Ac-dc power supply and control method thereof

Abstract

The ACDC power supply has an AC-DC converter ACDC, a primary-side DC capacitor C1, an insulation type DC-DC converter DCDC, and a secondary-side DC capacitor C2. Each 1 phase has m (m: an integer of 2 or more) units. A plurality of DC buses V dc21 and V dc22 are connected in series or in parallel with a plurality of secondary-side DC capacitors C2. The voltage of the plurality of DC buses V dc21 and V dc22 is supplied to a load or a power supply. When power imbalance occurs due to the condition of the load or the power supply, the output voltage is maintained while maintaining the voltage balance of the secondary-side DC voltage and the primary-side DC voltage of each unit. In the ACDC power supply, the voltage balance of each DC bus is achieved when power imbalance occurs without using an additional balancing circuit or a multi-winding power frequency transformer.

Description

Technical Field

[0001] This invention relates to an SST (Solid State Transformer) method, which connects multiple power converters (AC-DC converter + insulated DC-DC converter) in series or in parallel in applications with AC input and multiple DC bus outputs, and to a technique for achieving balance of DC voltages. Background Technology

[0002] Non-patent document 1 describes circuit methods and control methods for power imbalance on each DC bus. As a circuit method, it discloses a method of achieving voltage balance on the DC bus when there is power imbalance by connecting a balancing circuit. It also discloses a method of achieving voltage balance on each DC bus when there is power imbalance by using a power frequency multi-winding transformer and a power converter, thereby eliminating the need for a balancing circuit.

[0003] In Non-Patent Document 2, an SST method using a high-frequency multi-winding transformer is employed in the circuit that generates multiple DC buses. In this method, by making the multi-winding transformer operate at a high frequency, it is possible to reduce its size compared to a power frequency transformer.

[0004] Patent Document 1 discloses an SST method for generating two DC buses from high-voltage AC. Furthermore, an insulated DC-DC converter is connected between the two DC buses to achieve voltage balance.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Publication No. 2023-510035

[0008] Patent Document 2: Japanese Patent Application Publication No. 2022-50739

[0009] Non-patent literature

[0010] Non-Patent Literature 1: S. Rivera, R. Lizana F, S. Kouro, T. Dragicevic and B. Wu, “Bipolar DC Power Conversion: State-of-the-Art and Emerging Technologies,” IEEE Journal of Emerging and Selected Topics in Power Electronics, April 2021, Vol. 9, No. 2, pp. 1192-1204.

[0011] Non-Patent Literature 2: H. Kim, J. Baek, M. Kim, H. Yun, D. Jeong and J. Cho, “A 13.2kV / 150kVA Solid State Transformer for a Bipolar LVDC Distribution System”, 2019 IEEE Third International Conference on DC Microgrids (ICDCM), Matsue, Japan, 2019, pp. 1-4

[0012] Non-Patent Literature 3: Isamu Kinoshita and Hitoshi Haga, "LLC Converter for PEV Charger with Wide Range Voltage Gain Using 6-Switch Bridge", Journal of Electrical Engineering, Vol. 140, No. 1, pp. 36-44

[0013] Non-Patent Literature 4: Hayato Higa, Harusuke Takuma, Keisuke Kusaka, and Junichi Ito, “Development of a T-type Dual Active Bridge DC-DC Converter with Operating Mode Switching Method for Wide Voltage Drive Range”, Journal of Electrical Engineering, Vol. 139, No. 4, pp. 388-400 (2019). Summary of the Invention

[0014] The technical problem that the invention aims to solve

[0015] When the power supply to multiple DC buses is unbalanced, the voltage across each DC bus becomes unbalanced. To address this situation, the withstand voltage of the DC buses, as well as the withstand voltage required on the load side connected to the DC buses, increases, leading to increased cost and size.

[0016] According to the methods disclosed in Non-Patent Document 1 and Patent Document 1, a multi-winding power frequency transformer or balancing circuit is required, which increases the size and cost.

[0017] According to the method disclosed in Non-Patent Document 2, the balance of DC bus voltage when there is power imbalance among the DC buses is not mentioned.

[0018] Based on the above, the technical challenge of ACDC power supplies lies in achieving voltage balance of each DC bus when there is power imbalance without using additional balancing circuits or multi-winding power frequency transformers.

[0019] Technical solutions for solving technical problems

[0020] The present invention was made in view of the above-mentioned problems. One aspect of it is an AC-DC power supply having m (m is an integer greater than or equal to 2) cells per phase, wherein each cell comprises: an AC-DC converter; a primary-side DC capacitor connected to the DC side of the AC-DC converter; an isolated DC-DC converter having one DC side connected to the primary-side DC capacitor; and a secondary-side DC capacitor connected to the other DC side of the isolated DC-DC converter. The AC-DC power supply has multiple DC buses formed by multiple secondary-side DC capacitors connected in series or parallel, supplying voltages of the multiple DC buses to a load or power source. The AC-DC power supply is characterized in that, when a power imbalance occurs due to the condition of the load or the power source, it outputs a voltage while maintaining voltage balance between the voltage of the DC buses (i.e., the secondary-side DC voltage) and the voltage of the primary-side DC capacitors of each cell (i.e., the primary-side DC voltage).

[0021] Furthermore, as one embodiment, the control unit of the AC-DC converter comprises: a primary-side DC voltage average value control unit, which generates a system current active component command value based on the primary-side DC voltage average value command value and the primary-side DC voltage average value across all units; a system current control unit, which generates a system voltage active component command value and a system voltage reactive component command value based on the system current active component command value and the system current reactive component command value; and a primary-side DC voltage phase-to-phase balance control unit, which generates a primary-side DC voltage phase-to-phase balance control value based on the primary-side DC voltage phase-to-phase average value of each phase and the primary-side DC voltage of each unit, wherein the system voltage active component command value and the system voltage reactive component command value are transformed into values ​​on a fixed coordinate system and multiplied by the primary-side... The control unit of the isolated DC-DC converter comprises: a primary-side DC voltage individual balance control unit that generates a primary-side DC voltage individual balance control value based on the primary-side DC voltage; and a secondary-side DC voltage individual control unit that generates a secondary-side DC voltage individual control value based on the secondary-side DC voltage. The control unit further comprises subtracting the primary-side DC voltage individual balance control value from the secondary-side DC voltage individual control value, performing current control based on the subtraction result and the primary-side DC voltage, and generating the gate signal of the isolated DC-DC converter based on the result of the current control.

