Dual power supply switching system and method of operation thereof

Abstract

A dual power supply switching system and method of operation are provided. [Solution] A dual power supply switching system selects a first power supply or a second power supply to supply power to a load connected to an inductive device, and includes a first thyristor, a second thyristor, a third thyristor, a fourth thyristor, and a controller. When the supply power switches from the first power supply to the second power supply, the controller controls the first thyristor and the second thyristor to be turned off, respectively, and determines whether the commutation possible time has arrived based on the power parameters of the first static switch and the second static switch. The controller calculates a total magnetic flux based on the current magnetic flux of the inductive device and the estimated magnetic flux of the second power supply. If the commutation possible time has arrived, the controller turns on at least one of the third thyristor and the fourth thyristor according to the total magnetic flux being less than a threshold.

Description

[Technical Field]

[0001] The present disclosure relates to a switching system and a method of operation thereof, and more particularly to a dual power supply switching system and a method of operation thereof. [Background technology]

[0002] A static transfer switch (STS) is an essential component in a data center's power supply system, supplying uninterruptible power to loads such as critical equipment. It typically contains multiple silicon-controlled rectifiers. A static transfer switch is typically powered by two or more independent power sources, and if the preferred primary power source exceeds its tolerance range, it automatically switches from the preferred power source to the backup power source to provide uninterruptible power. This ensures a continuous power supply to critical equipment, preventing power cuts and forced shutdowns.

[0003] Typically, the output of a hitless transfer system is connected to critical equipment via a transformer. Because transformers are inductive devices, they suffer from magnetic flux saturation. Therefore, if the primary power supply falls outside its tolerance range and the transfer between the two power sources is improper, a high inrush current will be generated in the downstream transformer. If the inrush current is too high, it can overload upstream circuits or trip a circuit breaker, causing a power outage for the entire system. Therefore, to avoid excessive inrush current, traditional power transfer methods turn on the backup power supply's silicon-controlled rectifier after the current through the primary power supply's silicon-controlled rectifier reaches zero. However, this transfer method must wait until the current reaches zero, which risks causing the output voltage to drop too low and shutting down critical equipment. Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, how to design a dual power supply switching system and its operating method that can avoid inappropriate switching of the dual power supplies is an important issue that has been considered by the inventors of the present application.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a dual power supply switching system and an operating method thereof. [Means for solving the problem]

[0006] In order to achieve the above object, a dual power supply switching system according to the present disclosure selects a first power supply or a second power supply to supply power to a load connected to an inductive device, and includes a first static switch, a second static switch, and a controller, wherein the first static switch is connected to the first power supply and the inductive device and includes a first thyristor and a second thyristor connected in anti-parallel to each other, the second static switch is connected to the second power supply and the inductive device and includes a third thyristor and a fourth thyristor connected in anti-parallel to each other, the fourth thyristor has a forward bias in the same direction as the first thyristor, and the controller is configured to select whether a power supply is the first power supply or the second power supply. and selectively controls the first thyristor, the second thyristor, the third thyristor, and the fourth thyristor according to the fact that, when a power supply switches from the first power supply to the second power supply, the controller controls the first thyristor and the second thyristor to be turned off, respectively, and determines whether a commutation possible time has been reached based on power parameters of the first static switch and the second static switch; the controller calculates a total magnetic flux based on a current magnetic flux of the inductive device and an estimated magnetic flux of the second power supply; and when the commutation possible time has been reached, turns on at least one of the third thyristor and the fourth thyristor according to the fact that the total magnetic flux is less than a threshold.

[0007] In order to achieve the above object, a method for operating a dual power source switching system according to the present disclosure is provided, the dual power source switching system including a first static switch and a second static switch connected to an inductive device, the first static switch including a first thyristor and a second thyristor connected in anti-parallel to each other, and the second static switch including a third thyristor and a fourth thyristor connected in anti-parallel to each other, the method including: a step a) of controlling the first thyristor and the second thyristor to be turned off when a power supply is switched from a first power source to a second power source; a step b) of calculating a total magnetic flux based on a current magnetic flux of the inductive device and an estimated magnetic flux of the second power source; a step c) of determining whether a commutation possible time has been reached based on power parameters of the first static switch and the second static switch; and a step d) of determining whether the total magnetic flux is less than a threshold value if the commutation possible time has been reached; and a step d) of performing a step d2 of turning on at least one of the third thyristor and the fourth thyristor depending on whether the total magnetic flux is less than the threshold value. [Effects of the Invention]

