Ac / DC conversion device, rotating machine driving device, and refrigeration cycle application apparatus

Abstract

An AC / DC conversion device (2) comprises: a rectifier circuit (20) that includes at least one switching element (215) and that rectifies power-supply voltage imparted from an AC power source (1); a capacitor (216) that is connected to DC bus bars (9a, 9b) and that smooths the voltage output by the rectifier circuit (20); a reactor (212) that is disposed closer to the AC power source (1) than the capacitor (216) is; 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 source (1) side than the capacitor (216) is. The control unit (6) controls the terminal voltage of the capacitor (216) so that such voltage is at least the minimum value of the capacitor (216) terminal voltage which is determined according to the relationship between the inductance value of the reactor (212) and the power generated by the rectifier circuit (20).

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 repeated trials to determine whether or not a system complies with harmonic standards. This method has the drawback of requiring exponentially increasing trials as the number of pulses increases. Furthermore, since there are no clear guidelines for quantitatively and uniquely designing control gains, it takes a long time to complete the design. To address this issue, a method for suppressing power supply harmonics employs a proportional sinusoidal (PS) controller, in which an S (sinusoidal) controller with high tracking performance for sinusoidal commands is connected in parallel with a proportional (P) controller. However, since the operable range of such a PS controller varies depending on the power supply voltage, bus voltage, reactor inductance value, and other factors, it is necessary to determine operating conditions within the operable range based on principles in order to achieve a stable and desired operating state.

[0006] The present disclosure has been made in consideration of the above, and aims to provide an AC-DC conversion device that is capable of performing stable current control 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 and smoothing the output voltage of the rectifier circuit, a reactor 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 controls the terminal voltage of the capacitor to be equal to or greater than a minimum value determined by the relationship between the inductance value of the reactor and the power generated in the rectifier circuit.

[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, and to perform stable current control.

[0009] FIG. 1 is a block diagram showing a configuration example of a rotary machine drive device according to a first embodiment; FIG. 2 is a circuit diagram showing a configuration example of an AC / DC converter according to a first embodiment; FIG. 3 is a diagram showing a configuration example of a control unit provided in an AC / DC converter according to a first embodiment; FIG. 4 is a diagram showing examples of operating waveforms of a power supply voltage, a bus voltage, and a power supply current when the control unit of an AC / DC converter according to a first embodiment is provided with a PS controller; FIG. 5 is a diagram showing an example of current harmonic characteristics when the control unit of an AC / DC converter according to a first embodiment is provided with a PS controller; FIG. 1 shows an example of the operable range of control by the partial switching method when the inductance value of the reactor in the AC / DC converter is set to 1 mH, 5 mH, and 10 mH. FIG. 2 shows an example of the configuration of an AC / DC converter according to embodiment 2. FIG. 3 shows an example of the configuration of an AC / DC converter according to embodiment 3. FIG. 4 shows an example of the configuration of an AC / DC converter according to embodiment 5. FIG. 6 shows an example of the configuration of an AC / DC converter according to embodiment 7. FIG. 8 shows an example of the configuration of an AC / DC converter according to embodiment 9. FIG. 10 shows an example of the configuration of a refrigeration cycle application device according to embodiment 10.

[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 V ｄｃ The voltage detector 217a detects the power supply voltage. The current detector 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, a case where the control unit 6 performs current PS control will be described. Fig. 3 is a diagram showing an example of the configuration of the control unit 6 provided in the AC-DC converter 2 according to the first embodiment. The control unit 6 includes a PS controller 60, which is a current controller that performs current PS control. The transfer function G when current PS control is performed in a configuration using the PS controller 60 as shown in Fig. 3 is ＡＣＲ（ｓ） can be expressed by the following equation (1).

[0020]

[0021] In equation (1), ACR stands for Automatic Current Regulator. ｐＡＣＲ is the proportional gain, and K ｓＡＣＲis the S control gain, and ω ｎ is the angular frequency, and s is the Laplace operator. In the PS controller 60, 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 60 is configured such that an upper P controller is connected in parallel with a lower S 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 6 controls the current command value I Ｌ ＊ and the excitation signal. Ｌ ＊ 3 shows a configuration in which the control unit 6 generates a switching signal, but the portions preceding the PS controller 60 and succeeding the PS controller 60 have general configurations, and therefore detailed description thereof will be omitted.