[0022] Additionally, as another approach, the control unit of the AC-DC converter is characterized by comprising: a primary-side DC voltage average value control unit, which generates a system current active component command value based on the primary-side DC voltage average value command value and the primary-side DC voltage full-unit average value; a system current control unit, which generates a system voltage active component command value and a system voltage reactive component command value based on the system current active component command value and the system current reactive component command value; and a primary-side DC voltage phase-to-phase balance control unit, which generates a primary-side DC voltage phase-to-phase balance control value based on the primary-side DC voltage phase-to-phase average value of each phase and the primary-side DC voltage of each unit, wherein the system voltage active component command value and the system voltage reactive component command value are transformed into values ​​on fixed coordinates, multiplied by the primary-side DC voltage full-unit average value, and the primary-side DC voltage phase-to-phase balance control value is subtracted from the multiplication result to generate the value. The control unit of the isolated DC-DC converter includes: a primary-side DC voltage individual balancing control unit that generates a primary-side DC voltage individual balancing control value based on the primary-side DC voltage; a secondary-side DC voltage balancing control unit that generates a secondary-side DC voltage balancing control value based on the secondary-side DC voltage; and a secondary-side DC voltage total value control unit that generates a secondary-side DC voltage total value control value based on the secondary-side DC voltage total value command value and the secondary-side DC voltage total value. The control unit subtracts the value obtained by adding the primary-side DC voltage individual balancing control value to the secondary-side DC voltage total value control value. Current control is performed based on the subtracted value and the primary-side DC voltage. The gate signal of the isolated DC-DC converter is generated based on the result of the current control.

[0023] Additionally, as an embodiment, the primary-side DC voltage average value control unit comprises: a first total value calculation unit that calculates the total value of the primary-side DC voltage of all units and outputs it as the primary-side DC voltage total value of all units; a total unit average value calculation unit that calculates the primary-side DC voltage total unit average value based on the product of the primary-side DC voltage total unit value and the reciprocal of the total number of units; a first subtractor that calculates the deviation between the primary-side DC voltage average value command value and the primary-side DC voltage total unit average value; and a first amplifier that amplifies the output of the first subtractor and outputs it as the system current active component command value.

[0024] Additionally, as an embodiment, the system current control unit comprises: a second subtractor for subtracting the system current active component from the system current active component command value; a second amplifier for amplifying the output of the second subtractor and outputting it as the system voltage active component command value; a third subtractor for subtracting the system current reactive component from the system current reactive component command value; and a third amplifier for amplifying the output of the third subtractor and outputting it as the system voltage reactive component command value.

[0025] Additionally, as an embodiment, the primary-side DC voltage phase-to-phase balance control unit comprises: a second total value calculation unit that calculates the total value of the primary-side DC voltage within a phase and outputs it as the primary-side DC voltage phase-to-phase total value; a phase-to-phase average value calculation unit that calculates the phase-to-phase average value of the primary-side DC voltage for each phase based on the product of the primary-side DC voltage phase-to-phase total value and the reciprocal of the number of units in the phase; a fourth subtractor that calculates the deviation between the phase-to-phase average value of the primary-side DC voltage for each phase and the primary-side DC voltage of each unit in the phase; a fourth amplifier that amplifies the output of the fourth subtractor; and a first multiplier that multiplies the output of the fourth amplifier by the sign of the system current value of each phase and outputs it as the primary-side DC voltage phase-to-phase balance control value.

[0026] Additionally, as an embodiment, the primary-side DC voltage individual balancing control unit comprises: a third total value calculation unit that calculates the total value of the primary-side DC voltage of the units connected to each DC bus; a third average value calculation unit that calculates the average value of the primary-side DC voltage of the units connected to each DC bus by multiplying the output of the third total value calculation unit by the reciprocal of the number of units connected to each DC bus; a band-stop filter that filters out the system frequency twice-multiplied component of the primary-side DC voltage of the units connected to each DC bus; a fifth subtractor that outputs the difference between the average value of the primary-side DC voltage of the DC bus and the output of the band-stop filter; a fifth amplifier that amplifies the output of the fifth subtractor; and a second multiplier that multiplies the output of the fifth amplifier by the turns ratio of the transformer of the AC-DC converter to the transformer of the insulated DC-DC converter and outputs the primary-side DC voltage individual balancing control value.

[0027] Additionally, as an embodiment, the secondary-side DC voltage individual control unit comprises: a sixth subtractor for calculating the difference between the secondary-side DC voltage command value and the secondary-side DC voltage of each DC bus; a sixth amplifier for amplifying the output of the sixth subtractor; and a third multiplier for calculating the product of the output of the sixth amplifier and the reciprocal of the number of units connected to the DC bus, and outputting the product as the secondary-side DC voltage individual control value.

[0028] Additionally, as an embodiment, the secondary-side DC voltage balance control unit comprises: an eighth subtractor for calculating the deviation between the average value of the secondary-side DC voltage and the secondary-side DC voltage of each DC bus; and a seventh amplifier for amplifying the output of the eighth subtractor and outputting it as the secondary-side DC voltage balance control value.

[0029] Additionally, as an embodiment, the secondary-side DC voltage total value control unit comprises: a 9th subtractor that calculates the difference between the secondary-side DC voltage total value command value and the secondary-side DC voltage total value of all DC buses; an 8th amplifier that amplifies the output of the 9th subtractor; and a 4th multiplier that calculates the product of the output of the 8th amplifier and the reciprocal of the total number of units and outputs it as the secondary-side DC voltage total value control value.

[0030] Invention Effects

[0031] According to the present invention, in an ACDC power supply, voltage balance of each DC bus can be achieved when there is power imbalance without the use of additional balancing circuits or multi-winding power frequency transformers. Attached Figure Description

[0032] Figure 1 This is a diagram showing the SST main circuit structure that generates multiple DC buses.

[0033] Figure 2 This is a block diagram showing the control section of an AC-DC converter.

[0034] Figure 3 This is a block diagram showing the control section of the insulated DC-DC converter according to Embodiment 1.

[0035] Figure 4 This is a block diagram showing the control section of the insulated DC-DC converter according to Embodiment 2.

[0036] Figure Labels

[0037] 12: Primary side DC voltage average value control unit; 13: System current control unit; 14: Primary side DC voltage phase balance control unit; 24, 38: Primary side DC voltage individual balance control unit; 25: Secondary side DC voltage individual control unit; 39: Secondary side DC voltage balance control unit; 40: Secondary side DC voltage total value control unit. Detailed Implementation

[0038] The following is based on Figures 1-4 Detailed description of embodiments 1 and 2 of the AC / DC power supply of this invention.

[0039] [Implementation Method 1]

[0040] Figure 1The SST main circuit structure for generating multiple DC buses is shown. For example... Figure 1 As shown, the converter comprises: an AC-DC converter (ACDC) connected to a high-voltage AC system; a primary-side DC capacitor C1 connected to the DC side of the AC-DC converter (ACDC); an isolated DC-DC converter (DCDC) with one DC side connected to the primary-side DC capacitor C1; and a secondary-side DC capacitor C2 connected to the other DC side of the isolated DC-DC converter (DCDC). The AC-DC converter (ACDC) and the isolated DC-DC converter (DCDC) can be selected from conventionally known converters as appropriate. Since AC-DC converters (ACDC) and isolated DC-DC converters (DCDC) are well-known, detailed descriptions are omitted here.

[0041] Here, an AC-DC converter (ACDC), a primary-side DC capacitor (C1), an isolated DC-DC converter (DCDC), and a secondary-side DC capacitor (C2) are considered as one unit. The number of units per phase is set to m (m is an integer greater than or equal to 2). Additionally, three units of three phases are considered as one generator set. The number of generator sets is set to n (n is an integer greater than or equal to 2).