[0008] The present disclosure provides a method for operating a dual power supply switching system that switches between dual power supplies. The method mainly uses four independent control signals to control gate terminals, so that the first static switch and the second static switch independently turn on the corresponding thyristors while ensuring that the total magnetic flux does not exceed a threshold during a specific period of commutation, thereby shortening the switching time of the power supply switching and reducing the inrush current.

[0009] In order to better understand the techniques, means, and advantages of the present disclosure made to achieve the objects of the present disclosure, the objects and features of the present disclosure will be better understood based on the detailed description of the present disclosure and the accompanying drawings, which are provided for reference and explanation only and are not intended to limit the present disclosure. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a circuit block diagram of a dual power supply switching system of the present disclosure. [Figure 2] 3A to 3C are waveform diagrams of a first power supply, a second power supply, and an output power supply of the present disclosure. [Figure 3] 10 is a flowchart illustrating a determination of a commutation possible time of the dual power supply switching system of the present disclosure. [Figure 4] 10 is a flowchart illustrating switching timing of the dual power source switching system of the present disclosure. [Figure 5A] 4 is a flowchart showing switching timing in the first embodiment of the dual power supply switching system of the present disclosure. [Figure 5B] FIG. 2 is a schematic waveform diagram of the first embodiment of the dual power supply switching system of the present disclosure. [Figure 6A] 10 is a flowchart showing switching timing in a second embodiment of the dual power supply switching system of the present disclosure. [Figure 6B] FIG. 10 is a schematic waveform diagram of a second embodiment of the dual power supply switching system of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] The technical contents and detailed description of the present disclosure will be described below with reference to the drawings.

[0012] FIG. 1 is a circuit block diagram of a dual power supply switching system according to the present disclosure. Referring to FIG. 1, the dual power supply switching system 100 primarily powers a load 121 and includes a static switch device, an inductive device 120, and a controller 134. The static switch device includes a first static switch 130 and a second static switch 131. The load 121 may be, for example, but is not limited to, a critical load that requires continuous, uninterrupted operation, such as a server or a communication system. The first static switch 130 is connected to a first power source 110, and the second static switch 131 is connected to a second power source 111. The inductive device 120 includes a first side winding 120A and a second side winding 120B. The first side winding 120A is connected to the first static switch 130 and the second static switch 131, and the second side winding 120B is connected to the load 121. The controller 134 detects the power supply power of the first power source 110 and the second power source 111, and detects the output power received by the inductive device 120, thereby adjusting and controlling the first static switch 130 and the second static switch 131. Here, the controller 134 mainly selects the first power source 110 or the second power source 111 to supply power to the load 121 connected to the inductive device 120. Note that in one embodiment, the controller 134 may be a digital signal processor (DSP), but is not limited thereto, and a physical circuit capable of performing circuit control using a signal, a control device with built-in control software, etc. are considered to be within the scope of this embodiment.

[0013] Specifically, the dual power supply switching system 100 further includes a voltage sensor (not shown) and current sensors 132 and 133. The voltage sensor and current sensor 132 and 133 are electrically connected to the first power supply 110 and the second power supply 111, respectively, to detect voltage signals V1 and V2 and current signals I1 and I2 (i.e., power supply power, but not limited to this) corresponding to the first power supply 110 and the second power supply 111. In addition, the voltage sensor is connected to the first side winding 120A or the second side winding 120B of the inductive device 120 to detect a voltage signal Vo corresponding to the first side winding 120A or the second side winding 120B.

