Swiss rectifier and passive control method thereof

Abstract

The application provides a SWISS rectifier and a passive control method thereof, which comprises an AC filter, an uncontrolled rectifier, a harmonic injection unit, a first DC / DC converter, a second DC / DC converter and a load R L The input end of the AC filter is connected with a three-phase AC source, the output end of the AC filter is connected with the AC end of the uncontrolled rectifier, the first DC end of the uncontrolled rectifier is connected with the first end of the first DC / DC converter to a first connection point, the second DC end of the uncontrolled rectifier is connected with the first end of the second DC / DC converter to a second connection point, the second end of the first DC / DC converter and the second end of the second DC / DC converter are connected to a third connection point, the first end of the harmonic injection unit is connected with the third DC end of the uncontrolled rectifier, and the second end of the harmonic injection unit is connected with the third connection point. The application improves the anti-interference ability of the SWISS rectifier, and the control process is simple and easy to realize.

Description

Technical Field

[0001] This invention relates to the field of SWISS rectifier technology, and in particular to a SWISS rectifier and its passive control method. Background Technology

[0002] To improve power quality on the AC side, rectifiers often employ power factor correction (PFC) technology. Rectifiers based on boost or buck PFC are widely used in applications such as electric vehicle charging, high-power lighting, and electric heating. Among these, the SWISS rectifier is a buck PFC type with short-circuit protection, which can limit load current and achieve constant voltage and constant current output. However, existing SWISS rectifier control methods are complex and have low interference immunity. Summary of the Invention

[0003] The purpose of this invention is to propose a SWISS rectifier and its passive control method, thereby solving the technical problems of complex process and low anti-interference capability of existing SWISS rectifier control methods.

[0004] On the one hand, a SWISS rectifier is provided, comprising:

[0005] AC filter, uncontrolled rectifier, harmonic injection unit, first DC / DC converter, second DC / DC converter and load R L ;

[0006] The input terminal of the AC filter is connected to a three-phase AC source, and the output terminal of the AC filter is connected to the AC terminal of the uncontrolled rectifier. The first DC terminal of the uncontrolled rectifier and the first terminal of the first DC / DC converter are connected to a first connection point. The second DC terminal of the uncontrolled rectifier and the first terminal of the second DC / DC converter are connected to a second connection point. The second terminals of the first DC / DC converter and the second DC / DC converter are connected to a third connection point. The first terminal of the harmonic injection unit is connected to the third DC terminal of the uncontrolled rectifier, and the second terminal of the harmonic injection unit is connected to the third connection point. The load R L It is connected between the third terminal of the first DC / DC converter and the third terminal of the second DC / DC converter;

[0007] The AC filter is used to filter out high-order harmonics from a three-phase AC source;

[0008] The uncontrolled rectifier is used to rectify the filtered voltage to obtain the rectified voltage;

[0009] The harmonic injection unit is used to compensate for the dead zone of the input current of the non-conducting phase in the uncontrolled rectifier, so as to achieve the correction of unity power factor.

[0010] The first DC / DC converter and the second DC / DC converter are used to process the rectified voltage output by the uncontrolled rectifier and output a constant DC voltage.

[0011] Preferably, the AC filter includes a filter inductor unit and a filter capacitor unit; the filter inductor unit includes a first inductor L. a Second inductor L b and the third inductor L c The filter capacitor unit includes a first capacitor C. a Second capacitor C b and the third capacitor C c ;

[0012] The first inductor L a The second inductor L b and the third inductor L c The first terminals are respectively connected to a three-phase AC power source; the first inductor L a The second terminal is connected to the third capacitor C c The first end is connected, and the second inductor L b The second terminal is connected to the second capacitor C b The first end is connected, and the third inductor L c The second terminal is connected to the first capacitor C a The first end is connected; the first capacitor C a The second capacitor C b and the third capacitor C c The second ends are connected to each other.

[0013] Preferably, the uncontrolled rectifier includes a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, and a sixth diode D6;

[0014] The cathodes of the first diode D1, the second diode D2, and the third diode D3 are interconnected at the first connection point, and the anode of the first diode D1 is connected to the third capacitor C. c The first terminal, the first inductor L a The second terminal, the anode of the second diode D2, is connected to the second capacitor C. b The first terminal, the second inductor L b At the second terminal, the anode of the third diode D3 is connected to the first capacitor C. a The first terminal, the third inductor L cThe second end;

[0015] The anodes of the fourth diode D4, the fifth diode D5, and the sixth diode D6 are interconnected at the second connection point, and the cathode of the fourth diode D4 is connected to the third capacitor C. c The first terminal, the first inductor L a At the second terminal, the cathode of the fifth diode D5 is connected to the second capacitor C. b The first terminal, the second inductor L b At the second terminal, the cathode of the sixth diode D6 is connected to the first capacitor C. a The first terminal, the third inductor L c The second end.

