634 are equal is exemplified, but the absolute values ​​of the upper limit value and the lower limit value may be different.

[0099] Voltage control unit 63 performs control so that voltage deviation 66, which is the deviation between first voltage command value 71 and detected value 81 of the bus voltage, becomes zero. As shown in Fig. 16 , first voltage command value 71 is determined by the sum of third voltage command value 73 and voltage command value manipulated variable 79. Voltage command value manipulated variable 79 is controlled by limiter 78 so as to suppress windup in the light load region.

[0100] Next, a procedure for determining the voltage command value manipulated variable 79 will be described. First, the phase calculator 74a calculates a first phase θ1, which is the phase of the fundamental wave included in the second current command value 68. Similarly, the phase calculator 74b uses the power supply current detection value 83 to calculate a second phase θ2, which is the phase of the fundamental wave included in the power supply current. The subtractor 75 calculates the phase difference δ between the first phase θ1 and the second phase θ2.

[0101] The phase difference δ calculated by the subtractor 75 is input to the integral input determination unit 76. The integral input determination unit 76 determines the input value ψ of the integrator 77 based on the following equation (8).

[0102]

number

[0103] The meaning of the above formula (8) will be explained. When windup occurs in the control unit 6 in the light load region, the polarity of the second current command value 68 and the power supply current is reversed. At this time, the absolute value |δ| of the phase difference δ becomes 180° or a value close to 180°. Therefore, the integral input determination unit 76 determines whether or not the polarity is reversed by comparing the absolute value |δ| of the phase difference δ with a threshold value. Specifically, if the absolute value |δ| of the phase difference δ satisfies |δ|>π+ε or |δ|<π-ε, the integral input determination unit 76 determines that the polarity of the second current command value 68 and the power supply current is not reversed, and sets the input value ψ of the integrator 77 to the phase difference δ. Here, π+ε is a threshold value, and ε is a minute set value at which the polarity of the second current command value 68 and the power supply current can be considered to be reversed. The set value ε can be determined arbitrarily in consideration of the characteristics of the control unit 6. Furthermore, if the absolute value |δ| of the phase difference δ satisfies π-ε≦|δ|≦π+ε, integral input determination unit 76 determines that the polarity of second current command value 68 and the power supply current is reversed, and sets input value ψ of integrator 77 to zero. Setting input value ψ to integrator 77 in this manner enables a configuration in which integral calculation is performed only when windup occurs in the light load region.

[0104] The integrator 77 performs integration based on the phase difference δ to calculate the increase amount of the voltage command value. The calculated increase amount of the voltage command value is input to the limiter 78. The limiter 78 limits the output value so as not to command an excessive voltage command value manipulated variable 79. This function is a limit function for preventing an excessive increase in the command value of the bus voltage. The increase amount of the voltage command value is set so as not to exceed the withstand voltages of the switching element 215 and the capacitor 216. When the limit function is activated, the limiter 78 inputs an integration stop signal 92 to the integrator 77 to stop the calculation of the integrator 77. This function is the integration stop function described above. When the voltage command value manipulated variable 79 output from the limiter 78 to the adder 72 is to be reset, a reset signal 91 is input to the integrator 77. This reset signal 91 corrects the output of the integrator 77 to a specified set value. This function is the correction function described above.

[0105] Fig. 17 is a diagram showing an example of operating waveforms in a light load region when anti-windup control is applied to the AC-DC converter 2 according to embodiment 3. The upper part of Fig. 17 shows the waveforms of the bus voltage command value and the bus voltage, the middle part shows the waveforms of the current command value and the power supply current, and the lower part shows the waveforms of the duty before and after limiting. The horizontal axis represents time.

[0106] The bus voltage command value corresponds to the first voltage command value 71 described above, and the current command value corresponds to the second current command value 68 described above. The duty before limiting is calculated by multiplying the second voltage command value 70, which is the output of the current control unit 64, by the bus voltage V dc The duty after limiting is a value that is limited to a range of 0 to 1. In other words, the duty after limiting is limited to 1 in the section where the duty value before limiting exceeds 1.

