Standby switching device

Abstract

The application discloses a kind of backup switching device, and backup switching device provides uninterrupted power supply switching to the circuit of later stage.Backup switching device includes the main circuit switch of coupling main power supply, the standby circuit switch of coupling standby power supply, first switch group, second switch group and control unit, the first switch group includes first bidirectional switch and first bypass switch, and the second switch group includes second bidirectional switch and second bypass switch.Control unit provides switch signal control respectively first bidirectional switch, first bypass switch, second bidirectional switch and second bypass switch, so that the circuit of later stage is powered by main power supply or by standby power supply.

Description

[0001] This application is a divisional application of the patent application filed on August 30, 2018, with application number 201811002986.0 and entitled "Backup Switching Device and Control Method Thereof". Technical Field

[0002] This invention relates to a switching device, and more particularly to a backup switching device. Background Technology

[0003] Currently, backup systems are widely used in various data centers and server power input stages to improve power supply reliability and flexibility. In recent years, due to demands for system space and equipment capacity utilization, backup circuits have gradually been integrated into power supply units rather than being individual system components. However, current backup systems are not only bulky but also expensive; therefore, integrated power supply designs must be considered.

[0004] Therefore, how to design a backup switching device that achieves high efficiency and cost-effectiveness by reducing control circuits and simplifying control methods is a major issue that the inventors of this case intend to overcome and solve. Summary of the Invention

[0005] The purpose of this invention is to provide a backup switching device that solves the problems of low power switching efficiency and high circuit cost.

[0006] To achieve the aforementioned objective, the backup switching device proposed in this invention provides uninterrupted power supply switching for downstream circuits. The backup switching device includes a main circuit switch, a backup circuit switch, a first switch group, a second switch group, and a control unit. The main circuit switch is coupled to the main power supply. The backup circuit switch is coupled to the backup power supply, wherein the main circuit switch and the backup circuit switch are respectively configured for the main power supply and the backup power supply. The first switch group is coupled to the main circuit switch and the backup circuit switch, and includes a first bidirectional switch and a first bypass switch coupled in parallel to the first bidirectional switch. The second switch group is coupled to the main circuit switch and the backup circuit switch, and includes a second bidirectional switch and a second bypass switch coupled in parallel to the second bidirectional switch. The control unit provides switching signals to control the first bidirectional switch, the first bypass switch, the second bidirectional switch, and the second bypass switch, so that the downstream circuits are powered by either the main power supply or the backup power supply.

[0007] The proposed backup switching device can reduce the conduction stress of the switch, improve the reliability of the switch, be applicable to circuit topologies including zero-current switches, and enable the miniaturization of subsequent circuits while ensuring sufficient power supply time after power failure.

[0008] Another object of the present invention is to provide a backup switching device for switching uninterrupted power supply to a downstream circuit.

[0009] To achieve the aforementioned objectives, the backup switching device proposed in this invention comprises: a main circuit switch coupled to a first live wire terminal and a first neutral wire terminal of a main power supply; a backup circuit switch coupled to a second live wire terminal and a second neutral wire terminal of a backup power supply; a first switch group coupled to the first live wire terminal via the main circuit switch, coupled to the second live wire terminal via the backup circuit switch, and coupled to the subsequent circuit; a second switch group coupled to the first neutral wire terminal via the main circuit switch, coupled to the second neutral wire terminal via the backup circuit switch, and coupled to the subsequent circuit; and a control unit; wherein the control unit is used to control the on / off state of a first power supply path corresponding to the main power supply, and to control the on / off state of a second power supply path corresponding to the backup power supply, so that the subsequent circuit is powered by the main power supply or by the backup power supply.

[0010] 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 accompanying drawings are provided for reference and illustration only and are not intended to limit this invention. Attached Figure Description

[0011] Figure 1 This is a circuit block diagram of the backup switching device of the present invention.

[0012] Figure 2 This is a timing waveform diagram of the backup switching device of the present invention during normal startup.

[0013] Figure 3A This is a timing waveform diagram of the backup switching device of the present invention operating during power supply switching in the event of an abnormal voltage drop.

[0014] Figure 3B This is a timing waveform diagram of the backup switching device of the present invention operating under abnormal undervoltage power supply switching.

[0015] Figure 4 This is a flowchart of the first embodiment of the zero-current switching method of the backup switching device of the present invention.

[0016] Figure 5 This is a flowchart of a second embodiment of the zero-current switching method for the backup switching device of the present invention.