[0016] Preferably, the harmonic injection unit includes a first switching unit SW1, a second switching unit SW2, and a third switching unit SW3;

[0017] The first terminal of the first switching unit SW1 is connected to the third capacitor C. c The first terminal, the first inductor L a The second terminal of the second switching unit SW2 is connected to the second capacitor C. b The first terminal, the second inductor L b The second terminal of the third switching unit SW3 is connected to the first capacitor C. a The first terminal, the third inductor L c The second ends of the first switch unit SW1, the second switch unit SW2 and the third switch unit SW3 are interconnected at the third connection point.

[0018] The first switching unit SW1 includes a first power device and a second power device. The control terminals of the first power device and the second power device are connected to each other and serve as the control terminals of the switching unit. The emitters of the first power device and the second power device are connected to each other to form a first common emitter. The collector of the first power device serves as the first terminal of the first switching unit SW1, and the collector of the second power device serves as the second terminal of the first switching unit SW1. A ninth diode is disposed between the first common emitter and the collector of the first power device. The anode of the ninth diode is connected to the first common emitter, and the cathode of the ninth diode is connected to the collector of the first power device.

[0019] The second switching unit SW2 includes a third power device and a fourth power device. The control terminals of the third power device and the fourth power device are interconnected, serving as the control terminals of the switching unit. The emitters of the third power device and the fourth power device are interconnected, forming a second common emitter. The collector of the third power device serves as the first terminal of the second switching unit SW2, and the collector of the fourth power device serves as the second terminal of the second switching unit SW2. A tenth diode is disposed between the second common emitter and the collector of the third power device. The anode of the tenth diode is connected to the second common emitter, and the cathode of the tenth diode is connected to the collector of the third power device.

[0020] The third switching unit SW3 includes a fifth power device and a sixth power device. The control terminals of the fifth power device and the sixth power device are interconnected, serving as the control terminals of the switching unit. The emitters of the fifth power device and the sixth power device are interconnected, forming a third common emitter. The collector of the fifth power device serves as the first terminal of the third switching unit SW3, and the collector of the sixth power device serves as the second terminal of the third switching unit SW3. An eleventh diode is disposed between the third common emitter and the collector of the fifth power device. The anode of the eleventh diode is connected to the third common emitter, and the cathode of the eleventh diode is connected to the collector of the fifth power device.

[0021] Preferably, the first DC / DC converter includes a first controllable switch T1, a first DC inductor L1, and a seventh diode D. y1 The first terminal of the first controllable switch T1 and the first terminal of the uncontrollable rectifier are connected to the first connection point, and the second terminal of the first controllable switch T1 is connected to the first terminal of the first DC inductor L1 and the seventh diode D. y1 The cathode, the second terminal of the first DC inductor L1 is connected to the first terminal of the DC capacitor C and the load R. L The first terminal, the seventh diode D y1 The anode is connected to the third connection point.

[0022] Preferably, the second DC / DC converter includes a second controllable switch T2, a second DC inductor L2, and an eighth diode D. y2 The first terminal of the second controllable switch T2 and the second terminal connected to the uncontrollable rectifier are connected to the second connection point. The second terminal of the second controllable switch T2 is connected to the first terminal of the second DC inductor L2 and the eighth diode D. y2 The anode of the second DC inductor L2 is connected to the second terminal of the DC capacitor C and the load R. LThe second terminal, the eighth diode D y2 The cathode is connected to the third connection point.

[0023] On the other hand, a passive control method for a SWISS rectifier is also provided, for controlling the SWISS rectifier, comprising the following steps:

[0024] Calculate the first potential difference between the first connection point and the third connection point, the second potential difference between the third connection point and the second connection point, and the peak line voltage based on the three-phase line voltage of the three-phase AC source.

[0025] Based on the peak line voltage and the load R L The actual voltage, the load R L The reference voltage and the actual current of the first DC inductor L1 or the second DC inductor L2 are used to calculate the equivalent duty cycle of the first DC / DC converter and the second DC / DC converter.

[0026] The first duty cycle of the first DC / DC converter and the second duty cycle of the second DC / DC converter are calculated based on the first potential difference, the second potential difference, the peak line voltage, and the equivalent duty cycle.

[0027] The first and second DC / DC converters are turned on or off according to the first and second duty cycles, so that the output voltage of the SWISS rectifier remains constant.

[0028] Preferably, the calculation of the first duty cycle of the first DC / DC converter and the second duty cycle of the second DC / DC converter specifically includes:

[0029] Obtain the load R L The load R is calculated using the actual voltage and the reference voltage of the load. L The actual voltage and the load R L The voltage difference between the reference voltages;

[0030] The voltage difference is processed by proportional-integral processing to obtain the reference current of the first DC inductor L1 or the second DC inductor L2;

[0031] Based on the peak line voltage and the load R L The equivalent duty cycle is calculated from the actual voltage, the actual current of the first DC inductor L1 or the second DC inductor L2, and the reference current of the first DC inductor L1 or the second DC inductor L2.

