Transformer modules and solid state transformers

Abstract

A transformer module includes an AC-DC converter, a DC-DC converter and a controller. The AC-DC converter receives an AC voltage and includes a first bridge arm, a second arm and a DC link. The first bridge arm has a plurality of first switches. The DC link is configured to generate a DC link voltage. The DC-DC converter is configured to receive the DC link voltage and includes a plurality of second switches. This controller is configured to: detecting a first detection signal of the AC-DC converter and a second detection signal of the DC-DC converter; in response to the first detection signal being in an abnormal state, reducing the DC link voltage through the second switches; and in response to the second detection signal being in the abnormal state, reducing the DC link voltage through the first switches.

Description

Transformer modules and solid-state transformers This invention relates to a transformer module and a solid-state transformer, and more particularly to a transformer module and a solid-state transformer for DC link voltage levels. When the transformer module inside a solid-state transformer enters bypass mode, ideally the DC link voltage of the transformer module will decrease over time. However, in the prior art, the DC link voltage actually increases over time because the stray capacitors inside the transformer module discharge in bypass mode, causing the DC link voltage to rise, which in turn damages other internal components of the transformer module. How to reduce the DC link voltage by offsetting the discharge voltage of stray capacitors in the transformer module in bypass mode is an important issue that needs to be addressed by those skilled in the art. This disclosure provides a transformer module. The transformer module includes: an AC-DC converter, a DC-DC converter, and a controller. The AC-DC converter receives an AC voltage and includes a bypass switch circuit, a first bridge arm, a second bridge arm, and a DC link. The first bridge arm is coupled to the bypass switch circuit and has a plurality of first switches. The second bridge arm is coupled to the first bridge arm. The DC link is coupled to the first and second bridge arms to generate a DC link voltage. The DC-DC converter is coupled to the DC link to receive the DC link voltage and includes a plurality of second switches. The plurality of second switches are coupled to the DC link. The controller is coupled to the AC-DC converter and the DC-DC converter and is used to: detect a first detection signal from the AC-DC converter and a second detection signal from the DC-DC converter; reduce the DC link voltage via the second switches in response to an abnormal state of the first detection signal; and reduce the DC link voltage via the first switches in response to an abnormal state of the second detection signal. This disclosure also provides a solid-state transformer. This solid-state transformer receives an AC voltage and includes multiple transformer modules. Each of these transformer modules includes an AC-DC converter, a DC-DC converter, and a controller. The AC-DC converter receives the AC voltage and includes a bypass switch circuit, a first arm, a second arm, and a DC link. The first arm is coupled to the bypass switch circuit and has multiple first switches. The second arm is coupled to the first arm, and the DC link is coupled to the first arm and the second arm to generate a DC link voltage. The DC-DC converter is coupled to the DC link to receive the DC link voltage and includes multiple second switches. The multiple second switches are coupled to the DC link. The controller is coupled to the AC-DC converter and the DC-DC converter and is used to: detect a first detection signal from the AC-DC converter and a second detection signal from the DC-DC converter; reduce the DC link voltage via the second switches in response to an abnormal state of the first detection signal; and reduce the DC link voltage via the first switches in response to an abnormal state of the second detection signal. The inputs of the multiple transformer modules are connected in series, and the outputs are connected in parallel. In summary, the transformer module and solid-state transformer of the present invention can utilize their own first and second switches to reduce the DC link voltage when the transformer module enters the bypass mode. The embodiments of this disclosure will be described below with reference to the relevant drawings. In the drawings, the same reference numerals denote the same or similar elements or method flows. Please refer to Figure 1, which is a schematic diagram of a transformer module 100 according to an embodiment of this disclosure. In the embodiment of Figure 1, the transformer