[0017] Among them, the attached figures are labeled

[0018] 11 Main circuit switch

[0019] 12,12' spare circuit switch

[0020] 21 First Switch Group

[0021] 211 First bidirectional switch

[0022] 212 First Bypass Switch

[0023] 22 Second Switch Group

[0024] 221 Second bidirectional switch

[0025] 222 Second Bypass Switch

[0026] 30 control units

[0027] 40-stage circuit

[0028] Vm main power supply

[0029] Vb,Vb' Backup power

[0030] S1 First Switch Signal

[0031] S2 Second Switch Signal

[0032] SBD bidirectional switching signal

[0033] SBP bypass switch signal

[0034] The live wire of the Lm mains power supply

[0035] Nm main power supply neutral terminal

[0036] Lb,Lb' The live wire end of the backup power supply

[0037] Nb,Nb' Neutral terminal of backup power supply

[0038] t1~t3 time points

[0039] t1'~t5' time points

[0040] t1”~t7” time points

[0041] Steps S11 to S18

[0042] Steps S21 to S29 Detailed Implementation

[0043] The technical content and detailed description of the present invention are explained below with reference to the accompanying drawings.

[0044] Please see Figure 1The diagram shown is a circuit block diagram of the backup switching device of the present invention. The backup switching device includes a main circuit switch 11, a backup circuit switch 12, a first switch group 21, a second switch group 22, and a control unit 30. The main circuit switch 11 is coupled to the main power supply Vm, which can be, for example, AC power or a generator, but is not limited thereto; that is, the main power supply Vm is used as the primary power source for supplying power to the downstream circuit 40. The backup circuit switch 12 is coupled to the backup power supply Vb, which can be, for example, another AC power source or a generator, or an AC backup power source obtained by converting renewable energy (e.g., solar, wind, hydropower, geothermal, etc.) from DC to AC power. In other words, when the main power supply Vm malfunctions and cannot supply power to the downstream circuit 40, the backup power supply Vb is switched to continue providing uninterrupted power to the downstream circuit 40, enabling the downstream circuit 40 to operate normally. Figure 1 The diagram shows multiple backup power supplies Vb, Vb', etc. However, the following description will take one backup power supply Vb as an example.

[0045] The first switch group 21 is coupled to the main circuit switch 11 and the standby circuit switch 12. The first switch group 21 includes a first bidirectional switch 211 and a first bypass switch 212 coupled in parallel to the first bidirectional switch 211. The second switch group 22 is coupled to the main circuit switch 11 and the standby circuit switch 12. The second switch group 22 includes a second bidirectional switch 221 and a second bypass switch 222 coupled in parallel to the second bidirectional switch 221. The main circuit switch 11, the standby circuit switch 12, the first bypass switch 212, and the second bypass switch 222 can be relay switches or semiconductor components; the first bidirectional switch and the second bidirectional switch can be composed of two semiconductor switches connected in reverse parallel, wherein each semiconductor switch can be a metal-oxide-semiconductor field-effect transistor (MOSFET), an insulated-gate bipolar transistor (IGBT), or composed of two silicon controlled rectifiers (SCRs) connected in reverse parallel, but is not limited thereto.

[0046] The control unit 30 provides multiple switch signals to control the aforementioned switches, including providing a first switch signal S1 to control the main circuit switch 11, providing a second switch signal S2 to control the standby circuit switch 12, providing a bidirectional switch signal SBD to control the first bidirectional switch 211 and the second bidirectional switch 221, and providing a bypass switch signal SBP to control the first bypass switch 212 and the second bypass switch 222.

[0047] The backup switching device of the present invention further includes a power detection unit (not shown). The power detection unit can detect the voltage (current, frequency, or other electrical parameters) of the main power supply Vm and provide the detected information (result) to the control unit 30, so that the control unit 30 knows the power supply status of the main power supply Vm. Similarly, the power detection unit can also detect the backup power supply Vb and provide the detected information to the control unit 30, so that the control unit 30 knows the standby power supply status of the backup power supply Vb.

[0048] When the main power supply Vm can supply power normally, the control unit 30 turns on the main circuit switch 11, the first switch group 21, and the second switch group 22, so that the main power supply Vm supplies power to the downstream circuit 40. Conversely, when the main power supply Vm cannot supply power normally, such as when an abnormal voltage drop or abnormal undervoltage occurs, the control unit 30 turns off the first switch group 21 and the second switch group 22, then turns off the main circuit switch 11, and finally turns on the backup circuit switch 12, and turns on the first switch group 21 and the second switch group 22, so that the downstream circuit 40 is disconnected from the abnormal main power supply Vm, and is supplied by the backup power supply Vb to maintain the uninterrupted power supply to the downstream circuit 40, so that the downstream circuit 40 can work normally, which will be explained in detail later.