[0032] The proportional integral is performed according to the following formula:

[0033]

[0034] Among them, i L * represents the reference current of either the first DC inductor L1 or the second DC inductor L2, k p k i V is the proportional-integral coefficient. dc For load R L The actual voltage, V dc * represents the load R L The reference voltage.

[0035] Preferably, the equivalent duty cycles of the first DC / DC converter and the second DC / DC converter are calculated according to the following formula:

[0036]

[0037] Where D0 is the equivalent duty cycle, and L is the inductance value of the first DC inductor L1 and the second DC inductor L2; i L * represents the reference current of either the first DC inductor L1 or the second DC inductor L2, V dc The actual voltage of the load is r11, where r11 is the damping injection coefficient, and i L Vmax is the actual current of the first DC inductor L1 or the second DC inductor L2, and Vmax is the peak value of the line voltage.

[0038] Preferably, the first duty cycle of the first DC / DC converter and the second duty cycle of the second DC / DC converter are calculated according to the following formula:

[0039]

[0040] Wherein, D1 is the first duty cycle, D2 is the second duty cycle, D0 is the equivalent duty cycle, and v py Let v be the first potential difference. yn Vmax is the second potential difference, and Vmax is the peak value of the line voltage.

[0041] In summary, implementing the embodiments of the present invention has the following beneficial effects:

[0042] The SWISS rectifier and its passive control method provided by this invention perform passive control on the DC-side DC / DC converter of the SWISS rectifier based on the load voltage, the actual and reference values ​​of the DC-side current of the SWISS rectifier, and the peak value of the AC-side line voltage. This improves the anti-interference capability of the SWISS rectifier and the control process is simple and easy to implement. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0044] Figure 1 This is a schematic diagram of a SWISS rectifier according to an embodiment of the present invention.

[0045] Figure 2 This is a schematic diagram of the main flow of a SWISS rectifier and its passive control method in an embodiment of the present invention.

[0046] Figure 3 This is a logic diagram of a SWISS rectifier and its passive control method according to an embodiment of the present invention.

[0047] Figure 4 This is the equivalent circuit of the first DC / DC converter and the second DC / DC converter in the embodiments of the present invention. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0049] like Figure 1 The diagram shown is a schematic representation of an embodiment of a Swiss rectifier provided by the present invention. In this embodiment, it includes: an AC filter, an uncontrolled rectifier, a harmonic injection unit, a first DC / DC converter, a second DC / DC converter, and a load R. L The input terminal of the AC filter is connected to a three-phase AC source, and the output terminal of the AC filter is connected to the AC terminal of the uncontrolled rectifier. The first DC terminal of the uncontrolled rectifier and the first terminal of the first DC / DC converter are connected to a first connection point. The second DC terminal of the uncontrolled rectifier and the first terminal of the second DC / DC converter are connected to a second connection point. The second terminals of the first DC / DC converter and the second DC / DC converter are connected to a third connection point. The first terminal of the harmonic injection unit is connected to the third DC terminal of the uncontrolled rectifier, and the second terminal of the harmonic injection unit is connected to the third connection point. The load R LIt is connected between the third terminal of the first DC / DC converter and the third terminal of the second DC / DC converter; in this embodiment, the SWISS rectifier includes: an AC filter 110, an uncontrolled rectifier 120, a harmonic injection unit 130, a first DC / DC converter 140, a second DC / DC converter 150, a DC capacitor C, and a load R. L .

[0050] The AC filter 110 includes a filter inductor unit and a filter capacitor unit; the filter inductor unit includes a first inductor L. a Second inductor L b and the third inductor L c The filter capacitor unit includes a first capacitor C. a Second capacitor C b and the third capacitor C c The first inductor L a The second inductor L b and the third inductor L c The first terminals are respectively connected to a three-phase AC power source; the first inductor L a The second terminal is connected to the third capacitor C c The first end is connected, and the second inductor L b The second terminal is connected to the second capacitor C b The first end is connected, and the third inductor L c The second terminal is connected to the first capacitor C a The first end is connected; the first capacitor C a The second capacitor C b and the third capacitor C c The second terminals are interconnected. The AC filter 110 is used to filter out high-order harmonics from the three-phase AC source; the AC filter 110 is connected to the AC source N (e.g., a three-phase AC power grid) to filter out high-order harmonics from the AC source N. The AC voltage output from the AC source N is filtered by the AC filter 110 to obtain a filtered voltage. This filtered voltage is output from the AC filter 110 to the uncontrolled rectifier 120 as its input.

[0051] In this embodiment, the AC filter 110 may include a filter inductor unit and a filter capacitor unit. Further, the filter inductor unit includes a first inductor L. a Second inductor L b and the third inductor L c The filter capacitor unit includes a first capacitor C. a Second capacitor C b and the third capacitor C c First inductor L a Second inductor Lb and the third inductor L c The first terminals are connected to AC source N; the first inductor L a The second terminal and the third capacitor C c The first end is connected, and the second inductor L b The second terminal and the second capacitor C b The first end is connected, and the third inductor L c The second terminal is connected to the first capacitor C a The first terminal is connected; the first capacitor C a Second capacitor C b and the third capacitor C c The second ends are connected to each other.