[0014] FIG. 2 is a waveform diagram of the first power source, the second power source, and the output power source of the present disclosure. Referring to FIG. 2, the voltage waveforms of the first power source 110 and the second power source 111 have a phase difference, but this is only a rough representation and are not correlated with each other. That is, the switching control method of the present invention is primarily used to control magnetic flux, regardless of the magnitude of the phase difference. The controller 134 acquires the voltage signals V1, V2, and Vo and integrates the voltage signals V1, V2, and Vo to calculate magnetic fluxes f1 and f2 corresponding to the first power source 110 and the second power source 111, and the magnetic flux fo on the inductive device 120. Here, magnetic flux f1 is the integral of the voltage signal V1, magnetic flux f2 is the integral of the voltage signal V2, and magnetic flux fo is the integral of the voltage signal Vo. The magnetic fluxes f1 and fo coincide because the first static switch 130 is turned on, connecting the first power source 110 to the inductive device 120. Here, the integral of voltage is magnetic flux, and the integral of a sine wave remains a sine wave, so the magnetic fluxes f1, f2 and estimated magnetic flux fo remain sinusoidal waveforms.

[0015] Referring again to FIG. 1, the first static switch 130 and the second static switch 131 each include a plurality of silicon controlled rectifiers (SCRs). The first thyristor 130a and the second thyristor 130b of the first static switch 130 are connected in anti-parallel to each other, and the third thyristor 131a and the fourth thyristor 131b of the second static switch 131 are also connected in anti-parallel to each other. These thyristors 130a to 131b may be, but are not limited to, silicon controlled rectifiers (SCRs). The anodes / cathodes of the first thyristor 130a and the third thyristor 131a are arranged in the same direction, and the anodes / cathodes of the second thyristor 130b and the fourth thyristor 131b are arranged in the same direction. Therefore, the first thyristor 130a and the fourth thyristor 131b are forward biased in the same direction, and the second thyristor 130b and the third thyristor 131a are forward biased in the same direction.

[0016] The thyristors 130a-131b have a characteristic that the controller 134 cannot turn off the thyristors 130a-131b via the gate terminals when current is flowing. Therefore, the thyristors 130a-131b can only be turned off after the current naturally becomes zero or after the anode current is canceled using a forced commutation technique. Therefore, the present disclosure provides an operating method for a dual power supply switching system that operates power supply switching of a dual power supply. This operating method mainly uses four independent control signals Sc1-Sc4 to control the gate terminals. Therefore, the first static switch 130 and the second static switch 131 independently turn on the corresponding thyristors while ensuring that the total magnetic flux does not exceed a threshold during a specific switching period, thereby shortening the switching time of the power supply switching and reducing inrush current. After explaining the structural features of the present disclosure, a further explanation of the operating method will be provided later, so a detailed explanation will be omitted here.

[0017] Specifically, the controller 134 of the present disclosure selectively controls the first thyristor 130a, the second thyristor 130b, the third thyristor 131a, and the fourth thyristor 131b based on whether the supplied power source is the first power source 110 or the second power source 111. Here, the controller 134 may be used to continuously calculate in real time the magnetic fluxes f1, f2, and f0 captured by the first power source 110, the second power source 111, and the downstream inductive device 120 (which may be, for example, but is not limited to, an inductive element such as a transformer). When a power supply failure occurs (for example, but not limited to, when the first power supply 110 becomes abnormal), the controller 134 provides control signals Sc1 and Sc2, respectively, to turn off the thyristors 130a and 130b in the operating path of the first power supply 110, and provides control signals Sc3 and Sc4, respectively, to turn on the thyristors 131a and 131b in the standby path (i.e., the second power supply 111) based on the magnetic flux calculated from the currently detected voltage signals V1, V2, and Vo and according to a specific operating method designed by the present disclosure. This prevents a high inrush current from being generated in the downstream inductive device 120 due to improper switching between the two power supplies, and also prevents the output power supply from dropping to the point where it cannot maintain stable operation of the load 121 due to waiting for the current in the silicon-controlled rectifier to become zero. Here, a specific operating method designed by the present disclosure can provide step-by-step control signals Sc3 and Sc4 to turn on thyristors 131a and 131b separately, respectively (i.e., turn on only one of thyristors 131a and 131b during a specific period during commutation).