[0042] In Embodiment 1 and Embodiment 2 described later, the secondary-side DC capacitors C2 are connected in series or in parallel to form a DC bus V. dc21 or DC bus V dc22 Additionally, the DC bus V dc21 、 or V dc22 、 or V dc21 +V dc22 The power is supplied to the load. Additionally, each unit (AC-DC converter, DC-DC converter) has a switching element. The voltage and current of each unit can be controlled by switching the elements on and off.

[0043] In addition, the xth secondary voltage V connected within phase a will be... dc2x The primary side DC voltage of the kth unit is set to V. dc1axk (x = 1, 2, k = number of units connected to each DC bus = 1, 2...n / 2).

[0044] Figure 2 A block diagram of the control section of an AC-DC converter (ACDC) is shown. Figure 2 The control unit of the AC-DC converter shown is common in both Embodiment 1 and Embodiment 2 described later. The control unit of the AC-DC converter includes a primary-side DC voltage average value control unit 12, a system current control unit 13, and a primary-side DC voltage phase balance control unit 14, and generates three-phase voltage command values.

[0045] Input the following signals into this control unit.

[0046] Primary side DC voltage average value command value V dc1_ave_ref

[0047] Three-phase system current value i U i V i W

[0048] Three-phase system voltage value V u V v V w

[0049] The active component of the system current i on the rotating coordinate system d The reactive component of the system current i q

[0050] System current reactive component command value i q_ref

[0051] Primary side DC voltage V dc1axk

[0052] DC voltage V on the primary side of each phase dc1uxk V dc1vxk V dc1wxk

[0053] System voltage active component command value V d_ref System voltage reactive component command value V q_ref

[0054] With the three-phase system voltage value V u V v V w Synchronous phase ωt.

[0055] Figure 2 The primary side DC voltage average value control unit 12 and the system current control unit 13 of (a) are configured as follows.

[0056] The first total value calculation unit 1 of the primary-side DC voltage average value control unit 12 calculates the total primary-side DC voltage of all units (3m = 3 phases × m units per phase) as the total primary-side DC voltage of all units. The total unit average value calculation unit 2 calculates the product of the total primary-side DC voltage of all units and the reciprocal of the total number of units (3m). The output of the total unit average value calculation unit 2 is the total primary-side DC voltage average value V of all units. dc1_ave .

[0057] The first subtractor 3 calculates the average value of the primary-side DC voltage command value V. dc1_ave_ref The average value of the primary side DC voltage across all cells, V dc1_aveThe deviation. The first amplifier (PI amplifier) ​​4 amplifies the output of the first subtractor 3 and outputs the command value i of the active component of the system current. d_ref .

[0058] PLL (Phase Locked Loop) 5 is input to the three-phase system voltage value V. u V v V w The output phase ωt is synchronized with the system.

[0059] The first dq converter 6 receives the input three-phase system voltage value V. u V v V w The phase ωt is used to perform a dq transformation and output as a value on a rotating coordinate system synchronized with the system (the active component of the system voltage V). d System voltage reactive component V q If PLL 5 is normal, then the reactive component V of the system voltage output from the first dq converter 6 will be... q It is zero in steady state.

[0060] The second dq converter 7 is input with the three-phase system current value i. u i v i w The phase ωt is used to perform a dq transformation and output as a value on a rotating coordinate system synchronized with the system (the active component of the system current i). d The reactive component of the system current i q ).

[0061] The second subtractor 8 of the system current control unit 13 calculates the output of the first amplifier 4, which is the command value i of the active component of the system current. d_ref The output of the second dq converter 7 is the active component of the system current i. d The deviation. The third subtractor 9 calculates the command value i of the reactive component of the system current. q_ref The output of the second dq converter 7 is the reactive component of the system current i. q The deviation. Here, the command value i of the reactive component of the system current is adjusted in conjunction with the power factor. q_ref .

[0062] The second and third amplifiers (PI amplifiers) 10 and 11 amplify the outputs of the second and third subtractors 8 and 9. The outputs of the second and third amplifiers 10 and 11 are the command value V of the active component of the system voltage on the rotating coordinate system. d_ref and the system voltage reactive component command value V q_ref .

[0063] Figure 2The primary side DC voltage phase balance control unit 14 and the gate generation (generation of switching element on / off command) of (b) are configured as follows.

[0064] The second total value calculation unit 15 of the primary-side DC voltage phase balance control unit 14 calculates the total value of the primary-side DC voltage within the phase and outputs it as the primary-side DC voltage phase total value. The phase average value calculation unit 16 calculates the product of the primary-side DC voltage phase total value and the reciprocal of the number of units m in the phase to calculate the primary-side DC voltage phase average value V for each phase. dc1a_ave .

[0065] Subtractor 4 (17) calculates the intra-phase average value V of the primary-side DC voltage for each phase. dc1a_ave DC voltage V on the primary side of each unit within the phase dc1uxk The deviation. The fourth amplifier (PI amplifier) ​​18 amplifies the output of the fourth subtractor 17. The first multiplier 19 multiplies the output of the fourth amplifier 18 by the system current value (i). u The symbol is ). The output of the first multiplier 19 is the phase balance control value of the primary side DC voltage of each unit. Each phase outputs m (i.e., the number of units) primary side DC voltage phase balance control values.

[0066] The dq inverter 20 is input with the command value V of the active component of the system voltage on the rotating coordinate system. d_ref System voltage reactive component command value V q_ref The phase ωt transforms the value on the rotating coordinate system, synchronized with the system, into the value on the fixed coordinate system. Multipliers 21u, 21v, and 21w obtain the output of the dq inverter 20 and the average value V of the primary-side DC voltage across all cells. dc1_ave The accumulation of.

[0067] The fifth subtractors 22u, 22v, and 22w obtain the difference between the outputs of multipliers 21u, 21v, and 21w and the primary-side DC voltage balance control value of each phase and unit. The outputs of the fifth subtractors 22u, 22v, and 22w are the three-phase voltage command values ​​V of the AC-DC converters (ACDC) in each phase and unit. u_ref1 ...V u_refm V v_ref1 ...V v_refm V w_ref1 ...V w_refm .

[0068] The PWM controllers 23u, 23v, and 23w are based on the three-phase voltage command value V of the AC-DC converter. u_ref1 ...V u_refm V v_ref1 ...V v_refm V w_ref1 ...V w_refmThe signal is then processed using PWM to convert it into a gating signal and input to the switching elements of each unit in the AC-DC converter.

[0069] Figure 3 A block diagram of the control unit of the isolated DC-DC converter (DCDC) of Embodiment 1 is shown. The control unit of the isolated DC-DC converter (DCDC) of Embodiment 1 includes a primary-side DC voltage individual balancing control unit 24 and a secondary-side DC voltage individual control unit 25.

[0070] Input the following signals into this control unit.

[0071] Secondary side DC voltage command value V dc21_ref V dc22_ref

[0072] Connected to DC bus V dc21 (or V) dc22 The primary side DC voltage V of the cell dc1a1k .

[0073] Figure 3 The control section of the insulated DC-DC converter is configured as follows.