[0052] The uncontrolled rectifier 120 includes a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, and a sixth diode D6; the cathodes of the first diode D1, the second diode D2, and the third diode D3 are interconnected at the first connection point, and the anode of the first diode D1 is connected to the third capacitor C. c The first terminal, the first inductor L a The second terminal, the anode of the second diode D2, is connected to the second capacitor C. b The first terminal, the second inductor L b At the second terminal, the anode of the third diode D3 is connected to the first capacitor C. a The first terminal, the third inductor L c The second terminal; the anodes of the fourth diode D4, the fifth diode D5, and the sixth diode D6 are interconnected at the second connection point, and the cathode of the fourth diode D4 is connected to the third capacitor C. c The first terminal, the first inductor L a At the second terminal, the cathode of the fifth diode D5 is connected to the second capacitor C. b The first terminal, the second inductor L b At the second terminal, the cathode of the sixth diode D6 is connected to the first capacitor C. a The first terminal, the third inductor L c The second terminal. The uncontrolled rectifier 120 is used to rectify the filter voltage to obtain a rectified voltage; the uncontrolled rectifier 120 is connected to the output terminal of the AC filter 110 and is used to rectify the filter voltage to obtain a rectified voltage.

[0053] In this embodiment, the uncontrolled rectifier 120 includes a first diode D1 to a sixth diode D6, wherein the cathodes of the first diode D1, the second diode D2, and the third diode D3 are interconnected, and this connection point is denoted as the first connection point p. The anode of the first diode D1 is connected to the third capacitor C. c The first terminal (i.e., the first inductor L) a The second terminal of the second diode D2 is connected to the anode of the second capacitor C. b The first terminal (i.e., the second inductor L) b The second terminal of the third diode (D3) is connected to the anode of the first capacitor C. a The first terminal (i.e., the third inductor L) c The second terminal); the anodes of the fourth diode D4, the fifth diode D5, and the sixth diode D6 are interconnected, and this connection point is denoted as the second connection point n. The cathode of the fourth diode D4 is connected to the third capacitor C. c The first terminal (i.e., the first inductor L) a The cathode of the fifth diode D5 is connected to the second capacitor C (the second terminal of the diode). b The first terminal (i.e., the second inductor L) b The second terminal of the sixth diode (D6) is connected to the cathode of the first capacitor C. a The first terminal (i.e., the third inductor L) c (the second end).

[0054] The harmonic injection unit 130 includes a first switching unit SW1, a second switching unit SW2, and a third switching unit SW3; the first terminal of the first switching unit SW1 is connected to the third capacitor C. c The first terminal, the first inductor L a The second terminal of the second switching unit SW2 is connected to the second capacitor C. b The first terminal, the second inductor L b The second terminal of the third switching unit SW3 is connected to the first capacitor C. a The first terminal, the third inductor L cThe second terminals of the first switching unit SW1, the second switching unit SW2, and the third switching unit SW3 are interconnected at the third connection point. The first switching unit SW1 includes a first power device and a second power device, whose control terminals are interconnected as the control terminals of the switching unit. The emitters of the first power device and the second power device are interconnected to form a first common emitter. The collector of the first power device serves as the first terminal of the first switching unit SW1, and the collector of the second power device serves as the second terminal of the first switching unit SW1. A ninth diode is disposed between the first common emitter and the collector of the first power device, with the anode of the ninth diode connected to the first common emitter and the cathode of the ninth diode connected to the collector of the first power device. The second switching unit SW2 includes a third power device and a fourth power device, whose control terminals are interconnected as the control terminals of the switching unit. The emitters of the third power device and the fourth power device are interconnected to form a first common emitter. The second common emitter; the collector of the third power device serves as the first terminal of the second switching unit SW2, the collector of the fourth power device serves as the second terminal of the second switching unit SW2, a tenth diode is disposed between the second common emitter and the collector of the third power device, the anode of the tenth diode is connected to the second common emitter, and the cathode of the tenth diode is connected to the collector of the third power device; the third switching unit SW3 includes a fifth power device and a sixth power device, the control terminals of the fifth power device and the sixth power device are interconnected, serving as the control terminals of the switching unit; the emitters of the fifth power device and the sixth power device are interconnected to form a third common emitter; the collector of the fifth power device serves as the first terminal of the third switching unit SW3, the collector of the sixth power device serves as the second terminal of the third switching unit SW3, an eleventh diode is disposed between the third common emitter and the collector of the fifth power device, the anode of the eleventh diode is connected to the third common emitter, and the cathode of the eleventh diode is connected to the collector of the fifth power device. The harmonic injection unit 130 is used to perform dead-time compensation of the input current of the non-conducting phase in the uncontrolled rectifier, so as to achieve unity power factor correction. The harmonic injection unit 130 is connected to the uncontrolled rectifier 120 and is used to perform dead-time compensation of the uncontrolled rectifier 120. Thus, dead-time compensation of the input current of the non-conducting phase in the uncontrolled rectifier 120 is performed to achieve unity power factor correction.