module 100 includes an AC-DC converter 110, a DC-DC converter 120, and a controller 130. The AC-DC converter 110 can be a bridge AC-DC converter circuit or any conventional AC-DC converter circuit, used to receive AC voltage and convert it into DC voltage. In this embodiment, the AC-DC converter 110 receives AC voltage VAC1 through its input terminal. The AC-DC converter 110 includes a bypass switch circuit BS1, bridge arms BA1 and BA2, and a DC link DCL1. The bypass switch circuit BS1 can be used to control whether the AC voltage VAC1 flows into the AC-DC converter 110 from its input terminal. The input terminal of the bypass switch circuit BS1 can receive the AC voltage VAC1, one output terminal of the bypass switch circuit BS1 is coupled to bridge arm BA1, and the other output terminal of the bypass switch circuit BS1 is coupled to bridge arm BA2. Bridge arms BA1 and BA2 can convert the AC voltage VAC1 from the bypass switch circuit BS1 into a DC voltage and apply this DC voltage to the DC link DCL1 to generate a DC link voltage VDCL1. Bridge arm BA1 can be coupled to bypass switch circuit BS1 to receive AC voltage VAC1. Bridge arm BA1 includes switches SW1_1, SW1_2, SW1_3, and SW1_4. Switches SW1_1, SW1_2, SW1_3, and SW1_4 are connected in series. Switches SW1_1, SW1_2, SW1_3, and SW1_4 can be transistor switching elements. DC link DCL1 is coupled to bridge arms BA1 and BA2 to generate DC link voltage VDCL1. More precisely, DC link DCL1 can be connected in parallel with bridge arms BA1 and BA2. The first end of DC link DCL1 can be coupled to one end of switch SW1_1, and the second end of DC link DCL1 can be coupled to one end of switch SW1_4, so that switches SW1_1, SW1_2, SW1_3, and SW1_4 receive DC link voltage VDCL1 when they are connected in series. The DC-DC converter 120 can be a DC transformer, a DC voltage regulator circuit, or any conventional DC-DC conversion circuit, used to adjust and output the DC voltage at its input terminal. In this embodiment, the DC-DC converter 120 is coupled to the DC link DCL1, receives the DC link voltage VDCL1 through the input terminal, and outputs the DC voltage VDC1 according to the DC link voltage VDCL1. The DC-DC converter 120 includes switches SW2_1, SW2_2, SW2_3, and SW2_4. Switches SW2_1, SW2_2, SW2_3, and SW2_4 are connected in series. One end of switch SW1_1 and one end of switch SW1_4 are respectively coupled to the two terminals of the DC link DCL1, so that switches SW2_1, SW2_2, SW2_3, and SW2_4 receive the DC link voltage VDCL1 when they are connected in series. Furthermore, switches SW2_1, SW2_2, SW2_3, and SW2_4 can be transistors or any known components used for turning on or off circuits; this invention does not limit this. The controller 130 is coupled to the AC-DC converter 110 and the DC-DC converter 120. The controller 130 can receive and detect the detection signal DS1 of the AC-DC converter 110 and the detection signal DS2 of the DC-DC converter 120. In this embodiment, the detection signal DS1 is used to indicate whether the AC-DC converter 110 is operating normally. When the detection signal DS1 is in a normal state, it means that the AC-DC converter 110 is operating normally; when the detection signal DS1 is in an abnormal state, it means that the AC-DC converter 110 may be malfunctioning. The detection signal DS1 can be any signal within the AC-DC converter 110 (for example, at least one of the input current within the AC-DC converter 110, the voltage of an internal component not shown in Figure 1, or the DC link voltage VDCL1; this invention is not limited thereto). When the detection signal DS1 is in an abnormal state, the AC-DC converter 110 malfunctions. The controller 130 can then activate the bypass switch circuit BS1, putting the transformer module 100 into bypass mode. In bypass mode, the input terminals of the AC-DC converter 110 are short-circuited, attempting to block the flow of AC voltage VAC1 into the AC-DC converter 110. During this period, the controller 130 can detect the increase in DC link voltage VDCL1 due to the discharge of stray capacitors within the AC-DC converter 110. When the DC link voltage VDCL1 rises to a preset maximum value (for example, the DC link voltage VDCL1 rises by 5 percent from the time the detection signal DS1 enters an abnormal state; the present invention does not limit the specific voltage value), the controller 130 can control the switches SW2_1, SW2_2, SW2_3, and SW2_4 of the DC-DC converter 120 through the control signal CS2, and use the switches SW2_1, SW2_2, SW2_3, and SW2_4 to reduce the DC link voltage VDCL1 (for example, the DC link voltage VDCL1 can be reduced to 50 percent, 10 percent, or zero volts of its voltage value when it enters an abnormal state; the present invention does not limit the specific