[0023] Furthermore, the control unit 6 includes a PS controller 60 as a current controller, but the configuration of the PS controller 60 is not limited to the example shown in Fig. 3. For example, the control unit 6 may include a PS controller 60 including a plurality of S controllers. In this manner, the control unit 6 includes the PS controller 60, which is a current controller that controls the power supply current of the AC power supply 1, and the PS controller 60, which is a current controller, includes at least one controller that satisfies the internal model principle for a sine wave.

[0024] FIG. 4 shows the power supply voltage and bus voltage V when the control unit 6 of the AC-DC converter 2 according to the first embodiment includes a PS controller 60. ｄｃ 4 is a diagram showing an example of the operating waveforms of the bus voltage V ｄｃ 4 shows the waveforms of the absolute value of the power supply voltage and 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 is almost equal to the power supply current command value. From this, if a PS controller 60 with high tracking performance for sine wave input is applied to the control unit 6, the bus voltage V ｄｃ It can be seen that even under the condition that the absolute value of the power supply voltage V is equal to or less than the peak value, the fundamental wave of the detected power supply current can follow the power supply current command value. ｄｃ The results are for operating conditions where the absolute value of the power supply voltage is less than the peak value. ｄｃ It goes without saying that even under operating conditions where the absolute value of the power supply voltage exceeds the peak value, the fundamental wave of the detected power supply current follows the power supply current command value.

[0025] FIG. 5 shows an example of current harmonic characteristics when the control unit 6 of the AC-DC converter 2 according to the first embodiment includes a PS controller 60. 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 the current harmonic standard is not limited to this standard. In FIG. 5, the solid lines indicate the second through fortieth 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 second through fortieth 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 2 is operated at rated power, excluding the fundamental component of the power supply current. In this paper, the second through fortieth harmonics are defined as "low-order harmonics." According to Figure 5, the waveforms of the dashed lines are lower than the waveforms of the solid lines for the 2nd to 40th orders. This shows that if a PS controller 60 with high tracking performance for sine wave input is applied to the control unit 6, the low-order harmonics contained in the power supply current will comply with the harmonic standard value for the power supply current. Note that Figure 5 shows the harmonic components during rated operation as an example, but it goes without saying that the effect of suppressing harmonic components by the PS controller 60 can be obtained even during times other than rated operation.

[0026] Here, the current PS control by the PS controller 60 is performed by controlling the power supply voltage v of the AC power supply 1. ｓ , bus voltage V ｄｃ The operable range varies depending on factors such as the inductance value L of the reactor 212. Therefore, in order to obtain a stable and desired operating state in the PS controller 60, it is necessary to determine the operating conditions within the operable range based on the principles. In this embodiment, the bus voltage V ｄｃ is the power supply voltage V ｓ The following describes a case where the operable region of current PS control by the PS controller 60 is specified under conditions where the current PS is smaller than the peak value of the current PS, and the PS controller 60 is operated under operating conditions in accordance with the specified region.

[0027] First, in the AC-DC converter 2, the minimum bus voltage V that can control the current PS according to the inductance value L of the reactor 212 and the power generated in the rectifier circuit 20 is calculated. ｄｃ The bus voltage V ｄｃ is the power supply voltage V ｓ When the peak value of the rectifier circuit 20 is smaller than the peak value of the rectifier circuit 200, the rectifier circuit 20 operates in a mixed mode of a boost chopper mode in which the switching element 215 performs switching and a diode rectifier mode in which the switching element 215 does not perform switching. In the diode rectifier mode, a current flows through the reactor 212 according to the voltage applied to the reactor 212 and the inductance value L of the reactor 212. In the AC-DC converter 2, current feedback control must be performed taking into account the power generated in the rectifier circuit 20 in the diode rectifier mode. This is because the AC-DC converter 2 cannot control the power below the power generated in the rectifier circuit 20 in the diode rectifier mode. The operating range of the AC-DC converter 2 will be clearly indicated using a mathematical formula. Hereinafter, for simplicity, current feedback control will be simply referred to as feedback control.