[0055] In this embodiment, the harmonic injection unit 130 includes a first switching unit SW1, a second switching unit SW2, and a third switching unit SW3; the first terminal of the first switching unit SW1 is connected to the third capacitor C. c The first terminal (i.e., the first inductor L) a The second terminal of the second switching unit SW2 is connected to the second capacitor C. b The first terminal (i.e., the second inductor L) b The second terminal of the third switching unit SW3 is connected to the first capacitor C. a The first terminal (i.e., the third inductor L) c The second ends of the first switch unit SW1, the second switch unit SW2, and the third switch unit SW3 are interconnected to the third connection point.

[0056] In this embodiment, the first switching unit SW1, the second switching unit SW2, and the third switching unit SW3 may have the same structure. Further, this identical structure may include: a first power device (e.g., an IGBT) and a second power device (e.g., an IGBT), wherein the control terminals (e.g., gates) of the first and second power devices are connected as the control terminals of the switching unit; the emitters of the first and second power devices are connected; and the collectors of the first and second power devices respectively serve as the first and second terminals of the switching unit. Further, a diode is also connected between the emitter and collector of the first and second power devices, with the anode of the diode connected to the emitter and the cathode connected to the collector.

[0057] In this circuit, the first switching unit SW1, the second switching unit SW2, and the third switching unit SW3 correspond to phases A, B, and C, respectively. When the instantaneous voltage of a phase (e.g., phase A) of the AC source N is at its maximum, the corresponding diode (e.g., D1) conducts, meaning only one of D1-D3 conducts. When the instantaneous voltage of a phase (e.g., phase B) is at its minimum, the corresponding diode (e.g., D5) conducts, meaning only one of D4-D6 conducts. Therefore, only two of the three phases conduct and current flows. For the non-conducting phase (e.g., phase C), harmonic current injection control is applied, controlling the switch (e.g., switching unit SW3) in switching unit SW1, switching unit SW2, or switching unit SW3 corresponding to the non-conducting phase to conduct, providing an additional current path to compensate for the current dead zone.

[0058] The first DC / DC converter 140 includes a first controllable switch T1, a first DC inductor L1, and a seventh diode D. y1The first terminal of the first controllable switch T1 and the first terminal of the uncontrollable rectifier are connected to the first connection point, and the second terminal of the first controllable switch T1 is connected to the first terminal of the first DC inductor L1 and the seventh diode D. y1 The cathode, the second terminal of the first DC inductor L1 is connected to the first terminal of the DC capacitor C and the load R. L The first terminal, the seventh diode D y1 The anode is connected to the third connection point. The second DC / DC converter 150 includes a second controllable switch T2, a second DC inductor L2, and an eighth diode D. y2 The first terminal of the second controllable switch T2 and the second terminal connected to the uncontrollable rectifier are connected to the second connection point. The second terminal of the second controllable switch T2 is connected to the first terminal of the second DC inductor L2 and the eighth diode D. y2 The anode of the second DC inductor L2 is connected to the second terminal of the DC capacitor C and the load R. L The second terminal, the eighth diode D y2 The cathode is connected to the third connection point. The first DC / DC converter 140 and the second DC / DC converter 150 are used to process the rectified voltage output by the uncontrolled rectifier and output a constant DC voltage. The first DC / DC converter 140 and the second DC / DC converter 150 are respectively cascaded with the uncontrolled rectifier 120 to output a constant DC voltage based on the rectified voltage output by the controlled rectifier 120.

[0059] In this embodiment, the first DC / DC converter 140 is connected to the first terminal (e.g., the first connection point p) of the uncontrolled rectifier 120, and the second DC / DC converter 150 is connected to the second terminal (e.g., the second connection point n) of the uncontrolled rectifier 120.

[0060] In this embodiment, the first DC / DC converter 140 includes a first controllable switch T1, a third inductor L1, and a seventh diode D. y1 In this configuration, the first terminal of the first controllable switch T1 (e.g., the collector of the IGBT) is connected to the first terminal of the uncontrolled rectifier 120 (e.g., the first connection point p), and the second terminal of the first controllable switch T1 (e.g., the emitter of the IGBT) is connected to the first terminal of the third inductor L1 and the seventh diode D. y1 The cathode, the second terminal of the third inductor L1, is connected to the first terminal of the DC capacitor C and the load R. L The first end.

[0061] In this embodiment, the second DC / DC converter 150 includes a second controllable switch T2, a fourth inductor L2, and an eighth diode D. y2In this configuration, the first terminal of the second controllable switch T2 (e.g., the emitter of the IGBT) is connected to the second terminal of the uncontrolled rectifier 120 (e.g., the second connection point n), and the second terminal of the second controllable switch T2 (e.g., the collector of the IGBT) is connected to the first terminal of the fourth inductor L2 and the eighth diode D. y2 The anode of the fourth inductor L2 is connected to the second terminal of the DC capacitor C and the load R. L The second terminal. The seventh diode D. y1 anode and eighth diode D y2 The cathode is connected to the fourth connection point, denoted as point y. This point y is connected to the third connection point, or may be the same point.

