Ac / DC conversion device, rotary machine drive device, and refrigeration cycle application device

Abstract

An AC / DC conversion device (2) comprises: a rectifier circuit (20) that has at least one switching element (215) and rectifies a power supply voltage applied from an AC power supply (1); a capacitor (216) that is connected to DC bus lines and smooths the output voltage of the rectifier circuit (20); a reactor (212) that is disposed closer to the AC power supply (1) side than the capacitor (216); and a control unit (6) that generates a switching signal for controlling the switching element (215). The switching element (215) is disposed closer to the AC power supply (1) side than the capacitor (216). The control unit (6) is provided with a current controller group including a first current controller targeting the fundamental wave of the AC power supply (1) and one or more second current controllers targeting the harmonics of the AC power supply (1) and generates the switching signal on the basis of the output from the current controller group.

Description

AC / DC converters, rotating machine drives, and refrigeration cycle application equipment

[0001] The present disclosure relates to an AC / DC converter that converts AC power into desired DC power, and to a rotating machine drive device and refrigeration cycle equipment that are equipped with the AC / DC converter.

[0002] A power factor correction circuit is typically used to obtain DC voltage from an AC power source. A power factor correction circuit maintains a constant bus voltage and controls the power supply current to comply with harmonic standards. A power factor correction circuit and its control method, the "simple switching method" (also known as the "partial switching method"), performs switching at least once per half cycle of the power supply voltage, which is the voltage of the AC power supply. This method has the advantage of being able to control the bus voltage lower than the peak value of the power supply voltage. However, when the bus voltage is set lower than the peak value of the AC power supply using the simple switching method, the operating circuit switches from a boost chopper to a capacitor-input diode rectifier, which can distort the power supply current.

[0003] To address this issue, the conventional technology disclosed in Patent Document 1 below determines whether the combination of reactor capacity and switching timing complies with harmonic standards by repeating the design for each load power.

[0004] Japanese Patent Application Laid-Open No. 2000-125545

[0005] However, the conventional technology described in Patent Document 1 involves a method of repeatedly testing whether or not compliance with harmonic standards is possible, which results in an exponential increase in the number of tests as the number of pulses increases. Furthermore, there is a problem with the lack of clear guidelines for quantitatively and uniquely designing control gains, which results in a significant amount of time required to complete the design. To address this issue, a method for suppressing power supply harmonics involves using a PS (Proportional Sinusoidal) controller, in which an S (Sinusoidal) controller with high tracking performance for sinusoidal command signals is connected in parallel to a P (Proportional) controller. However, even when using such a PS controller, it is difficult to achieve control that suppresses harmonics of a specific order.

[0006] The present disclosure has been made in consideration of the above, and aims to provide an AC-DC conversion device that can suppress desired harmonics while complying with harmonic standards without relying on trial and error adjustments.

[0007] In order 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 a single-phase AC power supply, a capacitor connected to a DC bus that smoothes the output voltage of the rectifier circuit, a reactor that is arranged on the single-phase AC power supply side of the capacitor, and a control unit that generates a switching signal to control the switching element. The switching element is arranged on the single-phase AC power supply side of the capacitor. The control unit includes a current controller group including a first current controller that controls the fundamental wave of the single-phase AC power supply and one or more second current controllers that control harmonics of the single-phase AC power supply, and generates the switching signal based on outputs from the current controller group.

[0008] The AC-DC converter according to the present disclosure has the advantage of being able to comply with harmonic standards without relying on trial-and-error adjustments, while also being able to suppress desired harmonics.

[0009] FIG. 1 is a block diagram showing a configuration example of a rotary machine drive device according to the first embodiment; FIG. 2 is a circuit diagram showing a configuration example of an AC / DC converter according to the first embodiment; FIG. 3 is a diagram showing an example of the configuration of a control unit that performs current PS control in an AC / DC converter as a comparative example; FIG. 4 is a diagram showing example operation waveforms of a power supply voltage, a bus voltage, and a power supply current when the PS controller shown in FIG. 3 is applied to the control unit as a comparative example; FIG. 5 is a diagram showing an example of current harmonic characteristics when the PS controller shown in FIG. 3 is applied to the control unit as a comparative example; FIG. 2 shows a configuration example of a PS controller provided in a control unit of an AC-DC converter according to embodiment 3. FIG. 1 shows an example of a configuration of a PS controller provided in a control unit of an AC-DC converter according to embodiment 3. FIG. 1 shows an effect when the PS controller shown in FIG. 12 is applied to the control unit of an AC-DC converter according to embodiment 3. FIG. 2 shows an example of a configuration of a PS controller provided in a control unit of an AC-DC converter according to embodiment 3. FIG. 3 shows an example of a configuration of a PS controller provided in a control unit of an AC-DC converter according to embodiment 3.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An AC-DC converter, a rotary machine drive device, and a refrigeration cycle application device according to embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0011] Embodiment 1. Fig. 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 supply 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. The AC power supply 1 is a single-phase AC power supply that applies a power supply voltage to the AC-DC converter 2. 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.

[0012] 2 is a circuit diagram showing a configuration example of the AC-DC converter 2 according to embodiment 1. The AC-DC converter 2 according to embodiment 1 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 detector 211 and voltage detectors 217a and 217b as means for detecting voltage or current.