[0018] Furthermore, the controller 134 detects the first current (i.e., current signal I1) flowing through the first static switch 130 using the first current sensor 132 to determine whether the first static switch 130 is on or off. That is, the controller 134 can determine whether the first static switch 130 is turned on / off correctly based on the first current (i.e., current signal I1) to determine whether the entire dual power supply switching system 100 operates normally. Meanwhile, the controller 134 can easily determine whether the thyristors 130a and 130b are turned on / off correctly by detecting the voltages across the thyristors 130a and 130b (based on the voltage signals V1 and Vo). Meanwhile, the controller 134 can determine whether the second static switch 131 is turned on / off correctly based on the second current (i.e., current signal I2) to determine whether the entire dual power supply switching system 100 operates normally. Furthermore, by detecting the voltages across the thyristors 130a and 130b (using the voltage signals V2 and Vo), it is possible to check whether the thyristors 130a and 130b are turned on and off correctly.

[0019] In Figure 2, Φ max is the preset upper limit of magnetic flux, -Φ max is a preset lower limit magnetic flux. The main feature of the present disclosure is that after the dual power supply is switched, the magnetic flux fo of the downstream inductive device 120 becomes equal to the upper limit magnetic flux Φ max and the lower limit of magnetic flux -Φ max The purpose is to prevent the magnetic flux fo from exceeding the range, causing the inductive device 120 to be saturated and resulting in an excessive inrush current. max and lower limit magnetic flux -Φ max are all thresholds Φ thz In the present disclosure, the current magnetic flux Φ at the time when the inductive device 120 is about to switch is mainly taken as an example that the first power source 110 (i.e., the main power source) switches to the second power source 111 (i.e., the backup power source). LoadReal , and the estimated magnetic flux Φ of the second power supply 111 futureThe timing of switching the thyristors 131a and 131b is determined by acquiring and calculating the estimated magnetic flux Φ future The calculation formula is expressed by the following formula 1 or 2.

[0020]

number

[0021]

number

[0022] By calculating the above formulas 1 and 2, after switching from the first power source 110 to the second power source 111, the future magnetic flux applied to the inductive device 120 in addition to the current magnetic flux (i.e., the sum of the current magnetic flux and the future magnetic flux) is the total magnetic flux Φ all The total magnetic flux Φ all The calculation formula is as follows:

[0023]

number

[0024] Therefore, the total magnetic flux after switching Φ all is set to a threshold Φ to avoid high inrush currents in the downstream inductive device 120 due to improper switching between the two power sources. thz In view of the turn-off characteristics of the thyristors 130a to 131b, the total magnetic flux Φ all is the threshold Φ thz In addition to considering that the switching speed of the dual power supply must be smaller, it must also be considered whether a reverse bias can be provided to force the first static switch 130 to be turned off at the same time that the second static switch 131 is turned on, in order to accelerate the switching speed of the dual power supply.

[0025] FIG. 3 is a flowchart for determining the commutation time available in the dual power supply switching system of the present disclosure. Referring to FIGS. 1 and 2 together, the flowchart in FIG. 3 is primarily for determining whether the commutation time available has been reached, and primarily illustrates switching from the first power supply 110 (i.e., the main power supply) to the second power supply 111 (i.e., the backup power supply). When the commutation time available is reached, turning on the corresponding thyristors 131a and 131b provides a reverse bias to forcibly turn on the first static switch 130. Therefore, when the power supply is about to switch from the first power supply 110 to the second power supply 111, the controller 134 provides control signals Sc1 and Sc2, respectively, to control the first thyristor 130a and the second thyristor 130b to be turned off. At this time, either the first static switch 130 or the second static switch 131 may not be turned off smoothly, or both may be turned off smoothly. Therefore, the controller 134 determines whether either the first static switch 130 or the second static switch 131 is turned off or whether both are turned off based on detecting the power parameters of the first static switch 130 and the second static switch 131. This also determines whether the thyristors 130a and 130b that are not turned off have reached the commutation enable time. Here, the power parameters may be the voltage signals V1, V2, and Vo or the current signals I1 and I2.

