Single-phase and three-phase compatible ac-dc conversion circuit and discharge control method thereof

Abstract

A single-phase and three-phase compatible AC / DC conversion circuit is configured between an AC side and a DC side. The AC side has a three-phase power supply. The AC / DC conversion circuit includes a first switching element, a second switching element, a third switching element, three sets of switching bridge arms, a fourth switching element, a pre-charge resistor, a capacitor set, and a control unit. Each switching bridge arm includes an upper switch and a lower switch connected in series. The fourth switching element is coupled between a first phase of the three-phase power supply and a common connection point of a switching bridge arm corresponding to a second phase of the three-phase power supply. The control unit controls the fourth switching element to be conductive, controls the upper switch of the switching bridge arm coupled to the first switching element to be conductive, and controls the lower switch of the switching bridge arm coupled to the fourth switching element to be conductive to provide a discharge path, so that the capacitor set is discharged through the pre-charge resistor on the discharge path. The present application also relates to a charging and discharging control method of a single-phase and three-phase compatible AC / DC conversion circuit.

Description

Technical Field

[0001] This invention relates to an AC-DC conversion circuit and its discharge control method, and particularly to an AC-DC conversion circuit compatible with both single-phase and three-phase circuits and its discharge control method. Background Technology

[0002] In response to global environmental changes, countries around the world are increasingly emphasizing the concept of green energy and environmental protection. With the rapid development of electrification and intelligent technologies in recent years, automakers have also begun to actively develop electric vehicles (EVs) to reduce carbon emissions. For EVs, the on-board charger is the core component, primarily responsible for transferring charging energy to the high-voltage battery. Furthermore, as EVs continue to evolve, battery range is increasing, and the demand for charging power is also rising. This has led to a shift from single-phase chargers to three-phase chargers. Considering the different charging conditions users may encounter, on-board chargers with single-phase and three-phase compatibility capabilities will bring greater convenience to users.

[0003] However, it should be noted that even when the onboard charger stops charging, the capacitors in its internal circuitry still retain energy. For the safety of users and technicians, a discharge path is needed to release this energy. Generally, the energy release methods can be divided into two technologies: passive discharging and active discharging.

[0004] The former (passive discharge) utilizes a dummy load within the onboard charger's internal circuitry for natural discharge; however, its discharge time is quite long. The latter (active discharge) uses additional parallel circuitry combined with power switching to release capacitor energy, thus achieving the shortest discharge time. However, active discharge requires additional circuitry, increasing circuit cost and control complexity.

[0005] Therefore, how to design an AC-DC conversion circuit compatible with both single-phase and three-phase circuits and its discharge control method to solve the problems and technical bottlenecks of the existing technology is an important research topic for the inventors of this disclosure. Summary of the Invention

[0006] One objective of this invention is to provide an AC-DC converter circuit that is compatible with both single-phase and three-phase operation and has discharge control, thereby solving the problems of the prior art.

[0007] To achieve the aforementioned objectives, the present invention proposes an AC-DC converter circuit with discharge control, compatible with both single-phase and three-phase operation, configured between the AC side and the DC side, wherein the AC side has a three-phase power supply. The AC-DC converter circuit with discharge control includes a first switching element, a second switching element, a third switching element, a switch bridge arm group, a fourth switching element, a pre-charge resistor, a capacitor bank, and a control unit. The switch bridge arm group includes three sets of switch bridge arms. Each switch bridge arm includes an upper switch and a lower switch connected in series; the multiple common contacts of the upper switch and the corresponding lower switch are coupled to the three-phase power supply through the first switching element, the second switching element, and the third switching element, respectively. The fourth switching element is coupled between the common contacts of the switch bridge arms of the first phase of the three-phase power supply and the corresponding second phase of the three-phase power supply. The pre-charge resistor is coupled in parallel to the first switching element. The capacitor bank is coupled in parallel to the switch bridge arm group to form the DC side. The control unit controls the fourth switching element to turn on, controls the upper switch of the switching bridge arm coupled to the first switching element to turn on, and controls the lower switch of the switching bridge arm coupled to the fourth switching element to turn on to provide a discharge path, so that the capacitor bank discharges through the pre-charge resistor on the discharge path.