[0028] 6 is a diagram showing an example of an operating waveform of the AC-DC converter 2 according to the first embodiment. In FIG. 6, the upper diagram shows the bus voltage V ｄｃ and power supply voltage v ｓ The lower diagram shows the operating waveform of the reactor current i Ｌ The horizontal axis indicates the phase, and the power supply voltage v ｓ 6 shows the range of the positive half cycle of the rectifier circuit 20. Based on the operating waveforms shown in FIG. 6, the power generated in the rectifier circuit 20 when the rectifier circuit 20 is operating in the diode rectifier mode is derived. First, the current equation for the current flowing when the rectifier circuit 20 is operating in the diode rectifier mode is derived. As a prerequisite, the system voltage supplied from the AC power source 1, i.e., the power supply voltage v ｓ is defined as equation (2).

[0029]

[0030] In equation (2), V ｓ is the power supply voltage V ｓis the effective value of √(2)×V, and ω is the angular frequency. ｓ is the power supply voltage V ｓ where √(2) represents the square root of 2.

[0031] (1) α section: 0≦θ≦α (0≦t≦t １ ) Power supply voltage V ｓ is the bus voltage V ｄｃ Since the reactor current i Ｌ１ is expressed as equation (3).

[0032]

[0033] (2) β section: α≦θ≦α+β(t １ ≦t≦t ２ The differential equation for the reactor 212 in the β section where the rectifier circuit 20 operates in the diode rectifier mode is given by equation (4).

[0034]

[0035] In equation (4), time t is t １ More than t ２ If we assume that the time is any of the following, and time-integrate both sides, we obtain equation (5). Note that since the initial value is zero, there is no need to consider the initial value.

[0036]

[0037] When converted into a phase, equation (5) becomes equation (6).

[0038]

[0039] (3) π-(α+β) interval: α+β≦θ≦π(t ２ ≦t≦T / 2) Since the current is blocked by the diode included in the rectifier circuit 20, the reactor current i flowing through the reactor 212 Ｌ３ is expressed as equation (7).

[0040]

[0041] The above is the current equation for the current that flows when the rectifier circuit 20 is operating in diode rectifier mode. Since only the β section contributes to the power, we will use the β section to consider the power generated by the rectifier circuit 20. The power P is given by equation (8).

[0042]

[0043] Solving equation (8), bus voltage V ｄｃ Summarizing this, the power P can be expressed by equation (9).

[0044]

[0045] Here, the power supply voltage v ｓ The effective value V ｓ Bus voltage V based on ｄｃ The concept of voltage ratio k, which represents the ratio between the power supply voltage v and the ｓ The effective value V ｓ and bus voltage V ｄｃ The voltage ratio k is defined by equation (10).

[0046]

[0047] Here, the range of the voltage ratio k is expressed by equation (11).

[0048]

[0049] The upper limit of equation (11) represents the limit at which the rectifier circuit 20 can operate in the diode rectifier mode, and the power supply voltage v ｓ and the bus voltage V ｄｃ The condition is that the voltage ratio k is applied to the power equation, which is given by equation (12).

[0050]

[0051] In order for the AC-DC converter 2 to perform feedback control, it is necessary to operate the rectifier circuit 20 in a region equal to or greater than the power P calculated by equation (12). Here, the power controlled by feedback control is defined as P ＦＢ Then, equation (12) is transformed into equation (13).

[0052]

[0053] When equation (13) is solved with respect to the voltage ratio k, the condition for the voltage ratio k that allows feedback control is expressed by equation (14).

[0054]

[0055] 7 is a diagram showing an example of an operable range of control by the partial switching method when the inductance value L of the reactor 212 in the AC-DC converter 2 according to the first embodiment is 5 mH. In FIG. 7, the horizontal axis represents the power P, and the vertical axis represents the voltage ratio k. The operable range shown in FIG. 7 is calculated by dividing the power P in equation (14) by the ＦＢ The graph was created by varying the power consumption from 0 to 3000 W. The lower region shown in Fig. 7 is the feedback control-inhibited region, i.e., the region where control by the partial switching method is impossible, and the upper region shown in Fig. 7 is the feedback control-possible region, i.e., the region where control by the partial switching method is possible.

[0056] 8 is a diagram showing an example of the operable range of control by the partial switching method when the inductance value L of the reactor 212 in the AC-DC converter 2 according to embodiment 1 is set to 1 mH, 5 mH, and 10 mH. When the inductance value L of the reactor 212 is large, at 10 mH, operation by feedback control, i.e., control by the partial switching method, is possible even under conditions of a heavy load and a small voltage ratio k. On the other hand, when the inductance value L of the reactor 212 is small, at 1 mH, the dependency of the voltage ratio k on the power P becomes small, and it can be seen that the operable voltage ratio k by feedback control, i.e., control by the partial switching method, is approximately constant.