[0026] 3, the controller 134 provides control signals Sc1 and Sc2 to turn off the first thyristor 130a and the second thyristor 130b, respectively, and then determines whether a voltage difference between the first voltage of the first power supply 110 (corresponding to the voltage signal V1) and the load voltage of the inductive device 120 (corresponding to the voltage signal Vo) is greater than a voltage threshold (S100). If the controller 134 determines that the voltage difference is greater than the voltage threshold, the two thyristors 130a and 130b of the first static switch 130 are turned off, indicating that a mismatch occurs between the power supplies received by the first power supply 110 and the inductive device 120. Therefore, the controller 134 determines that the third thyristor 131a and the fourth thyristor 131b have reached their commutation enable times (S120).

[0027] Conversely, if the determination result in step S100 is negative (NO), it means that the thyristors 130a, 130b of the first static switch 130 have not yet been turned off. Therefore, the controller 134 determines whether the first current (corresponding to the current signal I1) is greater than zero (S140). If the first current (corresponding to the current signal I1) is greater than zero, it means that the first thyristor 130a has not been turned off. Then, the controller 134 proceeds to step S160 and determines whether the second voltage (corresponding to the voltage signal V2) is greater than the load voltage of the inductive device 120 (corresponding to the voltage signal Vo). If the controller 134 determines that the second voltage (corresponding to the voltage signal V2) is greater than the load voltage of the inductive device 120 (corresponding to the voltage signal Vo), it means that the controller 134 can turn on the third thyristor 131a for a certain period thereafter to provide a reverse bias and forcibly turn off the first thyristor 130a. Therefore, the controller 134 determines that the third thyristor 131a has reached the commutation enabled time (S180). Conversely, if the determination result in step S160 is negative (No), the process returns to step S100 and continues detection and determination.

[0028] If the determination result of step S140 is negative (NO), this means that the second thyristor 130b is not turned off. Therefore, the process proceeds to step S200, where the controller 134 determines whether the second voltage (corresponding to the voltage signal V2) is smaller than the load voltage of the inductive device 120 (corresponding to the voltage signal Vo). If the controller 134 determines that the second voltage (corresponding to the voltage signal V2) is smaller than the load voltage of the inductive device 120 (corresponding to the voltage signal Vo), this means that the controller 134 can turn on the fourth thyristor 131b for a certain period thereafter to provide a reverse bias and forcibly turn off the second thyristor 130b. Therefore, the controller 134 determines that the fourth thyristor 131b has reached the commutation enable time (S220). Conversely, if the determination result of step S200 is negative (NO), the process returns to step S100 and continues detection and determination. Note that, in one embodiment, the flowchart of FIG. 3 is applicable to, but not limited to, the circuit architecture of FIG. 1. A multi-power supply switching system that can forcibly commutate by supplying a reverse bias voltage is considered to be included in the scope of this embodiment.

[0029] When the commutation time is reached, the controller 134 calculates the current magnetic flux Φ of the inductive device 120. LoadReal and the estimated magnetic flux Φ of the second power source 111 future The total magnetic flux Φ all When the commutation possible time is reached, the controller 134 calculates the total magnetic flux Φ all is the threshold Φ thz Determine whether the total magnetic flux Φ all is the threshold Φ thz , the controller 134 turns on at least one of the third thyristor 131a and the fourth thyristor 131b accordingly. That is, the controller 134 may turn on only the third thyristor 131a, only the fourth thyristor 131b, or may turn on the third thyristor 131a and the fourth thyristor 131b simultaneously. The switching timing of each thyristor will be described in detail later, so a detailed description thereof will be omitted here.

[0030] 4 is a flowchart illustrating the switching timing of the dual power supply switching system of the present disclosure. Referring to FIGS. 1-3 together, after the commutation enable time is reached, the controller 134 controls the total magnetic flux Φ all is the threshold Φ thz Therefore, the controller 134 determines the switching timing of each thyristor to avoid a situation where a high inrush current occurs in excess of the current flux Φ LoadReal and estimated magnetic flux Φ future Based on the polar k flux The polarity k can be calculated. flux The calculation formula is expressed as the following formula 4.