[0008] The proposed AC-DC conversion circuit with discharge control, compatible with both single-phase and three-phase operation, enables both single-phase and three-phase charging without requiring additional circuit components, thus achieving active discharge. Furthermore, to prevent damage to the components and pre-charging resistor caused by the large current generated by the instantaneous conduction of the power switching element, a switching technology is introduced for improvement. This optimizes the pulse width modulation and adjusts the duty cycle of the power switching element, effectively reducing the current stress on the power switching element and improving its tolerance and system reliability.

[0009] Another objective of this invention is to provide a charging and discharging control method for an AC-DC converter circuit compatible with both single-phase and three-phase operation, thereby solving the problems of the prior art.

[0010] To achieve the aforementioned objective, the present invention proposes a charging and discharging control method for a single-phase and three-phase compatible AC-DC conversion circuit. The AC-DC conversion circuit receives AC power. The AC-DC conversion circuit includes: three sets of switch arms, a fourth switching element, a pre-charging resistor, and a capacitor bank. Each switch arm includes an upper switch and a lower switch connected in series. Multiple common contacts of the upper switch and the corresponding lower switch are coupled to the three-phase power supply through a first switching element, a second switching element, and a third switching element, respectively. The fourth switching element is coupled between the common contacts of the switch arms of the first phase of the three-phase power supply and the corresponding second phase of the three-phase power supply. The pre-charging resistor is coupled in parallel to the first switching element. The capacitor bank is coupled in parallel to each switch arm. The discharge control method includes: (a) charging the capacitor bank with an AC power supply in a single-phase or three-phase manner; (b) controlling the fourth switching element to turn on when it is determined that the capacitor bank is about to discharge; (c) controlling the upper switch of the switching bridge arm coupled to the first switching element to turn on and controlling the lower switch of the switching bridge arm coupled to the fourth switching element to turn on to provide a discharge path; and (d) discharging the capacitor bank through a pre-charge resistor on the discharge path.

[0011] The proposed charging and discharging control method for a single-phase and three-phase compatible AC-DC converter circuit enables both single-phase and three-phase compatible charging without requiring additional circuit components, thus achieving active discharging. Furthermore, to prevent damage to the components and pre-charging resistor caused by the large current generated by the instantaneous conduction of the power switching element, a switching technology is introduced for improvement. This optimizes the pulse width modulation control and adjusts the duty cycle of the power switching element, effectively reducing the current stress on the power switching element and improving its tolerance and system reliability.

[0012] To gain a deeper understanding of the techniques, means, and effects employed by this invention to achieve its intended purpose, please refer to the following detailed description and accompanying drawings. It is believed that the purpose, features, and characteristics of this invention can be understood in a thorough and specific manner from these drawings. However, the drawings are provided for reference and illustration only and are not intended to limit the scope of this invention. Attached Figure Description

[0013] Figure 1 : This is a circuit diagram of the AC-DC conversion circuit compatible with both single-phase and three-phase circuits of the present invention.

[0014] Figure 2 This is a circuit diagram showing the switching element state of the AC-DC conversion circuit compatible with both single-phase and three-phase operation of the present invention during single-phase charging operation.

[0015] Figure 3 This is a circuit diagram showing the switching element states of the AC-DC conversion circuit compatible with both single-phase and three-phase operation of the present invention during three-phase charging operation.

[0016] Figure 4 : This is a circuit diagram showing the switching element state during discharge operation of the AC-DC conversion circuit compatible with single-phase and three-phase of the present invention.

[0017] Figure 5 : This is a circuit diagram showing the current path of the AC-DC conversion circuit compatible with single-phase and three-phase in this invention during discharge operation.

[0018] Figure 6 This is a flowchart of the discharge control method for the AC-DC conversion circuit compatible with both single-phase and three-phase circuits of the present invention.