[0057] Bus voltage V ｄｃ is the power supply voltage V ｓWhen feedback control is performed under the condition that the current is smaller than the peak value of , the control unit 6 of the AC-DC converter 2 needs to operate the rectifier circuit 20 under the condition that formula (14) is satisfied. The feedback control may be a control configuration in which the current control system is a minor loop and the outer loop has a voltage control system, or a control configuration in which only the voltage control system is included, or a control configuration in which the outer loop of the voltage control system has a phase control system that controls the switching pause period. Regardless of the control system included in the AC-DC converter 2, it is necessary to perform control while satisfying formula (14).

[0058] In this way, the control unit 6 calculates the bus voltage V, which is the terminal voltage of the capacitor 216 determined by the relationship between the inductance value L of the reactor 212 and the power P generated in the rectifier circuit 20. ｄｃ The bus voltage V of the capacitor 216 is greater than the minimum value of ｄｃ The control unit 6 further controls the power supply voltage v ｓ In the half cycle of the power supply voltage v ｓ From the zero crossing of the power supply voltage V ｓ is the bus voltage V of the capacitor 216 ｄｃ α, the period until the power supply voltage v ｓ In the half cycle of the power supply voltage v ｓ is the bus voltage V of the capacitor 216 ｄｃ β, which is the period during which the power supply voltage v ｓ The bus voltage V of the capacitor 216 is ｄｃ The control unit 6 also controls the minimum value of the power P when the rectifier circuit 20 operates as a capacitor-input diode rectifier by adjusting the power supply voltage v applied to the reactor 212. ｓ The power P in feedback control is derived from the relation ＦＢ The bus voltage V of the capacitor 216 is set to be equal to or greater than the power P when the capacitor 216 operates as a capacitor-input diode rectifier. ｄｃ Controls the minimum value of

[0059] As described above, according to this embodiment, the control unit 6 of the AC / DC converter 2 determines the minimum bus voltage V that can control the current PS according to the inductance value L of the reactor 212 and the power P generated in the rectifier circuit 20. ｄｃ The bus voltage V ｄｃ is controlled to perform feedback control, i.e., current PS control by the PS controller 60. This enables the control unit 6 to perform stable current control while complying with harmonic standards without relying on trial and error adjustments.

[0060] The control unit 6 performs feedback control, i.e., current PS control by the PS controller 60, in a region where feedback control, i.e., current PS control by the PS controller 60, is possible, but in a region where feedback control, i.e., current PS control by the PS controller 60, is not possible, the control unit 6 turns off the switching of the switching element 215 and performs passive operation. For example, the control unit 6 may perform a passive operation by controlling the bus voltage V of the capacitor 216. ｄｃ is equal to or less than the terminal voltage command value of the capacitor 216, the switching signal to the switching element 215 may be turned off to cause the rectifier circuit 20 to operate as a capacitor-input type diode rectifier.

[0061] Embodiment 2 In embodiment 2, a different example of the AC-DC converter 2 including the control unit 6 described in embodiment 1 will be described. Components having the same or equivalent functions as components of the AC-DC converter 2 described in embodiment 1 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0062] FIG. 9 is a diagram illustrating a configuration example of an AC-DC converter 2 according to a second embodiment. In the AC-DC converter 2 of FIG. 9, 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 second embodiment, a configuration is described in which PIR (Proportional Integral Resonant) control is applied as control by the control unit 6 of the AC-DC converter 2.

[0063] 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.

[0064] 2 and 9, 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.

[0065] 9, 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. 9 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.

[0066] 9 may be used in the first embodiment, and the simple switching circuit of Fig. 2 may be used in the second 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.

[0067] 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 (15).

[0068]

[0069] In the above formula (15), K ｐ is 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 embodiment. The use of a PIR controller can also provide the same effect as the PS control.

[0070] As described above, PIR control is applied to the control unit 6 according to the second embodiment. Even when PIR control is applied instead of PS control, the same effects as those of the first embodiment can be obtained.