[0031]

number

[0032] Here, sgn is a sign function for determining the sign of a real number. Therefore, the current magnetic flux Φ LoadReal and estimated magnetic flux Φ future If the positive and negative of are the same, the polarity is positive, and if they are opposite, the polarity is negative. Since the magnetic flux calculation and switching operation of the dual power supply switching system are performed in half cycle units, the current magnetic flux Φ LoadReal is positive, and the estimated future magnetic flux Φ future If is negative, the total accumulated magnetic flux Φ all is the threshold Φ thz (Conversely, the current magnetic flux Φ LoadReal (The same applies when Sc1 is negative.) Therefore, by using the reverse bias voltage, it is possible to forcibly turn off the thyristors that are not turned off, thereby achieving the function of forcibly commutating. Therefore, in step S300 of FIG. 4, the first power supply 110 supplies power to the load 121, and the first thyristor 130a and the second thyristor 130b are turned on. Next, in step S300, the controller 134 attempts to switch the power supply from the first power supply 110 to the second power supply 111, so it provides control signals Sc1 and Sc2 to turn on the first thyristor 130a and the second thyristor 130b, respectively.

[0033] Thereafter, the determination result of any one of step S120, step S180, and step S220 in Fig. 3 is obtained. If the determination result is step S120 or step S180, the process may wait for a suitable timing and proceed to step S320 in Fig. 4. Therefore, the controller 134 determines the polarity k flux It can be determined whether the polarity k is reversed and whether the second voltage (corresponding to the voltage signal V2) is greater than zero. flux is reversed and the second voltage (corresponding to voltage signal V2) is greater than zero, the controller 134 provides a control signal Sc3 to the third thyristor 131a to turn on the third thyristor 131a and force the first thyristor 130a to turn on, while the controller 134 has not yet provided a control signal Sc4 to turn on the fourth thyristor 131b.

[0034] In step S320, the first thyristor 130a is forced off by turning on the third thyristor 131a, and the second thyristor 130b is smoothly turned on when the controller 134 provides the control signal Sc2. Therefore, the remaining fourth thyristor 131b is not yet turned on. However, to turn on the fourth thyristor 131b, the total magnetic flux Φ is increased by 1 / 2 after the fourth thyristor 131b is turned on to avoid excessive inrush current in the inductive device 120. all is the threshold Φ thz Therefore, in step S320, it is necessary to wait for a timing to turn on the fourth thyristor 131b and then proceed to step S340, in which the third thyristor 131a and the fourth thyristor 131b are turned on. That is, in step S320, the controller 134 determines whether the total magnetic flux Φ all is the threshold Φ thz and whether the second voltage (corresponding to the voltage signal V2) is less than zero. all is the threshold Φ thzIf the total magnetic flux Φ all is the threshold Φ thz Therefore, the controller 134 may turn on the third thyristor 131a and the fourth thyristor 131b independently. After turning on the third thyristor 131a, the controller 134 determines whether the second voltage (corresponding to the voltage signal V2) is smaller than zero and whether the total magnetic flux Φ is smaller than zero so as to prevent an excessively large inrush current from being generated in the inductive device 120. all is the threshold Φ thz Based on this, the fourth thyristor 131b may be turned on.

[0035] Meanwhile, the determination and operation methods from step S300 to step S360 are similar to the determination and operation mechanisms from step S300 to step S320, with the only difference being that the fourth thyristor 131b is turned on first, and the other details are the same, so a description thereof will be omitted here.Similarly, the determination and operation methods from step S360 to step S340 are similar to the determination and operation methods from step S320 to step S340, with the only difference being that the third thyristor 131a is turned on last, and the other details are the same, so a description thereof will be omitted here.

[0036] On the other hand, if a specific condition is met in step S300, the process can proceed directly to step S340 to complete the switching of the dual power supply. Specifically, if the determination result is step S120, it means that after the controller 134 provides the control signals Sc1 and Sc2 to the first thyristor 130a and the second thyristor 130b, the first thyristor 130a and the second thyristor 130b are smoothly turned off. Under this condition, the controller 134 controls the total magnetic flux Φ all is the threshold Φ thz smaller than and polar k flux The controller 134 can determine whether the total magnetic flux Φ all is the threshold Φ thzSmaller and polar k flux If it is determined that the voltages Sc3 and Sc4 are the same, the control signals Sc3 and Sc4 are simultaneously provided to the third thyristor 131a and the fourth thyristor 131b to complete the switching of the dual power sources without causing excessive inrush current to the inductive device 120. Note that in one embodiment, the flowchart of FIG. 4 is applicable to, but not limited to, the circuit architecture of FIG. 1. A multi-power source switching system that can forcibly commutate by supplying a reverse bias voltage is within the scope of this embodiment.