[0019] Explanation of reference numerals in the attached figures:

[0020] S AC Communication side

[0021] S DC DC side

[0022] V L1N First phase voltage

[0023] V L2N Second phase voltage

[0024] V L3N Third phase voltage

[0025] N AC1 First communication node

[0026] N AC2 Second communication node

[0027] N AC3 Third communication node

[0028] N: Neutral node

[0029] 10: Switch bridge arm assembly

[0030] 20: Diode bridge arm

[0031] 30: Capacitor bank

[0032] 40: Control Unit

[0033] 11: First switch bridge arm

[0034] 12: Second switch bridge arm

[0035] 13: Third switch bridge arm

[0036] Q1: First switch

[0037] Q2: Second switch

[0038] Q3: Third switch

[0039] Q4: Fourth Switch

[0040] Q5: Fifth Switch

[0041] Q6: Sixth Switch

[0042] D1: First diode

[0043] D2: Second diode

[0044] C1: First capacitor

[0045] C2: Second capacitor

[0046] N1: First node

[0047] N2: Second node

[0048] N3: Third Node

[0049] N4: Fourth Node

[0050] N5: Fifth Node

[0051] RL1: First switching element

[0052] RL2: Second switching element

[0053] RL3: Third switching element

[0054] RL4: Fourth Switching Element

[0055] RL5: Fifth switching element

[0056] RL6: Sixth Switching Element

[0057] RL7: Seventh Switching Element

[0058] RL8: Eighth switching element

[0059] R1: Pre-charge resistor

[0060] L1: First phase inductor

[0061] L2: Second phase inductor

[0062] L3: Third phase inductor

[0063] S CON Control signals Detailed Implementation

[0064] The technical content and detailed description of the present invention are explained below with reference to the accompanying drawings.

[0065] Please see Figure 1 The diagram shown is a circuit diagram of the AC-DC conversion circuit compatible with both single-phase and three-phase circuits of the present invention. The AC-DC conversion circuit is configured on the AC side S.AC With DC side S DC Between. Among them, the communication side S AC Therefore, an AC power supply, such as a three-phase AC power supply or a single-phase AC power supply, will be provided, as detailed later. Thus, the single-phase and three-phase compatible AC-DC converter circuit of the present invention is a single-phase and three-phase compatible AC-DC converter circuit. Furthermore, in different embodiments, a bidirectional circuit architecture is a preferred implementation of the single-phase and three-phase compatible AC-DC converter circuit, but the present invention is not limited thereto.

[0066] Due to the AC side S AC It can provide both three-phase AC power and single-phase AC power, therefore the AC side S AC Having the first communication node N AC1 Second communication node N AC2 Third communication node N AC3 And the neutral node N. Taking a three-phase power supply as an example, the first phase voltage V of the three-phase power supply... L1N Configured on the first communication node N AC1 The second phase voltage V of the three-phase power supply between the neutral node N and the neutral node N. L2N Configured on the second AC node N AC2 Between the neutral node N and the third phase voltage V of the three-phase power supply L3N Configured on the third communication node N AC3 Between and neutral node N.

[0067] The single-phase and three-phase compatible AC-DC conversion circuit includes a switch bridge arm group 10, a fourth switching element RL4, a fifth switching element RL5, a pre-charge resistor R1, a diode bridge arm 20, a capacitor group 30, and a control unit 40.

[0068] The switch bridge arm group 10 includes three sets of switch bridge arms connected in parallel, namely the first switch bridge arm 11, the second switch bridge arm 12, and the third switch bridge arm 13. The first switch bridge arm 11 includes a first switch Q1 and a second switch Q2 that are both connected to the first node N1, and the first node N1 is coupled to the first AC node N through the first switching element RL1. AC1 When the first switching element RL1 is turned on, the first node N1 can be coupled to the first phase voltage V through the first phase inductor L1. L1N The second switch arm 12 includes a third switch Q3 and a fourth switch Q4 both connected to the second node N2, and the second node N2 is coupled to the second AC node N through the second switching element RL2. AC2 When the second switching element RL2 is turned on, the second node N2 can be coupled to the second phase voltage V through the second phase inductor L2. L2NThe third switch arm 13 includes a fifth switch Q5 and a sixth switch Q6 connected to the third node N3, and the third node N3 is coupled to the third AC node N through the third switching element RL3. AC3 When the third switching element RL3 is turned on, the third node N3 can be coupled to the third phase voltage V through the third phase inductor L3. L3N .