[0107] In the upper part of Fig. 17, the areas indicated by dashed ellipses are sections where the bus voltage command value is smaller than the bus voltage, and the areas indicated by chain-dotted ellipses are sections where the bus voltage command value is larger than the bus voltage. In the middle part of Fig. 17, in the sections indicated by the corresponding dashed ellipses, the power supply current and the current command value are out of phase with each other, whereas in the sections indicated by the corresponding chain-dotted ellipses, the power supply current and the current command value are in phase with each other. It can be seen that the AC-DC converter 2 according to the third embodiment has a function of automatically boosting the bus voltage command value, and therefore can prevent the polarity of the power supply current and the current command value from being reversed.

[0108] 18 is a flowchart illustrating an algorithm according to the control method of the third embodiment. First, the phase calculator 74a calculates the first phase θ1 (step S31). As described above, the first phase θ1 is the phase of the fundamental wave included in the second current command value 68. Furthermore, the phase calculator 74b calculates the second phase θ2 (step S32). As described above, the second phase θ2 is the phase of the fundamental wave included in the power supply current.

[0109] The subtractor 75 calculates the phase difference δ between the first phase θ1 and the second phase θ2 (step S33). The integral input determination unit 76 determines whether the phase difference δ is within a preset threshold range of approximately 180 degrees (step S34).

[0110] If the phase difference δ is outside the range of a preset threshold of about 180 degrees (step S34, No), the bus voltage command value manipulation unit 90 determines the voltage command value manipulation amount by integrating the phase difference δ (step S35). Thereafter, the process returns to step S31, and the process from step S31 is repeated. If the phase difference δ is within the range of a preset threshold of about 180 degrees (step S34, Yes), the process returns to step S31 without performing the integration, and the process from step S31 is repeated.

[0111] As described above, the AC-DC converter according to the third embodiment includes a rectifier circuit having at least one switching element and rectifying a power supply voltage applied from an AC power supply, a capacitor smoothing the output voltage of the rectifier circuit, a reactor arranged closer to the AC power supply than the capacitor, and a control unit generating a switching signal for controlling the switching element. The control unit includes a voltage control unit generating a first current command value using a voltage deviation that is the difference between a bus voltage command value and the bus voltage, a current control unit generating a voltage command value for generating a switching signal using a current deviation that is the difference between a second current command value obtained by making the first current command value follow a sine wave and the power supply current, and a bus voltage command value manipulation unit manipulating the bus voltage command value. The current control unit includes a proportional sine wave controller including a proportional controller and a sine wave tracking controller. The bus voltage command value manipulation unit includes a phase calculator that calculates a phase difference between the phase of the second current command value and the phase of the fundamental wave of the power supply current, and an integrator that integrates the phase difference. When the phase difference is outside a preset threshold range of around 180 degrees, the bus voltage command value manipulation unit operates the integrator or continues the operation of the integrator to perform control to increase the bus voltage command value, and when the phase difference is within the threshold range, stops the operation of the integrator and interrupts the control to increase the bus voltage command value. The AC-DC converter according to the third embodiment makes it possible to suppress windup by manipulating the bus voltage command, and can obtain the same effects as those of the first and second embodiments. Furthermore, the AC-DC converter according to the third embodiment can be used in combination with the technique of the first or second embodiment, and when used in combination with the technique of the first or second embodiment, the windup suppression effect can be enhanced.

[0112] Furthermore, a control method for an AC-DC converter according to a third embodiment is a control method for an AC-DC converter that is applied to an AC-DC converter including: a rectifier circuit having at least one switching element and rectifying a power supply voltage applied from an AC power supply; a capacitor connected to a DC bus and smoothing an output voltage of the rectifier circuit; a reactor arranged closer to the AC power supply than the capacitor; and a control unit that generates a switching signal for controlling the switching element, wherein the control unit is equipped with a proportional sine wave controller including a proportional controller and a sine wave tracking controller. The control method for an AC-DC converter according to the third embodiment can be a process including the following first to fourth steps. In the first step, a first phase, which is the phase of a fundamental wave of a current command value that has been made to follow a sine wave, is calculated. In the second step, a second phase, which is the phase of a fundamental wave of a power supply current flowing through the AC power supply, is calculated. In the third step, a phase difference between the first phase and the second phase is calculated. In the fourth step, if the phase difference is outside a preset threshold range of around 180 degrees, the phase difference is integrated to determine a voltage command value manipulated variable. The voltage command value manipulated variable is a control variable that increases the bus voltage command value. By using the control method for an AC-DC converter including these first to fourth steps, it is possible to prevent the occurrence of windup even when a PS controller is used for current feedback control.