[0049] The following sections explain the operation of the backup switching device during normal power-on and during power switching. Please refer to [link / reference]. Figure 2 The diagram shows the timing waveforms of the backup switching device during normal startup. It should be noted that the switching signals in this specification use a high level to turn on the switch and a low level to turn off the switch as an example, but this is not a limitation. In practice, the switching signal can be modified to turn on the switch at a low level and turn off the switch at a high level, depending on the circuit design. When the control unit 30 learns that the main power supply Vm is supplying power normally, the control unit 30 provides a high-level first switching signal S1 at time point t1 to turn on the main circuit switch 11. Since the main power supply Vm is decoupled from the subsequent circuit 40 before the main circuit switch 11 is turned on, and since the turn-on time of the main circuit switch 11 is affected by circuit delay when a relay switch is used, the time point t1 can be any time point, but it will generally be controlled to correspond to the time point when the main power supply Vm is at zero voltage or low voltage.

[0050] Then, after the control unit 30 confirms that the main power supply Vm maintains normal power supply, it provides a high-level bidirectional switch signal SBD at time point t2, simultaneously turning on the first bidirectional switch 211 and the second bidirectional switch 221, so that the main power supply Vm begins to supply power to the subsequent circuit 40. Since the main power supply Vm is already in standby power supply state before the first bidirectional switch 211 and the second bidirectional switch 221 are turned on, and since the first bidirectional switch 211 and the second bidirectional switch 221 are semiconductor switches, meaning there is no delay in their turn-on time, the turn-on time can be accurately controlled. Therefore, time point t2 can be the time point when the main power supply Vm is at zero voltage, so that the first bidirectional switch 211 and the second bidirectional switch 221 can be turned on at zero voltage. Correspondingly, zero current flows through the first bidirectional switch 211 and the second bidirectional switch 221 at the moment of turn-on, thereby reducing the conduction stress of the switches and improving the reliability of the switches. At this time, the main power supply Vm can supply power to the subsequent circuit 40.

[0051] Therefore, when the main power supply Vm is in the positive half-cycle, the power supply path is the live wire terminal Lm of the main power supply Vm, the main circuit switch 11, the first bidirectional switch 211, the subsequent circuit 40, the second bidirectional switch 221, the main circuit switch 11, and the neutral wire terminal Nm of the main power supply Vm. Conversely, when the main power supply Vm is in the negative half-cycle, the power supply path is the neutral wire terminal Nm of the main power supply Vm, the main circuit switch 11, the second bidirectional switch 221, the subsequent circuit 40, the first bidirectional switch 211, the main circuit switch 11, and the live wire terminal Lm of the main power supply Vm.

[0052] Then, at time point t3, the control unit 30 provides a high-level bypass switch signal SBP to simultaneously turn on the first bypass switch 212 and the second bypass switch 222. Since the first bidirectional switch 211 and the second bidirectional switch 221 are already in the on state before the first bypass switch 212 and the second bypass switch 222 are turned on, a very small on-state voltage (approximately 0.2 to 0.7 volts) is applied across the first bypass switch 212 and the second bypass switch 222, respectively. Therefore, when the control unit 30 controls the first bypass switch 212 and the second bypass switch 222 to turn on, the first bypass switch 212 and the second bypass switch 222 can be turned on under a relatively small voltage. Correspondingly, a small current flows through the first bypass switch 212 and the second bypass switch 222 at the moment of on-state, thereby reducing the on-state stress of the switches and improving their reliability.

[0053] Since the impedances of the first bypass switch 212 and the second bypass switch 222 are much smaller than those of the first bidirectional switch 211 and the second bidirectional switch 221, the loop current flows through the first bypass switch 212 and the second bypass switch 222 when the first bypass switch 212 and the second bypass switch 222 are turned on. Furthermore, since the impedances of the first bypass switch 212 and the second bypass switch 222 are much smaller than those of the first bidirectional switch 211 and the second bidirectional switch 221, the control unit 30 does not need to explicitly provide the bidirectional switch signal SBD to control the first bidirectional switch 211 and the second bidirectional switch 221.

[0054] At this time, when the main power supply Vm is in the positive half-cycle, the power supply path is the live wire terminal Lm of the main power supply Vm, the main circuit switch 11, the first bypass switch 212, the subsequent circuit 40, the second bypass switch 222, the main circuit switch 11, and the neutral wire terminal Nm of the main power supply Vm. Conversely, when the main power supply Vm is in the negative half-cycle, the power supply path is the neutral wire terminal Nm of the main power supply Vm, the main circuit switch 11, the second bypass switch 222, the subsequent circuit 40, the first bypass switch 212, the main circuit switch 11, and the live wire terminal Lm of the main power supply Vm.