[0062] like Figure 2 and Figure 3 The diagram shown is a schematic representation of an embodiment of a passive control method for a SWISS rectifier provided by the present invention. This embodiment includes:

[0063] The first potential difference between the first connection point and the third connection point, the second potential difference between the third connection point and the second connection point, and the peak line voltage are calculated based on the three-phase line voltage of the three-phase AC source. Specifically, the calculation of the first duty cycle of the first DC / DC converter and the second duty cycle of the second DC / DC converter includes:

[0064] Obtain the load R L The load R is calculated using the actual voltage and the reference voltage of the load. L The actual voltage and the load R L The voltage difference between the reference voltages;

[0065] The voltage difference is processed by proportional-integral processing to obtain the reference current of the first DC inductor L1 or the second DC inductor L2;

[0066] Based on the peak line voltage and the load R L The equivalent duty cycle is calculated from the actual voltage, the actual current of the first DC inductor L1 or the second DC inductor L2, and the reference current of the first DC inductor L1 or the second DC inductor L2.

[0067] The proportional integral is performed according to the following formula:

[0068]

[0069] Among them, i L * represents the reference current of either the first DC inductor L1 or the second DC inductor L2, k p k i V is the proportional-integral coefficient.dc For load R L The actual voltage, V dc * represents the load R L The reference voltage.

[0070] The first potential difference is calculated based on the maximum value of the three-phase line voltages; the second potential difference is calculated based on the minimum value of the three-phase line voltages.

[0071] Based on the peak line voltage and the load R L The actual voltage, the load R L Based on the reference voltage and the actual current of the first DC inductor L1 or the second DC inductor L2, the equivalent duty cycle of the first DC / DC converter and the second DC / DC converter is calculated; specifically, the equivalent duty cycle of the first DC / DC converter and the second DC / DC converter is calculated according to the following formula:

[0072]

[0073] Where D0 is the equivalent duty cycle, and L is the inductance value of the first DC inductor L1 and the second DC inductor L2; i L * represents the reference current of either the first DC inductor L1 or the second DC inductor L2, V dc The actual voltage of the load is r11, where r11 is the damping injection coefficient, and i L Vmax is the actual current of the first DC inductor L1 or the second DC inductor L2, and Vmax is the peak value of the line voltage.

[0074] Based on the first potential difference, the second potential difference, the peak line voltage, and the equivalent duty cycle, the first duty cycle of the first DC / DC converter and the second duty cycle of the second DC / DC converter are calculated; specifically, the first duty cycle of the first DC / DC converter and the second duty cycle of the second DC / DC converter are calculated according to the following formulas:

[0075]

[0076] Wherein, D1 is the first duty cycle, D2 is the second duty cycle, D0 is the equivalent duty cycle, and v py Let v be the first potential difference. yn Vmax is the second potential difference, and Vmax is the peak value of the line voltage.

[0077] The first and second DC / DC converters are turned on or off according to the first and second duty cycles, so that the output voltage of the SWISS rectifier remains constant.

[0078] In this embodiment, based on Figure 1 From the circuit structure shown, the equations for the first or second DC / DC converter can be obtained as follows:

[0079]

[0080] Among them, i L For DC inductors (e.g.) Figure 1 The actual current v of the third inductor L1 or the fourth inductor L2 in the circuit. py and v yn D1 and D2 are the potentials of the first connection point (p) to the third connection point (y), i.e., the first potential difference; and the potential of the third connection point (y) to the second connection point (n), i.e., the second potential difference. D1 and D2 are the duty cycles of the first controllable switch T1 and the second controllable switch T2, respectively.

[0081] Due to D1v py +D2v yn ≤0.866Vmax, where Vmax is the peak value of the line voltage in the above formula. If the equivalent duty cycle D0 is defined as:

[0082]

[0083] The above formula can then be expressed as:

[0084]

[0085] in, Figure 1 The first and second DC / DC converters in the circuit can be equivalent to a buck converter circuit, such as... Figure 4 The diagram shows the equivalent circuits of the first and second DC / DC converters according to an embodiment of the present invention. T0 is the equivalent switching transistor, and its duty cycle corresponds to D0. Therefore, it can be represented in EL model form:

[0086]

[0087] in,

[0088] To satisfy the requirement of passivity, a passive controller can be designed as follows:

[0089]

[0090] Where Xe=XX* is the error vector, Rd=diag{r11,g22} is the damping injection coefficient matrix, and r11,g22 are the damping injection coefficients. Expanding from this, the governing equations are:

[0091]

[0092] Where D0 is the equivalent duty cycle, and L is the inductance value of the first DC inductor and the second DC inductor; i L * represents the reference current of either the first or second DC inductor, V dc The actual voltage of the load is r11, where r11 is the damping injection coefficient, and i L Vmax is the actual current of the first DC inductor or the second DC inductor, and Vmax is the peak value of the line voltage.

