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) side 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) includes a current controller that controls the current of the AC power source (1), and in accordance with the operating state of the AC / DC conversion device (2), the control unit changes the code of a signal which is based on the output from the current controller.

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 uses repeated trials to confirm compliance with harmonic standards, resulting in a problem that the number of trials exponentially increases as the number of pulses increases. Furthermore, because a quantitative and unique design guideline for control gain design is unclear, a long time is required to complete the design. Furthermore, because a simplified control method using only bus voltage feedback control is used, a long time is required to complete the design because a quantitative and unique design guideline for control gain design is unclear. To solve the above problem, it is necessary to provide current feedback control in the minor loop of the bus voltage feedback control to suppress the effects of power supply current distortion. However, a simple PAM (Pulse Amplitude Modulation) circuit, such as one consisting of two diode bridges, one semiconductor switch, one reactor, and one capacitor, cannot directly apply the control of a widely used PFC (Power Factor Correction) circuit using a boost chopper.

[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 enabling current control using a simple PAM circuit.

[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 includes a current controller that controls the current of the single-phase AC power supply and changes the sign of a signal based on an output from the current controller in accordance with the operating state of the AC-DC converter.

[0008] The AC-DC conversion device according to the present disclosure has an effect that it can comply with harmonic standards without relying on trial-and-error adjustments and can realize current control by a simple PAM circuit.

[0009] Block diagram showing a configuration example of a rotary machine drive device according to Embodiment 1 Circuit diagram showing a configuration example of an AC-DC conversion device according to Embodiment 1 Diagram showing a configuration example when the AC-DC conversion device according to Embodiment 1 is regarded as a simple PAM circuit Diagram showing an example of a current control system of a boost chopper shown in Fig. 3(b) Diagram showing an example of a current controller of a boost chopper shown in Fig. 3(b) considering carrier comparison Diagram showing an example of an operation mode in a simple PAM circuit shown in Fig. 3(a) First diagram showing the relationship between the converter voltage, which is the voltage applied to a single-phase diode bridge cell in the simple PAM circuit shown in Fig. 3(a), and the voltage across the switching element Diagram showing an example of a current controller included in the control unit of the AC-DC conversion device according to Embodiment 1 Diagram showing an example of an operation waveform under the operation condition where the bus voltage > the power supply voltage of the AC power supply in the AC-DC conversion device according to Embodiment 1 Diagram showing an example of an operation waveform under the operation condition where the bus voltage < |the power supply voltage of the AC power supply| in the AC-DC conversion device according to Embodiment 1 Diagram showing an example of a current controller included in the control unit of the AC-DC conversion device according to Embodiment 2 Second diagram showing the relationship between the converter voltage, which is the voltage applied to a single-phase diode bridge cell in the simple PAM circuit shown in Fig. 3(a), and the voltage across the switching element Diagram showing an example of a current controller included in the control unit of the AC-DC conversion device according to Embodiment 3 Third diagram showing the relationship between the converter voltage, which is the voltage applied to a single-phase diode bridge cell in the simple PAM circuit shown in Fig. 3(a), and the voltage across the switching element Diagram showing a configuration example of an AC-DC conversion device according to Embodiment 4 Diagram showing a configuration example of an AC-DC conversion device according to Embodiment 5 Diagram showing a configuration example of a refrigeration cycle application device according to Embodiment 6

[0010] Hereinafter, the AC-DC conversion device, the rotary machine drive device, and the refrigeration cycle application device according to the embodiments of the present disclosure will be described in detail based on the drawings.

[0011] Embodiment 1. Fig. 1 is a block diagram showing an example of the configuration of a rotating machine driving device 8 according to Embodiment 1. The rotating machine driving device 8 is connected to an AC power supply 1 and a load 4 including a motor 41. The rotating machine driving device 8 includes an AC-DC converter 2 and a DC-AC converter 3. The AC power supply 1 is a single-phase AC power supply that applies a power supply voltage to the AC-DC converter 2. When the rotating machine driving device 8 is used in an air conditioner, the load 4 is a compressor or a fan, and the motor 41 is a compressor motor or a fan motor.

[0012] 2 is a circuit diagram showing a configuration example of the AC-DC converter 2 according to embodiment 1. The AC-DC converter 2 according to embodiment 1 mainly includes a control unit 6, a rectifier circuit 20, a reactor 212, and a capacitor 216. The AC-DC converter 2 also includes a current detector 211 and voltage detectors 217a and 217b as means for detecting voltage or current.