[0055] Please see Figure 3A The diagram shown is a timing waveform diagram of the backup switching device of the present invention operating during power supply switching in the event of an abnormal voltage drop. "Power supply switching in the event of an abnormal voltage drop" refers to the need to switch to backup power supply Vb to continuously supply power to the downstream circuit 40 when an abnormal voltage drop occurs in the main power supply Vm, so that the downstream circuit 40 can operate normally. The specific explanation is as follows.

[0056] Before time point t1', the main power supply Vm normally supplies power to the subsequent circuit 40. (Continuing from the previous point...) Figure 2 The backup switching device operates under normal startup conditions. Therefore, before time point t1', the high-level first switch signal S1 turns on the main circuit switch 11, the high-level bidirectional switch signal SBD turns on the first bidirectional switch 211 and the second bidirectional switch 221, and the high-level bypass switch signal SBP turns on the first bypass switch 212 and the second bypass switch 222. Furthermore, the low-level second switch signal S2 turns off the backup circuit switch 12.

[0057] At time t1', the power detection unit detects an abnormal voltage drop in the main power supply Vm. Incidentally, the control unit 30 can determine the nature of this voltage drop based on the detection result. If the voltage drop is only a momentary voltage decrease, and the main power supply Vm immediately returns to its normal supply voltage, the control unit 30 confirms that the voltage drop is not an abnormal voltage drop in the main power supply Vm. Conversely, if the voltage drop persists for a sufficient judgment time, the control unit 30 confirms that the main power supply Vm has experienced an abnormal voltage drop. Therefore, at time t2', the control unit 30 simultaneously provides a low-level first switch signal S1 to turn off the main circuit switch 11, a low-level bidirectional switch signal SBD to turn off the first bidirectional switch 211 and the second bidirectional switch 221, and a low-level bypass switch signal SBP to turn off the first bypass switch 212 and the second bypass switch 222. In other words, since the main power supply Vm has experienced an abnormal voltage drop, the control unit 30 can control these switches to be simultaneously turned off, or to turn them off in any order.

[0058] That is, during the time interval from time point t1' to time point t2', the control unit 30 confirms that the main power supply Vm has experienced an abnormal voltage drop, and the control unit 30 decouples the power supply loop between the main power supply Vm and the downstream circuit 40. At this time, the energy stored in the output capacitor (bulk capacitor) of the downstream circuit 40, such as the power factor corrector circuit, can be discharged, so that the main power supply Vm and the downstream circuit 40 are in a decoupled state, and the backup power supply Vb has not yet been connected to supply power to the downstream circuit 40, so that the downstream circuit 40 can still maintain (i.e., have sufficient hold-up time) to operate normally.

[0059] When the control unit 30 turns off the main circuit switch 11, the first bidirectional switch 211 and the second bidirectional switch 221, and the first bypass switch 212 and the second bypass switch 222 (e.g., at time t2'), it also provides a high-level second switch signal S2 to turn on the backup circuit switch 12, so that the backup power supply Vb is in standby power supply state. However, in practical applications, in order to avoid the problem of short circuit between the two power supplies caused by the simultaneous power supply of the main power supply Vm and the backup power supply Vb in case of an abnormality, a delay time is added after time t2', for example, the backup circuit switch 12 is turned on at time t3'. In this way, the break-before-make switch achieves uninterrupted switching between different input power supplies. Similarly, before the backup circuit switch 12 is turned on, the backup power supply Vb is decoupled from the subsequent circuit 40. Furthermore, when the backup circuit switch 12 uses a relay switch, its turn-on time will be affected by the circuit delay. Therefore, the time point t3' can be any time point, but it will basically be controlled to be the time point when the backup power supply Vb is at zero voltage or low voltage.

[0060] Then, after the control unit 30 confirms that the backup power supply Vb is in standby power supply state, it provides a high-level bidirectional switching signal SBD at time point t4', simultaneously turning on the first bidirectional switch 211 and the second bidirectional switch 221, so that the backup power supply Vb begins to supply power to the subsequent circuit 40. Since the backup power supply Vb is already in standby power supply state before the first bidirectional switch 211 and the second bidirectional switch 221 are turned on, and since the first bidirectional switch 211 and the second bidirectional switch 221 are semiconductor switches, meaning there is no delay in their turn-on time, the turn-on time can be accurately controlled. Therefore, time point t4' can be the time point when the backup power supply Vb is at zero voltage, so that the first bidirectional switch 211 and the second bidirectional switch 221 can be turned on at zero voltage. Correspondingly, zero current flows through the first bidirectional switch 211 and the second bidirectional switch 221 at the moment of turn-on, thereby reducing the conduction stress of the switches and improving the reliability of the switches. At this time, the backup power supply Vb can supply power to the subsequent circuit 40.