[0013] The rectifier circuit 20 includes single-phase diode bridge cells 213a and 213b, each of which is formed by connecting four diodes in a bridge configuration, 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 source 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 is located closer to the AC power source 1 than the capacitor 216. The switching element 215 performs a switching operation at least once per half cycle of the power source voltage. In this way, the rectifier circuit 20 includes at least one switching element 215 and rectifies the power source voltage applied from the AC power source 1.

[0014] 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 is connected between the DC bus 9 a and the DC bus 9 b. The capacitor 216 smoothes the output voltage of the rectifier circuit 20.

[0015] The voltage detection unit 217b detects the bus voltage Vdc, 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 between the AC power supply 1 and the rectifier circuit 20.

[0016] 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.

[0017] An example of the switching element 215 is an insulated gate bipolar transistor (IGBT) as 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 metal-oxide-semiconductor field-effect transistor (MOSFET).

[0018] 2 is configured as a closed loop using the detected values ​​of the voltage detectors 217a, 217b and the current detector 211, but may be configured as an open loop using a target value, an estimated value, etc. When the AC-DC converter 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 detectors 217a, 217b and the current detector 211.

[0019] As described above, the control unit 6 generates a switching signal based on the detection values ​​of the voltage detection units 217a, 217b and the current detection unit 211. There are various methods for the control unit 6 to generate a switching signal, but here we will explain a case where the control unit 6 performs current PS control. Fig. 3 is a diagram showing an example of the configuration of a control unit 6A that performs current PS control in an AC-DC converter as a comparative example. The transfer function G when current PS control is performed in a configuration using a PS controller 60A as shown in Fig. 3 is ＡＣＲ（ｓ） can be expressed by the following equation (1).

[0020]

[0021] In equation (1), ACR is an abbreviation for Automatic Current Regulator. ｐＡＣＲ is the proportional gain, and K ｓＡＣＲ is the S control gain, and ω ｎ is the angular frequency, and s is the Laplace operator. In the PS controller 60A, the proportional gain K ｐＡＣＲ , S control gain K ｓＡＣＲ and angular frequency ω ｎ can be determined arbitrarily. PS control is a control that introduces S control, which is a Laplace transform expression of a cos function, in addition to proportional control (P control). As shown in FIG. 3, the PS controller 60A has a configuration in which a lower S controller is connected in parallel to an upper P controller. The S controller controls the angular frequency ω ｎ It has the feature of improving the tracking performance for sinusoidal input. In the S controller, the angular frequency ω ｎ The reason why 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, it can track the command value without deviation.

[0022] In the configuration shown in FIG. 3, the control unit 6A controls the current command value I Ｌ ＊ and the excitation signal. Ｌ ＊ 3 shows a configuration in which the control unit 6A generates a switching signal, but the portions preceding the PS controller 60A and succeeding the PS controller 60A have a general configuration, and therefore detailed description thereof will be omitted.

[0023] FIG. 4 shows, as a comparative example, example waveforms of the power supply voltage, bus voltage Vdc, and power supply current when the PS controller 60A shown in FIG. 3 is applied to the control unit 6A. The upper part of FIG. 4 shows waveforms of the bus voltage Vdc and the absolute value of the power supply voltage, while the lower part of FIG. 4 shows waveforms of the detected power supply current, the fundamental component of the detected power supply current, and the power supply current command value. As shown in the lower part of FIG. 4, the fundamental component of the detected power supply current nearly matches the power supply current command value. This indicates that if the PS controller 60A, which has high tracking performance for sinusoidal inputs, is applied to the control unit 6A, the fundamental component of the detected power supply current can track the power supply current command value even under conditions where the bus voltage Vdc is equal to or less than the peak absolute value of the power supply voltage. Note that FIG. 4 shows results for operating conditions where the bus voltage Vdc is equal to or less than the peak absolute value of the power supply voltage. However, it goes without saying that the fundamental component of the detected power supply current tracks the power supply current command value even under operating conditions where the bus voltage Vdc exceeds the peak absolute value of the power supply voltage.

[0024] FIG. 5 shows an example of current harmonic characteristics when the PS controller 60A shown in FIG. 3 is applied to the control unit 6A as a comparative example. The current harmonic standard used in FIG. 5 is IEC (International Electrotechnical Commission) 61000-3-2 Class A. Note that IEC 61000-3-2 Class A is an example of a current harmonic standard and is not limited to this standard. In FIG. 5, the solid lines indicate the 2nd to 40th current harmonic standard values ​​specified in IEC 61000-3-2 Class A. Also, in FIG. 5, the dashed lines indicate the effective values ​​of the 2nd to 40th harmonic components during rated operation. The harmonic components during rated operation represent the remaining components of the power supply current flowing when the AC-DC converter is operated at rated power, minus the fundamental component of the power supply current. In this paper, the 2nd to 40th harmonics are defined as "low-order harmonics." 5, the waveforms of the dashed lines are lower than the waveforms of the solid lines for the second through fortieth orders. This shows that if the PS controller 60A, which has high tracking performance for sine wave input, is applied to the control unit 6A, the low-order harmonics contained in the power supply current will comply with the harmonic standard value for the power supply current. Note that while FIG. 5 shows the harmonic components during rated operation as an example, it goes without saying that the effect of suppressing harmonic components by the PS controller 60A can be obtained even during times other than rated operation.