[0013] The rectifier circuit 20 includes single-phase diode bridge cells 213a and 213b, each of which is formed by connecting four diodes in a bridge configuration, and a switching element 215 connected in parallel across the single-phase diode bridge cell 213b. The single-phase diode bridge cells 213a and 213b are connected in parallel to each other across the AC power source 1. The rectifier circuit 20 shown in FIG. 2 is called a "simple switching circuit." The single-phase diode bridge cell 213b and the switching element 215 form a switching cell 225. The switching element 215 is located closer to the AC power source 1 than the capacitor 216. The switching element 215 performs a switching operation at least once per half cycle of the power source voltage. In this way, the rectifier circuit 20 includes at least one switching element 215 and rectifies the power source voltage applied from the AC power source 1.

[0014] The reactor 212 is arranged closer to the AC power supply 1 than the capacitor 216. The rectifier circuit 20 receives the power supply voltage applied from the AC power supply 1 via the reactor 212 and rectifies the received power supply voltage. The capacitor 216 is connected between the DC bus 9 a and the DC bus 9 b. The capacitor 216 smoothes the output voltage of the rectifier circuit 20.

[0015] The voltage detection unit 217b detects the bus voltage Vdc, which is the voltage of the DC buses 9a and 9b to which the capacitor 216 is connected. The voltage detection unit 217a detects the power supply voltage. The current detection unit 211 detects the power supply current flowing between the AC power supply 1 and the rectifier circuit 20.

[0016] The control unit 6 receives the detection values ​​of the voltage detection units 217a and 217b and the current detection unit 211. The control unit 6 generates a switching signal for controlling the on / off of the switching element 215 based on the detection values.

[0017] An example of the switching element 215 is an insulated gate bipolar transistor (IGBT) as shown in the figure, but is not limited to an IGBT. Any element capable of switching operation may be used as the switching element 215. Another example of the switching element 215 is a metal-oxide-semiconductor field-effect transistor (MOSFET).

[0018] 2 is configured as a closed loop using the detected values ​​of the voltage detectors 217a, 217b and the current detector 211, but may be configured as an open loop using a target value, an estimated value, etc. When the AC-DC converter 2 is configured as an open loop, it is also possible to control the switching element 215 without using the detected values ​​of the voltage detectors 217a, 217b and the current detector 211.

[0019] Next, the operation of the AC-DC converter 2 shown in FIG. 2 when viewed as a simplified PAM circuit will be described. FIG. 3 is a diagram illustrating an example of the configuration of the AC-DC converter 2 according to the first embodiment when viewed as a simplified PAM circuit. FIG. 3(a) illustrates the simplified PAM circuit, and FIG. 3(b) illustrates an equivalent circuit of the simplified PAM circuit shown in FIG. 3(a) when focusing on the DC component. As shown in FIG. 3(a), the simplified PAM circuit is composed of two single-phase diode bridge cells 213a and 213b, a switching element 215, which is a semiconductor switch, a reactor 212, and a capacitor 216. For simplicity, the simplified PAM circuit shown in FIG. 3(a) replaces the subsequent components, i.e., the capacitor 216, the DC-AC converter 3, and the load 4, with a voltage source 241. The equivalent circuit shown in Fig. 3(b) is a boost chopper composed of a reactor 212, a switching element 215, and a diode 218. The AC-DC converter 2 can be designed to have a current control system based on the control of the boost chopper. In Fig. 3(b), a voltage source 242 supplies the DC component of the power supply voltage from the AC power source 1.

[0020] Generally, when designing a current control system, it is necessary to derive a plant. In the current control system, the reactor 212 is the plant, so it is sufficient to derive a differential equation related to the reactor 212. As shown in FIG. 3, the inductance of the reactor 212 is L, and the power supply voltage from the AC power supply 1 is V. ｉｎ and the voltage applied to the single-phase diode bridge cell 213a is V ｃｎｖ and the voltage applied to the reactor 212 is V Ｌ and the voltage across the switching element 215 is V ＩＧＢＴ and the output voltage is V ｏｕｔ and the current flowing through the reactor 212 is i Ｌ and the Laplace operator is s, the differential equation for the reactor 212 is expressed by equation (1), and when equation (1) is Laplace transformed, it becomes equation (2).