[0061] At this time, when the backup power supply Vb is in the positive half-cycle, the power supply path is the live wire terminal Lb of the backup power supply Vb, the backup circuit switch 12, the first bidirectional switch 211, the subsequent circuit 40, the second bidirectional switch 221, the backup circuit switch 12, and the neutral wire terminal Nb of the backup power supply Vb. Conversely, when the backup power supply Vb is in the negative half-cycle, the power supply path is the neutral wire terminal Nb of the backup power supply Vb, the backup circuit switch 12, the second bidirectional switch 221, the subsequent circuit 40, the first bidirectional switch 211, the backup circuit switch 12, and the live wire terminal Lb of the backup power supply Vb.

[0062] Then, at time point t5', the control unit 30 provides a high-level bypass switch signal SBP to simultaneously turn on the first bypass switch 212 and the second bypass switch 222. Since the first bidirectional switch 211 and the second bidirectional switch 221 are already in the on state before the first bypass switch 212 and the second bypass switch 222 are turned on, a very small on-state voltage (approximately 0.2 to 0.7 volts) is applied across the first bypass switch 212 and the second bypass switch 222, respectively. Therefore, when the control unit 30 controls the first bypass switch 212 and the second bypass switch 222 to turn on, the first bypass switch 212 and the second bypass switch 222 can be turned on under a relatively small voltage. Correspondingly, a small current flows through the first bypass switch 212 and the second bypass switch 222 at the moment of on-state, thereby reducing the on-state stress of the switches and improving their reliability.

[0063] Since the impedances of the first bypass switch 212 and the second bypass switch 222 are much smaller than those of the first bidirectional switch 211 and the second bidirectional switch 221, the loop current flows through the first bypass switch 212 and the second bypass switch 222 when the first bypass switch 212 and the second bypass switch 222 are turned on. Furthermore, since the impedances of the first bypass switch 212 and the second bypass switch 222 are much smaller than those of the first bidirectional switch 211 and the second bidirectional switch 221, the control unit 30 does not need to explicitly provide the bidirectional switch signal SBD to control the first bidirectional switch 211 and the second bidirectional switch 221.

[0064] At this time, when the backup power supply Vb is in the positive half-cycle, the power supply path is the live wire terminal Lb of the backup power supply Vb, the backup circuit switch 12, the first bypass switch 212, the subsequent circuit 40, the second bypass switch 222, the backup circuit switch 12, and the neutral wire terminal Nb of the backup power supply Vb. Conversely, when the backup power supply Vb is in the negative half-cycle, the power supply path is the neutral wire terminal Nb of the backup power supply Vb, the backup circuit switch 12, the second bypass switch 222, the subsequent circuit 40, the first bypass switch 212, the backup circuit switch 12, and the live wire terminal Lb of the backup power supply Vb.

[0065] Please see Figure 3B The diagram shown is a timing waveform diagram of the backup switching device of the present invention operating under abnormal undervoltage power supply switching. "Abnormal undervoltage power supply switching" refers to the need to switch to backup power supply Vb to continuously supply power to the downstream circuit 40 when the main power supply Vm experiences an abnormal undervoltage, so that the downstream circuit 40 can operate normally. The abnormal undervoltage power supply switching and... Figure 3A The technical details regarding power supply switching during abnormal voltage drops will not be repeated here; they will be explained separately.

[0066] Before time point t1", the main power supply Vm normally supplies power to the subsequent circuit 40. At time point t1", the power detection unit detects an abnormal undervoltage in the main power supply Vm. If this undervoltage phenomenon persists within a sufficient judgment time, the control unit 30 confirms that the main power supply Vm has an abnormal undervoltage. That is, during the time interval from time point t1" to time point t2", the control unit 30 confirms that the main power supply Vm has an abnormal undervoltage, and the control unit 30 decouples the power supply loop between the main power supply Vm and the subsequent circuit 40.

[0067] Therefore, at time t2", since the voltage across the first bypass switch 212 and the second bypass switch 222 is relatively small, the control unit 30 first provides a low-level bypass switch signal SBP to turn off the first bypass switch 212 and the second bypass switch 222. Then, at time t3", the control unit 30 provides a low-level bidirectional switch signal SBD to turn off the first bidirectional switch 211 and the second bidirectional switch 221. Finally, at time t4", the control unit 30 provides a low-level first switch signal S1 to turn off the main circuit switch 11, thereby decoupling the power supply circuit between the main power supply Vm and the subsequent circuit 40.