[0074] The third total value calculation unit 26 of the primary side DC voltage individual balance control unit 24 calculates the voltage connected to each DC bus V. dc21 (or V) dc22 The total value of the primary-side DC voltage of the units is calculated. In this embodiment 1, since the total number of units is 3m and there are 2 DC buses, the total value is the primary-side DC voltage of 3m / 2 units. The third average value calculation unit 27 calculates the product of the output of the third total value calculation unit 26 and the reciprocal of the number of units connected to each DC bus (2 / 3m), and calculates the V connected to each DC bus. dc21 (or V) dc22 The average value of the primary side DC voltage of the unit, i.e., the average value of the primary side DC voltage of the DC bus, V. dc11_ave .

[0075] The band-stop filter (BEF) 28 filters out the signal connected to the DC bus V. dc21 (or DC bus V) dc22 The system frequency twice-multiplied component of the primary-side DC voltage of each unit. The fifth subtractor 29 obtains the average value V of the primary-side DC voltage of the DC bus. dc11_aveThe difference between the output of the band-stop filter 28 corresponding to each unit and the output of the fifth amplifier (P amplifier) ​​30. The fifth amplifier (P amplifier) ​​30 amplifies the output of the fifth subtractor 29. The second multiplier 31 calculates the product of the output of the fifth amplifier 30 and the turns ratio N1 / N2 of the transformer of the AC-DC converter and the transformer of the isolated DC-DC converter. Here, let N1 be the number of turns of the transformer of the AC-DC converter and N2 be the number of turns of the transformer of the isolated DC-DC converter. The output of the second multiplier 31 is the individual balance control value of the primary side DC voltage (the output of the second multiplier 31 is 3m / 2 when x=1 and x=2).

[0076] The sixth subtractor 32 of the secondary side DC voltage individual control unit 25 obtains the secondary side DC voltage command value V. dc21_ref With secondary side DC voltage V dc21 (or secondary side DC voltage command value V) dc22_ref With secondary side DC voltage V dc22 The difference is calculated by the sixth amplifier (PI amplifier) ​​33, which amplifies the output of the sixth subtractor 32. The third multiplier 34 calculates the product of the output of the sixth amplifier 33 and the reciprocal (2 / 3m) of the number of units connected to each DC bus. The output of the third multiplier 34 is the individual control value of the secondary side DC voltage.

[0077] The 7th subtractor 35 obtains the difference between the individual control value of the secondary side DC voltage and the individual balance control value of the primary side DC voltage (when x=1 and x=2, the output of the 7th subtractor 35 is 3m / 2 respectively).

[0078] The current control unit 36 ​​takes the output of the 7th subtractor 35 and the primary-side DC voltage (3m / 2 voltages for x=1 and x=2 respectively) as inputs. In a DAB (Dual Active Bridge) converter, the phase difference command value is the output; in an LLC converter, the frequency command value is the output.

[0079] The PWM controller 37 performs PWM processing based on the output of the current control unit 36, converts it into a gating signal, and inputs it to the switching element of the isolated DC-DC converter (DCDC) of each unit.

[0080] [Description of Function and Operation]

[0081] like Figure 1 As shown in the structure, in a configuration with multiple DC buses (V dc21 V dc22 In the structure, the secondary-side DC outputs are connected in series, and the load or power supply is connected to each DC bus (V). dc21 V dc22) and the output (V) obtained by connecting each DC terminal two in series. dc21 +V dc22 Therefore, V of each DC bus dc21 V dc22 This results in a power imbalance. Therefore, when there is a power imbalance on each DC bus, it is necessary to maintain the voltage of the DC bus, i.e., the secondary side DC voltage (V). dc21 V dc22 And the voltage of the primary-side DC capacitor C1 in each unit, i.e., the primary-side DC voltage V. dc1axk While balancing the voltage, the output voltage is also balanced.

[0082] In the control of the AC-DC converter, phase balance control of the primary side DC voltage and average value control of the primary side DC voltage are performed.

[0083] First of all, Figure 2 In the primary-side DC voltage average value control unit 12 of all cells shown in (a), the primary-side DC voltage average value V of all cells is controlled by the first amplifier 4. dc1_ave The command value V of the primary side DC voltage average value dc1_ave_ref The deviation is amplified, and the command value i of the active component of the system current on the rotating coordinate is output. d_ref Additionally, the command value i of the reactive component of the system current on the rotating coordinate is calculated based on the command value of the power factor. q_ref It can also perform power factor control of system current.

[0084] In the system current control unit 13, the active component command value I of the system current is used. d_ref and the command value i of the reactive component of the system current q_ref With the active component of the system current i d and the reactive component of the system current i q The deviation is determined by using the command value V of the active component of the system voltage on the rotating coordinate system, output by amplifiers 2 and 3 (10 and 11). d_ref and the system voltage reactive component command value V q_ref .

[0085] exist Figure 2 In (b), phase-to-phase DC voltage balance control is performed on the primary side. Balance control is achieved by adjusting the AC / DC voltage command values ​​of each unit.

[0086] First, using the 4th amplifier 18, the intra-phase average value V of the primary-side DC voltage is... dc1u_ave The primary side DC voltage V of each unit within the phase dc1uxkThe deviation is amplified. However, since the sign of the unit voltage command value for achieving voltage balance changes with the direction of the system current on the three-phase coordinates, the sign of the system current is obtained using the sign block and multiplied with the output of the fourth amplifier 18.

[0087] Next, the active component command value V of the system voltage on the rotating coordinate is obtained using the dq inverse converter 20. d_ref System voltage reactive component command value V q_ref The phase difference ωt synchronized with the system voltage is transformed into three-phase coordinates. The output of the dq inverter 20 and the average value V of the primary-side DC voltage across the entire cell are obtained. dc1_ave The product is used to calculate the three-phase voltage command value without considering the imbalance of the primary side DC voltage.

[0088] The voltage command value for each phase is calculated by obtaining the difference between the phase-to-phase balance control value of the primary-side DC voltage of each unit and the three-phase voltage command value without considering the imbalance of the primary-side DC voltage. Finally, the voltage command values ​​are processed by comparing them with the triangular wave carrier signal using PWM controllers 23u, 23v, and 23w to generate the gate signal for the AC-DC converter.

[0089] exist Figure 3 In the control of an insulated DC-DC converter, for each DC bus (V dc21 V dc22 Perform individual balancing control of the primary side DC voltage and individual control of the secondary side DC voltage.

[0090] In the primary-side DC voltage individual balancing control unit 24, the DC bus V is connected to... dc21 (x=1) or DC bus V dc22 The primary-side DC voltage of the (x=2) unit is balanced. However, a voltage ripple with twice the system frequency is generated in the primary-side DC voltage of each phase. This voltage ripple causes control instability when the gain of the P control is increased, so it is passed through a band-stop filter (BEF)28 that only filters out the twice-frequency component of the system frequency.

[0091] Since the output of the fifth amplifier 30 is the current of the primary side DC capacitor C1, the current of the secondary side DC capacitor C2 can be calculated by taking the product of the output of the fifth amplifier 30 and the transformer turns ratio N1 / N2.

[0092] Next, in the secondary side DC voltage individual control unit 25, the secondary side DC voltage command value V is... dc21_ref With secondary side DC voltage V dc21The deviation is input to the 6th amplifier 33. By obtaining the product of the output of the 6th amplifier 33 and the reciprocal of the number of units connected to the DC bus (3m / 2), the current i of the secondary side DC capacitor C2 of each unit is calculated. dc21 .