[0021] L x di Ｌ / dt=V ｃｎｖ -V ｉｎ ... (1) iＬ = (V ｃｎｖ -V ｉｎ ) / Ls ... (2)

[0022] Fig. 4 is a diagram showing an example of a current control system of the boost chopper shown in Fig. 3(b). Fig. 4(a) is a current control plant obtained by Laplace transforming equation (2). Fig. 4(b) is a current control system when a PI (Proportional Integral) controller is used as the current controller. In Fig. 4, K ｐＡＣＲ is the proportional gain, and K ｉＡＣＲ is the integral gain. ｐＡＣＲ and K. ｉＡＣＲ By designing the above, it is possible to control the current with a desired response. Note that the controller is not limited to PI control, and any controller such as proportional control, integral control, sine wave tracking controller, or two-degree-of-freedom controller may be used.

[0023] 5 is a diagram showing an example of a current controller for the boost chopper shown in FIG. 3(b) that takes into account carrier comparison. In FIG. 5, the output voltage V ｏｕｔ The voltage V across the switching element 215 is the control variable. ＩＧＢＴ In addition, since the current controller shown in FIG. 5 is an off-duty based control system, a not operator is provided in the output stage, but it is also possible to change the configuration to an on-duty based control system and configure it so that the not operator is not provided in the output stage.

[0024] 6 is a diagram showing an example of an operation mode of the simple PAM circuit shown in FIG. 7. FIG. 7 is a diagram showing an example of an operation mode of the simple PAM circuit shown in FIG. ｃｎｖ and the voltage V across the switching element 215 ＩＧＢＴ As shown in FIG. 6, the simple PAM circuit is configured such that the power supply voltage V ｉｎ The operation mode can be roughly divided into four states depending on the polarity of the input voltage and the state of the switching element 215. In FIG. 6(a), the switching element 215 is turned off and the power supply voltage V ｉｎ 6(b) shows the case where the polarity of the power supply voltage V from the AC power supply 1 is positive when the switching element 215 is on.ｉｎ 6(c) shows the case where the polarity of the power supply voltage V from the AC power supply 1 is positive when the switching element 215 is off. ｉｎ 6(d) shows the case where the polarity of the power supply voltage V from the AC power supply 1 is negative when the switching element 215 is on. ｉｎ The polarity of is negative.

[0025] In this way, when the switching element 215 is off, the simple PAM circuit operates as a diode rectifier, and the current path of the simple PAM circuit is as shown in Fig. 6(a) or Fig. 6(c). When the switching element 215 is on, the current path of the simple PAM circuit short-circuits the power supply as shown in Fig. 6(b) or Fig. 6(d), and energy is stored in the reactor 212. The AC-DC converter 2 appropriately controls the on / off of the switching element 215 and controls the energy of the reactor 212, thereby storing energy in the power supply voltage V ｉｎ can be boosted.

[0026] Here, the voltage V applied to the reactor 212 of the simple PAM circuit Ｌ Consider the voltage V applied to the reactor 212. Ｌ is the power supply voltage V of the AC power supply 1 ｉｎ and converter voltage V ｃｎｖ This relationship can be confirmed from the operation waveforms in FIG.

[0027] V Ｌ =V ｉｎ -V ｃｎｖ …(3)

[0028] In FIG. 7, the first stage is a gate signal output from the control unit 6 to the switching element 215 so that the control unit 6 controls the on / off of the switching element 215, and the second stage is a power supply voltage V ｉｎ The third stage is the voltage V applied to the reactor 212. Ｌ and the fourth stage is the converter voltage V ｃｎｖ The fifth row shows the voltage V ＩＧＢＴ The sixth row shows the power supply current of the AC power supply 1, which is the current i Ｌ is.

