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

Abstract

An AC / DC conversion device (2) comprises: a rectifier circuit (20) that has a switching element (215) and rectifies a power supply voltage applied from an AC power supply (1); a capacitor (216) that is connected to DC bus lines (9a, 9b) and smooths the output voltage of the rectifier circuit (20); a reactor (212) that is disposed closer to the AC power supply (1) side than the capacitor (216); and a control unit (6) that generates a switching signal for controlling the switching element (215). The control unit (6) has an R controller (621D) for reducing harmonic components contained in the power supply current flowing between the AC power supply (1) and the rectifier circuit (20), and generates the switching signal so that the harmonic components conform to the harmonic specification value of the power supply current.

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

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

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

[0005] However, the conventional technology described in Patent Document 1 involves a method of checking whether compliance with harmonic standards can be achieved through repeated trials, which has the problem that the number of trials increases exponentially as the number of pulses increases. Furthermore, there is no clear guideline for quantitatively and uniquely designing control gains, which has the problem that it takes a long time to complete the design.

[0006] Therefore, instead of a trial-and-error approach, a control method that feeds back current and voltage has been considered. For example, a PS (Proportional Sinusoidal) controller is devised, in which a P (Proportional) controller and an S (Sinusoidal transfer function) controller that has good tracking ability for sinusoidal command are connected in parallel. This method eliminates the need for a trial-and-error approach, making it possible to shorten the time required for design work.

[0007] On the other hand, in order to reduce a specific order component using a PS controller, an S controller must be provided in parallel for each specific order component. Furthermore, the power supply harmonic standards set standard values ​​for each order component from the 2nd to the 40th order of the power supply frequency. Therefore, when there are many order components to be reduced, the number of S controllers connected in parallel increases, resulting in another problem of a very large computational load.

[0008] The present disclosure has been made in consideration of the above, and aims to obtain an AC-DC conversion device that can comply with harmonic standards while shortening the time required for design work and suppressing an increase in computational load.

[0009] 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, a capacitor, a reactor, and a control unit. The rectifier circuit has at least one switching element and rectifies a power supply voltage applied from an AC power supply. The capacitor is connected to a DC bus and smoothes the output voltage of the rectifier circuit. The reactor is arranged closer to the AC power supply than the capacitor, and the switching element is arranged closer to the AC power supply than the capacitor. The control unit has a repetitive controller that reduces harmonic components contained in a power supply current flowing between the AC power supply and the rectifier circuit, and when generating a switching signal for controlling the switching element, generates the switching signal so that the harmonic components contained in the power supply current comply with the harmonic standard value for the power supply current.

[0010] The AC-DC converter according to the present disclosure has the effect of being able to comply with harmonic standards while shortening the time required for design work and suppressing an increase in the calculation load.

[0011] 7 is a block diagram illustrating an example of the configuration of a rotating machine drive device according to embodiment 1; FIG. 8 is a circuit diagram illustrating an example of the configuration of an AC / DC converter according to embodiment 1; FIG. 9 is a block diagram illustrating an example of the configuration of a control unit according to embodiment 1; FIG. 10 is a block diagram illustrating an example of the configuration of a voltage control unit according to embodiment 1; FIG. 11 is a block diagram illustrating an example of the configuration of a current control unit according to embodiment 1;Figures showing examples of operating waveforms of bus voltage and power supply current. Block diagram showing a first configuration example when the current controller shown in FIG. 5 is composed of an R controller and a PS controller. Block diagram showing a first configuration example of the R controller shown in FIG. 12. Block diagram showing a second configuration example when the current controller shown in FIG. 5 is composed of an R controller and a PS controller. Board diagram showing the transfer characteristics of a controller obtained by applying the R controller shown in FIG. 13 to the current controller shown in FIG. 12. Block diagram showing a second configuration example of the R controller shown in FIG. 12. Board diagram showing the transfer characteristics of a controller obtained by applying the R controller shown in FIG. 16 to the current controller shown in FIG. 12. Figure showing an example of current harmonic characteristics when the current controller shown in FIG. 6 is applied to the current control unit in FIG. 7. Figure showing an example of current harmonic characteristics when the current controller shown in FIG. 12 is applied to the current control unit in FIG. 7. Block diagram showing a third configuration example of the R controller shown in FIG. 12. Figure showing a configuration example of an AC-DC conversion device according to Embodiment 2. Figure showing a configuration example of an AC-DC conversion device according to Embodiment 3. Figure showing a configuration example of an AC-DC conversion device according to Embodiment 4. Figure showing a configuration example of an AC-DC conversion device according to Embodiment 5. Figure showing a configuration example of an AC-DC conversion device according to Embodiment 6. Figure showing a configuration example of an AC-DC conversion device according to Embodiment 7. Figure showing a configuration example of an AC-DC conversion device according to Embodiment 8. Figure showing a configuration example of an AC-DC conversion device according to Embodiment 9. Figure showing a configuration example of an AC-DC conversion device according to Embodiment 10. Figure showing a configuration example of an AC-DC conversion device according to Embodiment 11. Figure showing a configuration example of an AC-DC conversion device according to Embodiment 12. Figure showing a configuration example of an AC-DC conversion device according to Embodiment 13. Figure showing a configuration example of an AC-DC conversion device according to Embodiment 14. Figure showing a configuration example of a refrigeration cycle application device according to Embodiment 15.

[0012] Hereinafter, with reference to the accompanying drawings, an AC-DC conversion device, a rotary machine drive device, and a refrigeration cycle application device according to embodiments of the present disclosure will be described in detail.

[0013] 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 source 1 and a load 4 including a motor 41. The rotating machine driving device 8 includes an AC-DC converter 2 and a DC-AC converter 3. When the rotating machine driving device 8 is used in an air conditioner, the load 4 is a compressor or a fan, and the motor 41 is a compressor motor or a fan motor.

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

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

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

[0017] The voltage detector 217b detects the bus voltage, which is the voltage of the DC buses 9a and 9b to which the capacitor 216 is connected. The voltage 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.

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

[0019] An example of the switching element 215 is an 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).

[0020] 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.