[0093] The difference between the output of the secondary-side DC voltage individual control unit 25 and the output of the primary-side DC voltage individual balancing control unit 24 is used as the command value for the secondary-side DC capacitor current. This command value for the secondary-side DC capacitor current is then compared with the value connected to the DC bus V. dc21 The primary-side DC voltage (x=1) is input to the current control unit 36. In the current control unit 36, a phase difference command value is output via a DAB converter, and a frequency command value is output via an LLC converter. Finally, the phase difference command value or the frequency command value is input to the PWM controller 37 to generate the gate signal for the isolated DC-DC converter (DCDC).

[0094] As an example of a current control unit and PWM controller for an LLC converter, Non-Patent Document 3 has been disclosed. In the current control of Non-Patent Document 3, a VCO (Voltage-Controlled Oscillator) is used to transform the output value of the PI controller into a desired frequency value, and this frequency value is input to a carrier generator, thereby generating a triangular wave carrier with the desired frequency. The PWM controller generates a gating signal by comparing the triangular wave carrier with a duty cycle command value.

[0095] As an example of a current control unit employing a DAB converter, non-patent document 4 has already disclosed this. Using a formula relating the current command value and the phase difference, a phase difference command value is calculated based on the current command value. Next, as an example of a PWM controller, as shown in patent document 2, a sawtooth wave carrier is compared with the phase difference command value to generate a gating signal that achieves the phase difference command value.

[0096] [Effect]

[0097] According to Embodiment 1, in the SST mode with multiple DC buses for high-voltage AC input and output, when there is a power imbalance between the DC buses due to the load or power supply conditions, the primary side DC voltage and the secondary side DC voltage of each unit can be balanced.

[0098] Furthermore, according to this embodiment 1, compared with Non-Patent Document 1 and Patent Document 1, no power frequency transformer is required and no additional balancing circuit is needed when power imbalance occurs on each DC bus, thus avoiding the need for large-scale production and increases in size and cost.

[0099] Furthermore, compared to Non-Patent Document 2, since the DC voltage of each unit can be reliably balanced and controlled, the withstand voltage of the device can be suppressed, and the increase in size and cost can be avoided.

[0100] According to this embodiment 1, since the change of the number of series connections in the DC bus can be handled simply by adding a control block in coordination with the number of series connections (x) of the DC bus, the software implementation is relatively simple.

[0101] [Implementation Method 2]

[0102] The main circuit and the control unit of the AC-DC converter (ACDC) in this embodiment 2 are the same as those in embodiment 1. Figure 4 This diagram shows the control unit of the isolated DC-DC converter (DCDC) of Embodiment 2. The control unit of the isolated DC-DC converter (DCDC) of Embodiment 2 includes a primary side DC voltage individual balancing control unit 38, a secondary side DC voltage balancing control unit 39, and a secondary side DC voltage total value control unit 40 (which may also be a current control unit).

[0103] In this control unit, compared with Embodiment 1, the following signals are added for input.

[0104] The total secondary DC voltage command value V dc2_ref

[0105] The total secondary DC voltage V dc21 +V dc22

[0106] Secondary side DC voltage V dc21 and V dc22 The average value of the secondary side DC voltage V dc2_ave .

[0107] Figure 4 The primary side DC voltage individual balance control unit 38 and embodiment 1 ( Figure 3 The primary-side DC voltage individual balancing control unit 24 is the same. Figure 4 In the control unit of the insulated DC-DC converter (DCDC), the following blocks have been added and modified compared to Embodiment 1.

[0108] The 8th subtractor 42 of the secondary-side DC voltage balance control unit 39 obtains the secondary-side DC voltage V. dc21 (or V) dc22 ) and the average value of the secondary side DC voltage V dc2_ave The difference. The 7th amplifier (P amplifier) ​​43 amplifies the output of the 8th subtractor 42. The output of the 7th amplifier 43 is the secondary side DC voltage balance control value.

[0109] The first adder 44 obtains the sum of the output of the seventh amplifier 43 (secondary side DC voltage balance control value) and the output of the primary side DC voltage individual balance control unit 38 (primary side DC voltage individual balance control value).

[0110] The 9th subtractor 45 of the secondary side DC voltage total value control unit 40 obtains the secondary side DC voltage total value command value V. dc2_ref The total value of V with the secondary side DC voltage dc21 +V dc22 The difference. The 8th amplifier (PI amplifier) ​​46 amplifies the output of the 9th subtractor 45. The 4th multiplier 47 multiplies the output of the 8th amplifier 46 by the reciprocal of the total number of units in the 3 phases, 1 / 3n. The output of the 4th multiplier 47 is the secondary side DC voltage total control value. The 7th subtractor 35 subtracts the value obtained by adding the secondary side DC voltage balance control value to the primary side DC voltage individual balance control value from the secondary side DC voltage total control value. The following steps are the same as in Embodiment 1.

[0111] [Description of Function and Operation]

[0112] In this embodiment 2, as Figure 4 As shown, a secondary-side DC voltage balance control unit 39 and a secondary-side DC voltage total value control unit 40 are added to Embodiment 1.

[0113] The secondary side DC voltage total value control unit 40 controls the secondary side DC voltage total value V. dc21 +V dc22 The output of the secondary-side DC voltage total value control unit 40 is input to the current control and gating generation block (both x=1 and x=2). However, since the secondary-side DC voltages cannot be balanced, secondary-side DC voltage balancing control is applied.

[0114] First, input the secondary side DC voltage V to the 7th amplifier 43. dc21 V dc22 The average value of the secondary side DC voltage V dc2_ave With each secondary side DC voltage V dc21 V dc22 The deviation is then calculated. Next, the sum of the output of the 7th amplifier 43 and the output of the primary-side DC voltage individual balancing control unit 38 is obtained and input to the current control unit 36 ​​corresponding to the x value. The current control unit 36 ​​thereafter is the same as in Embodiment 1.

[0115] [Effect]

[0116] According to this embodiment 2, the same effect as that of embodiment 1 is achieved.

[0117] In this second embodiment, regardless of the number of series units connected to the DC bus, there is always one secondary-side DC voltage controller. Therefore, since voltage control and current control can be switched during operation, it is also applicable to large-capacity battery charging and discharging devices that require constant voltage charging (voltage control) and constant current charging (current control).

