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

Abstract

An AC-DC conversion device (2) has at least one switching element (215) and is provided with: a rectification circuit (20) that rectifies power supply voltage from an AC power source (1); a capacitor (216) that smooths output voltage of the rectification circuit (20); a reactor (212) disposed closer to the AC power source (1) than the capacitor (216); and a control unit (6) for generating a switching signal for controlling the switching element (215). The switching element (215) is disposed closer to the AC power source (1) than the capacitor (216), and the control unit (6) generates a switching signal such that the pulse width of the switching signal when turning the switching element (215) ON satisfies a conditional expression defined by the period from the zero-cross of the power supply voltage to output of the switching signal, the effective value of the power supply voltage, the inductance of the reactor (212), the angular frequency of power supply current of the AC power source (1), and a specified overcurrent threshold.

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 compliance with harmonic standards is possible, which results in an exponential increase in the number of trials as the number of pulses increases. Furthermore, there is a problem with control gain design, as there is no clear guideline for quantitatively and uniquely designing it, which results in a long time required to complete the design. To address this issue, a method for suppressing power supply harmonics is available that uses a PS (Proportional Sinusoidal) controller, in which an S (Sinusoidal) controller with high tracking performance for sinusoidal wave commands is connected in parallel to a P (Proportional) controller. However, even when using such a PS controller, due to the characteristics of the operating conditions, it is necessary to switch from passive operation, which does not perform switching, to feedback control, which performs switching. However, due to the characteristics of the operating conditions, there is a possibility of overcurrent occurring during switching, which requires countermeasures.

[0006] The present disclosure has been made in consideration of the above, and aims to provide an AC / DC conversion device that can comply with harmonic standards without relying on trial and error adjustments, while suppressing the occurrence of overcurrent.

[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 located closer to the single-phase AC power supply than the capacitor, and a control unit that generates a switching signal to control the switching element. The switching element is located closer to the single-phase AC power supply than the capacitor. The control unit generates the switching signal so that the pulse width of the switching signal when turning on the switching element satisfies a conditional expression defined by the period from a zero-crossing of the power supply voltage of the single-phase AC power supply to the output of the switching signal, the effective value of the power supply voltage of the single-phase AC power supply, the inductance of the reactor, the angular frequency of the power supply current of the single-phase AC power supply, and a specified overcurrent threshold.

[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 suppressing the occurrence of overcurrent.

[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 the AC / DC converter according to the first embodiment; FIG. 4 is a diagram showing an example of operation waveforms of a power supply voltage, a bus voltage, and a power supply current when the control unit of the AC / DC converter according to the 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 the AC / DC converter according to the first embodiment is provided with a PS controller;

[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 bus voltage V is equal to or less than the peak value of the absolute value of the power supply voltage, 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, in the AC-DC converter 2, the control unit 6 controls the bus voltage V ｄｃ is smaller than the peak value of the power supply voltage, the bus voltage V ｄｃ When controlling the bus voltage V, due to the characteristics of the operating conditions, it is necessary to switch from passive operation, in which the switching element 215 is not switched, to feedback control, in which the switching element 215 is switched. At this time, if the operating conditions, for example, the timing at which the switching element 215 is turned on and the pulse width of the switching signal, which is the period during which the switching element 215 is turned on, are not appropriate, there is a possibility that an overcurrent, an overvoltage, etc. will occur in the AC / DC converter 2 when the control is switched. Therefore, the control unit 6 needs to take measures to suppress the occurrence of an overcurrent, an overvoltage, etc. when the control is switched. In this embodiment, the control unit 6ｄｃ is smaller than the peak value of the power supply voltage, the timing to start feedback control, i.e., the timing to turn on the switching element 215, is set to the zero cross of the power supply voltage or the period when the power supply current of the AC power supply 1 becomes zero, thereby preventing the occurrence of overcurrent, overvoltage, etc. In this embodiment, the feedback control refers to the current PS control described above.

[0027] Below, we will explain the operating conditions under which the switching element 215 is switched while suppressing the occurrence of overcurrent, overvoltage, and the like in the AC-DC converter 2. Specifically, since overcurrent, overvoltage, and the like occur in the AC-DC converter 2 during the first pulse after the start of feedback control by the switching element 215, the conditions under which overcurrent, overvoltage, and the like occur will be described using, as an example, the operating waveforms during partial switching control in which the switching element 215 is switched once. Note that the timing at which overcurrent and overvoltage occur is assumed to be the same, and the following description will be given using a case in which the occurrence of overcurrent is suppressed as an example. Furthermore, the concept of this embodiment can also be applied to control in which the control unit 6 switches the switching element 215 two or more times per half cycle of the power supply voltage of the AC power source 1, and the control unit 6 can suppress the occurrence of overcurrent even during such control.