[0021] 3 is a block diagram showing an example configuration of the control unit 6 according to the first embodiment. The control unit 6 includes a voltage control unit 61, a current control unit 62, and a switching signal generation unit 63. The voltage control unit 61 generates a first current command value using a first voltage command value. The current control unit 62 generates a second voltage command value using the first current command value. The switching signal generation unit 63 generates a switching signal using the second voltage command value.

[0022] 4 is a block diagram showing an example configuration of the voltage control unit 61 according to the first embodiment. The voltage control unit 61 includes a voltage controller 611 and a subtractor 612. The voltage control unit 61 generates a first current command value using a first voltage command value that is a command value for the bus voltage. More specifically, the subtractor 612 generates a voltage deviation that is the difference between the first voltage command value and the voltage detected by the voltage detection unit 217b. The voltage controller 611 generates the first current command value using the voltage deviation output from the subtractor 612. The voltage controller 611 can be configured as, for example, a proportional integral (PI) controller.

[0023] The transfer function G when the voltage controller 611 is configured as a PI controller ＡＶＲ（ｓ） can be expressed by the following equation (1).

[0024]

[0025] Here, the transfer function G ＡＶＲ（ｓ） "AVR" in the above is an abbreviation for "Automatic Voltage Regulator." Also, in the above formula (1), K ｐＡＶＲ is the proportional gain, and K ｉＡＶＲ is the integral gain and s is the Laplace operator. In the PI controller, the proportional gain K ｐＡＶＲ and integral gain K ｉＡＶＲ can be determined arbitrarily. ｐＡＶＲ may be set to zero and configured as an I (Integral) controller, or an integral gain K ｉＡＶＲ may be set to zero and configured as a P controller.

[0026] FIG. 5 is a block diagram showing an example configuration of the current control unit 62 according to the first embodiment. The current control unit 62 includes a current controller 621, a subtractor 622, and a multiplier 623. The current control unit 62 generates a second voltage command value using a second current command value obtained by causing the first current command value to follow a sine wave. More specifically, the multiplier 623 multiplies the first current command value by an excitation signal. The excitation signal is a sine wave synchronized with the phase of the power supply voltage. The sine wave is generated based on the voltage phase, which is the phase of the detected voltage detected by the voltage detection unit 217a. The output of the multiplier 623 is input to the subtractor 622 as a second current command value. The subtractor 622 generates a current deviation, which is the difference between the second current command value and the detected current detected by the current detection unit 211. The current controller 621 generates the second voltage command value using the current deviation output from the subtractor 622. The current controller 621 can be configured as, for example, a PS controller.

[0027] Fig. 6 is a block diagram showing an example of the configuration in which the current controller 621 shown in Fig. 5 is configured as a PS controller. As shown in Fig. 6, the PS controller is a controller configured in such a way that a P controller 621A and an S controller 621B are connected in parallel, and the outputs of the P controller 621A and the S controller 621B are added by an adder 621C and output. The S controller 621B outputs a signal having an angular frequency ω ｎ In the S controller 621B, the angular frequency ω ｎ The reason why the tracking performance improves for a pulsating input can be explained by the internal model principle. The internal model principle states that if the controller's denominator has the same factor as the denominator polynomial of the command value expressed in Laplace transform, the command value can be tracked without deviation. Note that the current controller 621 may be configured as a PIS (Proportional Integral Sinusoidal) controller by inserting an I controller in parallel with the PS controller.

[0028] Transfer function G when the current controller 621 is configured as a PS controller ＡＣＲ（ｓ） can be expressed by the following equation (2).

[0029]

[0030] Here, the transfer function G ＡＣＲ（ｓ） "ACR" in the above expression is an abbreviation for "Automatic Current Regulator." ｐＡＣＲ is the proportional gain, and K ｓＡＣＲ is the S control gain, and ω ｎ is the angular frequency and s is the Laplace operator. In the PS controller, the proportional gain K ｐＡＣＲ , S control gain K ｓＡＣＲ and angular frequency ω ｎ can be determined arbitrarily.

[0031] Fig. 7 is a block diagram showing a configuration example in which a target value filter 624 is introduced into the current control unit 62 shown in Fig. 5. Fig. 8 is a block diagram used to explain the transfer function of the current control system 7 in the AC-DC converter 2 including the current control unit 62 shown in Fig. 7.

[0032] In Fig. 7, a target value filter 624 is inserted in the preceding stage of the current control unit 62 shown in Fig. 5. The target value filter 624 is inserted in order to adjust the response of the transfer function of the current control unit 62 shown in Fig. 5. Specifically, the response of the transfer function of the current control unit 62 is adjusted by ensuring that the zero points of the transfer function of the current control unit 62 are canceled out by the poles of the target value filter 624.

[0033] Here, the closed loop transfer function G in the current control system 7 of FIG. ｃｌｏｓｅ（ｓ） can be expressed by the following equation (3).

[0034]

[0035] In the above formula (3), G ｃ is the transfer function of any controller 72, and G Ｐ is the transfer function of an arbitrary controlled plant 73. If the above equation (3) has a zero point, the closed-loop response cannot be determined by the poles alone. Therefore, the closed-loop transfer function G ｃｌｏｓｅ（ｓ） A target value filter 74 having the same pole as the zero point of is inserted in the front stage of the closed loop. Then, the transfer function G Ｆ（ｓ） and the closed loop transfer function G ｃｌｏｓｅ（ｓ）The desired response is realized by canceling out the influence of the zero point between the target value filter 74 and the transfer function G′. ｃｌｏｓｅ（ｓ） can be expressed by the following equation (4).

[0036]

[0037] In the above formula (4), G Ｘ is an arbitrary transfer function. Ｘ is the transfer function G' ｃｌｏｓｅ（ｓ） The transfer function G may be set to the value of the zeroth power of the Laplace operator s in the denominator polynomial of the above equation, or may have any zero point. Ｆ（ｓ） The controller response can be adjusted by applying the target value filter 74 having the following formula: Note that a PI controller may also be used as a controller that achieves the same effect as the target value filter 74.

[0038] Here, the transfer function G of the target value filter 74 Ｆ（ｓ） (=G Ｘ / (G Ｃ G Ｐ ) can be expressed, for example, by the following equation (5).