[0029] In the boost chopper shown in FIG. 3(b), the voltage V applied to the reactor 212 Ｌ Of which, the converter voltage V ｃｎｖ The voltage corresponding to this is the voltage V between both ends of the switching element 215. ＩＧＢＴ Therefore, by turning on and off the switching element 215, the voltage V applied to the reactor 212 Ｌ On the other hand, in the simple PAM circuit shown in FIG. 3(a), the converter voltage V ｃｎｖ and the voltage V across the switching element 215 ＩＧＢＴ The voltage that can be controlled by turning on and off the switching element 215 in the simple PAM circuit shown in FIG. ＩＧＢＴ Therefore, the voltage V applied to the reactor 212 Ｌ In order to control the voltage V ＩＧＢＴ Using the converter voltage V ｃｎｖ It is necessary to express

[0030] The converter voltage V ｃｎｖ and the voltage V across the switching element 215 ＩＧＢＴ When comparing the operating waveforms of the AC power supply 1, the power supply voltage V ｉｎ When the polarity of is positive, the converter voltage V ｃｎｖ and the voltage V across the switching element 215 ＩＧＢＴ However, the power supply voltage V of the AC power supply 1 ｉｎ When the polarity of the switching element 215 becomes negative, the single-phase diode bridge cell 213b, which is a diode rectifier in the front stage of the switching element 215, ＩＧＢＴ is always positive, the voltage V ＩＧＢＴ and the negative converter voltage V ｃｎｖ The converter voltage V ｃｎｖ and the voltage V across the switching element 215 ＩＧＢＴ To match this, the power supply voltage V of the AC power supply 1 ｉｎ When the polarity of is negative, the voltage V across the switching element 215 ＩＧＢＴ Therefore, the converter voltage V ｃｎｖis the sign function sign, and the current i flowing through the reactor 212 Ｌ , and the voltage V across the switching element 215 ＩＧＢＴ Using the above, it can be expressed as equation (4).

[0031] V ｃｎｖ =sign(i Ｌ ) x V ＩＧＢＴ …(4)

[0032] 8 is a diagram illustrating an example of a current controller provided in the control unit 6 of the AC-DC converter 2 according to the first embodiment. In the power factor correction circuit, the current i Ｌ is the power supply voltage V of AC power supply 1 ｉｎ Therefore, the current command value is set to the power supply voltage V of the AC power supply 1. ｉｎ In this paper, the current command value is set to the power supply voltage V of the AC power supply 1. ｉｎ The sine wave to be excited may be phase shifted or the power supply voltage V of the AC power supply 1 may be synchronized. ｉｎ A frequency other than the frequency of the power supply voltage V of the AC power supply 1 may be used. ｉｎ 8 is obtained by adding a configuration for multiplying the sign function sign to the current controller shown in FIG. 5. In this way, the current controller shown in FIG. 8 realizes current control using a simple PAM circuit, and therefore, in the subsequent stage of the PI controller, the voltage V across the switching element 215 is ＩＧＢＴ Regarding the current i flowing through the reactor 212, Ｌ The sign is changed depending on the polarity of the current. Note that the current controller is not limited to PI control.

[0033] FIG. 9 shows a case where the bus voltage Vdc>the power supply voltage V of the AC power supply 1 in the AC-DC converter 2 according to the first embodiment. ｉｎ This operating condition is the same as that of a general power factor correction operation, and the power supply voltage V ｉｎ The power supply current, i.e., the current i flowing through the reactor 212 Ｌ 9, the power supply current, i.e., the current i flowing through the reactor 212, is controlled to be synchronized.Ｌ 10 shows that the bus voltage Vdc<|power supply voltage V of the AC power supply 1 in the AC-DC converter 2 according to the first embodiment. ｉｎ 10 is a diagram illustrating an example of an operating waveform when the bus voltage Vdc is the power supply voltage V ｉｎ 10, the power supply current of the AC power supply 1, i.e., the current i flowing through the reactor 212, is smaller than the peak value of Ｌ Although some distortion is observed, it is clear that the device is operating stably.

[0034] In this way, the control unit 6 includes a current controller that controls the current of the AC power supply 1, which is a single-phase AC power supply, and changes the sign of a signal based on the output from the current controller in accordance with the operating state of the AC-DC converter 2. The signal based on the output from the current controller is a duty, and is a voltage V across the switching element 215 input to the configuration of sign(iL) in FIG. ＩＧＢＴ In the first embodiment, the control unit 6 determines the operating state of the AC-DC converter 2 as the current i Ｌ The voltage V across the switching element 215 varies depending on the polarity of the signal. ＩＧＢＴ The control unit 6 detects the power supply current flowing between the AC power supply 1 and the rectifier circuit 20, that is, the current i Ｌ By acquiring the current i flowing through the reactor 212, Ｌ It is possible to grasp the polarity of

[0035] As described above, according to this embodiment, the control unit 6 of the AC / DC converter 2 controls the power supply current of the AC power supply 1, i.e., the current i flowing through the reactor 212, in order to realize current control using the simple PAM circuit. Ｌ Specifically, in the first embodiment, the control unit 6 compensates the sign of the duty in accordance with the polarity of the current i Ｌ The duty, i.e., the voltage V across the switching element 215, is determined according to the polarity of ＩＧＢＴThe sign of the AC / DC converter 2 is changed. This allows the AC / DC converter 2 to achieve current control in the simple PAM circuit and enable quantitative control design. The AC / DC converter 2 can achieve current control using the simple PAM circuit while complying with harmonic standards without relying on trial-and-error adjustments.