voltage value). In this embodiment, the detection signal DS2 is used to indicate whether the DC-DC converter 120 is operating normally. When the detection signal DS2 is in a normal state, it means that the DC-DC converter 120 is operating normally; when the detection signal DS2 is in an abnormal state, it means that the DC-DC converter 120 may be malfunctioning. The detection signal DS2 can be any signal within the DC-DC converter 120 (for example, at least one of the input current, DC voltage VDC1, or output current of the DC-DC converter 120; this invention is not limited thereto). When the detection signal DS2 is in an abnormal state, the DC-DC converter 120 malfunctions, and the controller 130 can also put the transformer module 100 into bypass mode. During this period, the controller 130 can detect the voltage value of the DC link voltage VDCL1. When the voltage value of the DC link voltage VDCL1 rises to the preset maximum value, the controller 130 controls the switches SW1_1, SW1_2, SW1_3, and SW1_4 in the AC-DC converter 110 through the control signal CS1, and uses the switches SW1_1, SW1_2, SW1_3, and SW1_4 to reduce the DC link voltage VDCL1 (for example, the DC link voltage VDCL1 can be reduced to fifty percent, ten percent, or zero volts of its voltage value when it enters the abnormal state; the present invention does not limit the specific voltage value). In this embodiment, the controller 130 can repeatedly switch switches SW1_1, SW1_2, SW1_3, and SW1_4 through the control signal CS1, or repeatedly switch switches SW2_1, SW2_2, SW2_3, and SW2_4 through the control signal CS2. By utilizing the hard switching characteristics of these switches, the DC link voltage VDCL1 is consumed, thereby causing the DC link voltage VDCL1 to decrease. In addition to the above, in some embodiments, if both detection signal DS1 and detection signal DS2 are in an abnormal state, the controller 130 may activate the overvoltage protection function of the transformer module 100 when the DC link voltage VDCL1 rises to the preset maximum value, thereby shutting down the transformer module 100. In summary, the transformer module 100 can use switches SW1_1, SW1_2, SW1_3, SW1_4 and switches SW2_1, SW2_2, SW2_3, SW2_4 to reduce the DC link voltage VDCL1 after the transformer module 100 enters the bypass mode. Please refer to Figure 2, which is a schematic diagram of a transformer module 200 according to an embodiment of this disclosure. In Figure 2, the transformer module 200 includes an AC-DC converter 210, a DC-DC converter 220, and a controller 230. The transformer module 200 in Figure 2 corresponds to the transformer module 100 in Figure 1. Specifically, the transformer module 200 can be used to illustrate the component configuration details of the transformer module 100, and the AC-DC converter 210, DC-DC converter 220, and controller 230 in Figure 2 can respectively correspond to the AC-DC converter 110, DC-DC converter 120, and controller 130 in Figure 1. In one embodiment of Figure 2, the AC-DC converter 210 includes a bypass switch circuit BS1, bridge arms BA1 and BA2, and a DC link DCL1. Furthermore, the AC-DC converter 210 includes resistors R1, R2, R3, and R4, and capacitors C1, C2, C3, and C4. Resistors R1, R2, R3, and R4 are connected in series. The first terminal of resistor R1 is coupled to the first terminal of DC link DCL1, the second terminal of resistor R1 is coupled to the first terminal of resistor R2, the second terminal of resistor R2 is coupled to the first terminal of resistor R3, the second terminal of resistor R3 is coupled to the first terminal of resistor R4, and the second terminal of resistor R4 is coupled to the second terminal of DC link DCL1. Resistor R1 is connected in parallel with capacitor C1, resistor R2 with capacitor C2, resistor R3 with capacitor C3, and resistor R4 with capacitor C4. The bypass switch circuit BS1 includes switches SBS1 and SBS2, and a copper sheet switch RLY. The two terminals of the AC-DC converter 210 input are coupled to the first terminal of switch SBS1 and the second terminal of switch SBS2, respectively. The second terminal of switch SBS1 is coupled to the first terminal of switch SBS2. The two terminals of the copper sheet switch RLY are coupled to the first terminal of switch SBS1 and the second terminal of switch SBS2, respectively. Bridge arm BA1 includes switches SW1_1, SW1_2, SW1_3, and SW1_4, as well as diodes DP1 and DN1. The first terminal of switch SW1_1 is coupled to bridge arm BA2 and the first terminal of resistor R1. The second terminal of switch SW1_1 is coupled to the first terminal of switch SW1_2 and the cathode of diode DP1. The second terminal of switch SW1_2 is coupled to the first terminal of bypass switch circuit BS1, the first terminal of copper sheet switch