[0025] 5, as described above, the low-order harmonics contained in the power supply current comply with the harmonic standard values ​​for the power supply current, but the third to seventh harmonics tend to be high. Therefore, in this embodiment, a case will be described in which the control unit 6 suppresses desired harmonics by configuring S controllers in multiple stages. Hereinafter, as shown in the upper part of FIG. 4, a case will be described in which the bus voltage Vdc, which is the voltage of the DC bus, is lower than the peak value of the power supply voltage of the AC power supply 1. However, the present invention is also applicable to a case in which the bus voltage Vdc, which is the voltage of the DC bus, does not become lower than the peak value of the power supply voltage of the AC power supply 1.

[0026] FIG. 6 is a first diagram illustrating a configuration example of a PS controller 60 included in the control unit 6 of the AC-DC converter 2 according to the first embodiment. In the configuration of the control unit 6 of the AC-DC converter 2 according to the first embodiment, the PS controller 60A of the control unit 6A shown in FIG. 3 is replaced with the PS controller 60 shown in FIG. 6. As shown in FIG. 6, the PS controller 60 includes a P controller 61, S controllers 62-1 to 62-n, and an adder 63. The S controllers 62-1 to 62-n are collectively referred to as a current controller group 64. The P controller 61 is a controller that performs general P control. The S controller 62-1 is a controller that controls the fundamental wave of the power supply current. The S controller 62-2 is a controller that controls the first harmonic of the power supply current. The S controller 62-n is a controller that controls the (n-1)th harmonic of the power supply current. The adder 63 adds the outputs from the P controller 61 and the S controllers 62-1 to 62-n to obtain a voltage command value V ｃｔｒｌ In the following description, when there is no need to distinguish between the S controllers 62-1 to 62-n, they may be referred to as S controllers 62. Note that although the example in FIG. 6 shows a case where n is an integer of 3 or more, n may be any integer of 2 or more.

[0027] The PS controller 60 shown in Fig. 6 has an n-stage configuration in which n S controllers 62 are connected in parallel, i.e., a multi-stage configuration. The PS controller 60 shown in Fig. 6 has two or more S controllers 62 arranged for the purpose of reducing harmonics. Note that the harmonic reduction means of the PS controller 60 is not limited to the S controller 62, and an R (Resonance) controller, a controller that performs simple Fourier series expansion, or the like may also be used. As an example, the transfer function G of an R controller, which is a type of sine wave tracking control, Ｒ（ｓ） is shown in equation (2).

[0028]

[0029] In equation (2), K ｒ is the resonance control gain, and ω １ is the angular frequency of the current control response, and ω ２ is the angular frequency of the sine wave command to be followed. The control unit 6 calculates such a transfer function G Ｒ（ｓ）The control unit 6 can obtain the same effect as when the PS controller 60 is used, even when the R controller is used.

[0030] FIG. 7 is a second diagram showing a configuration example of the PS controller 60 included in the control unit 6 of the AC-DC converter 2 according to the first embodiment. Specifically, the PS controller 60 shown in FIG. 7 is a current controller including an S controller 62 for controlling the fundamental wave and the seventh harmonic, and includes a P controller 61, S controllers 62-1 and 62-2, and an adder 63. That is, FIG. 7 shows the case where n=2. In the example of FIG. 7, the S controller 62-1 is a controller for controlling the fundamental wave of the power supply current. The S controller 62-2 is a controller for controlling the seventh harmonic as the first harmonic of the power supply current. In FIG. 7, the fundamental wave of the power supply current is controlled by a fundamental wave angular frequency ω １ｆ and the seventh harmonic of the power supply current is expressed as the seventh angular frequency ω ７ｆ It is expressed as:

[0031] 8A and 8B are diagrams showing the effect of applying the PS controller 60 shown in FIG. 7 to the control unit 6 of the AC-DC converter 2 according to the first embodiment. In FIG. 8A, FIG. 8A shows the operating waveforms and harmonic characteristics when the PS controller 60A shown in FIG. 3 is applied to the control unit 6A, and FIG. 8B shows the operating waveforms and harmonic characteristics when the PS controller 60 shown in FIG. 7 is applied to the control unit 6. FIG. 9 is a diagram showing an example of current harmonic characteristics when the PS controller 60 shown in FIG. 7 is applied to the control unit 6 of the AC-DC converter 2 according to the first embodiment. It can be seen from FIGS. 8 and 9 that when the PS controller 60A shown in FIG. 3 is applied, a seventh harmonic is present, but when the PS controller 60 provided with the S controller 62-2 for the seventh harmonic is applied as shown in FIG. 7, the seventh harmonic can be reduced to zero.

[0032] In this way, the control unit 6 of the AC-DC converter 2 can reduce harmonics by providing an S controller 62-2 that reduces a specific frequency in addition to the S controller 62-1 for fundamental wave control. That is, the control unit 6 is provided with a current controller group 64 including an S controller 62-1 that is a current controller that controls the fundamental wave of the AC power supply 1, and one or more S controllers 62-2 to 62-n that are current controllers that control the harmonics of the AC power supply 1, and generates a switching signal based on the output from the current controller group 64. In the following description, the S controller 62-1 may be referred to as a first current controller, and the S controllers 62-2 to 62-n may be referred to as second current controllers.

[0033] In addition, in the control unit 6, the S controller 62-1, which is a current controller targeting the fundamental wave of the current controller group 64, and the S controllers 62-2 to 62-n, which are one or more current controllers targeting harmonics, are capable of following command values ​​based on the internal model principle, similar to the S controller of the PS controller 60A shown in Figure 3.