[0039]

[0040] Moreover, the above formula (2) can be expressed as the following formula (6).

[0041]

[0042] Therefore, by multiplying the above equation (5) by the above equation (6), it is clear that the zeros of equation (6) are canceled out by the poles of equation (5). In this way, pole-zero cancellation can be achieved by inserting the target value filter 74 in the front stage of the closed loop.

[0043] 9 is a block diagram showing an example configuration of switching signal generation unit 63 according to embodiment 1. Switching signal generation unit 63 includes a normalizer 630, a carrier signal generator 631, and a comparator 632. Normalizer 630 normalizes the second voltage command value input to switching signal generation unit 63. Note that if the control gain of current controller 621 that outputs the second voltage command value is designed taking normalization into consideration, normalizer 630 becomes unnecessary.

[0044] The carrier signal generator 631 generates a carrier signal used to generate a switching signal and outputs it to the comparator 632. The carrier signal is a bipolar or unipolar signal having a triangular waveform that operates at a given frequency. The comparator 632 generates a switching signal based on the output of the scaler 630 and the output of the carrier signal generator 631. More specifically, the comparator 632 compares the output value of the scaler 630 with the output value of the carrier signal generator 631, and if the output value of the scaler 630 is greater than the output value of the carrier signal generator 631, it outputs a signal to turn on the switching element 215. On the other hand, if the output value of the scaler 630 is smaller than the output value of the carrier signal generator 631, the comparator 632 outputs a signal to turn off the switching element 215. Conversely, the configuration may be such that an ON operation signal is generated when the output value of the scaler 630 is smaller than the output value of the carrier signal generator 631, and an OFF operation signal is generated when the output value of the scaler 630 is larger than the output value of the carrier signal generator 631.

[0045] Furthermore, the carrier signal generated by the carrier signal generator 631 does not have to be triangular wave, and any configuration may be used as long as it is possible to generate a switching signal from the second voltage command value.

[0046] Next, we will explain the points to consider when configuring the switching signal generating unit 63. To suppress switching loss in the switching element 215 in the switching cell 225, it is desirable to reduce the number of switching operations. To reduce the number of switching operations, the switching frequency can be reduced. On the other hand, if the switching frequency is reduced too much, the frequency components of the carrier signal will be included in components up to the 40th order of the fundamental frequency defined by the current harmonic standards.

[0047] Here, the fundamental frequency is the frequency of the power supply voltage, which in Japan is 50 Hz or 60 Hz. The 40th order of 50 Hz is 2 kHz, and the 40th order of 60 Hz is 2.4 kHz. Therefore, when the frequency of the power supply voltage is 50 Hz, the carrier frequency, which is the frequency of the carrier signal, must be 2 kHz or higher. Also, when the frequency of the power supply voltage is 60 Hz, the carrier frequency must be 2.4 kHz or higher. This can be expressed mathematically as in the following equation (7).

[0048]

[0049] In the above formula (7), f ｓｗ is the carrier frequency, and f ｓｉ is the carrier frequency f ｓｗ is the frequency of the sidebands relative to ｓ is the frequency of the power supply voltage, and n is an integer equal to or greater than 1.

[0050] In the first embodiment, the carrier frequency f ｓｗ is the frequency of the sideband f ｓｉ The component of the harmonic component is determined so as to satisfy the harmonic standard. Specifically, the component is determined so as to satisfy the following equation (8).

[0051]

[0052] In the above formula (8), N ｓｗ is the number of switching times in one cycle of the power supply voltage. ｓｗ / f ｓ ) is the frequency of the power supply voltage f ｓCarrier frequency f ｓｗ and the carrier frequency f ｓｗ is the frequency of the power supply voltage f ｓ Divide by the frequency of the power supply voltage f ｓ That is, in the first embodiment, the number of switching times N in one cycle of the power supply voltage is ｓｗ occurs at least once, and the carrier frequency f ｓｗ is the frequency of the power supply voltage f ｓ The value divided by (f ｓｗ / f ｓ ) shall be determined as follows:

[0053] In the first embodiment, the number of switching times N in one cycle of the power supply voltage is ｓｗ However, it is not necessary to satisfy the above formula (8) in the entire operation range of the load 4. For example, when the load 4 operates in a light load range, the switching operation of the switching element 215 may be stopped, and therefore the above formula (8) does not need to be satisfied.

[0054] Next, the operating characteristics when PS control is applied to the current controller 621 will be clarified by comparing them with the conditions when PI control is applied to the current controller 621.

[0055] Fig. 10 is a diagram showing example operating waveforms of the power supply voltage, bus voltage, and power supply current when PI control is applied to the current controller 621 shown in Fig. 7. The upper part of Fig. 10 shows waveforms of the absolute values ​​of the bus voltage and power supply voltage. The lower part of Fig. 10 shows waveforms of the detected power supply current, the fundamental wave component of the detected power supply current, and the power supply current command value. The detected power supply current is the detected waveform of the power supply current detected by the current detection unit 211.

[0056] The operating conditions in Fig. 10 are those in which the bus voltage is equal to or less than the peak absolute value of the power supply voltage, as shown in the upper part of Fig. 10. Under these conditions, the rectifier circuit 20 operates as a capacitor-input diode rectifier circuit rather than as a boost circuit, making it impossible to control the bus voltage. In this case, an excessive value accumulates in the PI control integrator, causing a windup phenomenon, and the detected power supply current cannot follow the power supply current command value.

[0057] In contrast, Fig. 11 is a diagram showing example operating waveforms of the power supply voltage, bus voltage, and power supply current when PS control is applied to the current controller 621 shown in Fig. 7. As with Fig. 10, the upper part of Fig. 11 shows waveforms of the absolute values ​​of the bus voltage and power supply voltage, and the middle part of Fig. 11 shows waveforms of the detected power supply current, the fundamental wave component of the detected power supply current, and the power supply current command value. The lower part of Fig. 11 shows a switching signal for controlling the switching element 215.