[0068] A delay is added after time point t4”, for example, at time point t5”, the control unit 30 provides a high-level second switch signal S2 to turn on the backup circuit switch 12, making the backup power supply Vb standby. Then, after confirming that the backup power supply Vb is in standby mode, the control unit 30 provides a high-level bidirectional switch signal SBD at time point t6” (the time when the backup power supply Vb has zero voltage) to simultaneously turn on the first bidirectional switch 211 and the second bidirectional switch 221, so that the backup power supply Vb begins to supply power to the downstream circuit 40. Finally, at time point t7”, a high-level bypass switch signal SBP is provided to simultaneously turn on the first bypass switch 212 and the second bypass switch 222. In this way, the backup power supply Vb is switched to continue supplying power to the downstream circuit 40 in the event of an abnormal undervoltage, so that the downstream circuit 40 can operate normally.

[0069] In summary, the backup switching device of the present invention can be used to switch backups in... Figure 3A time point t4' or Figure 3BAt time point t6", which is the time when the backup power supply Vb is at zero voltage, the first bidirectional switch 211 and the second bidirectional switch 221 are turned on to achieve zero-current switching. Therefore, the output of the backup switching device of the present invention can be applied to topologies that include zero-current switches. In addition, the backup switching device of the present invention can also be turned on earlier, before the time point when the backup power supply Vb is at zero voltage (i.e., time point t4' or t6"), that is, by reducing the control method of switching time, the first bidirectional switch 211 and the second bidirectional switch 221 are turned on when the voltage is not zero. This can also achieve the effect that the output of the backup switching device can be applied to topologies that include zero-current switches. The specific explanation is as follows.

[0070] Please see Figure 4 The diagram shows a flowchart of the first embodiment of the zero-current switching method of the backup switching device of the present invention. The steps of the zero-current switching method are as follows: When the main power supply Vm of the main circuit is normally powered (S11), the control unit 30 determines whether the main power supply Vm is normally powered (S12). If yes, the main power supply Vm continues to supply power to the downstream circuit 40. If no, it indicates that the main power supply Vm is abnormal. At this time, the control unit 30 or other control units of the backup switching device provide a notification signal to the downstream circuit 40, notifying the downstream circuit 40 to stop working (S13), so that the downstream circuit 40 stops working (S14) and generates a zero-current state.

[0071] Since the downstream circuit 40 is in a zero-current state, the control unit 30 provides a low-level bidirectional switch signal SBD to turn off the first bidirectional switch 211 and the second bidirectional switch 221, provides a low-level bypass switch signal SBP to turn off the first bypass switch 212 and the second bypass switch 222, and provides a low-level first switch signal S1 to turn off the main circuit switch 11 (S15), thereby decoupling the power supply loop between the main power supply Vm and the downstream circuit 40. Furthermore, since the downstream circuit 40 is in a zero-current state, there is no particular restriction on the order in which the first bidirectional switch 211 and the second bidirectional switch 221, the first bypass switch 212 and the second bypass switch 222, and the main circuit switch 11 are turned off.

[0072] Then, the control unit 30 provides a high-level second switch signal S2 to turn on the backup circuit switch 12 (S16). Next, the control unit 30 provides a notification signal to the downstream circuit 40 to notify it to resume operation (S17). Finally, the control unit 30 provides a high-level bidirectional switch signal SBD to simultaneously turn on the first bidirectional switch 211 and the second bidirectional switch 221, causing the backup power supply Vb to begin supplying power to the downstream circuit 40 (S18). This completes the continuous power supply of the backup power supply Vb to the downstream circuit 40, maintaining uninterrupted power supply and enabling the downstream circuit 40 to operate normally.

[0073] Please see Figure 5 The diagram shows a flowchart of the second embodiment of the zero-current switching method of the backup switching device of the present invention. As mentioned above, in order to reduce the switching time and enable the first bidirectional switch 211 and the second bidirectional switch 221 to be turned on earlier before the zero-voltage point, so as to realize the function that the output of the backup switching device can be applied to the topology including the zero-current switch, the steps of the zero-current switching method are as follows. After the backup circuit switch 12 is turned on (S21), the control unit 30 determines whether the backup power supply Vb is in a standby power supply state (S22). If not, the step (S22) continues to be executed. When the backup power supply Vb is in a standby power supply state, that is, when the step (S22) determines that it is, the control unit 30 or other control units of the backup switching device provide a notification signal to the downstream circuit 40 to notify the downstream circuit 40 to stop working (S23), so that the downstream circuit 40 stops working (S24), and a zero-current state is generated.