RLY, and the first terminal of switch SW1_3. The second terminal of switch SW1_3 is coupled to the first terminal of switch SW1_4 and the anode of diode DN1. The second terminal of switch SW1_4 is coupled to bridge arm BA2 and the second terminal of resistor R4. The anode of diode DP1 is coupled to the cathode of diode DN1, the anode of diode DP2, the cathode of diode DN2, resistors R2 and R3, and capacitors C2 and C3. Bridge arm BA2 includes switches SW3_1, SW3_2, SW3_3, and SW3_4, as well as diodes DP2 and DN2. The first terminal of switch SW3_1 is coupled to bridge arm BA1 and the first terminal of resistor R1. The second terminal of switch SW3_1 is coupled to the first terminal of switch SW3_2 and the cathode of diode DP2. The second terminal of switch SW3_2 is coupled to the second terminal of switch SBS2 in bypass switch circuit BS1, the second terminal of copper sheet switch RLY, and the first terminal of switch SW3_3. The second terminal of switch SW3_3 is coupled to the first terminal of switch SW3_4 and the anode of diode DN2. The second terminal of switch SW3_4 is coupled to bridge arm BA1 and the second terminal of resistor R4. DC link DCL1 includes capacitors CA and CB. The first terminal of capacitor CA is coupled to the first terminal of switch SW1_1 of bridge arm BA1 and the first terminal of switch SW3_1 of bridge arm BA2. The second terminal of capacitor CA is coupled to the first terminal of capacitor CB. The second terminal of capacitor CB is coupled to the second terminal of switch SW1_4 of bridge arm BA1 and the second terminal of switch SW3_4 of bridge arm BA2. When the transformer module 200 is operating normally, the bypass switch circuit BS1 is not conducting. Current IGI can flow from the input terminal of the AC-DC converter 110 through the first terminal of switch SBS1 and the first terminal of the copper sheet switch RLY, and then to the second terminal of switch SW1_2, subsequently flowing into bridge arm BA1. Voltage VC1 is generated across capacitor C1, voltage VC2 across capacitor C2, voltage VC3 across capacitor C3, and voltage VC4 across capacitor C4. DC link voltage VDCL1_P is generated across capacitor CA, and DC link voltage VDCL1_N is generated across capacitor CB. The DC link voltages VDCL1_P and VDCL1_N in Figure 2 can be used individually or in combination as the DC link voltage VDCL1 in Figure 1. In this embodiment, the DC-DC converter 220 includes switches SW2_1, SW2_2, SW2_3, SW2_4, S1, S2, S3, S4, capacitors CRP1, CRP2, CDC1, and transformer circuit TRF1. Transformer circuit TRF1 includes inductors LRP1 and LM1. The DC-DC converter 220 further includes switches SW4_1, SW4_2, SW4_3, SW4_4, S5, S6, S7, S8, capacitors CRP3, CRP4, CDC2, and transformer circuit TRF2. Transformer circuit TRF2 includes inductors LRP2 and LM2. The first terminal of switch SW2_1 is coupled to the first terminal of capacitor CA in DC link DCL1. The second terminal of switch SW2_1 is coupled to the first terminal of switch SW2_2 and the first terminal of capacitor CRP1. The second terminal of switch SW2_2 is coupled to the first terminal of switch SW2_3, the second terminal of capacitor CA, and the first terminal of capacitor CB. The second terminal of switch SW2_3 is coupled to the first terminal of switch SW2_4 and the first terminal of capacitor CRP2. The second terminal of switch SW2_4 is coupled to the second terminal of capacitor CB. Capacitors CRP1 and CRP2 are coupled to transformer circuit TRF1. The second terminal of capacitor CRP1 is coupled to inductor LRP1. The second terminal of capacitor CRP2 is coupled to inductor LM1 and transfers current ICRP1 to inductor LM1. The first terminal of switch SW4_1 is coupled to the first terminal of capacitor CA in DC link DCL1. The second terminal of switch SW4_1 is coupled to the first terminal of switch SW4_2 and the first terminal of capacitor CRP3. The second terminal of switch SW4_2 is coupled to the first terminal of switch SW4_3, the second terminal of capacitor CA, and the first terminal of capacitor CB. The second terminal of switch SW4_3 is coupled to the first terminal of switch SW4_4 and the first terminal of capacitor CRP4. The second terminal of switch SW4_4 is coupled to the second terminal of capacitor CB. Capacitors CRP3 and CRP4 are coupled to transformer circuit TRF2. The second terminal of capacitor CRP3 is coupled to inductor LRP2. The second terminal of capacitor CRP4 is coupled to inductor LM2 and transfers current ICRP2 to inductor LM2. In this embodiment, switches SBS1, SBS2, SW1_1, SW1_2, SW1_3, SW1_4, SW2_1, SW2_2, SW2_3, SW2_4, SW3_1, SW3_2, SW3_3, SW3_4, SW4_1, SW4_2, SW4_3, SW4_4, S1, S2, S3, S4, S5, S6, S7, and S8 can be conventional transistor switching elements. When the transformer module 200 is operating normally, the DC-DC converter 