[0113] Embodiment 4 In the fourth embodiment, a different example of the AC-DC converter 2 including the control unit 6 described in the first to third embodiments will be described. Components having the same or equivalent functions as those of the AC-DC converter 2 described in the first to third embodiments will be denoted by the same reference numerals, and overlapping descriptions will be omitted as appropriate.

[0114] Fig. 19 is a diagram illustrating a configuration example of an AC-DC converter 2 according to a fourth embodiment. The rectifier circuit 20 illustrated in Fig. 19 has a configuration called a full PAM (Pulse Amplitude Modulation) circuit. The rectifier circuit 20 includes a single-phase diode bridge cell 213a, a switching element 215, and a diode 218. In the single-phase diode bridge cell 213a, the switching element 215 performs a switching operation at least once per half cycle of the power supply voltage.

[0115] 19, the reactor 212 described in the configuration of FIG. 2 is disposed between the single-phase diode bridge cell 213a and the diode 218. The switching element 215 is disposed between the single-phase diode bridge cell 213a and the capacitor 216 and is connected in parallel to the single-phase diode bridge cell 213a and the capacitor 216. The current detection unit 211 described in the configuration of FIG. 2 is disposed between the single-phase diode bridge cell 213a and the diode 218.

[0116] 2 and 19, the positions and connection forms of the switching element 215 and the reactor 212 are different, but in both configurations, the switching element 215 and the reactor 212 are arranged closer to the AC power source 1 than the capacitor 216. This arrangement relationship is similar to that in other embodiments described later.

[0117] The control unit 6 generates and drives the switching element 215 with the switching signal 84 using the control method described in the first to third embodiments. As a result, the AC / DC converter 2 shown in Fig. 19 can also achieve the same effects as those of the first to third embodiments.

[0118] 19, the switching element 215 is shown as an IGBT, but any element capable of switching operation may be used. Furthermore, although the AC-DC converter 2 shown in FIG. 19 is configured as a closed loop, it may also be configured as an open loop. When the AC-DC converter 2 is configured as an open loop, the detection values ​​of the voltage detectors 217a and 217b and the current detector 211 do not need to be used.

[0119] Embodiment 5. In the fifth embodiment, a different example of the AC-DC converter 2 including the control unit 6 described in the first to fourth embodiments will be described. Components having the same or equivalent functions as those of the AC-DC converter 2 described in the first to fourth embodiments will be denoted by the same reference numerals, and overlapping descriptions will be omitted as appropriate.

[0120] Fig. 20 is a diagram showing a configuration example of an AC-DC converter 2 according to embodiment 5. In the AC-DC converter 2 of Fig. 20, a rectifier circuit 20 is configured with a single-phase H-bridge cell including four switching elements 220a, 220b, 220c, and 220d. Note that the configuration and operation of the rectifier circuit 20 shown in Fig. 20 are publicly known, and further description thereof will be omitted here.

[0121] The control unit 6 generates and drives the switching signals 84 for the four switching elements 220a, 220b, 220c, and 220d using the control methods described in the first to third embodiments. As a result, the AC-DC converter 2 shown in Fig. 20 can also achieve the same effects as those of the first to third embodiments.

[0122] 20, the switching elements 220a, 220b, 220c, and 220d are shown as IGBTs, but any elements capable of switching may be used. Furthermore, although the AC-DC converter 2 shown in FIG. 20 is configured as a closed loop, it may also be configured as an open loop. When the AC-DC converter 2 is configured as an open loop, the detection values ​​of the voltage detectors 217a and 217b and the current detector 211 do not need to be used.