[0036] In the first embodiment, the control unit 6 of the AC / DC converter 2 controls the duty, i.e., the voltage V across the switching element 215, during current control. ＩＧＢＴ The sign of the current i flows through the reactor 212 when the AC-DC converter 2 is in an operating state. Ｌ In the second embodiment, the control unit 6 uses other parameters to change the duty, i.e., the voltage V across the switching element 215. ＩＧＢＴ A case where the sign of is changed will be described.

[0037] In the second embodiment, the configurations of the rotary machine driving device 8, the AC / DC converter 2, etc. are the same as those in the first embodiment. In the second embodiment, the control unit 6 controls the power supply voltage V ｉｎ The voltage V across the switching element 215 varies depending on the polarity of the signal. ＩＧＢＴ The control unit 6 detects the power supply voltage V of the AC power supply 1 from the voltage detection unit 217a shown in FIG. ｉｎ By acquiring the power supply voltage V of the AC power supply 1, ｉｎ 11 is a diagram showing an example of a current controller provided in the control unit 6 of the AC-DC converter 2 according to the second embodiment. The difference from the first embodiment shown in FIG. 8 is that the sign function sign is a function of the power supply voltage V of the AC power supply 1. ｉｎ In the second embodiment, the sign is changed depending on the polarity of the converter voltage V ｃｎｖ is the sign function sign, and the power supply voltage V of the AC power supply 1 ｉｎ , and the voltage V across the switching element 215 ＩＧＢＴ Using the above, it can be expressed as equation (5).

[0038] V ｃｎｖ =sign(V ｉｎ ) × V ＩＧＢＴ …(5)

[0039] FIG. 12 shows the converter voltage V , which is the voltage applied to the single-phase diode bridge cell 213 a in the simple PAM circuit shown in FIG. ｃｎｖ and the voltage V across the switching element 215 ＩＧＢＴ 12 is a second diagram showing the relationship between the converter voltage V ｃｎｖ The sign function sign is different in the equations.

[0040] As described above, according to this embodiment, the control unit 6 of the AC / DC converter 2 controls the power supply voltage V of the AC power supply 1 to realize current control using the simple PAM circuit. ｉｎ Specifically, in the second embodiment, the control unit 6 compensates the sign of the duty in accordance with the polarity of the power supply voltage V ｉｎ The duty, i.e., the voltage V across the switching element 215, is determined according to the polarity of ＩＧＢＴ The sign of the AC / DC converter 2 is changed. This allows the AC / DC converter 2 to achieve current control in the simple PAM circuit and enable quantitative control design. The AC / DC converter 2 can achieve current control using the simple PAM circuit while complying with harmonic standards without relying on trial-and-error adjustments.

[0041] The control unit 6 controls the current i flowing through the reactor 212 described in the first embodiment. Ｌ and the power supply voltage V of the AC power supply 1 described in the second embodiment. ｉｎ The voltage V across the switching element 215 is ＩＧＢＴ It is also possible to change the sign of

[0042] In the first embodiment, the control unit 6 of the AC / DC converter 2 controls the duty, i.e., the voltage V across the switching element 215, during current control. ＩＧＢＴ The sign of the current i flows through the reactor 212 when the AC-DC converter 2 is in an operating state. Ｌ In the second embodiment, the control unit 6 of the AC / DC converter 2 controls the current by adjusting the duty, i.e., the voltage V across the switching element 215. ＩＧＢＴ The sign of the AC / DC converter 2 is the operating state of the power supply voltage V ｉｎIn the third embodiment, the control unit 6 uses other parameters to change the duty, i.e., the voltage V across the switching element 215. ＩＧＢＴ A case where the sign of is changed will be described.