[0069] The fourth switching element RL4 is coupled to the first AC node N. AC1 Between the second node N2, that is, when the fourth switching element RL4 is turned on, it is connected (bridging) between the first phase circuit and the second phase circuit in the three-phase power supply. The fifth switching element RL5 is coupled to the first AC node N. AC1 Between the third node N3, that is, when the fifth switching element RL5 is turned on, it is connected (bridging) between the first phase circuit and the third phase circuit in the three-phase power supply. The above switching element can be implemented using a relay.

[0070] The pre-charge resistor R1 is connected in parallel to the first switching element RL1. During the charging process of the electric vehicle (e.g., an electric car), the AC-DC converter circuit acts as a converter for the AC side S... AC The three-phase or single-phase AC power supply is converted to DC power on the S side. DC The output DC power supply is used to charge electric vehicles. Therefore, the pre-charge resistor R1 provides suppression of large currents, such as inrush currents, at the beginning of the charging process, for example, when a user starts charging an electric vehicle. This invention also addresses the issue of high voltage accumulation on the DC side S after charging is complete. DC To discharge the energy stored in the capacitor, a pre-charge resistor R1 is used as a component to provide the discharge path. Therefore, the pre-charge resistor R1 acts as a discharge resistor during the discharge process. That is, no additional circuit components are added during the discharge operation; the existing circuit architecture from the pre-charge process is used to discharge the energy stored in the capacitor. A detailed explanation of the operation of the pre-charge resistor R1 will be provided later.

[0071] Diode bridge arm 20 is coupled in parallel to switch bridge arm group 10. In this embodiment, diode bridge arm 20 includes a first diode D1 and a second diode D2 series coupled to the first diode D1 at the fourth node N4. In applications with different current ratings, each diode in diode bridge arm 20 may also use multiple diodes connected in parallel, therefore, it is not limited to... Figure 1 The diode bridge arm 20 shown is a constraint.

[0072] The capacitor bank 30 is coupled in parallel to the diode bridge arm 20 to form the DC side S. DCIn this embodiment, capacitor bank 30 includes a first capacitor C1 and a second capacitor C2 series coupled to the first capacitor C1 at the fifth node N5. In electric vehicle charging applications, capacitor bank 30 is used to store the DC power obtained by the AC-DC conversion circuit from three-phase or single-phase AC power, so that the DC side S... DC The output DC power is used by the next stage conversion circuit to charge the battery of the electric vehicle.

[0073] Control unit 40 provides control signal S CON Since the switching arms 11, 12, 13, and the switches Q1 to Q6, as well as the switching elements RL1 to RL8, are all controlled by the control unit 40, the control signal S shown is... CON It contains a plurality of signals corresponding to control switches Q1 to Q6 and switching elements RL1 to RL8, which will be described in detail below.

[0074] Furthermore, the single-phase and three-phase compatible AC-DC converter circuit also includes a sixth switching element RL6 and a seventh switching element RL7. One end of the sixth switching element RL6 is coupled to the diode bridge arm 20, and the other end is coupled to the seventh switching element RL7 at the neutral node N. Since this invention is a single-phase and three-phase compatible AC-DC converter circuit, the sixth switching element RL6 and the seventh switching element RL7 are used for control when supplying power in both single-phase and three-phase modes; that is, when the AC side S... AC If a single-phase AC power supply is used, then the sixth switching element RL6 is turned on (see [reference]). Figure 2 (as shown), or when the AC side S AC When supplying power to a three-phase AC power source, the seventh switching element RL7 is activated (see [reference]). Figure 3 (As shown), more details will follow later.

[0075] Furthermore, the AC-DC conversion circuit compatible with both single-phase and three-phase operation also includes an eighth switching element RL8. This eighth switching element RL8 is connected in series with the pre-charge resistor R1, forming a series structure, and this series structure is connected in parallel with the first switching element RL1. By including the eighth switching element RL8, the purpose of reliably disconnecting the pre-charge resistor R1 can be further achieved; however, the eighth switching element RL8 can also be omitted.