[0118] Although only specific examples have been described in detail in this invention, it is obvious to those skilled in the art that various modifications and alterations can be made within the scope of the technical concept of this invention, and such modifications and alterations are of course within the scope of the claims. Claims (as amended under Article 19 of the Treaty) 1. An AC-DC power supply, each phase having m units, wherein each unit comprises: an AC-DC converter; a primary-side DC capacitor connected to the DC side of the AC-DC converter; an isolated DC-DC converter having one DC side connected to the primary-side DC capacitor; and a secondary-side DC capacitor connected to the other DC side of the isolated DC-DC converter, the AC-DC power supply having multiple DC buses formed by multiple secondary-side DC capacitors connected in series or parallel, supplying voltages of the multiple DC buses to a load or power source, wherein m is an integer greater than or equal to 2, the AC-DC power supply being characterized in that... When a power imbalance occurs due to the condition of the load or the power supply, the output voltage is maintained while keeping the voltage of the DC bus (secondary side DC voltage) and the voltage of the primary side DC capacitor of each unit (primary side DC voltage) balanced. The control unit of the AC-DC converter includes: The primary side DC voltage average value control unit generates the system current active component command value based on the primary side DC voltage average value command value and the primary side DC voltage full unit average value; The system current control unit generates system voltage active component command values ​​and system voltage reactive component command values ​​based on the system current active component command values ​​and system current reactive component command values; and The primary-side DC voltage phase balance control unit generates a primary-side DC voltage phase balance control value based on the average value of the primary-side DC voltage in each phase and the primary-side DC voltage in each unit. Specifically, the active and reactive component command values ​​of the system voltage are transformed into values ​​on a fixed coordinate system, multiplied by the average value of the primary-side DC voltage across all units, and the phase-to-phase balance control value of the primary-side DC voltage is subtracted from the multiplication result to generate the voltage command value for each phase. The gate signal for the AC-DC converter is then generated based on this voltage command value. The control unit of the insulated DC-DC converter includes: The primary-side DC voltage individual balancing control unit generates primary-side DC voltage individual balancing control values ​​based on the primary-side DC voltage; and The secondary-side DC voltage individual control unit generates individual control values ​​for the secondary-side DC voltage based on the secondary-side DC voltage. Specifically, the individual control value of the primary side DC voltage is subtracted from the individual control value of the secondary side DC voltage, and current control is performed based on the subtraction result and the primary side DC voltage. The gate signal of the insulated DC-DC converter is generated based on the result of the current control. 2. An AC-DC power supply, each phase having m units, wherein each unit comprises: an AC-DC converter; a primary-side DC capacitor connected to the DC side of the AC-DC converter; an isolated DC-DC converter having one DC side connected to the primary-side DC capacitor; and a secondary-side DC capacitor connected to the other DC side of the isolated DC-DC converter, the AC-DC power supply having multiple DC buses formed by multiple secondary-side DC capacitors connected in series or parallel, supplying voltages of the multiple DC buses to a load or power source, wherein m is an integer greater than or equal to 2, the AC-DC power supply being characterized in that... When a power imbalance occurs due to the condition of the load or the power supply, the output voltage is maintained while keeping the voltage of the DC bus (secondary side DC voltage) and the voltage of the primary side DC capacitor of each unit (primary side DC voltage) balanced. The control unit of the AC-DC converter includes: The primary side DC voltage average value control unit generates the system current active component command value based on the primary side DC voltage average value command value and the primary side DC voltage full unit average value; The system current control unit generates system voltage active component command values ​​and system voltage reactive component command values ​​based on the system current active component command values ​​and system current reactive component command values; and The primary-side DC voltage phase balance control unit generates a primary-side DC voltage phase balance control value based on the average value of the primary-side DC voltage in each phase and the primary-side DC voltage in each unit. Specifically, the active and reactive component command values ​​of the system voltage are transformed into values ​​on a fixed coordinate system, multiplied by the average value of the primary-side DC voltage across all units, and the phase-to-phase balance control value of the primary-side DC voltage is subtracted from the multiplication result to generate the voltage command value for each phase. The gate signal for the AC-DC converter is then generated based on this voltage command value. The control unit of the insulated DC-DC converter includes: The primary-side DC voltage individual balance control unit generates a primary-side DC voltage individual balance control value based on the primary-side DC voltage. The secondary-side DC voltage balance control unit generates secondary-side DC voltage balance control values ​​based on the secondary-side DC voltage; and The secondary-side DC voltage total value control unit generates a secondary-side DC voltage total value control value based on the secondary-side DC voltage total value command value and the secondary-side DC voltage total value. Specifically, the value obtained by subtracting the individual balance control value of the primary side DC voltage plus the balance control value of the secondary side DC voltage from the total control value of the secondary side DC voltage is used to perform current control based on the subtracted value and the primary side DC voltage, and the gating signal of the insulated DC-DC converter is generated based on the result of the current control. 3. The AC-DC power supply according to claim 1 or 2, characterized in that, The primary-side DC voltage average value control unit includes: The first total value calculation unit calculates the total value of the primary side DC voltage of all cells and outputs it as the total value of the primary side DC voltage of all cells. The unit calculates the average value of the primary side DC voltage based on the product of the total value of the primary side DC voltage across all cells and the reciprocal of the total number of cells. The first subtractor calculates the deviation between the commanded average value of the primary-side DC voltage and the average value of the primary-side DC voltage across all cells; and The first amplifier amplifies the output of the first subtractor and outputs it as the command value of the active component of the system current. 4. The AC-DC power supply according to claim 1 or 2, characterized in that, The system current control unit includes: The second subtractor subtracts the active component of the system current from the command value of the active component of the system current. The second amplifier amplifies the output of the second subtractor and outputs it as the command value of the active component of the system voltage. The third subtractor subtracts the system current reactive component from the commanded value of the system current reactive component; and The third amplifier amplifies the output of the third subtractor and outputs it as the command value of the reactive component of the system voltage. 5. The AC-DC power supply according to claim 1 or 2, characterized in that, The primary-side DC voltage phase balance control unit includes: The second total value calculation unit calculates the total value of the primary side DC voltage within the phase and outputs it as the total value of the primary side DC voltage within the phase. The phase average value calculation unit calculates the phase average value of the primary side DC voltage for each phase based on the product of the total phase value of the primary side DC voltage and the reciprocal of the number of units in the phase. The fourth subtractor calculates the deviation between the average value of the primary side DC voltage of each phase and the primary side DC voltage of each unit within the phase. The fourth amplifier amplifies the output of the fourth subtractor; and The first multiplier multiplies the output of the fourth amplifier by the sign of the system current value of each phase and outputs the primary-side DC voltage phase balance control value. 6. The AC-DC power supply according to claim 1 or 2, characterized in that, The primary-side DC voltage individual balancing control unit includes: The third total value calculation unit calculates the total value of the primary side DC voltage of the unit connected to each DC bus; The third average value calculation unit calculates the product of the output of the third total value calculation unit and the reciprocal of the number of units connected to each DC bus, and calculates the average DC voltage of the primary side of the DC bus of the unit connected to each DC bus. A band-stop filter filters out the system frequency twice-times component of the primary-side DC voltage of the unit connected to each DC bus; The fifth subtractor outputs the difference between the average value of the DC voltage on the primary side of the DC bus and the output of the band-stop filter; The fifth amplifier amplifies the output of the fifth subtractor; and The second multiplier multiplies the output of the fifth amplifier by the turns ratio of the transformer of the AC-DC converter to the transformer of the insulated DC-DC converter and outputs the individual balance control value of the primary side DC voltage. 7. The AC-DC power supply according to claim 1, characterized in that, The individual control unit for the secondary-side DC voltage includes: The sixth subtractor calculates the difference between the secondary-side DC voltage command value and the secondary-side DC voltage of each of the aforementioned DC buses; The sixth amplifier amplifies the output of the sixth subtractor; and The third multiplier calculates the product of the output of the sixth amplifier and the reciprocal of the number of units connected to the DC bus, and outputs the individual control value of the secondary side DC voltage. 8. The AC-DC power supply according to claim 2, characterized in that, The secondary-side DC voltage balance control unit includes: The 8th subtractor calculates the deviation between the average secondary-side DC voltage and the secondary-side DC voltage of each DC bus; and The 7th amplifier amplifies the output of the 8th subtractor and outputs it as the secondary-side DC voltage balance control value. 9. The AC-DC power supply according to claim 2, characterized in that, The secondary-side DC voltage total value control unit includes: The 9th subtractor calculates the difference between the commanded value of the total secondary-side DC voltage and the total value of the secondary-side DC voltage of all DC buses; The eighth amplifier amplifies the output of the ninth subtractor; and The fourth multiplier calculates the product of the output of the eighth amplifier and the reciprocal of the total number of units, and outputs it as the control value of the total DC voltage on the secondary side. 10. A control method for an AC-DC power supply, wherein each phase of the AC-DC power supply has m units, wherein each unit comprises: an AC-DC converter; a primary-side DC capacitor connected to the DC side of the AC-DC converter; an isolated DC-DC converter having one DC side connected to the primary-side DC capacitor; and a secondary-side DC capacitor connected to the other DC side of the isolated DC-DC converter, the AC-DC power supply having multiple DC buses formed by multiple secondary-side DC capacitors connected in series or parallel, supplying voltages of the multiple DC buses to a load or power source, wherein m is an integer greater than or equal to 2, the control method for the AC-DC power supply being characterized in that... When a power imbalance occurs due to the condition of the load or the power supply, the control unit outputs a voltage while maintaining the voltage balance between the DC bus voltage (secondary side DC voltage) and the voltage of the primary side DC capacitor in each unit (primary side DC voltage). In the control unit of the AC-DC converter. The primary-side DC voltage average value control unit generates the system current active component command value based on the primary-side DC voltage average value command value and the primary-side DC voltage average value across all cells. The system current control unit generates system voltage active component command values ​​and system voltage reactive component command values ​​based on the system current active component command values ​​and system current reactive component command values, and The primary-side DC voltage phase balance control unit generates a primary-side DC voltage phase balance control value based on the average value of the primary-side DC voltage in each phase and the primary-side DC voltage in each unit. Specifically, the active and reactive component command values ​​of the system voltage are transformed into values ​​on a fixed coordinate system, multiplied by the average value of the primary-side DC voltage across all units, and the phase-to-phase balance control value of the primary-side DC voltage is subtracted from the multiplication result to generate the voltage command value for each phase. The gate signal for the AC-DC converter is then generated based on this voltage command value. In the control unit of the insulated DC-DC converter: The primary-side DC voltage individual balancing control unit generates a primary-side DC voltage individual balancing control value based on the primary-side DC voltage, and The secondary-side DC voltage individual control unit generates individual control values ​​for the secondary-side DC voltage based on the secondary-side DC voltage. Specifically, the individual control value of the primary side DC voltage is subtracted from the individual control value of the secondary side DC voltage, and current control is performed based on the subtraction result and the primary side DC voltage. The gate signal of the insulated DC-DC converter is generated based on the result of the current control. 11. A control method for an AC-DC power supply, wherein each phase of the AC-DC power supply has m units, wherein each unit comprises: an AC-DC converter; a primary-side DC capacitor connected to the DC side of the AC-DC converter; an isolated DC-DC converter having one DC side connected to the primary-side DC capacitor; and a secondary-side DC capacitor connected to the other DC side of the isolated DC-DC converter, the AC-DC power supply having multiple DC buses formed by multiple secondary-side DC capacitors connected in series or parallel, supplying voltages of the multiple DC buses to a load or power source, wherein m is an integer greater than or equal to 2, the control method for the AC-DC power supply being characterized in that... When a power imbalance occurs due to the condition of the load or the power supply, the control unit outputs a voltage while maintaining the voltage balance between the DC bus voltage (secondary side DC voltage) and the voltage of the primary side DC capacitor in each unit (primary side DC voltage). In the control unit of the AC-DC converter: The primary-side DC voltage average value control unit generates the system current active component command value based on the primary-side DC voltage average value command value and the primary-side DC voltage average value across all cells. The system current control unit generates system voltage active component command values ​​and system voltage reactive component command values ​​based on the system current active component command values ​​and system current reactive component command values, and The primary-side DC voltage phase balance control unit generates a primary-side DC voltage phase balance control value based on the average value of the primary-side DC voltage in each phase and the primary-side DC voltage in each unit. Specifically, the active and reactive component command values ​​of the system voltage are transformed into values ​​on a fixed coordinate system, multiplied by the average value of the primary-side DC voltage across all units, and the phase-to-phase balance control value of the primary-side DC voltage is subtracted from the multiplication result to generate the voltage command value for each phase. The gate signal for the AC-DC converter is then generated based on this voltage command value. In the control unit of the insulated DC-DC converter: The primary-side DC voltage individual balance control unit generates a primary-side DC voltage individual balance control value based on the primary-side DC voltage. The secondary-side DC voltage balance control unit generates secondary-side DC voltage balance control values ​​based on the secondary-side DC voltage, and The secondary side DC voltage total value control unit generates a secondary side DC voltage total value control value based on the secondary side DC voltage total value command value and the secondary side DC voltage total value. Specifically, the value obtained by subtracting the individual balance control value of the primary side DC voltage plus the balance control value of the secondary side DC voltage from the total control value of the secondary side DC voltage is used to perform current control based on the subtracted value and the primary side DC voltage, and the gating signal of the insulated DC-DC converter is generated based on the result of the current control.