[0123] Embodiment 6 21 is a diagram showing a configuration example of a refrigeration cycle apparatus 900 according to embodiment 6. The refrigeration cycle apparatus 900 according to embodiment 6 includes the rotating machine drive device 8 described in embodiment 1. The refrigeration cycle apparatus 900 according to embodiment 6 can be applied to products including a refrigeration cycle, such as air conditioners, refrigerators, freezers, and heat pump water heaters.

[0124] The refrigeration cycle device 900 includes a compressor 42 incorporating the motor 41 in the first embodiment, a four-way valve 902, an indoor heat exchanger 906, an expansion valve 908, and an outdoor heat exchanger 910 attached via refrigerant piping 912. Inside the compressor 42, there are provided a compression mechanism 904 that compresses the refrigerant, and a motor 41 that operates the compression mechanism 904. The refrigeration cycle device 900 can perform heating or cooling operation by switching the four-way valve 902.

[0125] The compression mechanism 904 is driven by a variable-speed controlled motor 41. During heating operation, as indicated by the solid arrows, the refrigerant is pressurized by the compression mechanism 904 and discharged, passes through the four-way valve 902, the indoor heat exchanger 906, the expansion valve 908, the outdoor heat exchanger 910, and the four-way valve 902, and returns to the compression mechanism 904. During cooling operation, as indicated by the dashed arrows, the refrigerant is pressurized by the compression mechanism 904 and discharged, passes through the four-way valve 902, the outdoor heat exchanger 910, the expansion valve 908, the indoor heat exchanger 906, and the four-way valve 902, and returns to the compression mechanism 904. During heating operation, the indoor heat exchanger 906 acts as a condenser to release heat, and the outdoor heat exchanger 910 acts as an evaporator to absorb heat. During cooling operation, the outdoor heat exchanger 910 acts as a condenser to release heat, and the indoor heat exchanger 906 acts as an evaporator to absorb heat. The expansion valve 908 reduces the pressure of the refrigerant and causes it to expand.

[0126] The refrigeration cycle applied device 900 according to the sixth embodiment has been described as including the rotating machine driving device 8 described in the first embodiment, but is not limited to this. The rotating machine driving device 8 may include the rectifier circuit 20 described in the second and third embodiments. Furthermore, the rotating machine driving device 8 may include a rectifier circuit other than the rectifier circuit 20 described in the first to third embodiments, as long as the control methods of the first to third embodiments can be applied.

[0127] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention. [Explanation of symbols]

[0128] REFERENCE SIGNS LIST 1 AC power source, 2 AC / DC converter, 3 DC / AC converter, 4 load, 6 control unit, 8 rotating machine drive device, 9a, 9b DC bus, 20 rectifier circuit, 41 motor, 42 compressor, 61a, 61b, 75, 6421 subtractor, 62 integrator, 63 voltage control unit, 64, 64a, 64b current control unit, 65 switching signal generation unit, 66 voltage deviation, 67 first current command value, 68 second current command value, 69 current deviation, 70 second voltage command value, 71 first voltage command value, 72, 633, 643 adder, 73 third voltage command value, 74a, 74b phase calculator, 76 integral input determination unit, 77, 632, 6423, 6424 Integrator, 78, 634, 644, 652, 6425 Limiter, 79 Voltage command value manipulated variable, 81 Bus voltage detection value, 82 Excitation signal, 83 Power supply current detection value, 84 Switching signal, 90 Bus voltage command value manipulation unit, 91 Reset signal, 92 Integration stop signal, 211 Current detection unit, 212 Reactor, 213a, 213b Single-phase diode bridge cell, 215, 220a, 220b, 220c, 220d Switching element, 216 Capacitor, 217a, 217b Voltage detection unit, 218 Diode, 225 Switching cell, 636 Voltage controller, 631, 641 Proportional controller, 635, 645, 6426 Saturation judgment signal, 642 Sine wave tracking controller, 646 Current controller, 651 Standardization unit, 653 carrier generation unit, 654 carrier comparison unit, 655,656 duty, 900 refrigeration cycle application equipment, 902 four-way valve, 904 compression mechanism, 906 indoor heat exchanger, 908 expansion valve, 910 outdoor heat exchanger, 912 refrigerant piping, 6422 frequency gain setter, 6427 sine wave tracking control gain setter.