[0076] The technical feature of this invention lies in its proposed AC-DC conversion circuit and control method, which enables both single-phase and three-phase compatible charging without requiring additional circuit components. Active discharge can be achieved using only the power switching components within the on-board charger's internal circuitry, coupled with a pre-charging resistor R1. Furthermore, to prevent damage to the components and pre-charging resistor R1 caused by the large current generated during the instantaneous conduction of the power switching components, a switching technique is introduced to optimize the pulse width modulation (PWM) control. This adjusts the duty cycle of the power switching components—the ratio of on to off time—effectively reducing current stress on the power switching components and improving their resilience and system reliability.

[0077] When a vehicle-mounted charger is in operation, it can be classified as single-phase or three-phase circuit operation depending on the input conditions of the charging station. Please refer to [link / reference]. Figure 2 The diagram shown illustrates the switching element states of the single-phase and three-phase compatible AC-DC converter circuit of this invention during single-phase charging operation. When the AC input is a single-phase voltage, the AC input will only have two terminals. For example, with the first phase voltage V... L1N Taking the supply voltage as an example, the first switching element RL1, the fourth switching element RL4, the fifth switching element RL5, and the sixth switching element RL6 are switched to the turned-on state (the remaining switching elements are turned-off), thus ensuring that only the first phase voltage V... L1N Through the AC-DC conversion circuit, each switch arm of the switch arm group 10 and the diode arm 20 form a totem pole PFC circuit to achieve energy transfer. Therefore, although the AC input is a single-phase voltage, by turning on the fourth switching element RL4 and the fifth switching element RL5, the three sets of parallel switch arms of the switch arm group 10 (i.e., the first switch arm 11, the second switch arm 12, and the third switch arm 13) can be used to couple the first phase voltage V. L1N All three sets of parallel switching arms participate in pulse width modulation (PWM) control, and the parallel arms can further utilize interleaved control. Therefore, idle arms are avoided, thus increasing output power. It is worth noting that the fifth switching element RL5 can be omitted depending on actual power requirements; in other words, the third switching arm 13 does not need to participate in the operation.

[0078] Please see Figure 3The diagram shows the switching element states of the AC-DC conversion circuit compatible with single-phase and three-phase operation of the present invention during three-phase charging. When the AC input is a three-phase voltage, the first switching element RL1, the second switching element RL2, the third switching element RL3, and the seventh switching element RL7 are switched to the on state (the remaining switching elements are in the off state). Thus, the first phase voltage V... L1N Second phase voltage V L2N Third phase voltage V L3N All circuits operate through an AC-DC conversion circuit, with the switch bridge arm group 10 and capacitor group 30 forming a half-bridge power factor correction (PFC) circuit topology to achieve the function of energy transfer.

[0079] Regardless of whether the AC input is single-phase or three-phase, energy still remains in the power capacitors (i.e., the first capacitor C1 and the second capacitor C2 of capacitor bank 30) when the on-board charger stops charging. Considering the operational safety of users and maintenance technicians, a discharge path is still needed to release this energy. Therefore, as described above, the technical solution for active discharge is achieved by using the power switching elements of the original on-board charger circuit in conjunction with the pre-charge resistor R1. The following steps illustrate the technical solution for the discharge operation.

[0080] First, when the on-board charger stops charging, the voltage of the first phase V is... L1N Second phase voltage V L2N Third phase voltage V L3N In the no-connection state, all switching elements return to the disconnected state, such as... Figure 1 As shown.

[0081] Then, to establish an energy release path for the power capacitors (first capacitor C1 and second capacitor C2), the eighth switching element RL8 and the fourth switching element RL4 are switched to the on state, and await the start of the discharge operation. For example... Figure 4 As shown, it is a circuit diagram of the switching element state of the AC-DC conversion circuit compatible with single-phase and three-phase of the present invention during discharge operation.