220 can receive DC link voltages VDCL1_P and VDCL1_N from the DC link DCL1. In the DC-DC converter 220, the two ends of capacitor CDC1 generate a DC voltage VDC1_1 and a DC output current IDC1. The two ends of capacitor CDC2 generate a DC voltage VDC1_2 and a DC output current IDC2. Both DC voltages VDC1_1 and VDC1_2 in Figure 2 can be used as DC voltage VDC1 in Figure 1. The controller 230 includes an AC-DC protection module 232 and a DC-DC protection module 234. The AC / DC protection module 232 detects multiple detection signals of the AC-DC converter 210 (corresponding to detection signal DS1 in Figure 1) and determines whether the AC-DC converter 210 is operating normally. The multiple detection signals include current IGI, voltage VC1, voltage VC2, voltage VC3, voltage VC4, DC link voltage VDCL1_P, and DC link voltage VDCL1_N. The DC / DC protection module 234 detects multiple detection signals of the DC-DC converter 220 (corresponding to detection signal DS2 in Figure 1) and determines whether the DC-DC converter 220 is operating normally. The multiple detection signals include current ICRP1, current ICRP2, DC output current IDC1, DC output current IDC2, DC voltage VDC1_1, and DC voltage VDC1_2. The controller 230 has a built-in voltage and current meter. When any of the aforementioned voltage and current values ​​does not fall within a preset range (for example, exceeding or falling below a certain preset level by a certain degree), it can be determined that the AC-DC converter 210 or the DC-DC converter 220 may have failed. When at least one of the AC-DC converter 210 or the DC-DC converter 220 fails, the controller 230 can control the bypass switch circuit BS1, multiple switches in the AC-DC converter 210 and the DC-DC converter 220 through control signals CS1_BS, CS1_1, CS1_2, CS1_3, CS1_4, CS2_1, CS2_2, CS2_3, and CS2_4. When the AC / DC protection module 232 determines that the AC-DC converter 210 has failed or the DC / DC protection module 234 determines that the DC-DC converter 220 has failed, the transformer module 200 enters bypass mode, and the controller 230 can adjust the control signal CS1_BS. In this embodiment, the control terminals of switches SBS1, SBS2, and the copper sheet switch RLY all receive the control signal CS1_BS. The control signal CS1_BS can turn on the bypass switch circuit BS1 when the AC-DC converter 210 or the DC-DC converter 220 fails, thus short-circuiting the input terminal of the AC-DC converter 210. When the AC / DC protection module 232 determines that the AC-DC converter 210 has failed while the DC-DC converter 220 can operate normally, the transformer module 200 enters bypass mode. Control signals CS1_1, CS1_2, CS1_3, and CS1_4 can be set to constant voltage to disconnect the switches in the AC-DC converter 210. Control signals CS2_1, CS2_2, CS2_3, and CS2_4 can be set to pulse width modulation signals. Furthermore, control signal CS2_1 can be transmitted to the control terminal of switch SW2_1, control signal CS2_2 can be transmitted to the control terminal of switch SW2_2, control signal CS2_3 can be transmitted to the control terminal of switch SW2_3, and control signal CS2_4 can be transmitted to the control terminal of switch SW2_4, so that switches SW2_1, SW2_2, SW2_3, and SW2_4 are turned on in a time-division manner, as shown in Figure 3. Please refer to Figures 2 and 3 simultaneously. Figure 3 shows the waveforms of pulse width modulation signals PWM1 to PWM4 according to an embodiment of this disclosure. The period of each of the pulse width modulation signals PWM1 to PWM4 is the time length T_total, the working time of the pulse is the time length T1, and the working period is less than 25%. The pulse width modulation signals PWM1 to PWM4 enter their working time sequentially. That is, pulse width modulation signal PWM1 can output a pulse first, followed by pulse width modulation signals PWM2, PWM3, and PWM4 outputting pulses in sequence, and then it is pulse width modulation signal PWM1 outputting a pulse again, and so on. Referring to the embodiment in Figure 2, when the AC / DC protection module 232 determines that the AC-DC converter 210 has failed while the DC-DC converter 220 can operate normally, the control signals CS2_1 to CS2_4 can be set to pulse width modulation signals PWM1 to PWM4 respectively, causing switches SW2_1, SW2_2, SW2_3, and SW2_4 to be switched sequentially. In this way, switches SW2_1, SW2_2, SW2_3, and SW2_4 can utilize the hard-switching characteristics of the switches to consume DC link voltages VDCL1_P and VDCL1_N, thereby causing VDCL1_P and VDCL1_N to decrease. In some embodiments, control signal CS2_1 can be transmitted to the control terminal of switch SW4_1, control signal CS2_2 can be transmitted to the control terminal of switch