[0034] As described above, according to this embodiment, in order to reduce low-order harmonics superimposed on the power supply current, the control unit 6 of the AC-DC converter 2 is provided with an S controller 62-1 for fundamental wave control and S controllers 62-2 to 62-n for reducing specific frequencies as sine wave tracking controllers that suppress low-order harmonics in the PS controller 60, which is a current controller. This allows the AC-DC converter 2 to comply with harmonic standards without relying on trial-and-error adjustments. Furthermore, the AC-DC converter 2 can suppress harmonics of specific orders, i.e., desired harmonics.

[0035] Second Embodiment In the AC-DC converter 2, when the bus voltage Vdc becomes greater than the peak value of the power supply voltage of the AC power supply 1, an overmodulation region occurs in which the duty ratio is 1 or greater. At this time, if multiple S controllers 62 are performing control in the PS controller 60 of the control unit 6, each S controller 62 performs control such that each S controller 62 follows its own command value. As a result, the controls of the S controllers 62 may interfere with each other, potentially preventing the control unit 6 from achieving the desired operation. For this reason, in a second embodiment, a case will be described in which a variable limiter is provided downstream of each S controller 62.

[0036] Fig. 10 is a first diagram showing a configuration example of a PS controller 60 included in a control unit 6 of an AC-DC converter 2 according to embodiment 2. In embodiment 2, the configuration of the control unit 6 of the AC-DC converter 2 is such that the PS controller 60A in the configuration of the control unit 6A shown in Fig. 3 is replaced with a PS controller 60 shown in Fig. 10. The PS controller 60 of embodiment 2 shown in Fig. 10 is configured by adding limiters 65, 66-1 to 66-n and a limit value generator 67 to the PS controller 60 of embodiment 1 shown in Fig. 6.

[0037] The limiter 65 is a limiter for limiting the output V Ｐ is the limit value V Ｌｉｍ（Ｐ） Here, the limit value V of the limiter 65 is Ｌｉｍ（Ｐ） is a specified value, but may be changed by the limit value generator 67. The limiter 66-1 is configured to Ｓ１ is the limit value V Ｌｉｍ（１） The limit value V of the limiter 66-1 is Ｌｉｍ（１） can be changed by the limit value generator 67. Similarly, the limiter 66-2 controls the output V Ｓ２ is the limit value V Ｌｉｍ（２） The limit value V of the limiter 66-2 is Ｌｉｍ（２） can be changed by the limit value generator 67. The limiter 66-n controls the output V Ｓｎ is the limit value V Ｌｉｍ（ｎ） The limit value V of the limiter 66-n is Ｌｉｍ（ｎ） can be changed by the limit value generator 67. The limit value generator 67 generates limit values ​​V Ｌｉｍ（１） ~V Ｌｉｍ（ｎ） Control appropriately and change as necessary.

[0038] Hereinafter, as in the first embodiment, a specific example in which there are two S controllers 62 will be described. FIG. 11 is a second diagram showing a configuration example of the PS controller 60 provided in the control unit 6 of the AC-DC converter 2 according to the second embodiment. The PS controller 60 shown in FIG. 11 specifically shows a current controller equipped with an S controller 62 for controlling the fundamental wave and the seventh harmonic, and includes a P controller 61, S controllers 62-1 and 62-2, an adder 63, limiters 65, 66-1 and 66-2, and a limit value generator 67. That is, FIG. 11 shows a case in which n=2. In the example of FIG. 11, the S controller 62-1 is a controller for controlling the fundamental wave of the power supply current. The S controller 62-2 is a controller for controlling the seventh harmonic as the first harmonic of the power supply current. In FIG. 11, the fundamental wave of the power supply current is controlled by a fundamental angular frequency ω １ｆ and the seventh harmonic of the power supply current is expressed as the seventh angular frequency ω ７ｆ The output V from the S controller 62-1 Ｓ１ The limit value V in the limiter 66-1 Ｌｉｍ（１） can be expressed as in equation (3).

[0039]

[0040] Generally, in order to transmit power, it is necessary to control the fundamental wave according to the command value. Ｓ１ Therefore, it is not desirable to limit the output V of the S controller 62-1. Ｓ１ The limit value V in the limiter 66-1 Ｌｉｍ（１） The limit value V is set to the bus voltage Vdc, which is the maximum voltage that the circuit can output. Ｌｉｍ（１） In the PS controller 60, the limit value generator 67, although simplified in FIGS. 10 and 11, obtains the detected value, i.e., the bus voltage Vdc, from the voltage detection unit 217b, and sets the limit value V Ｌｉｍ（１） can be set.

[0041] Output V of S controller 62-2 Ｓ２ The limit value V in the limiter 66-2 Ｌｉｍ（２）is set so as not to interfere with the operation of the S controller 62-1. Ｓ１ The limit value V in the limiter 66-1 Ｌｉｍ（１） That is, the bus voltage Vdc and the output V of the S controller 62-1 Ｓ１ The difference between Ｌｉｍ（２） The limit value V Ｌｉｍ（２） can be expressed as in equation (4).

[0042]

[0043] In the PS controller 60, the limit value generator 67, although simplified in FIGS. 10 and 11, obtains the detected value, i.e., the bus voltage Vdc, from the voltage detection unit 217b, and outputs the output Vdc of the S controller 62-1 from the limiter 66-1. Ｓ１ By obtaining the limit value V Ｌｉｍ（２） is calculated, and the limit value V is input to the limiter 66-2. Ｌｉｍ（２） In this way, the control unit 6 can suppress interference caused by a plurality of S controllers 62 by prioritizing fundamental wave control.