[0071] Embodiment 3 In embodiment 3, a different example of the AC-DC converter 2 including the control unit 6 described in embodiment 1 will be described. Note that components having the same or equivalent functions as components of the AC-DC converter 2 described in embodiment 1 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0072] Fig. 10 is a diagram showing a configuration example of an AC-DC converter 2 according to embodiment 3. In the AC-DC converter 2 shown in Fig. 10, 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. 10 are publicly known, and further description thereof will be omitted here.

[0073] The control unit 6 generates switching signals to drive the four switching elements 220a, 220b, 220c, and 220d using the control method described in embodiment 1. As a result, the AC-DC converter 2 shown in FIG. 10 can also achieve the same effects as those of embodiment 1.

[0074] 10, 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. 10 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.

[0075] Embodiment 4 In embodiment 4, a different example of the AC-DC converter 2 including the control unit 6 described in embodiment 1 will be described. Components having the same or equivalent functions as components of the AC-DC converter 2 described in embodiment 1 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0076] FIG. 11 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. 11, 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. 11, 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. 11 are publicly known, and therefore further description thereof will be omitted here.

[0077] The control unit 6 generates switching signals to drive the two switching elements 220c and 220d using the control method described in embodiment 1. As a result, the AC-DC converter 2 shown in FIG. 11 can also achieve the same effects as those of embodiment 1.

[0078] 11, 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. 11 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.

[0079] Embodiment 5 In embodiment 5, a different example of the AC-DC converter 2 including the control unit 6 described in embodiment 1 will be described. Components having the same or equivalent functions as components of the AC-DC converter 2 described in embodiment 1 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0080] FIG. 12 is a diagram illustrating a configuration example of an AC-DC converter 2 according to a fifth embodiment. In the AC-DC converter 2 of FIG. 12, 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. 12, the diodes 218a and 218c are arranged in the upper arms of two legs, and the switching elements 220b and 220d are arranged in the lower arms of two legs. Note that the configuration and operation of the rectifier circuit 20 illustrated in FIG. 12 are publicly known, and therefore further description thereof will be omitted here.

[0081] The control unit 6 generates switching signals to drive the two switching elements 220b and 220d using the control method described in embodiment 1. As a result, the AC-DC converter 2 shown in FIG. 12 can also achieve the same effects as those of embodiment 1.

[0082] 12, 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. 12 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.

[0083] Sixth Embodiment In a sixth embodiment, a different example of the AC-DC converter 2 including the control unit 6 described in the first embodiment will be described. Components having the same or equivalent functions as those of the AC-DC converter 2 described in the first embodiment will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0084] Fig. 13 is a diagram showing a configuration example of an AC-DC converter 2 according to a sixth embodiment. In the AC-DC converter 2 shown in Fig. 13, 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. 13, the capacitor 216 shown previously is represented as a capacitor 216a.

[0085] In the rectifier circuit 20 shown in FIG. 13, 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. Control unit 6 generates switching signals for controlling switching elements 220a, 220b, 220c, and 220d based on the detected values ​​of voltage detection units 217a, 217b, and 217c and current detection unit 211. The configuration and operation of rectifier circuit 20 shown in FIG. 13 are known, and further description thereof will be omitted here.

[0086] The control unit 6 generates switching signals to drive the four switching elements 220a, 220b, 220c, and 220d using the control method described in embodiment 1. As a result, the AC-DC converter 2 shown in FIG. 13 can also achieve the same effects as those of embodiment 1.

[0087] 13, 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. 13 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.

[0088] Embodiment 7 In embodiment 7, a different example of the AC-DC converter 2 including the control unit 6 described in embodiment 1 will be described. Components having the same or equivalent functions as components of the AC-DC converter 2 described in embodiment 1 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0089] Fig. 14 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. 14, a rectifier circuit 20 is configured with 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.

[0090] In a single-phase H-bridge cell 221 shown in Fig. 14, 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. 14, 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.

[0091] 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. 14 are publicly known, and further description thereof will be omitted here.

[0092] The control unit 6 generates switching signals to drive the six switching elements 220b, 220d, 220e, 220f, 220g, and 220h using the control method described in embodiment 1. As a result, the AC-DC converter 2 shown in FIG. 14 can also achieve the same effects as those of embodiment 1.

[0093] 14, 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. 14 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.