Claims

1. An AC-DC power supply, each phase having m units, wherein each unit comprises: an AC-DC converter; a primary-side DC capacitor connected to the DC side of the AC-DC converter; an isolated DC-DC converter having one DC side connected to the primary-side DC capacitor; and a secondary-side DC capacitor connected to the other DC side of the isolated DC-DC converter, the AC-DC power supply having multiple DC buses formed by multiple secondary-side DC capacitors connected in series or parallel, supplying voltages of the multiple DC buses to a load or power source, wherein m is an integer greater than or equal to 2, the AC-DC power supply being characterized in that... When a power imbalance occurs due to the condition of the load or the power supply, the output voltage is maintained while keeping the voltage of the DC bus (i.e., the secondary side DC voltage) and the voltage of the primary side DC capacitor of each unit (i.e., the primary side DC voltage) balanced.

2. The AC-DC power supply according to claim 1, characterized in that, The control unit of the AC-DC converter includes: The primary side DC voltage average value control unit generates the system current active component command value based on the primary side DC voltage average value command value and the primary side DC voltage full unit average value; The system current control unit generates system voltage active component command value and system voltage reactive component command value based on the system current active component command value and system current reactive component command value. as well as The primary-side DC voltage phase balance control unit generates a primary-side DC voltage phase balance control value based on the average value of the primary-side DC voltage in each phase and the primary-side DC voltage in each unit. Specifically, the active and reactive component command values ​​of the system voltage are transformed into values ​​on a fixed coordinate system, multiplied by the average value of the primary-side DC voltage across all units, and the phase-to-phase balance control value of the primary-side DC voltage is subtracted from the multiplication result to generate the voltage command value for each phase. The gate signal for the AC-DC converter is then generated based on this voltage command value. The control unit of the insulated DC-DC converter includes: The primary-side DC voltage individual balancing control unit generates primary-side DC voltage individual balancing control values ​​based on the primary-side DC voltage; and The secondary-side DC voltage individual control unit generates individual control values ​​for the secondary-side DC voltage based on the secondary-side DC voltage. Specifically, the individual control value of the primary side DC voltage is subtracted from the individual control value of the secondary side DC voltage, and current control is performed based on the subtraction result and the primary side DC voltage. The gate signal of the insulated DC-DC converter is generated based on the result of the current control.