[0044] Although the case where there are two S controllers 62 has been described, the limit value can be set in a similar way when there are three or more S controllers 62. For example, in the case of a PS controller 60 configuration in which there are three S controllers 62 and an S controller 62-3 and a limiter 66-3 are added to the configuration of FIG. 11, the output V of the S controller 62-3 is Ｓ３ The limit value V in the limiter 66-3 for Ｌｉｍ（３） can be expressed as in equation (5).

[0045]

[0046] In the above example, the control priorities are S controller 62-1 > S controller 62-2 > S controller 62-3, but the order of priorities may be reversed, such as S controller 62-1 > S controller 62-3 > S controller 62-2, or S controller 62-2 > S controller 62-1 > S controller 62-3. In this way, the control unit 6 further includes limiters 66-1 to 66-n and a limit value generator 67 that limit the operation amounts of the S controllers 62-1 to 62-n, which are the current controllers of the current controller group 64, and varies the limit values ​​of the limiters 66-1 to 66-n according to the control amounts of the fundamental wave current control and the harmonic current control, thereby suppressing interference by the S controllers 62-1 to 62-n.

[0047] As described above, according to this embodiment, the control unit 6 of the AC-DC converter 2 includes limiters 66-1 to 66-n, which are variable limiters for limiting the manipulated variable of each S controller 62, and a limit value generator 67. As a result, by limiting the manipulated variable of each S controller 62, the AC-DC converter 2 can suppress harmonics while suppressing interference caused by the control of the multiple S controllers 62.

[0048] Third Embodiment In a third embodiment, a case will be described in which the control unit 6 changes the phase of the fundamental wave before input to the PS controller 60, thereby widening the margin of the manipulated variable for sine wave tracking control.

[0049] 12 is a first diagram showing a configuration example of the PS controller 60 provided in the control unit 6 of the AC / DC converter 2 according to the third embodiment. Here, the S controller 62-2 controls the fifth harmonic, but the control flow of the PS controller 60 is the same as the control flow of the PS controller 60 according to the second embodiment shown in FIG. 11. As shown in FIG. 12, the control unit 6 controls the current command value I Ｌ ＊ In the third embodiment, when a sine wave of sin θ is multiplied as the excitation signal to be multiplied by, the phase of sin θ is shifted by δ to obtain sin(θ-δ), which is used as the current command value I Ｌ ＊The excitation signal is a sine wave synchronized with the phase of the power supply voltage. The control unit 6 can generate the sine wave, i.e., the excitation signal, based on the voltage phase, which is the phase of the voltage detected by the voltage detection unit 217a, for example.

[0050] Fig. 13 is a diagram showing the effect when the PS controller 60 shown in Fig. 12 is applied to the control unit 6 of the AC-DC converter 2 according to embodiment 3. Fig. 14 is a diagram showing an example of current harmonic characteristics when the PS controller 60 shown in Fig. 12 is applied to the control unit 6 of the AC-DC converter 2 according to embodiment 3.

[0051] Figure 13(a) shows the power supply current when the control unit 6 is equipped with an S controller 62-1 for the fundamental wave but not with an S controller 62-2 for the fifth harmonic, and when the phase of the excitation signal is not shifted.

[0052] Figure 13(b) shows the power supply current when the control unit 6 is equipped with an S controller 62-1 for the fundamental wave and an S controller 62-2 for the fifth harmonic, but the phase of the excitation signal is not shifted. Under the conditions shown in Figure 13(b), the control unit 6 can reduce the fifth harmonic by multi-stage S control, but cannot reduce it to zero, and other harmonics increase, as shown in Figure 14.

[0053] Figure 13(c) shows the power supply current when the control unit 6 includes an S controller 62-1 for the fundamental wave and an S controller 62-2 for the fifth harmonic, and the phase of the excitation signal is shifted. Phase shift control is a control that changes the phase of the power supply current to an arbitrary value without synchronizing it with the phase of the power supply voltage. In this case, the control unit 6 shifts the phase so that the peak value of the power supply current command value is at the phase of the intersection of the power supply voltage and the bus voltage Vdc. Note that the amount of phase shift is not limited to the above, and the control unit 6 may advance or delay the phase with respect to the power supply voltage. Under the conditions of Figure 13(c), the control unit 6 can improve the control margin required for harmonic suppression and reduce the fifth harmonic to zero by combining multi-stage S control with phase shift control, as shown in Figure 14.

[0054] Although the above description concerns a case where there are two S controllers 62, the present invention is also applicable to a case where there are three or more S controllers 62. The present invention is also applicable to a case where the PS controller 60 does not include the limiters 65, 66-1 to 66-n and the limit value generator 67. FIG. 15 is a second diagram showing a configuration example of the PS controller 60 included in the control unit 6 of the AC-DC converter 2 according to the third embodiment. While FIG. 15 illustrates a case where there are two S controllers 62, it is also possible to include three or more S controllers 62. In this way, by changing the phase of the fundamental wave current of the AC power source 1, the control unit 6 can increase the margin of the manipulated variable of one or more S controllers 62, which are current controllers targeting harmonics of the AC power source 1.