[0058] As shown in the middle part of Figure 11, the fundamental wave component of the detected power supply current is nearly identical to the power supply current command value. This shows that if PS control, which has high tracking performance for a sinusoidal input, is applied to the current controller 621, the fundamental wave of the detected power supply current can track the power supply current command value even under conditions in which the bus voltage is equal to or less than the peak absolute value of the power supply voltage. Note that Figure 11 shows the results for operating conditions in which the bus voltage is equal to or less than the peak absolute value of the power supply voltage, but it goes without saying that the fundamental wave of the detected power supply current will track the power supply current command value even under operating conditions in which the bus voltage exceeds the peak absolute value of the power supply voltage.

[0059] One of the features of the control technique of the first embodiment is that, in addition to applying a current controller 621 to the control unit 6, PS control, which has high tracking performance for a sine wave input, is further applied to the current controller 621. While the application of PS control to improve tracking performance for a sine wave input is considered to be a relatively common practice, the application of PS control to comply with harmonic standards is considered to be a novel technique that has never been used before.

[0060] On the other hand, as explained in the section "Problems to be Solved by the Invention," when reducing a specific order component using PS control, if there are many order components to be reduced, the number of PS controllers connected in parallel increases, resulting in a problem of a very large computational load. To address this problem, the control method of the first embodiment proposes using an R (Repetitive) controller in addition to the PS controller.

[0061] Fig. 12 is a block diagram showing a first example of the configuration in which the current controller 621 shown in Fig. 5 is configured with an R controller and a PS controller. In Fig. 12, an R controller 621D is inserted in the preceding stage of the PS controller shown in Fig. 6.

[0062] Fig. 13 is a block diagram showing a first example of the configuration of the R controller 621D shown in Fig. 12. As shown in Fig. 13, the R controller 621D can be configured by an adder 621D1 and a dead time controller 621D2. The transfer function G Ｙ can be expressed by the following equation (9).

[0063]

[0064] In the above equation (9), T represents the dead time in the dead time controller 621D2.

[0065] R control is one of the techniques for reducing harmonics using dead time elements. The advantage of R control over other harmonic reduction techniques is that a single R controller 621D can reduce multiple harmonics. The key point of the technique of the first embodiment using R control is that control of the power supply frequency component, which is the fundamental wave component, i.e., the primary component of the power supply frequency, is performed by a PS controller consisting of a P controller 621A, an S controller 621B, and an adder 621C, and harmonic components other than the fundamental wave component are reduced by the R controller 621D. In the first embodiment, this technique of separating the control achieves control that complies with power supply harmonic standards while suppressing an increase in the amount of calculation.

[0066] Fig. 14 is a block diagram showing a second configuration example in which the current controller 621 shown in Fig. 5 is configured with an R controller and a PS controller. Fig. 12 illustrates a configuration in which the R controller 621D is inserted in front of the PS controller shown in Fig. 6, but as shown in Fig. 14, the R controller 621D may be configured to be connected in parallel with the P controller 621A and the S controller 621B.

[0067] Fig. 15 is a Bode diagram showing the transfer characteristics of a controller in which the R controller 621D shown in Fig. 13 is applied to the current controller 621 shown in Fig. 12. The upper side of Fig. 15 is a gain diagram, and the lower side is a phase diagram. The horizontal axis of Fig. 15 represents frequency. In addition, the characteristics of Fig. 15 are obtained when the dead time T in the R controller 621D shown in Fig. 13 is set to T = 20 [ms] (= 1 / 50 [Hz]).

[0068] The gain diagram shows that gain peaks occur at 1f, 2f, 3f, etc., which are integer multiples of f=50 [Hz] corresponding to the dead time T. These gain peaks make it possible to simultaneously suppress harmonic components of multiple orders.

[0069] On the other hand, there are some points to note about R control. When the R controller 621D shown in FIG. 13 is used, the gain does not attenuate below 0 dB even in the high-frequency range. Therefore, depending on the transfer function of the entire control system including the controlled object, a phase margin may be lost, potentially causing the operation of the entire control system to become unstable. Therefore, instead of the R controller 621D shown in FIG. 13, the R controller 621D shown in FIG. 16 is used. FIG. 16 is a block diagram showing a second configuration example of the R controller 621D shown in FIG. 12. In the R controller 621D shown in FIG. 16, a low-pass filter 621D3 is inserted between the dead time controller 621D2 and the adder 621D1 in the configuration of the R controller 621D shown in FIG. 13.

[0070] Fig. 17 is a Bode diagram showing the transfer characteristics of a controller in which the R controller 621D shown in Fig. 16 is applied to the current controller 621 shown in Fig. 12. The set values ​​of the dead time T and the like are the same as those in Fig. 15.

[0071] 17, it can be seen that the gain peak in the high frequency range is suppressed. Such characteristics are obtained by applying the low-pass filter 621D3. The cutoff frequency that determines the characteristics of the low-pass filter 621D3 can be determined from the harmonic order to be reduced and the response constraints imposed by the control period.

[0072] Fig. 18 is a diagram showing an example of current harmonic characteristics when the current controller 621 shown in Fig. 6 is applied to the current control unit 62 of Fig. 7. Fig. 19 is a diagram showing an example of current harmonic characteristics when the current controller 621 shown in Fig. 12 is applied to the current control unit 62 of Fig. 7. That is, Fig. 18 shows current harmonic characteristics when only PS control is applied to the current control unit 62 of Fig. 7, and Fig. 19 shows current harmonic characteristics when both PS control and R control are applied to the current control unit 62 of Fig. 7.

[0073] The current harmonic standard used in Figures 18 and 19 is IEC 61000-3-2 Class A. Note that IEC 61000-3-2 Class A is an example of the current harmonic standard, and the current harmonic standard is not limited to this standard.

[0074] In Figures 18 and 19, the standard values ​​for current harmonics from the second to the fortieth order specified in IEC 61000-3-2 Class A are shown by solid lines. Also, in Figures 18 and 19, the effective values ​​of the second to the fortieth order harmonic components during rated operation are shown by dashed lines. In both figures, the horizontal axis indicates the harmonic order, and the vertical axis indicates the effective value of the current harmonics. The harmonic components during rated operation represent the remaining components remaining after subtracting the fundamental component of the power supply current from the power supply current that flows when the AC-DC converter 2 is operated at rated power. In this paper, the second to the fortieth order harmonics are defined as "low-order harmonics."