[0094] Embodiment 8 In embodiment 8, a different example of the AC-DC converter 2 including the control unit 6 described in embodiment 1 will be described. Components having the same or equivalent functions as components of the AC-DC converter 2 described in embodiment 1 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0095] FIG. 15 is a diagram illustrating a configuration example of an AC-DC converter 2 according to an eighth embodiment. In the AC-DC converter 2 of FIG. 15, 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. 15, 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.

[0096] 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. 15 are publicly known, and further description thereof will be omitted here.

[0097] The control unit 6 generates switching signals for the two switching elements 220a and 220b and drives them using the control method described in embodiment 1. As a result, the AC-DC converter 2 shown in Fig. 15 can also achieve the same effects as those of embodiment 1.

[0098] 15, 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. 15 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.

[0099] Embodiment 9 In embodiment 9, a different example of the AC-DC converter 2 including the control unit 6 described in embodiment 1 will be described. Components having the same or equivalent functions as components of the AC-DC converter 2 described in embodiment 1 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0100] FIG. 16 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. 16, 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. 16 are publicly known, and further description thereof will be omitted here.

[0101] The control unit 6 generates switching signals to drive the two switching elements 2193a and 2193b using the control method described in embodiment 1. As a result, the AC-DC converter 2 shown in Fig. 16 can also achieve the same effects as those of embodiment 1.

[0102] Although the switching elements 2193a and 2193b are illustrated as IGBTs in FIG. 16 , any elements capable of switching may be used. Furthermore, although the AC-DC converter 2 illustrated 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. Furthermore, although FIG. 16 illustrates 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 illustrated in the first to eighth embodiments may also be configured in an interleaved configuration.

[0103] Tenth Embodiment Fig. 17 is a diagram showing a configuration example of a refrigeration cycle-applied device 900 according to a tenth embodiment. The refrigeration cycle-applied device 900 according to the tenth embodiment includes the rotating machine drive device 8 described in the first embodiment. That is, the refrigeration cycle-applied device 900 includes the AC-DC converter 2 described in the first embodiment. The refrigeration cycle-applied device 900 according to the tenth embodiment can be applied to products equipped with a refrigeration cycle, such as air conditioners, refrigerators, freezers, and heat pump water heaters.

[0104] 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.

[0105] 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.

[0106] The refrigeration cycle applied device 900 according to the tenth 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 ninth 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 ninth embodiments, as long as the control method of the first embodiment can be applied.

[0107] 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.

[0108] 1 AC power supply, 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, 60 PS controller, 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 diode, 219 interleaved cell, 221 single-phase H-bridge cell, 222, 225 switching cell, 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.

Claims

1. a rectifier circuit having at least one switching element and rectifying a power supply voltage applied from a single-phase 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 single-phase AC power supply than the capacitor; a control unit that generates a switching signal for controlling the switching element; Equipped with the switching element is disposed closer to the single-phase AC power supply than the capacitor; the control unit controls the terminal voltage of the capacitor to be equal to or greater than a minimum value of the terminal voltage of the capacitor determined by a relationship between an inductance value of the reactor and power generated in the rectifier circuit. AC to DC converter.

2. The control unit further controls a minimum value of the terminal voltage of the capacitor using a period from a zero crossing of the power supply voltage until the power supply voltage exceeds the terminal voltage of the capacitor in a half cycle of the power supply voltage, a period during which the power supply voltage exceeds the terminal voltage of the capacitor in a half cycle of the power supply voltage, and an angular frequency of the power supply voltage.

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

3. the control unit derives the power when the rectifier circuit operates as a capacitor-input type diode rectifier from a relational expression of a power supply voltage applied to the reactor, and controls a minimum value of the terminal voltage of the capacitor so that the power in feedback control is equal to or greater than the power when the rectifier circuit operates as the capacitor-input type diode rectifier.

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

4. the control unit turns off the switching signal and causes the rectifier circuit to operate as the capacitor-input type diode rectifier when the minimum value of the terminal voltage of the capacitor is equal to or less than the terminal voltage command value of the capacitor.

4. The AC / DC converter according to claim 3.

5. the control unit includes a current controller that controls a power supply current of the single-phase AC power supply, and the current controller includes at least one controller that satisfies an internal model principle for a sine wave.

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

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

7. A refrigeration cycle device comprising the AC / DC converter according to any one of claims 1 to 5.