Claims

1. a rectifier circuit having at least one switching element and rectifying a power supply voltage applied from an AC power supply; a capacitor connected to the DC bus for smoothing the output voltage of the rectifier circuit; a reactor that is disposed closer to the AC power source than the capacitor; a control unit that generates a switching signal for controlling the switching element, the switching element is disposed closer to the AC power supply than the capacitor; The control unit a voltage control unit that generates a first current command value using a voltage deviation that is a difference between a first voltage command value that is a command value for a bus voltage that is a voltage of the DC bus and the bus voltage; a current control unit that generates a second voltage command value using a current deviation that is a difference between a second current command value obtained by making the first current command value follow a sine wave and a power supply current flowing through the AC power supply; a switching signal generating unit that generates the switching signal using the second voltage command value, the current control unit includes a proportional sine wave controller configured to include a proportional controller and a sine wave tracking controller, The sine wave tracking controller has a feedback loop including two integrators, and when one of the two integrators exceeds a predetermined threshold, the integral calculation of the one integrator is stopped, while the integral calculation of the other integrator continues without stopping.

1. An AC-DC converter comprising:

2. The power supply current includes: a first current component resulting from a voltage difference between the power supply voltage and the bus voltage and a rectification operation of the rectifier circuit; a second current component generated by switching the switching element; Under a power condition in which the two integrators exceed the threshold, the current amplitude of the second current component is smaller than the current amplitude of the first current component.

2. The AC / DC converter according to claim 1 .

3. a rectifier circuit having at least one switching element and rectifying a power supply voltage applied from an AC power supply; a capacitor connected to the DC bus for smoothing the output voltage of the rectifier circuit; a reactor that is disposed closer to the AC power source than the capacitor; a control unit that generates a switching signal for controlling the switching element, the switching element is disposed closer to the AC power supply than the capacitor; The control unit a voltage control unit that generates a first current command value using a voltage deviation that is a difference between a first voltage command value that is a command value for a bus voltage that is a voltage of the DC bus and the bus voltage; a current control unit that generates a second voltage command value using a current deviation that is a difference between a second current command value obtained by making the first current command value follow a sine wave and a power supply current flowing through the AC power supply; a switching signal generating unit that generates the switching signal using the second voltage command value, the current control unit includes a proportional sine wave controller configured to include a proportional controller and a sine wave tracking controller, The sine wave tracking controller is expressed by a difference equation including two-stage delay elements, which is obtained by discretizing a transfer function obtained by Laplace transforming a sine function or a cosine function, When the sum of the calculated value of the proportional controller and the calculated value of the sine wave tracking controller, or the output of the sine wave tracking controller, exceeds a predetermined threshold, updating of the input value, the output value, or both the input value and the output value of the sine wave tracking controller is stopped.

1. An AC-DC converter comprising:

4. The peak value of the power supply voltage is greater than the bus voltage.

4. The AC / DC converter according to claim 1, wherein the AC / DC converter is a DC-DC converter.

5. a rectifier circuit having at least one switching element and rectifying a power supply voltage applied from an AC power supply; a capacitor connected to the DC bus for smoothing the output voltage of the rectifier circuit; a reactor that is disposed closer to the AC power source than the capacitor; a control unit that generates a switching signal for controlling the switching element, the switching element is disposed closer to the AC power supply than the capacitor; The control unit a voltage control unit that generates a first current command value using a voltage deviation that is a difference between a bus voltage that is a voltage of the DC bus and a bus voltage command value that is a command value of the bus voltage; a current control unit that generates a voltage command value using a current deviation that is a difference between a second current command value obtained by making the first current command value follow a sine wave and a power supply current flowing through the AC power supply; a switching signal generation unit that generates the switching signal using the voltage command value; a bus voltage command value operation unit that operates the command value of the bus voltage, the current control unit includes a proportional sine wave controller configured to include a proportional controller and a sine wave tracking controller, The bus voltage command value operation unit a phase calculator that calculates a phase difference between a phase of the second current command value and a phase of a fundamental wave of the power supply current; an integrator that integrates the phase difference, When the phase difference is outside a range of a preset threshold value of about 180 degrees, the integrator is operated or the operation of the integrator is continued to perform control to increase the bus voltage command value; When the phase difference is within the threshold range, the operation of the integrator is stopped to interrupt the control for increasing the bus voltage command value.