[0074] Incidentally, in Figure 4 In the control method, the steps of the backup switching device providing a notification signal to the downstream circuit 40 to notify the downstream circuit 40 to stop working (S13) and the downstream circuit 40 stopping working (S14) are executed when the main power supply Vm is abnormal, i.e., when step (S12) is not determined to be abnormal. In contrast, in Figure 5 In the control method, the steps of the backup switching device providing a notification signal to the downstream circuit 40 to notify the downstream circuit 40 to stop working (S23) and the downstream circuit 40 to stop working (S24) can also be continued when the backup power supply Vb is in standby power supply state, that is, when step (S22) is determined to be yes.

[0075] After the downstream circuit 40 stops working (S24), a confirmation signal is provided to the control unit 30, allowing the control unit 30 to confirm that the downstream circuit 40 has stopped working (S25). When the control unit 30 confirms that the current is zero, it provides a high-level bidirectional switch signal SBD to simultaneously turn on the first bidirectional switch 211 and the second bidirectional switch 221, so that the backup power supply Vb starts to supply power to the downstream circuit 40 (S26), thereby achieving zero-current conduction of the first bidirectional switch 211 and the second bidirectional switch 221. Then, the control unit 30 provides a notification signal to the downstream circuit 40 to notify it to resume operation (S27). After the downstream circuit 40 resumes operation (S28), a confirmation signal is provided to the control unit 30, allowing the control unit 30 to confirm that the downstream circuit 40 has resumed operation (S29). Taking the power factor correction circuit as the downstream circuit 40 as an example, in order to achieve zero-current conduction of the first bidirectional switch 211 and the second bidirectional switch 221, the power factor correction circuit stops working before the first bidirectional switch 211 and the second bidirectional switch 221 are turned on, so that the first bidirectional switch 211 and the second bidirectional switch 221 are turned on in a zero-current state. Finally, after the first bidirectional switch 211 and the second bidirectional switch 221 are turned on with zero current, the power factor correction circuit resumes working.

[0076] The above step (S21) corresponds to Figure 3A time point t3' or Figure 3B The time point t5”, and steps (S22) to (S29) are at Figure 3A time point t4' or Figure 3B The switching is completed before the time point t6 (when the backup power supply Vb is at zero voltage). In other words, as long as it is determined that the backup power supply Vb is in standby power supply state and that the downstream circuit 40 has stopped working, the first bidirectional switch 211 and the second bidirectional switch 221 can be turned on. Thus, it is not necessary to wait until the backup power supply Vb reaches zero voltage before turning on the first bidirectional switch 211 and the second bidirectional switch 221, thereby achieving zero-current switching and effectively reducing the switching time. Based on this, the time when the main power supply Vm and the downstream circuit 40 are decoupled and the backup power supply Vb has not yet continued to supply power to the downstream circuit 40 can be significantly reduced. Therefore, the capacity and size of the output capacitor of the downstream circuit 40 can be reduced, and the miniaturization of the downstream circuit 40 can be easily achieved, while ensuring sufficient power supply retention time after power failure.

[0077] In summary, the present invention has the following features and advantages:

[0078] 1. By controlling the zero-current conduction of the first and second bidirectional switches, the current stress on the switches can be reduced and the reliability of the switches can be improved.

[0079] 2. By reducing the switching time control method, when the first bidirectional switch and the second bidirectional switch are turned on at non-zero voltage, the output of the backup switching device can be made applicable to topologies including zero-current switches.

[0080] 3. By reducing the switching time control method, the capacity and size of the output capacitor of the subsequent circuit can be reduced, and the miniaturization of the subsequent circuit can be easily achieved, while ensuring sufficient power supply time after power failure.

[0081] The above description is merely a detailed explanation and illustration of preferred embodiments of the present invention. However, the features of the present invention are not limited thereto and are not intended to limit the present invention. The scope of the present invention should be determined by the following claims. All embodiments that conform to the spirit of the claims 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 scope of the present invention can be covered by the protection scope of the following appended claims.

Claims

1. A backup switching device, characterized in that, The backup switching device provides uninterrupted power supply to a downstream circuit and includes: A main circuit switch is coupled to a main power supply; A backup circuit switch is coupled to a backup power supply; wherein the main circuit switch and the backup circuit switch are respectively set for the main power supply and the backup power supply. A first switch group, coupled to the main circuit switch and the standby circuit switch, the first switch group comprising: A first bidirectional switch; and A first bypass switch is connected in parallel to the first bidirectional switch; A second switch group, coupled to the main circuit switch and the standby circuit switch, the second switch group comprising: A second bidirectional switch; and A second bypass switch is connected in parallel to the second bidirectional switch; and One control unit; The first bidirectional switch and the second bidirectional switch are composed of two semiconductor switches. The control unit provides switch signals to control the first bidirectional switch, the first bypass switch, the second bidirectional switch, and the second bypass switch, so that the subsequent circuit is powered by the main power supply or by the backup power supply. When the main power supply fails to supply power, the control unit first shuts off the main circuit switch, the first bidirectional switch, the second bidirectional switch, and the first bypass switch and the second bypass switch, and then turns on the backup circuit switch, the first bidirectional switch, the second bidirectional switch, the first bypass switch, and the second bypass switch. After the backup circuit switch is turned on, and before the first bidirectional switch and the second bidirectional switch are turned on, the subsequent circuit stops working.