[0093] The reference current iL* of the first DC inductor or the second DC inductor can be obtained through PI control based on the actual load voltage and the reference voltage, including:

[0094]

[0095] Where, k p k i i is the proportional-integral coefficient. L * represents the reference current of either the first or second DC inductor, V dc V is the actual voltage of the load. dc * indicates the reference voltage for the load.

[0096] Based on the volt-second equivalence, we can obtain:

[0097]

[0098] Wherein, D1 is the first duty cycle, D2 is the second duty cycle, D0 is the equivalent duty cycle, and v py Let v be the first potential difference. yn Vmax is the second potential difference, and Vmax is the peak value of the line voltage.

[0099] Therefore, by controlling the first controllable switch T1 in the first DC / DC converter to turn on or off based on the first duty cycle D1, and by controlling the second controllable switch T2 in the second DC / DC converter to turn on or off based on the second duty cycle D2, the output voltage of the SWISS rectifier 100 can be kept constant, thereby enhancing its anti-interference capability.

[0100] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A passive control method for a Swiss rectifier, used to control a Swiss rectifier, the Swiss rectifier comprising: AC filter, uncontrolled rectifier, harmonic injection unit, first DC / DC converter, second DC / DC converter and load R L ; The input terminal of the AC filter is connected to a three-phase AC source, and the output terminal of the AC filter is connected to the AC terminal of the uncontrolled rectifier. The first DC terminal of the uncontrolled rectifier and the first terminal of the first DC / DC converter are connected to a first connection point. The second DC terminal of the uncontrolled rectifier and the first terminal of the second DC / DC converter are connected to a second connection point. The second terminals of the first DC / DC converter and the second DC / DC converter are connected to a third connection point. The first terminal of the harmonic injection unit is connected to the third DC terminal of the uncontrolled rectifier, and the second terminal of the harmonic injection unit is connected to the third connection point. The load R L It is connected between the third terminal of the first DC / DC converter and the third terminal of the second DC / DC converter; The AC filter is used to filter out high-order harmonics from a three-phase AC source; The uncontrolled rectifier is used to rectify the filtered voltage to obtain the rectified voltage; The harmonic injection unit is used to compensate for the dead zone of the input current of the non-conducting phase in the uncontrolled rectifier, so as to achieve the correction of unity power factor. The first DC / DC converter and the second DC / DC converter are used to process the rectified voltage output by the uncontrolled rectifier and output a constant DC voltage. The AC filter includes a filter inductor unit and a filter capacitor unit; the filter inductor unit includes a first inductor L. a Second inductor L b and the third inductor L c The filter capacitor unit includes a first capacitor C. a Second capacitor C b and the third capacitor C c ; The first inductor L a The second inductor L b and the third inductor L c The first terminals are respectively connected to a three-phase AC power source; the first inductor L a The second terminal is connected to the third capacitor C c The first end is connected, and the second inductor L b The second terminal is connected to the second capacitor C b The first end is connected, and the third inductor L c The second terminal is connected to the first capacitor C a The first end is connected; the first capacitor C a The second capacitor C b and the third capacitor C c The second ends are interconnected; The uncontrolled rectifier includes a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, and a sixth diode D6; The cathodes of the first diode D1, the second diode D2, and the third diode D3 are interconnected at the first connection point, and the anode of the first diode D1 is connected to the third capacitor C. c The first terminal, the first inductor L a The second terminal, the anode of the second diode D2, is connected to the second capacitor C. b The first terminal, the second inductor L b At the second terminal, the anode of the third diode D3 is connected to the first capacitor C. a The first terminal, the third inductor L c The second end; The anodes of the fourth diode D4, the fifth diode D5, and the sixth diode D6 are interconnected at the second connection point, and the cathode of the fourth diode D4 is connected to the third capacitor C. c The first terminal, the first inductor L a At the second terminal, the cathode of the fifth diode D5 is connected to the second capacitor C. b The first terminal, the second inductor L b At the second terminal, the cathode of the sixth diode D6 is connected to the first capacitor C. a The first terminal, the third inductor L c The second end; The harmonic injection unit includes a first switching unit SW1, a second switching unit SW2, and a third switching unit SW3; The first terminal of the first switching unit SW1 is connected to the third capacitor C. c The first terminal, the first inductor L a The second terminal of the second switching unit SW2 is connected to the second capacitor C. b The first terminal, the second inductor L b The second terminal of the third switching unit SW3 is connected to the first capacitor C. a The first terminal, the third inductor L c The second ends of the first switch unit SW1, the second switch unit SW2 and the third switch unit SW3 are interconnected at the third connection point. The first switching unit SW1 includes a first power device and a second power device. The control terminals of the first power device and the second power device are interconnected, serving as the control terminals of the switching unit. The emitters of the first power device and the second power device are interconnected, forming a first common emitter. The collector of the first power device serves as the first terminal of the first switching unit SW1, and the collector of the second power device serves as the second terminal of the first switching unit SW1. A ninth diode is disposed between the first common emitter and the collector of the first power device. The anode of the ninth diode is connected to the first common emitter, and the cathode of the ninth diode is connected to the collector of the first power device. The second switching unit SW2 includes a third power device and a fourth power device. The control terminals of the third power device and the fourth power device are interconnected, serving as the control terminals of the switching unit. The emitters of the third power device and the fourth power device are interconnected, forming a second common emitter. The collector of the third power device serves as the first terminal of the second switching unit SW2, and the collector of the fourth power device serves as the second terminal of the second switching unit SW2. A tenth diode is disposed between the second common emitter and the collector of the third power device. The anode of the tenth diode is connected to the second common emitter, and the cathode of the tenth diode is connected to the collector of the third power device. The third switching unit SW3 includes a fifth power device and a sixth power device. The control terminals of the fifth power device and the sixth power device are interconnected, serving as the control terminals of the switching unit. The emitters of the fifth power device and the sixth power device are interconnected, forming a third common emitter. The collector of the fifth power device serves as the first terminal of the third switching unit SW3, and the collector of the sixth power device serves as the second terminal of the third switching unit SW3. An eleventh diode is disposed between the third common emitter and the collector of the fifth power device. The anode of the eleventh diode is connected to the third common emitter, and the cathode of the eleventh diode is connected to the collector of the fifth power device. The first DC / DC converter includes a first controllable switch T1, a first DC inductor L1, and a seventh diode D. y1 The first terminal of the first controllable switch T1 and the first terminal of the uncontrollable rectifier are connected to the first connection point, and the second terminal of the first controllable switch T1 is connected to the first terminal of the first DC inductor L1 and the seventh diode D. y1 The cathode, the second terminal of the first DC inductor L1 is connected to the first terminal of the DC capacitor C and the load R. L The first terminal, the seventh diode D y1 The anode is connected to the third connection point; The second DC / DC converter includes a second controllable switch T2, a second DC inductor L2, and an eighth diode D. y2 The first terminal of the second controllable switch T2 and the second terminal of the uncontrollable rectifier are connected to the second connection point. The second terminal of the second controllable switch T2 is connected to the first terminal of the second DC inductor L2 and the eighth diode D. y2 The anode of the second DC inductor L2 is connected to the second terminal of the DC capacitor C and the load R. L The second terminal, the eighth diode D y2 The cathode is connected to the third connection point; The method is characterized by comprising the following steps: Calculate the first potential difference between the first connection point and the third connection point, the second potential difference between the third connection point and the second connection point, and the peak line voltage based on the three-phase line voltage of the three-phase AC source. The equivalent duty cycle of the first DC / DC converter and the second DC / DC converter is calculated based on the peak line voltage, the actual voltage of the load RL, the reference voltage of the load RL, and the actual current of the first DC inductor L1 or the second DC inductor L2. The first duty cycle of the first DC / DC converter and the second duty cycle of the second DC / DC converter are calculated based on the first potential difference, the second potential difference, the peak line voltage, and the equivalent duty cycle. The first and second DC / DC converters are turned on or off according to the first and second duty cycles, so that the output voltage of the SWISS rectifier remains constant.