SW4_2, control signal CS2_3 can be transmitted to the control terminal of switch SW4_3, and control signal CS2_4 can be transmitted to the control terminal of switch SW4_4, so that switches SW4_1~SW4_4 and switches SW2_1~SW2_4 are synchronously turned on in a time-division manner, thereby causing the DC link voltages VDCL1_P and VDCL1_N to drop faster. Following the embodiment described in Figure 2, when the DC / DC protection module 234 determines that the DC-DC converter 220 has failed while the AC-DC converter 210 can operate normally, control signals CS2_1, CS2_2, CS2_3, and CS2_4 can be set to constant voltages to disconnect the switches within the DC-DC converter 220; control signals CS1_1, CS1_2, CS1_3, and CS1_4 can be set to pulse width modulation signals, and control signal CS1_1 can be transmitted to the control terminal of switch SW1_1, control signal CS1_2 can be transmitted to the control terminal of switch SW1_2, control signal CS1_3 can be transmitted to the control terminal of switch SW1_3, and control signal CS1_4 can be transmitted to the control terminal of switch SW1_4, so that switches SW1_1, SW1_2, SW1_3, and SW1_4 are turned on in a time-division manner, as shown in Figure 3. In this case, control signals CS1_1~CS1_4 can be set to pulse width modulation signals PWM1~PWM4 respectively, causing switches SW1_1, SW1_2, SW1_3, and SW1_4 to be switched sequentially. In this way, switches SW1_1, SW1_2, SW1_3, and SW1_4 can utilize the hard-switching characteristics of the switches to consume DC link voltages VDCL1_P and VDCL1_N, thereby causing VDCL1_P and VDCL1_N to decrease. In some embodiments, control signal CS1_1 can be transmitted to the control terminal of switch SW3_1, control signal CS1_2 can be transmitted to the control terminal of switch SW3_2, control signal CS1_3 can be transmitted to the control terminal of switch SW3_3, and control signal CS1_4 can be transmitted to the control terminal of switch SW3_4, so that switches SW3_1~SW3_4 and switches SW1_1~SW1_4 are synchronously turned on in a time-division manner, thereby causing the DC link voltages VDCL1_P and VDCL1_N to drop faster. Please refer to Figure 4, which is a schematic diagram of a solid-state transformer 400 according to an embodiment of this disclosure. The solid-state transformer 400 may be a three-phase AC-DC voltage conversion circuit. Each phase of the solid-state transformer 400 includes multiple transformer modules (e.g., transformer modules 410_1, 410_2...410_N in Figure 4, where N can be any positive integer greater than 2; in some embodiments, that phase of the solid-state transformer 400 may only include transformer modules 410_1 and 410_2, and the present invention does not limit the number of transformer modules). The transformer modules 410_1 to 410_N in Figure 4 correspond to transformer module 100 in Figure 1 and transformer module 200 in Figure 2. Therefore, the component configuration and characteristics of transformer modules 410_1 to 410_N will not be described in detail here. It is worth mentioning that the input terminals of transformer modules 410_1 to 410_N are connected in series. Transformer modules 410_1 to 410_N can share the AC voltage VAC4 equally, that is, the voltage value connected to the input terminal of each transformer module 410_1 to 410_N is 1 / N times the AC voltage VAC4. In addition, the output terminals of transformer modules 410_1 to 410_N are connected in parallel. The output voltage of each of transformer modules 410_1 to 410_N is the same, namely the DC voltage VDC4. In summary, both the transformer module and the solid-state transformer of the present invention can utilize their own first and second switches to reduce the DC link voltage after the transformer module enters the bypass mode. Certain terms are used in the specification and claims to refer to specific elements. However, those skilled in the art will understand that the same element may be referred to by different names. The specification and claims do not distinguish elements by differences in name, but by differences in function. The term "comprising" as used in the specification and claims is an open-ended term and should be interpreted as "comprising but not limited to". In addition, unless otherwise specified in the instructions, any singular case usage also includes the meaning of the plural case. The above are merely preferred embodiments of this disclosure. Various modifications and equivalent changes can be made to this disclosure without departing from its scope or spirit. In summary, all modifications and equivalent changes to this disclosure made within the scope of the following claims are within the scope of this disclosure. 