[0075] Figure 18 shows that, among the low-order harmonics from the second to the fortieth, the fifth-order harmonic component does not meet the standard value. When only PS control is applied, if the fifth-order harmonic component does not meet the standard value as shown in Figure 18, for example, in the configuration of Figure 6, another S controller may be configured to be connected in parallel to the P controller 621A and the S controller 621B. The other S controller here is an S controller configured to contribute to reducing the fifth-order harmonic component.

[0076] 19, the waveforms of the dashed lines are lower than the waveforms of the solid lines for the 2nd to 40th orders, and all of the low-order harmonics from the 2nd to the 40th orders meet the standard values. Therefore, when comparing the case where both PS control and R control are applied to the current control unit 62 in FIG. 7 with the case where only PS control is applied, it can be said that the former makes it easier to control the low-order harmonics to meet the harmonic standard values ​​of the power supply current.

[0077] 18 and 19 show the harmonic components during rated operation as an example, but it goes without saying that the effect of suppressing harmonic components by the method of embodiment 1 can be obtained even during times other than rated operation.

[0078] As described above, the R controller 621D operates to reduce harmonic components other than the fundamental component contained in the power supply current. However, in the configuration of the R controller 621D shown in FIG. 13, there is a possibility that the R controller 621D may operate to reduce not only low-order harmonics but also the fundamental component. To mitigate such an operation, the R controller 621D shown in FIG. 20 may be used instead of the R controller 621D shown in FIG. 13. FIG. 20 is a block diagram showing a third example configuration of the R controller 621D shown in FIG. 12. In the R controller 621D shown in FIG. 20, a band-elimination filter 621D4 is inserted before the dead time controller 621D2 in the configuration of the R controller 621D shown in FIG. 13.

[0079] 20, the band elimination filter 621D4 operates to block the passage of the fundamental component input to the dead time controller 621D2, and therefore the fundamental component input to the adder 621D1 is also reduced. As a result, the control amount by which the fundamental component is reduced by the R controller 621D can be made smaller than that of the R controller 621D shown in FIG. 13, making it possible to suppress a deterioration in the original control performance.

[0080] As described above, the AC-DC converter according to the first embodiment includes a rectifier circuit that rectifies a power supply voltage applied from an AC power supply, a capacitor that smooths the output voltage of the rectifier circuit, and a reactor that is disposed closer to the AC power supply than the capacitor. The rectifier circuit includes at least one switching element that is disposed closer to the AC power supply than the capacitor. The control unit includes an R controller that reduces harmonic components contained in a power supply current flowing between the AC power supply and the rectifier circuit, and generates a switching signal for controlling the switching element so that the harmonic components contained in the power supply current comply with the harmonic standard value of the power supply current. The AC-DC converter according to the first embodiment enables compliance with the harmonic standard without relying on a trial-and-error adjustment method that repeatedly checks whether compliance with the harmonic standard is achieved. Furthermore, the AC-DC converter according to the first embodiment enables compliance with the harmonic standard while improving the input power factor, even under operating conditions in which the bus voltage exceeds the peak absolute value of the power supply voltage. Furthermore, according to the AC-DC converter of embodiment 1, even when there are many order components to be reduced, the R controller operates to reduce many order components. This eliminates the need to take measures such as increasing the number of S controllers connected in parallel, and makes it possible to comply with harmonic standards while suppressing an increase in the calculation load.

[0081] To achieve the above functions, the control unit according to the first embodiment is configured to include a voltage control unit that generates a first current command value using a first voltage command value that is a command value for a bus voltage, a current control unit that generates a second voltage command value using a second current command value that causes the first current command value to follow a sine wave, and a switching signal generation unit that generates a switching signal using the second voltage command value. The current control unit has a current controller, and an S controller that has good tracking ability for sine wave commands is used as the current controller. Furthermore, the input stage of the current control unit is configured to include a filter that operates a zero point of a feedback loop that feeds back the second voltage command value output by the current control unit to the input stage of the second current command value.

[0082] In the control unit configured as described above, control related to the fundamental component contained in the power supply current is mainly performed by the controller including the S controller, while control to reduce harmonic components other than the fundamental component is mainly performed by the controller including the R controller. By separating the control functions in this way, it is possible to achieve control that complies with power supply harmonic standards while suppressing an increase in the amount of calculations. Furthermore, by using the control unit configured as described above, it is no longer necessary to repeat the design for each load power to determine whether the combination of reactor capacity and switching timing complies with the harmonic standards, thereby eliminating trial-and-error adjustment work and shortening the time required for design work.

[0083] The R controller may include a band-elimination filter that blocks the passage of a fundamental component included in the power supply current. The band-elimination filter operates to block the passage of the fundamental component that is about to be input to the dead time controller included in the R controller. This reduces the control amount by which the fundamental component is reduced by the R controller, making it possible to suppress a deterioration in the original control performance.

[0084] It is desirable that the switching signal generator generates a switching signal so that the number of switching operations of the switching element in one cycle of the power supply voltage is at least one and is equal to or less than the carrier frequency normalized by the frequency of the power supply voltage. By generating such a switching signal, it is possible to suppress switching loss in the switching cell.

[0085] Furthermore, when the control system of the AC-DC converter is configured as a closed loop, it is configured to include a current detection unit that detects a power supply current flowing between the AC power supply and the rectifier circuit, a first voltage detection unit that detects a bus voltage, and a second voltage detection unit that detects a power supply voltage. When the control system of the AC-DC converter is configured as a closed loop, the first current command value may be generated using a voltage deviation that is the difference between the first voltage command value and the detected voltage detected by the first voltage detection unit, and the sine wave that excites the first current command value may be generated based on the voltage phase detected by the second voltage detection unit. Furthermore, the second voltage command value may be generated using a current deviation that is the difference between the second current command value and the detected current detected by the current detection unit.

[0086] 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.

[0087] Fig. 21 is a diagram showing a configuration example of an AC-DC converter 2 according to embodiment 2. In the AC-DC converter 2 shown in Fig. 21, 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. 21 are publicly known, and further description thereof will be omitted here.