[0055] As described above, according to this embodiment, the control unit 6 of the AC-DC converter 2 changes the phase of the fundamental wave current, i.e., the power supply current, of the AC power supply 1. This allows the AC-DC converter 2 to improve the harmonic suppression effect by increasing the margin of the manipulated variable of the sine wave tracking control.

[0056] Embodiment 4 In embodiment 4, a different example of the AC-DC converter 2 including the control unit 6 described in embodiments 1 to 3 will be described. Note that components having the same or equivalent functions as components of the AC-DC converter 2 described in embodiments 1 to 3 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0057] FIG. 16 is a diagram illustrating a configuration example of an AC-DC converter 2 according to a fourth embodiment. In the AC-DC converter 2 of FIG. 16, the rectifier circuit 20 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. In the fourth embodiment, a configuration will be described in which PIR (Proportional Integral Resonant) control is applied as control by the control unit 6 of the AC-DC converter 2.

[0058] 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 is disposed between the single-phase diode bridge cell 213a and the diode 218.

[0059] 2 and 16, 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.

[0060] 16, 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. 16 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.

[0061] 16 may be used in the first to third embodiments, and the simple switching circuit of FIG. 2 may be used in the fourth embodiment. That is, when the AC-DC converter 2 has a step-up function or a step-down function, the rectifier circuit 20 includes at least one switching element, but the control method described in this paper is applicable even if the control method for controlling the switching element is different.

[0062] Next, the transfer function of the PIR controller will be described. First, the transfer function G ＰＩＲ（ｓ） can be expressed by the following equation (6).

[0063]

[0064] In the above formula (6), K ｐis the proportional gain, and K ｉ is the integral gain, and K ｒ is the resonance control gain, and ω １ is the angular frequency of the current control response, and ω ２ is the angular frequency of the sine wave command to be followed. ＰＩＲ（ｓ） A PIR controller having the above formula may be applied to the control unit 6 of the first to third embodiments. The use of a PIR controller can also provide the same effects as the PS control.

[0065] As described above, PIR control is applied to the control unit 6 according to the fourth embodiment. Even when PIR control is applied instead of PS control, the same effects as those of the first to third embodiments can be obtained.

[0066] Embodiment 5 In embodiment 5, a different example of the AC-DC converter 2 including the control unit 6 described in embodiments 1 to 3 will be described. Note that components having the same or equivalent functions as components of the AC-DC converter 2 described in embodiments 1 to 3 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0067] Fig. 17 is a diagram showing a configuration example of an AC-DC converter 2 according to embodiment 5. In the AC-DC converter 2 shown in Fig. 17, 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. 17 are publicly known, and further description thereof will be omitted here.

[0068] The control unit 6 generates switching signals to drive 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. 17 can also achieve the same effects as those of the first to third embodiments.

[0069] 17, the switching elements 220a, 220b, 220c, and 220d are shown as IGBTs, but any elements capable of switching operation may be used. Furthermore, although the AC-DC converter 2 shown in FIG. 17 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.

[0070] Sixth Embodiment In a sixth 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.

[0071] FIG. 18 is a diagram illustrating a configuration example of an AC-DC converter 2 according to a sixth embodiment. In the AC-DC converter 2 of FIG. 18, a rectifier circuit 20 is configured with a single-phase H-bridge cell including two diodes 218a and 218b and two switching elements 220c and 220d. In the rectifier circuit 20 illustrated in FIG. 18, one leg is configured with a series circuit of the diodes 218a and 218b, and the other leg is configured with a series circuit of the switching elements 220c and 220d. The configuration and operation of the rectifier circuit 20 illustrated in FIG. 18 are publicly known, and therefore further description thereof will be omitted here.

[0072] The control unit 6 generates switching signals to drive the two switching elements 220c, 220d using the control methods described in the first to third embodiments. As a result, the AC-DC converter 2 shown in Fig. 18 can also achieve the same effects as those of the first to third embodiments.

[0073] 18, the switching elements 220c and 220d are shown as IGBTs, but any elements capable of switching operation may be used. Furthermore, although the AC-DC converter 2 shown in FIG. 18 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.

[0074] Embodiment 7 In embodiment 7, a different example of the AC-DC converter 2 including the control unit 6 described in embodiments 1 to 3 will be described. Components having the same or equivalent functions as components of the AC-DC converter 2 described in embodiments 1 to 3 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0075] Fig. 19 is a diagram illustrating a configuration example of an AC-DC converter 2 according to a seventh embodiment. In the AC-DC converter 2 of Fig. 19, a rectifier circuit 20 is configured with a single-phase H-bridge cell including two diodes 218a and 218c and two switching elements 220b and 220d. In the rectifier circuit 20 illustrated in Fig. 19, the diodes 218a and 218c are arranged in the upper arms of the two legs, and the switching elements 220b and 220d are arranged in the lower arms of the two legs. Note that the configuration and operation of the rectifier circuit 20 illustrated in Fig. 19 are publicly known, and further description thereof will be omitted here.

[0076] The control unit 6 generates switching signals to drive the two switching elements 220b and 220d using the control methods 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.

[0077] 19, the switching elements 220b and 220d are shown as IGBTs, but any elements 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.