2. The backup switching device as described in claim 1, characterized in that, The control unit provides a first switch signal to control the main circuit switch, a second switch signal to control the backup circuit switch, a bidirectional switch signal to control the first bidirectional switch and the second bidirectional switch, and a bypass switch signal to control the first bypass switch and the second bypass switch.

3. The backup switching device as described in claim 1, characterized in that, The downstream circuit stops operating before the main circuit switch, the first bidirectional switch, the second bidirectional switch, the first bypass switch, and the second bypass switch are turned off.

4. The backup switching device as described in claim 1 or 3, characterized in that, The control unit provides a notification signal to the downstream circuit, instructing the downstream circuit to stop working.

5. The backup switching device as described in claim 1, characterized in that, When the main power supply fails to supply power and the backup power supply is in standby mode, the control unit first turns on the first bidirectional switch and the second bidirectional switch, and then turns on the first bypass switch and the second bypass switch.

6. The backup switching device as described in claim 1, characterized in that, The main circuit switch, the backup circuit switch, the first bypass switch, and the second bypass switch are all relay switches.

7. The backup switching device as described in claim 1, characterized in that, The first bidirectional switch and the second bidirectional switch are composed of two semiconductor switches connected in reverse parallel.

8. The backup switching device as described in claim 7, characterized in that, The semiconductor switch is a metal-oxide-semiconductor field-effect transistor, an insulated-gate bipolar transistor, or a silicon controlled rectifier.

9. The backup switching device as described in claim 1, characterized in that, The subsequent circuit is a power factor correction circuit.

10. The backup switching device as described in claim 1, characterized in that, The backup power source is an AC backup power source converted from renewable energy.

11. A backup switching device, characterized in that, The backup switching device provides uninterrupted power supply to a downstream circuit and includes: A main circuit switch is coupled to a first live wire terminal and a first neutral wire terminal of a main power supply. A backup circuit switch is coupled to a second live wire terminal and a second neutral wire terminal of a backup power supply. A first switch group is coupled to the first live wire terminal via the main circuit switch, coupled to the second live wire terminal via the standby circuit switch, and coupled to the subsequent circuit. The first switch group includes: a first bidirectional switch; and a first bypass switch, which is coupled to the first bidirectional switch in parallel. A second switch group, coupled to the first neutral terminal via the main circuit switch, coupled to the second neutral terminal via the standby circuit switch, and coupled to the subsequent circuit, the second switch group includes: a second bidirectional switch; and a second bypass switch, coupled in parallel to the second bidirectional switch; and One control unit; The control unit is used to control the on or off of a first power supply path corresponding to the main power supply and to control the on or off of a second power supply path corresponding to the backup power supply, so that the downstream circuit is powered by the main power supply or by the backup power supply.

12. The backup switching device as described in claim 11, characterized in that, The first power supply path includes the first live wire terminal, the main circuit switch, the first bidirectional switch, the downstream circuit, the second bidirectional switch, the main circuit switch, and the first neutral wire terminal.

13. The backup switching device as described in claim 11, characterized in that, The first power supply path includes the first live wire terminal, the main circuit switch, the first bypass switch, the downstream circuit, the second bypass switch, the main circuit switch, and the first neutral wire terminal.

14. The backup switching device as described in claim 11, characterized in that, The second power supply path includes the second live wire terminal, the backup circuit switch, the first bidirectional switch, the downstream circuit, the second bidirectional switch, the backup circuit switch, and the second neutral wire terminal.

15. The backup switching device as described in claim 11, characterized in that, The second power supply path includes the second live wire terminal, the backup circuit switch, the first bypass switch, the downstream circuit, the second bypass switch, the backup circuit switch, and the second neutral wire terminal.

16. The backup switching device as described in claim 11, characterized in that, When the main power supply fails to supply power and the backup power supply is in standby mode, the control unit first simultaneously turns on the first bidirectional switch and the second bidirectional switch, and then simultaneously turns on the first bypass switch and the second bypass switch.

17. The backup switching device as described in claim 11, characterized in that, When the control unit determines that the main power supply is abnormal or when the control unit determines that the backup power supply is in standby power supply state, it provides a notification signal to the downstream circuit to notify the downstream circuit to stop working.

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