[0082] Then, initiate the discharge operation, such as... Figure 5As shown, this is a circuit diagram of the current path of the AC-DC conversion circuit compatible with single-phase and three-phase operation of the present invention during discharge. At this time, the eighth switching element RL8 and the fourth switching element RL4 remain in the on state, and the first switch Q1 of the first switching bridge arm 11 and the fourth switch Q4 of the second switching bridge arm 12 are switched to the on state. Further, the duty cycle of the power switching elements can be changed / adjusted in a timely manner by pulse width modulation (PWM), thereby enabling the power capacitors (first capacitor C1 and second capacitor C2) to discharge the pre-charge resistor R1. The discharge path is as follows... Figure 5 As indicated by the arrows, the discharge path control for capacitor bank 30 is achieved by control unit 40 controlling the conduction of the fourth switching element RL4, the eighth switching element RL8, the first switch Q1, and the fourth switch Q4. Therefore, the discharge path from capacitor bank 30 passes through the first switch Q1, the eighth switching element RL8, the pre-charge resistor R1, the fourth switching element RL4, and the fourth switch Q4. The eighth switching element RL8 can also be omitted and replaced by a short circuit; therefore, the discharge path does not include the eighth switching element RL8. The magnitude of the discharge current is directly affected by controlling the duty cycle ratio and the switching frequency. Therefore, the discharge current can be suppressed by controlling the duty cycle ratio and the switching frequency.

[0083] Finally, when the voltage of the power capacitors (first capacitor C1 and second capacitor C2) discharges to the safe operating area (SOA), the active switching modulation strategy ends. Therefore, the first switch Q1 and the fourth switch Q4 remain open, and all switching elements (including the eighth switching element RL8 and the fourth switching element RL4) are switched off. Thus, the switching and element states of the entire circuit are as follows: Figure 1 As shown, the voltage of the power capacitor discharges slowly and continuously.

[0084] Incidentally, the aforementioned AC-DC conversion circuit is only one implementation method, and not every component is necessary, as power conversion circuits can have different implementation methods. Figure 1For example, when single-phase operation does not require a large power application, the fifth switching element RL5 can be omitted. Alternatively, the diode bridge arm 20, the sixth switching element RL6, and the seventh switching element RL7 can also be omitted, and the fifth node N5 is directly connected to the neutral node N, so that both single-phase and three-phase operations use a half-bridge power factor correction circuit topology. In single-phase operation, the AC phase is connected to two bridge arms, while in three-phase operation, each phase is connected to a corresponding bridge arm. Therefore, the main concept of this invention is to use switching elements to achieve charging operations compatible with both single-phase and three-phase AC inputs, and after charging, to use the bridge arm switches, switching elements, and pre-charging resistors to form a discharge circuit to discharge the capacitor. As long as this purpose can be achieved, it is not limited to using only the aforementioned AC-DC conversion circuit.

[0085] Please see Figure 6 The diagram shows a flowchart of the discharge control method for a single-phase and three-phase compatible AC-DC converter circuit according to the present invention. The present invention discloses a charging and discharging control method for a single-phase and three-phase compatible AC-DC converter circuit, wherein the AC-DC converter circuit receives AC power. The AC-DC converter circuit includes: three sets of switch arms, a fourth switching element, a pre-charging resistor, and a capacitor bank. Each switch arm includes an upper switch and a lower switch connected in series. The upper switches and their corresponding common contacts are coupled to the AC power supply through a first switching element, a second switching element, and a third switching element, respectively. The fourth switching element is coupled between the common contacts of the switch arms of the first phase of the AC power supply and the corresponding second phase of the AC power supply. The pre-charging resistor is coupled in parallel to the first switching element. The capacitor bank is coupled in parallel to each switch arm.

[0086] The discharge control method includes the following steps. First, the AC power supply charges the capacitor bank in a single-phase or three-phase manner (S11). Then, when it is determined that the capacitor bank is about to discharge, the fourth switching element is turned on (S12). Then, the upper switch of the switching bridge arm coupled to the first switching element is turned on, and the lower switch of the switching bridge arm coupled to the fourth switching element is turned on to provide a discharge path (S13). Then, the capacitor bank discharges through the pre-charge resistor on the discharge path (S14).

[0087] Incidentally, the discharge control method provided by this invention can be used in the operation of the aforementioned single-phase and three-phase compatible AC-DC conversion circuits. Therefore, the specific details of the control method can be found in the corresponding specification, and will not be elaborated further here.

[0088] In summary, the present invention has the following features and advantages:

[0089] 1. By utilizing the existing pre-charge circuit architecture of the charging operation, the active discharge function can be achieved using only the original power switching components and the pre-charge resistor R1. Therefore, no additional components are needed, which can save circuit costs and reduce circuit size.