[0078] Embodiment 8 In embodiment 8, a different example of the AC-DC converter 2 including the control unit 6 described in embodiments 1 to 3 will be described. Note that components having the same or equivalent functions as components of the AC-DC converter 2 described in embodiments 1 to 3 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0079] Fig. 20 is a diagram showing a configuration example of an AC-DC converter 2 according to an eighth embodiment. In the AC-DC converter 2 shown in Fig. 20, the rectifier circuit 20 is configured with a single-phase H-bridge cell including two diodes 218a and 218b, four switching elements 220a, 220b, 220c, and 220d, a capacitor 216b, and a voltage detection unit 217c. The voltage detection unit 217c may be provided outside the rectifier circuit 20. Note that in Fig. 20, the capacitor 216 shown previously is represented as a capacitor 216a.

[0080] In the rectifier circuit 20 shown in FIG. 20 , one leg is formed by a series circuit of diodes 218a and 218b, and the other leg is formed by a series circuit of switching elements 220a, 220b, 220c, and 220d. Capacitor 216b is connected between the connection point of switching elements 220a and 220b and the connection point of switching elements 220c and 220d. Voltage detection unit 217c detects the voltage of capacitor 216b and outputs the detected value to control unit 6. Based on the detected values ​​of voltage detection units 217a, 217b, and 217c and current detection unit 211, control unit 6 generates switching signals for controlling 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.

[0081] The control unit 6 generates switching signals to drive 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.

[0082] 20, the switching elements 220a, 220b, 220c, and 220d are shown as IGBTs, but any elements capable of switching operation 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, 217b, and 217c and the current detector 211 do not need to be used.

[0083] Embodiment 9 In embodiment 9, a different example of the AC / DC converter 2 including the control unit 6 described in embodiments 1 to 3 will be described. Note that components having the same or equivalent functions as components of the AC / DC converter 2 described in embodiments 1 to 3 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0084] 21 is a diagram illustrating a configuration example of an AC-DC converter 2 according to a ninth embodiment. In the AC-DC converter 2 of FIG. 21 , a rectifier circuit 20 includes a single-phase H-bridge cell 221 and a switching cell 222. The single-phase H-bridge cell 221 includes two diodes 218a and 218c and two switching elements 220b and 220d. The switching cell 222 includes four switching elements 220e, 220f, 220g, and 220h, a capacitor 216c, and a voltage detection unit 217c. The voltage detection unit 217c may be provided outside the switching cell 222.

[0085] In a single-phase H-bridge cell 221 shown in Fig. 21, diodes 218a and 218c are arranged in the upper arms of two legs, and switching elements 220b and 220d are arranged in the lower arms of two legs. In a switching cell 222 shown in Fig. 21, four switching elements 220e, 220f, 220g, and 220h are bridge-connected. A capacitor 216c is connected in parallel to a first leg consisting of switching elements 220e and 220f and a second leg consisting of switching elements 220g and 220h.

[0086] The voltage detection unit 217c detects the voltage of the capacitor 216c and outputs the detected value to the control unit 6. The control unit 6 generates switching signals for controlling the switching elements 220b, 220d, 220e, 220f, 220g, and 220h based on the detected values ​​of the voltage detection units 217a, 217b, and 217c and the current detection unit 211. The configuration and operation of the rectifier circuit 20 shown in FIG. 21 are publicly known, and further description thereof will be omitted here.

[0087] The control unit 6 generates switching signals to drive the six switching elements 220b, 220d, 220e, 220f, 220g, and 220h using the control methods described in the first to third embodiments. As a result, the AC-DC converter 2 shown in Fig. 21 can also achieve the same effects as those of the first to third embodiments.

[0088] 21, the switching elements 220b, 220d, 220e, 220f, 220g, and 220h are shown as IGBTs, but any elements capable of switching operation may be used. Furthermore, although the AC-DC converter 2 shown in FIG. 21 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, 217b, and 217c and the current detector 211 do not need to be used.

[0089] Embodiment 10 In embodiment 10, a different example of the AC-DC converter 2 including the control unit 6 described in embodiments 1 to 3 will be described. Components having the same or equivalent functions as components of the AC-DC converter 2 described in embodiments 1 to 3 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0090] FIG. 22 is a diagram illustrating a configuration example of an AC-DC converter 2 according to a tenth embodiment. In the AC-DC converter 2 of FIG. 22, the rectifier circuit 20 is composed of a single-phase diode bridge cell 213a and a switching cell 225. The switching cell 225 includes a single-phase diode bridge cell 213b and a series circuit formed by two switching elements 220a and 220b. The series circuit is connected in parallel to the single-phase diode bridge cell 213b. In FIG. 22, the capacitor 216 in FIG. 2 is replaced with two capacitors 216a and 216b connected in series. The series-connected capacitors 216a and 216b are connected between the DC buses 9a and 9b.

[0091] The control unit 6 generates switching signals for controlling the switching elements 220a and 220b based on the detection values ​​of the voltage detection units 217a and 217b and the current detection unit 211. The configuration and operation of the rectifier circuit 20 shown in Fig. 22 are publicly known, and further description thereof will be omitted here.

[0092] The control unit 6 generates switching signals to drive the two switching elements 220a and 220b using the control methods described in the first to third embodiments. As a result, the AC-DC converter 2 shown in Fig. 22 can also achieve the same effects as those of the first to third embodiments.

[0093] 22, the switching elements 220a and 220b are shown as IGBTs, but any elements capable of switching operation may be used. Furthermore, although the AC-DC converter 2 shown in FIG. 22 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.