[0028] FIG. 6 shows the ON timing of the switching signal by the control unit 6 of the AC-DC converter 2 according to the first embodiment and the power supply current i Ｌ 6 is a diagram showing an example of the relationship between the excitation periods of the power supply current i Ｌ The power supply current i Ｌ In formulating the above, the phase expression is easier to handle than the time expression, so the power supply current i Ｌ As a prerequisite, the power supply voltage v ｓ is defined as equation (2). Note that V in equation (2) ｓ is the power supply voltage v supplied from the AC power supply 1 ｓ is the effective value of

[0029]

[0030] (1) α section: 0≦θ≦α(t ０ ≦t≦t １ In the α section, the switching element 215 is turned off and the power supply voltage v ｓ is the bus voltage V ｄｃ Since it is lower than Ｌ１ becomes zero, so we obtain equation (3).

[0031]

[0032] (2) β section: α≦θ≦α+β(t １ ≦t≦t ２ In the β section, the switching element 215 is turned on and energy is stored in the reactor 212. The differential equation for the reactor 212 in the β section is expressed by equation (4).

[0033]

[0034] In equation (4), as shown in FIG. 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).

[0035]

[0036] The power supply current i obtained by equation (5) Ｌ The equation is converted into a phase expression. If θ = ωt, the power supply current i in the phase-converted β section is Ｌ２ is expressed by equation (6).

[0037]

[0038] (3) γ interval: α+β≦θ≦α+β+γ(t ２ ≦t≦t ３ ) In the γ section, the power supply current i Ｌ is the section where current flows on the DC side. The differential equation for reactor 212 in section γ is expressed by equation (7).

[0039]

[0040] In equation (7), as shown in FIG. 6, when time t is t ２ More than t ３If we assume that the time is any of the following, and time-integrate both sides, we obtain equation (8).

[0041]

[0042] Here, the initial value of the γ section is considered. Since the initial value of the γ section is the final value of the β section, it is expressed by equation (9).

[0043]

[0044] Therefore, the power supply current i in the γ section Ｌ is expressed by equation (10).

[0045]

[0046] The power supply current i obtained by equation (10) Ｌ The equation is converted into a phase expression. If θ = ωt, the power supply current i in the phase-converted γ section is Ｌ３ is expressed by equation (11).

[0047]

[0048] (4) π-(α+β+γ) interval: α+β+γ≦θ≦π(t ３ ≦t≦T / 2) In the π-(α+β+γ) section, the switching element 215 is turned off and the power supply voltage v ｓ is the bus voltage V ｄｃ Since it is lower than Ｌ４ becomes zero, so we obtain equation (12).

[0049]

[0050] The above is the power supply voltage v of the AC power supply 1. ｓ When the switching element 215 is switched once in a half cycle of Ｌ As mentioned above, the power supply voltage v of the AC power supply 1 ｓ Similarly, when the switching element 215 is switched two or more times in a half cycle of the power supply current i Ｌ The following formula can be derived.

[0051] Next, we will derive the conditions under which the current during the excitation period of the β section, which mainly causes overcurrent, becomes an overcurrent. Ｌ The threshold for determining whether or not an overcurrent has occurred is the overcurrent threshold I ｏｃ Then, the condition for an overcurrent to occur can be expressed as equation (13) from equation (6).

[0052]

[0053] From equation (13), the phase of the falling edge of the switching signal that causes an overcurrent is expressed by equation (14).

[0054]

[0055] From equation (14), the conditional equation for the β section, which is the ON phase of the switching signal causing an overcurrent, is expressed by equation (15).

[0056]

[0057] In addition, the control unit 6 controls the power supply current i Ｌ is the overcurrent threshold I ｏｃ In order to prevent the power supply current i from exceeding the value of (15), it is necessary to perform control under the condition that satisfies the formula (15) in the β section, that is, to turn on the switching element 215. As formula (13) is obtained from formula (6) in the β section, Ｌ is the overcurrent threshold I ｏｃ In order not to exceed the overcurrent threshold I ｏｃ The conditions should be such that they do not exceed the limit.

[0058] The control unit 6 also controls the power supply current i Ｌ If an overcurrent does not occur, the switching element 215 may be turned on under the condition that it operates as a diode rectifier.

[0059] In this way, in the AC-DC converter 2, the control unit 6 determines whether the β section, which is the pulse width of the switching signal when the switching element 215 is turned on, is greater than the power supply voltage v ｓ The period from the zero crossing of the power supply voltage v ｓ The effective value V ｓ, the inductance L of the reactor 212, the power supply current i of the AC power supply 1 Ｌ and the angular frequency ω of the ｏｃ The switching signal is generated so as to satisfy the conditional expression defined by the following equation: ｓ The power supply current i flowing through the reactor 212 is derived from the relational expression of the voltage applied to the reactor 212 when the switching element 215 is turned on once in a half cycle of Ｌ is the overcurrent threshold I ｏｃ It is defined by the phase angle of the β section, which is the pulse width of the switching signal when the power supply voltage v ｓ The effective value V ｓ For this, multiply by √(2) to get the power supply voltage v of AC power supply 1. ｓ It may also be expressed as the maximum or peak value of √(2).