[0088] 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. 21 can also achieve the same effects as those of embodiment 1.

[0089] 21, 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. 21 is configured as a closed loop, it may also be configured as an open loop. When the AC-DC converter 2 is configured as an open loop, the detection values ​​of the voltage detectors 217a and 217b and the current detector 211 do not need to be used.

[0090] 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. 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.

[0091] FIG. 22 is a diagram illustrating a configuration example of an AC-DC converter 2 according to a third embodiment. In the AC-DC converter 2 of FIG. 22, 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. 22, 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. 22 are publicly known, and therefore further description thereof will be omitted here.

[0092] 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. 22 can also achieve the same effects as those of embodiment 1.

[0093] 22, 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. 22 is configured as a closed loop, it may also be configured as an open loop. When the AC-DC converter 2 is configured as an open loop, the detection values ​​of the voltage detectors 217a and 217b and the current detector 211 do not need to be used.

[0094] Embodiment 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.

[0095] FIG. 23 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. 23, 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. 23, 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. 23 are publicly known, and therefore further description thereof will be omitted here.

[0096] 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. 23 can also achieve the same effects as those of embodiment 1.

[0097] 23, 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. 23 is configured as a closed loop, it may also be configured as an open loop. When the AC-DC converter 2 is configured as an open loop, the detection values ​​of the voltage detectors 217a and 217b and the current detector 211 do not need to be used.

[0098] 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.

[0099] 24 is a diagram showing a configuration example of an AC-DC converter 2 according to embodiment 5. In the AC-DC converter 2 shown in FIG. 24 , the rectifier circuit 20 is configured with a single-phase H-bridge cell including two diodes 218 a and 218 b, four switching elements 220 a, 220 b, 220 c, and 220 d, a capacitor 216 b, and a voltage detection unit 217 c. The voltage detection unit 217 c may be provided outside the rectifier circuit 20.

[0100] In the rectifier circuit 20 shown in FIG. 24 , 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. 24 are known, and further description thereof will be omitted here.

[0101] 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. 24 can also achieve the same effects as those of embodiment 1.

[0102] 24, 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. 24 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.

[0103] 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.

[0104] 25 is a diagram illustrating a configuration example of an AC-DC converter 2 according to a sixth embodiment. In the AC-DC converter 2 of FIG. 25 , 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.

[0105] In a single-phase H-bridge cell 221 shown in Fig. 25, 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. 25, 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.

[0106] 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. 25 are known, and further description thereof will be omitted here.

[0107] 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. 25 can also achieve the same effects as those of embodiment 1.

[0108] 25, 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. 25 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.

[0109] 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.

[0110] FIG. 26 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. 26, 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. 26, 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.

[0111] 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. 26 are well known, and further description thereof will be omitted here.

[0112] 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. 26 can also achieve the same effects as those of embodiment 1.

[0113] 26, 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. 26 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.

[0114] 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.

[0115] Fig. 27 is a diagram showing a configuration example of an AC-DC converter 2 according to an eighth embodiment. While the AC-DC converter 2 in Fig. 21 shows a single-phase AC power supply 1, Fig. 27 shows this changed to a three-phase AC power supply 5. As a result, in the AC-DC converter 2 in Fig. 27, the rectifier circuit 20 is configured with a three-phase full-bridge cell 226 including six switching elements 220a, 220b, 220c, 220d, 220e, and 220f. Reactors 212a, 212b, and 212c are inserted in each phase between the three-phase AC power supply 5 and the rectifier circuit 20, and current detectors 211a and 211b are arranged in any two of the three phases.

[0116] The voltage detection unit 227 detects the voltage of each phase of the three-phase AC power supply 5 and outputs the detected value to the control unit 6. The current detection units 211a and 211b detect the currents flowing in any two of the three phases and output the detected values ​​to the control unit 6. The current in the remaining phase can be determined by calculation within the control unit 6, taking advantage of the fact that the currents in the phases are three-phase balanced.

[0117] The control unit 6 generates switching signals for controlling the switching elements 220a, 220b, 220c, 220d, 220e, and 220f based on the detection values ​​of the voltage detection units 217b and 227 and the current detection units 211a and 211b. Note that the configuration and operation of the rectifier circuit 20 shown in Fig. 27 are publicly known, and further description thereof will be omitted here.

[0118] The control unit 6 generates switching signals to drive the six switching elements 220a, 220b, 220c, 220d, 220e, and 220f using the control method described in embodiment 1. As a result, the AC-DC converter 2 shown in Fig. 27 can also achieve the same effects as those of embodiment 1.

[0119] Although the switching elements 220a, 220b, 220c, 220d, 220e, and 220f are shown as IGBTs in FIG. 27 , any elements capable of switching operation may be used. Although the AC-DC converter 2 shown in FIG. 27 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 227 and 217b and the current detectors 211a and 211b do not need to be used. Furthermore, the control according to the eighth embodiment may be performed on an αβ coordinate system or a three-phase coordinate system.

[0120] 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 embodiments 1 and 8 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0121] FIG. 28 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. 28, the rectifier circuit 20 includes a three-phase diode bridge cell 228 and a three-phase simplified PAM cell 229. The three-phase diode bridge cell 228 includes six diodes connected in a full bridge configuration. The three-phase simplified PAM cell 229 includes single-phase diode bridge cells 213a, 213b, and 213c, and switching elements 215a, 215b, and 215c connected in parallel to the single-phase diode bridge cells 213a, 213b, and 213c, respectively. The single-phase diode bridge cells 213a, 213b, and 213c are connected between the three-phase lines and the reactors 212a, 212b, and 212c and the three-phase diode bridge cell 228. The three-phase simple PAM cell 229 also includes a capacitor 216d, one end of which is connected to the single-phase diode bridge cells 213a, 213b, and 213c, and the other end of which is connected to the DC bus 9b. The capacitor 216d may be provided outside the three-phase simple PAM cell 229.

[0122] The control unit 6 generates switching signals for controlling the switching elements 215a, 215b, and 215c based on the detection values ​​of the voltage detection units 217b and 227 and the current detection units 211a and 211b. Note that the configuration and operation of the rectifier circuit 20 shown in Fig. 28 are publicly known, and further description thereof will be omitted here.