[0090] 2. The power switching element in the internal circuit of the vehicle charger, combined with the pre-charging resistor R1, can quickly discharge the voltage of the power capacitors (first capacitor C1 and second capacitor C2) to a safe voltage range, thereby improving the operational safety of users and maintenance technicians.

[0091] 3. To prevent damage to the components and pre-charge resistors caused by the large current generated by the instantaneous conduction of the power switching elements, a switching technology is introduced to improve the control of pulse width modulation (PWM) and optimize it in a timely manner. This adjusts the duty cycle of the power switching elements, i.e., the ratio of on to off time. This not only effectively reduces the current stress on the power switching elements, but also improves the withstand capability of the power switching elements and the reliability of the system.

[0092] The above description is merely a detailed explanation and accompanying drawings of preferred embodiments of the present invention, and the features of the present invention are not limited thereto, nor are they intended to limit the present invention. The full scope of the present invention should be determined by the claims. All embodiments that conform to the concept of the claims of the present invention and similar variations thereof should be included in the scope of the present invention. Any variations or modifications that can be easily conceived by those skilled in the art within the field of the present invention can be covered by the claims disclosed herein.

Claims

1. A single-phase and three-phase compatible AC-DC converter circuit, disposed between an AC side and a DC side, the AC side having a three-phase power supply, the AC-DC converter circuit comprising: A first switching element, a second switching element, and a third switching element; A switch bridge arm assembly, comprising: Three sets of switch bridge arms, each of which includes an upper switch and a lower switch connected in series; the multiple common contacts of the upper switch and the corresponding lower switch in the three sets of switch bridge arms are respectively coupled to the three-phase power supply through the first switching element, the second switching element and the third switching element; A fourth switching element is coupled between a first phase of the three-phase power supply and the common contact of the switching bridge arm corresponding to a second phase of the three-phase power supply. A pre-charge resistor is connected in parallel to the first switching element; A capacitor bank is connected in parallel to the switch bridge arm group to form the DC side; and A control unit controls the fourth switching element to be turned on, controls the upper switch of the switching bridge arm coupled to the first switching element to be turned on, and controls the lower switch of the switching bridge arm coupled to the fourth switching element to be turned on, so as to provide a discharge path, allowing the capacitor bank to discharge through the pre-charge resistor in the discharge path. in, The AC-DC converter circuit also includes: A diode bridge arm is connected in parallel to the switch bridge arm group; A sixth switching element is coupled to the diode bridge arm; and A seventh switching element is coupled to the sixth switching element and a neutral node of the three-phase power supply.

2. The AC-DC converter circuit compatible with single-phase and three-phase as described in claim 1, further comprising: A fifth switching element is coupled between the common contact of the first phase of the three-phase power supply and the switching arm of the corresponding third phase of the three-phase power supply.

3. The AC-DC converter circuit compatible with single-phase and three-phase as described in claim 1, further comprising: An eighth switching element is connected in series with the pre-charge resistor to form a series structure, and the series structure is connected in parallel with the first switching element.

4. The AC-DC converter circuit compatible with single-phase and three-phase as described in claim 1, wherein the three sets of switching bridge arms comprise: A first switch bridge arm includes a first switch and a second switch coupled to the first switching element; A second switch bridge arm, comprising a third switch and a fourth switch coupled to the second switching element; and A third switch bridge arm includes a fifth switch and a sixth switch coupled to the third switching element; The control unit controls the fourth switching element to be turned on and controls the first switch and the fourth switch to be turned on, so that the capacitor bank discharges through the pre-charge resistor.

5. The AC-DC converter circuit compatible with single-phase and three-phase as described in claim 3, wherein the three sets of switching bridge arms comprise: A first switch bridge arm includes a first switch and a second switch coupled to the first switching element; A second switch bridge arm, comprising a third switch and a fourth switch coupled to the second switching element; and A third switch bridge arm includes a fifth switch and a sixth switch coupled to the third switching element; The control unit controls the fourth switching element and the eighth switching element to be connected, and controls the first switch and the fourth switch to be connected, so that the capacitor bank is discharged through the pre-charge resistor.