[0060] As described above, according to this embodiment, the control unit 6 of the AC-DC converter 2 controls the bus voltage V ｄｃ is the power supply voltage v of AC power supply 1 ｓ , the timing to start the feedback control, i.e., the timing to turn on the switching element 215, is set to the power supply voltage v of the AC power supply 1. ｓ or the power supply current i of the AC power supply 1 Ｌ is set to zero. Specifically, the control unit 6 turns on the switching element 215 under the condition that formula (15) is satisfied. This allows the control unit 6 to comply with the harmonic standards without relying on trial and error adjustment, and also prevents overcurrent, overvoltage, and the like from occurring in the AC-DC converter 2 at the timing to start feedback control, i.e., at the timing to turn on the switching element 215.

[0061] In addition, the control unit 6 prevents the occurrence of overcurrent, overvoltage, etc. in the β section where the switching element 215 is turned on, and also controls the power supply voltage v of the AC power supply 1 to be lower than the β section in the section next to the β section. ｓ Even in the γ section where the value is large, the occurrence of overcurrent, overvoltage, etc. can be prevented.

[0062] 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.

[0063] FIG. 7 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. 7, 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 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.

[0064] 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.

[0065] 2 and 7, 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.

[0066] 7, 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. 7 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.

[0067] 7 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.

[0068] 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 (16).

[0069]

[0070] In the above formula (16), 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.

[0071] 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.

[0072] 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.

[0073] Fig. 8 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. 8, 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. 8 are publicly known, and further description thereof will be omitted here.

[0074] 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. 8 can also achieve the same effects as those of embodiment 1.

[0075] 8, 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. 8 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.

[0076] 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.

[0077] FIG. 9 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. 9, 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. 9, 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. 9 are publicly known, and therefore further description thereof will be omitted here.

[0078] 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. 9 can also achieve the same effects as those of embodiment 1.

[0079] 9, 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. 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.

[0080] 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.

[0081] Fig. 10 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. 10, 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. 10, 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. 10 are publicly known, and therefore further description thereof will be omitted here.

[0082] 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. 10 can also achieve the same effects as those of embodiment 1.

[0083] 10, 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. 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.

[0084] 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.

[0085] Fig. 11 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. 11, 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. 11, the capacitor 216 shown previously is represented as a capacitor 216a.

[0086] In the rectifier circuit 20 shown in FIG. 11 , 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. 11 are publicly known, and further description thereof will be omitted here.

[0087] 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. 11 can also achieve the same effects as those of embodiment 1.

[0088] 11, 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. 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, 217b, and 217c and the current detector 211 do not need to be used.

[0089] 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.

[0090] 12 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. 12, 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.

[0091] In a single-phase H-bridge cell 221 shown in Fig. 12, 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. 12, 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.

[0092] 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. 12 are publicly known, and further description thereof will be omitted here.

[0093] 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. 12 can also achieve the same effects as those of embodiment 1.

[0094] 12, 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. 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, 217b, and 217c and the current detector 211 do not need to be used.

[0095] 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.

[0096] FIG. 13 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. 13, 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. 13, 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.

[0097] 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. 13 are publicly known, and further description thereof will be omitted here.

[0098] The control unit 6 generates switching signals to drive the two switching elements 220a and 220b 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.

[0099] 13, 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. 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 and 217b and the current detector 211 do not need to be used.

[0100] 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.

[0101] FIG. 14 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. 14, 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. 14 are publicly known, and further description thereof will be omitted here.

[0102] 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. 14 can also achieve the same effects as those of embodiment 1.

[0103] Although the switching elements 2193a and 2193b are shown as IGBTs in FIG. 14 , 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 and 217b and the current detector 211 do not need to be used. Furthermore, although FIG. 14 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 eighth embodiments may also be configured in an interleaved configuration.

[0104] Tenth Embodiment Fig. 15 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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. 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, wherein the switching element is disposed on the single-phase AC power supply side of the capacitor, and the control unit generates the switching signal such that a pulse width of the switching signal when the switching element is turned on satisfies a conditional expression defined by a period from a zero crossing of the power supply voltage of the single-phase AC power supply until the switching signal is output, an effective value of the power supply voltage of the single-phase AC power supply, an inductance of the reactor, an angular frequency of a power supply current of the single-phase AC power supply, and a specified overcurrent threshold value.

2. The AC-DC conversion device according to claim 1, wherein the conditional expression is defined by a phase angle of the pulse width of the switching signal when a power supply current flowing through the reactor, which is derived from a relational expression of a voltage applied to the reactor when the switching element is turned on once per half cycle of the power supply voltage of the single-phase AC power supply, becomes the overcurrent threshold value.

3. The AC-DC conversion device according to claim 1 or 2, wherein the control unit includes a current controller for controlling the 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 with respect to a sine wave.

4. A rotary machine drive device comprising the AC-DC conversion device according to any one of claims 1 to 3.

5. A refrigeration cycle application device comprising the AC-DC conversion device according to any one of claims 1 to 3.

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