[0123] The control unit 6 generates switching signals to drive the three switching elements 215a, 215b, and 215c using the control method described in embodiment 1. As a result, the AC-DC converter 2 shown in Fig. 28 can also achieve the same effects as those of embodiment 1.

[0124] Although the switching elements 215a, 215b, and 215c are shown as IGBTs in FIG. 28 , any elements capable of switching operation may be used. Although the AC-DC converter 2 shown in FIG. 28 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 227 and 217b and the current detectors 211a and 211b do not need to be used. Furthermore, the control according to the ninth embodiment may be performed on an αβ coordinate system or a three-phase coordinate system.

[0125] Embodiment 10 In embodiment 10, 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 embodiments 1, 8, and 9 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0126] Fig. 29 is a diagram showing a configuration example of an AC-DC converter 2 according to embodiment 10. In the AC-DC converter 2 of Fig. 29, the capacitor 216d is removed from the configuration of the AC-DC converter 2 of Fig. 28. Other configurations are the same as or equivalent to those of Fig. 28.

[0127] The control unit 6 generates switching signals for controlling the switching elements 215a, 215b, and 215c based on the detection values ​​of the voltage detection units 227 and 217b and the current detection units 211a and 211b. The configuration and operation of the rectifier circuit 20 shown in Fig. 29 are publicly known, and further description thereof will be omitted here.

[0128] The control unit 6 generates switching signals to drive the three switching elements 215a, 215b, and 215c using the control method described in embodiment 1. As a result, the AC-DC converter 2 shown in Fig. 29 can also achieve the same effects as those of embodiment 1.

[0129] Although the switching elements 215a, 215b, and 215c are shown as IGBTs in FIG. 29 , any elements capable of switching operation may be used. Although the AC-DC converter 2 shown in FIG. 29 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 227 and 217b and the current detectors 211a and 211b do not need to be used. Furthermore, the control according to the tenth embodiment may be performed on an αβ coordinate system or a three-phase coordinate system.

[0130] Embodiment 11 In embodiment 11, 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 embodiments 1 and 8 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0131] 30 is a diagram showing a configuration example of an AC-DC converter 2 according to embodiment 11. In the AC-DC converter 2 of FIG. 30, the rectifier circuit 20 has a configuration called a full PAM circuit. The rectifier circuit 20 is configured to include a three-phase diode bridge cell 228, a switching element 215, and a diode 218.

[0132] The control unit 6 generates a switching signal for controlling the switching element 215 based on the detection values ​​of the voltage detection units 227, 217b and the current detection unit 211. The configuration and operation of the rectifier circuit 20 shown in Fig. 30 are publicly known, and further description thereof will be omitted here.

[0133] The control unit 6 generates a switching signal for driving the switching element 215 using the control method described in the first embodiment. As a result, the AC / DC converter 2 shown in Fig. 30 can also achieve the same effects as those of the first embodiment.

[0134] Although the switching element 215 is shown as an IGBT in FIG. 30 , any element capable of switching operation may be used. Furthermore, although the AC-DC converter 2 shown in FIG. 30 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 227 and 217 b and the current detector 211 do not need to be used. Furthermore, the control according to the eleventh embodiment may be performed on an αβ coordinate system or a three-phase coordinate system.

[0135] Embodiment 12 In embodiment 12, 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 embodiments 1, 8, and 11 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0136] Fig. 31 is a diagram showing a configuration example of an AC-DC converter 2 according to embodiment 12. In the AC-DC converter 2 of Fig. 31, the reactors 212a, 212b, and 212c that were arranged between the three-phase AC power supply 5 and the three-phase diode bridge cell 228 in the configuration of the AC-DC converter 2 of Fig. 30 are replaced with a reactor 212. In Fig. 31, the reactor 212 is arranged between the three-phase diode bridge cell 228 and the diode 218. The rest is the same as or equivalent to Fig. 30.

[0137] The control unit 6 generates a switching signal for controlling the switching element 215 based on the detection values ​​of the voltage detection units 227, 217b and the current detection unit 211. The configuration and operation of the rectifier circuit 20 shown in Fig. 31 are publicly known, and further description thereof will be omitted here.

[0138] The control unit 6 generates a switching signal for driving the switching element 215 using the control method described in the first embodiment. As a result, the AC / DC converter 2 shown in Fig. 31 can also achieve the same effects as those of the first embodiment.

[0139] Although the switching element 215 is shown as an IGBT in FIG. 31 , any element capable of switching operation may be used. Furthermore, although the AC-DC converter 2 shown in FIG. 31 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 227, 217b and the current detector 211 do not need to be used. Furthermore, the control according to the twelfth embodiment may be performed on an αβ coordinate system or a three-phase coordinate system.

[0140] Embodiment 13 In embodiment 13, 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 embodiments 1 and 8 will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0141] FIG. 32 is a diagram illustrating a configuration example of an AC-DC converter 2 according to a thirteenth embodiment. In the AC-DC converter 2 of FIG. 32 , the rectifier circuit 20 is configured with a three-phase diode bridge cell 228 and a three-phase bidirectional switching cell 231. The three-phase bidirectional switching cell 231 includes six switching elements 231a, 231b, 231c, 231d, 231e, and 231f. Also, in FIG. 32 , the capacitor 216 of FIG. 27 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. In the three-phase bidirectional switching cell 231, the switching elements 231a and 231b, the switching elements 231c and 231d, and the switching elements 231e and 231f are connected in series in pairs. Each series-connected pair is arranged for each phase between the three-phase diode bridge cell 228 and the connection point of the capacitors 216 a, 216 b. Note that the configuration and operation of the rectifier circuit 20 shown in FIG. 32 are well known, and further description thereof will be omitted here.

[0142] The control unit 6 generates switching signals to drive the six switching elements 231a, 231b, 231c, 231d, 231e, and 231f using the control method described in embodiment 1. As a result, the AC-DC converter 2 shown in Fig. 32 can also achieve the same effects as those of embodiment 1.