[0094] Embodiment 11 In embodiment 11, an example of an AC / DC converter 2 including a control unit 6 different from those described in embodiments 1 to 3 will be described. Components having the same or equivalent functions as components of the AC / DC converter 2 described in embodiments 1 to 3 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0095] FIG. 23 is a diagram illustrating a configuration example of an AC-DC converter 2 according to an eleventh embodiment. In the AC-DC converter 2 of FIG. 23, a rectifier circuit 20 is configured with a single-phase diode bridge cell 213a and an interleaved cell 219. The interleaved cell 219 is a full-PAM circuit configuration with two sets of reactors, switching elements, and diodes. Specifically, the interleaved cell 219 includes reactors 2191a and 2191b, diodes 2192a and 2192b, and switching elements 2193a and 2193b. The configuration and operation of the rectifier circuit 20 illustrated in FIG. 23 are publicly known, and further description thereof will be omitted here.

[0096] The control unit 6 generates switching signals to drive the two switching elements 2193a and 2193b using the control methods described in the first to third embodiments. As a result, the AC-DC converter 2 shown in Fig. 23 can also achieve the same effects as those of the first to third embodiments.

[0097] Although the switching elements 2193a and 2193b are shown as IGBTs in FIG. 23 , any elements capable of switching operation may be used. Furthermore, although the AC-DC converter 2 shown in FIG. 23 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. Furthermore, although FIG. 23 shows an example in which the interleaved cells 219 are configured in two stages, the interleaved cells 219 may also be configured in three or more stages. Furthermore, the rectifier circuits 20 shown in the first to tenth embodiments may also be configured in an interleaved configuration.

[0098] Embodiment 12. Figure 24 is a diagram showing a configuration example of a refrigeration cycle-applied device 900 according to embodiment 12. The refrigeration cycle-applied device 900 according to embodiment 12 includes the rotating machine drive device 8 described in embodiment 1. That is, the refrigeration cycle-applied device 900 includes the AC-DC converter 2 described in embodiment 1. The refrigeration cycle-applied device 900 according to embodiment 12 can be applied to products equipped with a refrigeration cycle, such as air conditioners, refrigerators, freezers, and heat pump water heaters.

[0099] The refrigeration cycle device 900 includes a compressor 42 incorporating the motor 41 of the first embodiment, a four-way valve 902, an indoor heat exchanger 906, an expansion valve 908, and an outdoor heat exchanger 910, all of which are 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.

[0100] 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.

[0101] The refrigeration cycle applied device 900 according to the twelfth embodiment has been described as including the rotating machine driving device 8 described in the first embodiment, but is not limited to this. The refrigeration cycle applied device 900 may include the rotating machine driving device 8 including the rectifier circuit 20 described in any of the second to eleventh embodiments. Furthermore, the refrigeration cycle applied device 900 may include a rectifier circuit other than the rectifier circuit 20 described in any of the first to eleventh embodiments, as long as the control techniques of the first to third embodiments can be applied.

[0102] 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.

[0103] 1 AC power supply, 2 AC / DC converter, 3 DC / AC converter, 4 load, 6, 6A control unit, 8 rotating machine drive device, 9a, 9b DC bus, 20 rectifier circuit, 41 motor, 42 compressor, 60, 60A PS controller, 61 P controller, 62-1 to 62-n S controller, 63 adder, 64 current controller group, 65, 66-1 to 66-n limiter, 67 limit value generator, 211 current detection unit, 212, 2191a, 2191b reactor, 213a, 213b single-phase diode bridge cell, 215, 220a to 220h, 2193a, 2193b switching element, 216, 216a to 216c capacitor, 217a to 217c Voltage detection unit, 218, 218a to 218c, 2192a, 2192b diodes, 219 interleaved cell, 221 single-phase H-bridge cell, 222, 225 switching cell, 900 refrigeration cycle applied equipment, 902 four-way valve, 904 compression mechanism, 906 indoor heat exchanger, 908 expansion valve, 910 outdoor heat exchanger, 912 refrigerant piping.

Claims

1. An AC-DC conversion device comprising: a rectifier circuit having at least one switching element for rectifying a power supply voltage applied from a single-phase AC power supply; a capacitor connected to a DC bus for smoothing the output voltage of the rectifier circuit; a reactor disposed on the single-phase AC power supply side of the capacitor; and a control unit for generating a switching signal for controlling the switching element. The switching element is disposed on the single-phase AC power supply side of the capacitor. The control unit includes a current controller group including a first current controller for the fundamental wave of the single-phase AC power supply and one or more second current controllers for the harmonics of the single-phase AC power supply, and generates a switching signal based on the output from the current controller group.

2. The AC-DC conversion device according to claim 1, wherein the voltage of the DC bus is lower than the peak value of the power supply voltage of the single-phase AC power supply.

3. The AC-DC conversion device according to claim 1 or 2, wherein the control unit further includes a limiter for limiting the operation amounts of the first current controller and the second current controller included in the current controller group, and the limit value of the limiter is made variable according to the control amounts of the fundamental wave current control and the harmonic current control.

4. The AC-DC conversion device according to any one of claims 1 to 3, wherein the control unit increases the margin of the operation amount of the second current controller by changing the phase of the fundamental wave current of the single-phase AC power supply.

5. The AC-DC conversion device according to any one of claims 1 to 4, wherein in the control unit, the first current controller and the second current controller included in the current controller group follow a command value based on the internal model principle.

6. A rotary machine drive device comprising the AC-DC conversion device according to any one of claims 1 to 5.

7. A refrigeration cycle application device comprising the AC-DC conversion device according to any one of claims 1 to 5.

Images