2. The method as described in claim 1, characterized in that, The calculation of the first duty cycle of the first DC / DC converter and the second duty cycle of the second DC / DC converter specifically includes: Obtain the load R L The load R is calculated using the actual voltage and the reference voltage of the load. L The actual voltage and the load R L The voltage difference between the reference voltages; The voltage difference is processed by proportional-integral processing to obtain the reference current of the first DC inductor L1 or the second DC inductor L2; Based on the peak line voltage and the load R L The equivalent duty cycle is calculated from the actual voltage, the actual current of the first DC inductor L1 or the second DC inductor L2, and the reference current of the first DC inductor L1 or the second DC inductor L2. The proportional integral is performed according to the following formula: Among them, i L k is the reference current for either the first DC inductor L1 or the second DC inductor L2. p k i V is the proportional-integral coefficient. dc For load R L The actual voltage, V dc For load R L The reference voltage.

3. The method as described in claim 2, characterized in that, The equivalent duty cycles of the first DC / DC converter and the second DC / DC converter are calculated using the following formula: Where D0 is the equivalent duty cycle, and L is the inductance value of the first DC inductor L1 and the second DC inductor L2; i L V is the reference current for either the first DC inductor L1 or the second DC inductor L2. dc The actual voltage of the load is r11, where r11 is the damping injection coefficient, and i L Vmax is the actual current of the first DC inductor L1 or the second DC inductor L2, and Vmax is the peak value of the line voltage.

4. The method as described in claim 3, characterized in that, The first duty cycle of the first DC / DC converter and the second duty cycle of the second DC / DC converter are calculated using the following formulas: Wherein, D1 is the first duty cycle, D2 is the second duty cycle, D0 is the equivalent duty cycle, and v py Let v be the first potential difference. yn Vmax is the second potential difference, and Vmax is the peak value of the line voltage.

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