[0043] In the third embodiment, the configurations of the rotary machine driving device 8, the AC / DC converter 2, etc. are the same as those in the first embodiment. In the third embodiment, the control unit 6 controls the power supply voltage V ｉｎ The AC power supply voltage phase estimation means is, for example, a PLL (Phase Locked Loop). The control unit 6 estimates the phase of the power supply voltage V of the AC power supply 1 estimated by the AC power supply voltage phase estimation means as the operating state of the AC-DC converter 2. ｉｎ The signal, i.e., the voltage V across the switching element 215, is generated in accordance with the phase of the signal or the sine wave generated from the estimated phase. ＩＧＢＴ 13 is a diagram showing an example of a current controller provided in the control unit 6 of the AC-DC converter 2 according to the third embodiment. The difference from the first embodiment shown in FIG. 8 is that a PLL is provided as an AC power supply voltage phase estimation means, and the sign of the sign function sign changes according to the estimation result of the PLL. In the third embodiment, the converter voltage V ｃｎｖ is a sign function sign, an estimation result of the PLL which is an AC power supply voltage phase estimation means, and a voltage V across the switching element 215 ＩＧＢＴ Using the above, it can be expressed as equation (6).

[0044] V ｃｎｖ =sign(PLL)×V ＩＧＢＴ …(6)

[0045] FIG. 14 shows the converter voltage V , which is the voltage applied to the single-phase diode bridge cell 213 a in the simple PAM circuit shown in FIG. ｃｎｖ and the voltage V across the switching element 215 ＩＧＢＴ 14 is a third diagram showing the relationship between the converter voltage V and the PLL waveform estimated by the PLL, which is the AC power supply voltage phase estimation means, in comparison with FIG. ｃｎｖ The sign function sign is different in the equations.

[0046] As described above, according to this embodiment, the control unit 6 of the AC / DC converter 2 realizes current control using a simple PAM circuit by estimating the power supply voltage V of the AC power supply 1 estimated by the PLL, which is the AC power supply voltage phase estimation means. ｉｎ Specifically, in the third embodiment, the control unit 6 compensates the sign of the duty in accordance with the phase of the power supply voltage V of the AC power supply 1 estimated by the PLL, which is the AC power supply voltage phase estimation means. ｉｎ The duty, i.e., the voltage V across the switching element 215 is calculated according to the phase of the sine wave or the estimated phase. ＩＧＢＴ The sign of the AC / DC converter 2 is changed. This allows the AC / DC converter 2 to achieve current control in the simple PAM circuit and enable quantitative control design. The AC / DC converter 2 can achieve current control using the simple PAM circuit while complying with harmonic standards without relying on trial-and-error adjustments.

[0047] The control unit 6 controls the duty, i.e., the voltage V across the switching element 215, in accordance with the phase after the operation to advance or delay the phase estimated by the PLL, which is the AC power supply voltage phase estimation means, or the sine wave generated from the phase after the operation. ＩＧＢＴ The sign of may be changed.

[0048] Furthermore, the control unit 6 controls the current i flowing through the reactor 212 described in the first embodiment. Ｌ , the polarity of the power supply voltage V of the AC power supply 1 described in the second embodiment. ｉｎ and the power supply voltage V of the AC power supply 1 estimated by the PLL, which is the AC power supply voltage phase estimation means described in the third embodiment. ｉｎ The voltage V across the switching element 215 is calculated by combining a sine wave generated from the phase of the switching element 215 or the estimated phase. ＩＧＢＴ The control unit 6 may use all three of the combinations described in the first to third embodiments, or may use a combination of any two of the three combinations described in the first to third embodiments.

[0049] Embodiment 4 In embodiment 4, a different example of the AC-DC converter 2 including the control unit 6 described in embodiments 1 to 3 will be described. Note that components having the same or equivalent functions as components of the AC-DC converter 2 described in embodiments 1 to 3 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0050] Fig. 15 is a diagram showing a configuration example of an AC-DC converter 2 according to embodiment 4. The AC-DC converter 2 shown in Fig. 15 is obtained by deleting the single-phase diode bridge cell 213b and adding diodes 218a and 218b to the AC-DC converter 2 shown in Fig. 2. Furthermore, the AC-DC converter 2 shown in Fig. 15 has a modified connection method for the switching element 215 compared to the AC-DC converter 2 shown in Fig. 2.