6. The AC-DC converter circuit compatible with single-phase and three-phase as described in claim 1, wherein the three sets of switching bridge arms comprise: A first switch bridge arm includes a first switch and a second switch coupled to the first switching element; A second switch bridge arm, comprising a third switch and a fourth switch coupled to the second switching element; and A third switch bridge arm includes a fifth switch and a sixth switch coupled to the third switching element; The control unit controls the first switching element and the fourth switching element to conduct, and controls the first switch bridge arm and the second switch bridge arm to operate, so that the first phase of the three-phase power supply charges the capacitor bank.

7. The AC-DC converter circuit compatible with single-phase and three-phase as described in claim 2, wherein the three sets of switching bridge arms comprise: A first switch bridge arm includes a first switch and a second switch coupled to the first switching element; A second switch bridge arm, comprising a third switch and a fourth switch coupled to the second switching element; and A third switch bridge arm includes a fifth switch and a sixth switch coupled to the third switching element; The control unit controls the first switching element, the fourth switching element, and the fifth switching element to turn on, and controls the first switch bridge arm, the second switch bridge arm, and the third switch bridge arm to operate, so that the first phase of the three-phase power supply charges the capacitor bank.

8. The AC-DC converter circuit compatible with single-phase and three-phase as described in claim 1, wherein the three sets of switching bridge arms comprise: A first switch bridge arm includes a first switch and a second switch coupled to the first switching element; A second switch bridge arm, comprising a third switch and a fourth switch coupled to the second switching element; and A third switch bridge arm includes a fifth switch and a sixth switch coupled to the third switching element; The control unit controls the first switching element, the second switching element, and the third switching element to be turned on, and controls the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch to operate, so that the three-phase power supply charges the capacitor bank.

9. A charging and discharging control method for a single-phase and three-phase compatible AC-DC converter circuit, wherein the AC-DC converter circuit receives an AC power supply; the AC-DC converter circuit includes: three sets of switch bridge arms, a fourth switching element, a pre-charging resistor, and a capacitor bank; each switch bridge arm includes an upper switch and a lower switch connected in series; the multiple common contacts of the upper switch and the corresponding lower switch of each switch bridge arm are respectively coupled to the AC power supply through a first switching element, a second switching element, and a third switching element; the fourth switching element is coupled between a first phase of the AC power supply and the common contact of the switch bridge arm corresponding to a second phase of the AC power supply; the pre-charging resistor is coupled in parallel to the first switching element; the capacitor bank is coupled in parallel to each switch bridge arm; the discharging control method includes: (a) The AC power supply charges the capacitor bank in a single-phase or three-phase manner; (b) When it is determined that the capacitor bank is about to discharge, the fourth switching element is turned on. (c) Controlling the upper switch of the switch bridge arm coupled to the first switching element to turn on, and controlling the lower switch of the switch bridge arm coupled to the fourth switching element to turn on to provide a discharge path; as well as (d) The capacitor bank discharges through the pre-charge resistor in the discharge path. The AC-DC conversion circuit also includes: A diode bridge arm is connected in parallel to the switch bridge arm group; A sixth switching element is coupled to the diode bridge arm; and A seventh switching element is coupled to the sixth switching element and a neutral node of the AC power supply.

10. The charging and discharging control method as described in claim 9, wherein the AC-DC conversion circuit further includes an eighth switching element, which is connected in series with the pre-charging resistor to form a series structure, and the series structure is connected in parallel with the first switching element. Step (b) further includes controlling the eighth switching element to be turned on.

11. The charging and discharging control method as described in claim 9, wherein in step (a), the first switching element, the second switching element, and the third switching element are controlled to be turned on, and the corresponding upper switch and the lower switch are controlled to operate, so that the AC power supply charges the capacitor bank in a three-phase manner.

12. The charging and discharging control method as described in claim 9, wherein in step (a), the first switching element and the fourth switching element are controlled to be turned on, and the corresponding upper switch and the lower switch are controlled to operate, so that one phase of the AC power supply charges the capacitor bank.

13. The charging and discharging control method as described in claim 9, wherein the AC-DC conversion circuit further includes a fifth switching element; in step (a), the first switching element, the fourth switching element, and the fifth switching element are controlled to be turned on, so that the three sets of switch bridge arms are coupled to one phase of the AC power supply to charge the capacitor bank.

Images