1. An AC-DC converter comprising:

6. The bus voltage command value operation unit a limit function for preventing an excessive increase in the bus voltage command value; an integration stop function that stops the calculation of the integrator when the limit function is activated; a correction function for correcting the output of the integrator to a specified set value; 6. The AC / DC converter according to claim 5, further comprising:

7. A rotary machine drive device comprising the AC / DC converter according to any one of claims 1 to 3, 5 and 6.

8. 7. A refrigeration cycle device comprising the AC / DC converter according to claim 1.

9. A control method for an AC / DC converter, the control method being applied to an AC / DC converter comprising: a rectifier circuit having at least one switching element and rectifying a power supply voltage applied from an AC power supply; a capacitor connected to a DC bus and smoothing an output voltage of the rectifier circuit; a reactor arranged closer to the AC power supply than the capacitor; and a control unit generating a switching signal for controlling the switching element, wherein the control unit is equipped with a proportional sine wave controller configured to include a proportional controller and a sine wave tracking controller, a first step of calculating a proportional control term using a current deviation that is a difference between a current command value that follows a sine wave and a power supply current that flows through the AC power supply; a second step of calculating a first integral term of the sine wave tracking control term using a difference between the current deviation and a second integral term of the sine wave tracking control term; a third step of setting the value of the first integral term to a predetermined upper limit value or a predetermined lower limit value when the first integral term calculated in the second step exceeds the predetermined upper limit value or the predetermined lower limit value; a fourth step of calculating the second integral term using the first integral term limited in the third step; a fifth step of generating a voltage command value for controlling the switching element by adding the proportional control term calculated in the first step and the first integral calculation term calculated in the second step; 1. A method for controlling an AC / DC converter, comprising:

10. A control method for an AC-DC converter including: a rectifier circuit having at least one switching element and rectifying a power supply voltage applied from an AC power supply; a capacitor connected to a DC bus and smoothing an output voltage of the rectifier circuit; a reactor arranged closer to the AC power supply than the capacitor; and a control unit that generates a switching signal for controlling the switching element, wherein the control unit includes a proportional sine wave controller having a proportional controller and a sine wave tracking controller, and the sine wave tracking controller is expressed by a difference equation including two stages of delay elements obtained by discretizing a transfer function obtained by Laplace transforming a sine function or a cosine function, a first step of calculating a proportional control term using a current deviation that is a difference between a current command value that follows a sine wave and a power supply current that flows through the AC power supply; a second step of calculating a sine wave tracking control term using the current deviation; a third step of adding the proportional control term calculated in the first step and the sine wave tracking control term calculated in the second step and calculating an added output thereof; a fourth step of updating the value of the S control term two samples before to the calculated value of the S control term one sample before when the added output calculated in the third step exceeds a preset upper limit value or a preset lower limit value; a fifth step of updating the value of the S control term of the previous sample to the calculated value of the S control term of the current sample when the sum output calculated in the third step exceeds a preset upper limit value or a preset lower limit value; 1. A method for controlling an AC / DC converter, comprising:

11. A control method for an AC / DC converter, the control method being applied to an AC / DC converter comprising: a rectifier circuit having at least one switching element and rectifying a power supply voltage applied from an AC power supply; a capacitor connected to a DC bus and smoothing an output voltage of the rectifier circuit; a reactor arranged closer to the AC power supply than the capacitor; and a control unit generating a switching signal for controlling the switching element, wherein the control unit is equipped with a proportional sine wave controller configured to include a proportional controller and a sine wave tracking controller, a first step of calculating a first phase, which is the phase of a fundamental wave of the current command value that is made to follow a sine wave; a second step of calculating a second phase, which is the phase of a fundamental wave of a power supply current flowing through the AC power supply; a third step of calculating a phase difference between the first phase and the second phase; a fourth step of integrating the phase difference when the phase difference is outside a predetermined threshold range of around 180 degrees to determine a voltage command value manipulated variable that is a control variable for increasing a bus voltage command value; 1. A method for controlling an AC / DC converter, comprising:

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