[0051] 15 , the AC-DC converter 2 realizes current control in the simple PAM circuit and enables quantitative control design by having the control unit 6 perform the control described in the first to third embodiments. The AC-DC converter 2 can achieve current control by the simple PAM circuit while complying with harmonic standards without relying on trial-and-error adjustments.

[0052] Embodiment 5 In embodiment 5, a different example of the AC-DC converter 2 including the control unit 6 described in embodiments 1 to 3 will be described. Note that components having the same or equivalent functions as components of the AC-DC converter 2 described in embodiments 1 to 3 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0053] Fig. 16 is a diagram showing a configuration example of an AC-DC converter 2 according to embodiment 5. The AC-DC converter 2 shown in Fig. 16 is obtained by deleting the single-phase diode bridge cell 213b from the AC-DC converter 2 shown in Fig. 2 and adding a diode 218. Furthermore, the AC-DC converter 2 shown in Fig. 16 has a different connection method for the switching element 215 from the AC-DC converter 2 shown in Fig. 2.

[0054] 16 , the AC-DC converter 2 realizes current control in the simple PAM circuit and enables quantitative control design by having the control unit 6 perform the control described in the first to third embodiments. The AC-DC converter 2 can achieve current control using the simple PAM circuit while complying with harmonic standards without relying on trial-and-error adjustments.

[0055] Sixth Embodiment Fig. 17 is a diagram showing a configuration example of a refrigeration cycle-applied device 900 according to a sixth embodiment. The refrigeration cycle-applied device 900 according to the sixth 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 sixth embodiment can be applied to products equipped with a refrigeration cycle, such as air conditioners, refrigerators, freezers, and heat pump water heaters.

[0056] 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.

[0057] 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.

[0058] The refrigeration cycle applied device 900 according to the sixth embodiment has been described as including the rotating machine drive device 8 described in the first embodiment, but is not limited to this. The refrigeration cycle applied device 900 may include the rotating machine drive device 8 including the AC-DC converter 2 described in any of the second to fifth embodiments. Furthermore, the rotating machine drive device 8 may include an AC-DC converter other than the AC-DC converter 2 described in any of the first to fifth embodiments, as long as the control techniques of the first to third embodiments can be applied.

[0059] 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.

[0060] 1 AC power source, 2 AC-DC converter, 3 DC-AC converter, 4 load, 6 control unit, 8 rotating machine drive device, 9a, 9b DC bus, 20 rectifier circuit, 41 motor, 42 compressor, 211 current detection unit, 212 reactor, 213a, 213b single-phase diode bridge cell, 215 switching element, 216 capacitor, 217a, 217b voltage detection unit, 218, 218a, 218b diode, 225 switching cell, 241, 242 voltage source, 900 refrigeration cycle applied equipment, 902 four-way valve, 904 compression mechanism, 906 indoor heat exchanger, 908 expansion valve, 910 outdoor heat exchanger, 912 refrigerant piping.

Claims

1. An AC-DC conversion device comprising: a rectifier circuit having at least one switching element for rectifying a power supply voltage applied from a single-phase AC power supply; a capacitor connected to a DC bus for smoothing the output voltage of the rectifier circuit; a reactor disposed on the single-phase AC power supply side of the capacitor; and a control unit for generating a switching signal for controlling the switching element, wherein the switching element is disposed on the single-phase AC power supply side of the capacitor, and the control unit includes a current controller for controlling the current of the single-phase AC power supply, and changes the sign of a signal based on the output from the current controller according to the operating state of the AC-DC conversion device.

2. The AC-DC conversion device according to claim 1, wherein the control unit changes the sign of the signal according to the polarity of the current flowing through the reactor as the operating state of the AC-DC conversion device.

3. The AC-DC conversion device according to claim 1 or 2, wherein the control unit changes the sign of the signal according to the polarity of the power supply voltage as the operating state of the AC-DC conversion device.

4. The AC-DC conversion device according to any one of claims 1 to 3, wherein the control unit includes an AC power supply voltage phase estimation means for estimating the phase of the power supply voltage, and changes the sign of the signal according to the phase of the power supply voltage estimated by the AC power supply voltage phase estimation means or a sine wave generated from the estimated phase as the operating state of the AC-DC conversion device.

5. The AC-DC conversion device according to claim 4, wherein the control unit changes the sign of the signal according to a phase after operation of advancing or delaying the phase estimated by the AC power supply voltage phase estimation means, or a sine wave generated from the phase after operation.

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

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

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