[0143] Although the switching elements 231a, 231b, 231c, 231d, 231e, and 231f are shown as IGBTs in FIG. 32 , any elements capable of switching operation may be used. Although the AC-DC converter 2 shown in FIG. 32 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 227 and 217b and the current detectors 211a and 211b do not need to be used. Furthermore, the control according to the thirteenth embodiment may be performed on an αβ coordinate system or a three-phase coordinate system.

[0144] Embodiment 14 In embodiment 14, 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.

[0145] FIG. 33 is a diagram illustrating a configuration example of an AC-DC converter 2 according to a fourteenth embodiment. In the AC-DC converter 2 of FIG. 33, the rectifier circuit 20 is composed of a single-phase diode bridge cell 213a and an interleaved cell 219. The interleaved cell 219 is obtained by combining two sets of a reactor 212, a switching element 215, and a diode 218 in the full-PAM circuit configuration described in FIG. 12. 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. 33 are publicly known, and further description thereof will be omitted here.

[0146] 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. 33 can also achieve the same effects as those of embodiment 1.

[0147] Although the switching elements 2193a and 2193b are shown as IGBTs in FIG. 33 , any elements capable of switching operation may be used. Furthermore, although the AC-DC converter 2 shown in FIG. 33 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. 33 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 fourteenth embodiments may also be configured in an interleaved configuration.

[0148] Fifteenth Embodiment Fig. 34 is a diagram showing a configuration example of a refrigeration cycle-applied device 900 according to a fifteenth embodiment. The refrigeration cycle-applied device 900 according to the fifteenth embodiment includes the rotating machine drive device 8 described in the first embodiment. The refrigeration cycle-applied device 900 according to the fifteenth embodiment can be applied to products equipped with a refrigeration cycle, such as air conditioners, refrigerators, freezers, and heat pump water heaters.

[0149] 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.

[0150] 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.

[0151] The refrigeration cycle applied device 900 according to the fifteenth 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 fourteenth 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 fourteenth embodiments, as long as the control method of the first embodiment can be applied.

[0152] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or the embodiments may be combined with each other, or part of the configuration may be omitted or modified without departing from the spirit of the invention. For example, the above-described control method may also be applied to a DC-AC converter.

[0153] 1 AC power supply, 2 AC / DC converter, 3 DC / AC converter, 4 Load, 5 Three-phase AC power supply, 6 Control unit, 7 Current control system, 8 Rotating machine drive unit, 9a, 9b DC bus, 20 Rectifier circuit, 41 Motor, 42 Compressor, 61 Voltage control unit, 62 Current control unit, 63 Switching signal generation unit, 72 Controller, 73 Control target plant, 74, 624 Target value filter, 211, 211a, 211b Current detection unit, 212, 212a, 212b, 212c, 2191a, 2191b Reactor, 213a, 213b, 213c Single-phase diode bridge cells, 215, 215a, 215b, 215c, 220a, 220b, 220c, 220d, 220e, 220f, 220g, 220h, 231a, 231b, 231c, 231d, 231e, 231f, 2193a, 2193b Switching elements, 216, 216a, 216b, 216c, 216d Capacitors, 217a, 217b, 217c, 227 Voltage detection units, 218, 218a, 218b, 218c, 2192a, 2192b Diodes, 219 Interleaved cells, 221 Single-phase H-bridge cells, 222, 225 Switching cells, 226 Three-phase full-bridge cells, 228 Three-phase diode bridge cells, 229 Three-phase simple PAM cell, 231 three-phase bidirectional switching cell, 611 voltage controller, 612, 622 subtractor, 621 current controller, 621A P controller, 621B S controller, 621C, 621D1 adder, 621D R controller, 621D2 dead time controller, 621D3 low-pass filter, 621D4 band-elimination filter, 623 multiplier, 630 normalizer, 631 carrier signal generator, 632 comparator, 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. A rectifier circuit having at least one switching element and rectifying the power supply voltage applied from an AC power supply, A capacitor connected to the DC bus and smoothing the output voltage of the rectifier circuit, A reactor located on the AC power supply side of the aforementioned capacitor, A control unit that generates a switching signal for controlling the switching element, Equipped with, The switching element is positioned on the AC power supply side of the capacitor. The control unit has a repeating controller that reduces harmonic components contained in the power supply current flowing between the AC power supply and the rectifier circuit. The aforementioned repeating controller has a band-rejection filter that prevents the passage of the fundamental wave component included in the power supply current. The control unit generates the switching signal such that the harmonic components conform to the harmonic standard values ​​of the power supply current. AC / DC converter.

2. The control unit, A voltage control unit that generates a first current command value using a first voltage command value which is a command value of the bus voltage, which is the voltage of the DC bus, A current control unit that generates a second voltage command value using a second current command value obtained by making the first current command value follow a sine wave, A switching signal generation unit that generates the switching signal using the second voltage command value, The AC-DC converter according to claim 1, comprising:

3. A current detection unit for detecting the power supply current, A first voltage detection unit for detecting the bus voltage, A second voltage detection unit for detecting the power supply voltage, Equipped with, The first current command value is generated using the voltage deviation, which is the difference between the first voltage command value and the detected voltage detected by the first voltage detection unit. The sine wave is generated based on the voltage phase detected by the second voltage detection unit. The second voltage command value is generated using the current deviation, which is the difference between the second current command value and the detected current detected by the current detection unit. The AC-DC converter according to claim 2.

4. The switching signal generation unit generates the switching signal such that the number of switching operations of the switching element in one cycle of the power supply voltage is one or more, and the carrier frequency, which is the frequency of the carrier signal, is less than or equal to a value normalized by the frequency of the power supply voltage. The AC-DC converter according to claim 2.

5. The current control unit has a sinusoidal transfer function controller. The AC-DC converter according to claim 4.

6. In the control unit, control of the fundamental wave component included in the power supply current is mainly performed on the side of the controller including the sinusoidal transfer function controller, and control to reduce harmonic components other than the fundamental wave component is mainly performed on the side of the controller including the repetition controller. The AC-DC converter according to claim 5.

7. A rotating machine drive device comprising an AC-DC converter according to any one of claims 1 to 6.

8. A refrigeration cycle application device comprising an AC-DC converter according to any one of claims 1 to 6.