100, 200, 410_1, 410_2, 410_N: Transformer Modules; 110, 210: AC-DC Converters; 120, 220: DC-DC Converters; 130, 230: Controllers; BS1: Bypass Switch Circuit; BA1, BA2: Bridge Arms; 232: AC / DC Protection Modules; 234: DC / DC Protection Modules; SW1_1, SW1_2, SW1_3, SW1_4, SW2_1, SW2_2, SW2_3 SW2_4, SW3_1, SW3_2, SW3_3, SW3_4, SW4_1, SW4_2, SW4_3, SW4_4, SBS1, SBS2, S1, S2, S3, S4, S5, S6, S7, S8: Switch DCL1: DC link VAC1, VAC4: AC voltage VDCL1, VDCL1_P, VDCL1_N: DC link voltage VDC1, VDC4: DC voltage DS1, DS2 Detection signals CS1, CS2, CS1_BS, CS1_1, CS1_2, CS1_3, CS1_4, CS2_1, CS2_2, CS2_3, CS2_4; Control signal RLY; Copper sheet switches DP1, DN1, DP2, DN2; Diodes R1, R2, R3, R4; Resistors C1, C2, C3, C4, CA, CB, CRP1, CRP2, CRP3, CRP4, CDC1, CDC2; Capacitors TRF1, TRF2; Transformer circuits LRP1, LM1, LRP2, LM2; Inductors IGI, ICRP1, ICRP2; Currents VC1, VC2, VC3, VC4; Voltages IDC1, IDC2; DC output currents VDC1_1, VDC1_2; DC voltages PWM1, PWM2, PWM3, PWM4; Pulse width modulation signals T_total, T1; Time length 400; Solid state transformer. Figure 1 is a schematic diagram of a transformer module according to an embodiment of this disclosure. Figure 2 is a schematic diagram of a transformer module according to an embodiment of this disclosure. Figure 3 is a waveform diagram of a pulse width modulation signal according to an embodiment of this disclosure. Figure 4 is a schematic diagram of a solid-state transformer according to an embodiment of this disclosure. 100: Transformer Module 110: AC-DC converter 120: DC-DC converter 130: Controller BS1: Bypass switch circuit BA1, BA2: Bridge Arm SW1_1, SW1_2, SW1_3, SW1_4, SW2_1, SW2_2, SW2_3, SW2_4: Switches DCL1: DC Link VAC1: AC voltage VDCL1: DC link voltage VDC1: DC voltage DS1, DS2: Detection signals CS1, CS2: Control signals

Claims

1. A transformer module includes: an AC-DC converter for receiving an AC voltage, and includes: a bypass switching circuit; a first bridge arm coupled to the bypass switching circuit, having a plurality of first switches; A second bridge arm is coupled to the first bridge arm; And a DC chain, coupled to the first bridge arm and the second bridge arm, to generate a DC chain voltage; An AC-DC converter, coupled to the DC link, for receiving the DC link voltage, and comprising: a plurality of second switches coupled to the DC link; and a controller coupled to the AC-DC converter and the DC-DC converter, for: detecting a first detection signal of the AC-DC converter and a second detection signal of the DC-DC converter; reducing the DC link voltage through the second switches in response to the first detection signal being in an abnormal state; and reducing the DC link voltage through the first switches in response to the second detection signal being in the abnormal state. The transformer module as described in claim 1, wherein the controller is further configured to: detect whether the DC link voltage rises to a preset maximum value in response to the first detection signal and the second detection signal being in the abnormal state simultaneously, so as to shut down the transformer module. The transformer module as described in claim 1, wherein the controller is further configured to: in response to the first detection signal being in the abnormal state, activate the bypass switch circuit and detect whether the DC link voltage rises from a first voltage level to a second voltage level; and in response to the DC link voltage being greater than or equal to the second voltage level, reduce the DC link voltage to below the first voltage level through the second switches. The transformer module as described in claim 1, wherein the controller is further configured to: in response to the second detection signal being in the abnormal state, activate the bypass switch circuit and detect whether the DC link voltage rises from a first voltage level to a second voltage level; and in response to the DC link voltage being greater than or equal to the second voltage level, reduce the DC link voltage to below the first voltage level through the first switches. The transformer module as described in claim 1, wherein the controller is further configured to: generate a plurality of pulse width modulation (PWM) signals; when the first detection signal is in the abnormal state, activate a corresponding one of the second switches through each of the PWM signals, wherein each of the second switches is time-divisionally activated; and when the second detection signal is in the abnormal state, activate a corresponding one of the first switches through each of the PWM signals, wherein each of the first switches is time-divisionally activated. The transformer module as described in Request 1, wherein the first switches and the second switches utilize a hard-switching characteristic to reduce the DC link voltage. As described in claim 1, the transformer module has a