3. The AC-DC power supply according to claim 1, characterized in that, The control unit of the AC-DC converter includes: The primary side DC voltage average value control unit generates the system current active component command value based on the primary side DC voltage average value command value and the primary side DC voltage full unit average value; The system current control unit generates system voltage active component command value and system voltage reactive component command value based on the system current active component command value and system current reactive component command value. as well as The primary-side DC voltage phase balance control unit generates a primary-side DC voltage phase balance control value based on the average value of the primary-side DC voltage in each phase and the primary-side DC voltage in each unit. Specifically, the active and reactive component command values ​​of the system voltage are transformed into values ​​on a fixed coordinate system, multiplied by the average value of the primary-side DC voltage across all units, and the phase-to-phase balance control value of the primary-side DC voltage is subtracted from the multiplication result to generate the voltage command value for each phase. The gate signal for the AC-DC converter is then generated based on this voltage command value. The control unit of the insulated DC-DC converter includes: The primary-side DC voltage individual balance control unit generates a primary-side DC voltage individual balance control value based on the primary-side DC voltage. The secondary-side DC voltage balance control unit generates secondary-side DC voltage balance control values ​​based on the secondary-side DC voltage; and The secondary-side DC voltage total value control unit generates a secondary-side DC voltage total value control value based on the secondary-side DC voltage total value command value and the secondary-side DC voltage total value. Specifically, the value obtained by subtracting the individual balance control value of the primary side DC voltage plus the balance control value of the secondary side DC voltage from the total control value of the secondary side DC voltage is used to perform current control based on the subtracted value and the primary side DC voltage, and the gating signal of the insulated DC-DC converter is generated based on the result of the current control.

4. The AC-DC power supply according to claim 2 or 3, characterized in that, The primary-side DC voltage average value control unit includes: The first total value calculation unit calculates the total value of the primary side DC voltage of all cells and outputs it as the total value of the primary side DC voltage of all cells. The unit calculates the average value of the primary side DC voltage based on the product of the total value of the primary side DC voltage across all cells and the reciprocal of the total number of cells. The first subtractor calculates the deviation between the commanded average value of the primary side DC voltage and the average value of the primary side DC voltage across all cells; as well as The first amplifier amplifies the output of the first subtractor and outputs it as the command value of the active component of the system current.

5. The AC-DC power supply according to claim 2 or 3, characterized in that, The system current control unit includes: The second subtractor subtracts the active component of the system current from the command value of the active component of the system current. The second amplifier amplifies the output of the second subtractor and outputs it as the command value of the active component of the system voltage. The third subtractor subtracts the system current reactive component from the system current reactive component command value; as well as The third amplifier amplifies the output of the third subtractor and outputs it as the command value of the reactive component of the system voltage.

6. The AC-DC power supply according to claim 2 or 3, characterized in that, The primary-side DC voltage phase balance control unit includes: The second total value calculation unit calculates the total value of the primary side DC voltage within the phase and outputs it as the total value of the primary side DC voltage within the phase. The phase average value calculation unit calculates the phase average value of the primary side DC voltage for each phase based on the product of the total phase value of the primary side DC voltage and the reciprocal of the number of units in the phase. The fourth subtractor calculates the deviation between the average value of the primary side DC voltage of each phase and the primary side DC voltage of each unit within the phase. The fourth amplifier amplifies the output of the fourth subtractor; as well as The first multiplier multiplies the output of the fourth amplifier by the sign of the system current value of each phase and outputs the primary-side DC voltage phase balance control value.

7. The AC-DC power supply according to claim 2 or 3, characterized in that, The primary-side DC voltage individual balancing control unit includes: The third total value calculation unit calculates the total value of the primary side DC voltage of the unit connected to each DC bus; The third average value calculation unit calculates the product of the output of the third total value calculation unit and the reciprocal of the number of units connected to each DC bus, and calculates the average DC voltage of the primary side of the DC bus of the unit connected to each DC bus. A band-stop filter filters out the system frequency twice-times component of the primary-side DC voltage of the unit connected to each DC bus; The fifth subtractor outputs the difference between the average value of the DC voltage on the primary side of the DC bus and the output of the band-stop filter; The fifth amplifier amplifies the output of the fifth subtractor; as well as The second multiplier multiplies the output of the fifth amplifier by the turns ratio of the transformer of the AC-DC converter to the transformer of the insulated DC-DC converter and outputs the individual balance control value of the primary side DC voltage.

8. The AC-DC power supply according to claim 2, characterized in that, The individual control unit for the secondary-side DC voltage includes: The sixth subtractor calculates the difference between the secondary-side DC voltage command value and the secondary-side DC voltage of each of the aforementioned DC buses; The sixth amplifier amplifies the output of the sixth subtractor; as well as The third multiplier calculates the product of the output of the sixth amplifier and the reciprocal of the number of units connected to the DC bus, and outputs the individual control value of the secondary side DC voltage.

9. The AC-DC power supply according to claim 3, characterized in that, The secondary-side DC voltage balance control unit includes: The 8th subtractor calculates the deviation between the average secondary-side DC voltage and the secondary-side DC voltage of each DC bus; and The 7th amplifier amplifies the output of the 8th subtractor and outputs it as the secondary-side DC voltage balance control value.

10. The AC-DC power supply according to claim 3, characterized in that, The secondary-side DC voltage total value control unit includes: The 9th subtractor calculates the difference between the commanded value of the total secondary-side DC voltage and the total value of the secondary-side DC voltage of all DC buses; The 8th amplifier amplifies the output of the 9th subtractor; as well as The fourth multiplier calculates the product of the output of the eighth amplifier and the reciprocal of the total number of units, and outputs it as the control value of the total DC voltage on the secondary side.

11. A control method for an AC-DC power supply, wherein each phase of the AC-DC power supply has m units, wherein each unit comprises: an AC-DC converter; a primary-side DC capacitor connected to the DC side of the AC-DC converter; an isolated DC-DC converter having one DC side connected to the primary-side DC capacitor; and a secondary-side DC capacitor connected to the other DC side of the isolated DC-DC converter, the AC-DC power supply having multiple DC buses formed by multiple secondary-side DC capacitors connected in series or parallel, supplying voltages of the multiple DC buses to a load or power source, wherein m is an integer greater than or equal to 2, the control method for the AC-DC power supply being characterized in that... When a power imbalance occurs due to the condition of the load or the power supply, the control unit outputs a voltage while maintaining the voltage balance between the DC bus voltage (secondary side DC voltage) and the voltage of the primary side DC capacitor of each unit (primary side DC voltage).

Images