plurality of third switches, wherein in response to the second detection signal being in the abnormal state, the controller reduces the DC link voltage through the first switches and the third switches. The transformer module as described in claim 1, wherein the DC-DC converter further includes: a plurality of fourth switches coupled to the DC link, wherein in response to the first detection signal being in the abnormal state, the controller reduces the DC link voltage through the second switches and the fourth switches. The transformer module as described in claim 1, wherein the first detection signal is generated based on at least one of the input current of the AC-DC converter, a first internal voltage, and the DC link voltage, and the second detection signal is generated based on at least one of the input current of the DC-DC converter, the output voltage of the DC-DC converter, and the output current of the DC-DC converter. A solid-state transformer that receives an AC voltage includes: a plurality of transformer modules, each of the transformer modules including: an AC-DC converter for receiving an AC voltage divider based on the AC voltage, and including: a bypass switching circuit; a first bridge arm coupled to the bypass switching circuit, having a plurality of first switches; A second bridge arm is coupled to the first bridge arm; And a DC chain, coupled to the first bridge arm and the second bridge arm, to generate a DC chain voltage; An AC-DC converter, coupled to the DC link, for receiving the DC link voltage, and comprising: a plurality of second switches coupled to the DC link; and a controller coupled to the AC-DC converter and the DC-DC converter, for: detecting a first detection signal of the AC-DC converter and a second detection signal of the DC-DC converter; reducing the DC link voltage through the second switches in response to the first detection signal being in an abnormal state; and reducing the DC link voltage through the first switches in response to the second detection signal being in the abnormal state, wherein the input terminals of the transformer modules are connected in series and the output terminals of the transformer modules are connected in parallel. The solid-state transformer as described in claim 10, wherein the controller is further configured to: detect whether the DC link voltage rises to a preset maximum value in response to the first detection signal and the second detection signal being in the abnormal state simultaneously, so as to shut down the solid-state transformer. The solid-state transformer as described in claim 10, wherein the controller is further configured to: in response to the first detection signal being in the abnormal state, activate the bypass switch circuit and detect whether the DC link voltage rises from a first voltage level to a second voltage level; and in response to the DC link voltage being greater than or equal to the second voltage level, reduce the DC link voltage to below the first voltage level through the second switches. The solid-state transformer as described in claim 10, wherein the controller is further configured to: in response to the second detection signal being in the abnormal state, activate the bypass switch circuit and detect whether the DC link voltage rises from a first voltage level to a second voltage level; and in response to the DC link voltage being greater than or equal to the second voltage level, reduce the DC link voltage to below the first voltage level through the first switches. The solid-state transformer as described in claim 10, wherein the controller is further configured to: generate a plurality of pulse width modulation signals; when the first detection signal is in the abnormal state, activate a corresponding one of the second switches through each of the pulse width modulation signals, wherein each of the second switches is time-divisionally activated; and when the second detection signal is in the abnormal state, activate a corresponding one of the first switches through each of the pulse width modulation signals, wherein each of the first switches is time-divisionally activated. As described in claim 10, the solid-state transformer wherein the first switches and the second switches utilize a hard-switching characteristic to reduce the DC link voltage. The solid-state transformer as described in claim 10, wherein the first detection signal is generated based on at least one of the input current of the AC-DC converter, a first internal voltage, and the DC link voltage, and the second detection signal is generated based on at least one of the input current of the DC-DC converter, the output voltage of the DC-DC converter, and the output current of the DC-DC converter.

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