[0037] FIG. 5A is a flowchart showing the switching timing of the first embodiment of the dual power supply switching system of the present disclosure. FIG. 5B is a schematic waveform diagram of the first embodiment of the dual power supply switching system of the present disclosure. Referring to FIGS. 1 to 4 together, FIG. 5A shows the flow of the switching timing from step S300 to step S340 of FIG. 4, and FIG. 5B is a corresponding schematic waveform diagram. In FIG. 5B, waveform (A) includes the first voltage (corresponding to voltage signal V1) of the first power supply 110, the second voltage (corresponding to voltage signal V2) of the second power supply 111, and the load voltage (corresponding to voltage signal Vo) of the inductive device 120. Waveform (B) includes the first current (corresponding to current signal I1) of the first power supply 110 and the second current (corresponding to current signal I2) of the second power supply 111. Waveform (C) shows the total magnetic flux Φ of the inductive device 120. all Includes:

[0038] At time t1, the controller 134 determines that the third thyristor 131a and the fourth thyristor 131b have reached the commutation enable time (step S120, FIG. 3). However, the controller 134 determines that if switching is performed at this time, the total magnetic flux Φ all is the threshold Φ thz If the time reaches time t2, the controller 134 waits without switching the third thyristor 131a and the fourth thyristor 131b to determine that the total magnetic flux Φ all is the threshold Φ thzSince it is determined that V is smaller than V1, the control signals Sc3 and Sc4 are provided to turn on the third thyristor 131a and the fourth thyristor 131b, thereby switching the input source (i.e., the power supply) from the first power supply 110 to the second power supply 111, thereby completing the power supply switching operation (step S340, FIG. 4). Before time t2, the load 121 is powered by the first power supply 110, so the voltage waveform Vo is the same as the voltage waveform V1. After time t2, the load 121 is powered by the second power supply 111, so the voltage waveform Vo is the same as the voltage waveform V2.

[0039] 6A is a flowchart showing the switching timing of the second embodiment of the dual power supply switching system of the present disclosure. FIG. 6B is a schematic waveform diagram of the second embodiment of the dual power supply switching system of the present disclosure. Referring to FIGS. 1 to 5B together, waveforms (A) to (C) in FIG. 6A are the same as those in FIG. 5A, and therefore will not be described here. At time t1, the controller 134 switches polarity k flux is reversed, and the controller 134 determines that the third thyristor 131a has reached the commutation enable time (step S180, FIG. 3). Therefore, the controller 134 first provides a control signal Sc3 to turn on the third thyristor 131a. By turning on the third thyristor 131a, the first thyristor 130a is forcibly turned off (step S320, FIG. 4). At this time, the voltage waveform Vo switches from the voltage waveform V1 to the voltage waveform V2. After that, when time t2 is reached, the second voltage (corresponding to the voltage signal V2) is already smaller than zero. At this time, the controller 134 can naturally change direction and turn on the fourth thyristor 131b, but if the fourth thyristor 131b is turned on at this time, the total magnetic flux Φ all is the threshold Φ thz If the waiting time reaches t3, the controller 134 determines that the total magnetic flux Φ all is the threshold Φ thzTherefore, at time t3, the controller 134 turns on the fourth thyristor 131b to complete the power supply switching operation (step S340, FIG. 4).

[0040] The above describes in detail preferred embodiments of the present disclosure with reference to the accompanying drawings. However, it goes without saying that the present disclosure is not limited to such examples, and the scope of the present disclosure is not limited thereto. The entire scope of the present disclosure is based on the following claims. The spirit of the present disclosure and similar modifications that satisfy the claims of the present disclosure should be included in the scope of the present disclosure. Those skilled in the art can easily think of modifications and alterations within the technical scope of the present disclosure, and such modifications and alterations are also included in the scope of the following claims. [Explanation of symbols]

[0041] 100 Dual Power Switching System 120 Inductive devices 120A 1st side winding 120B 2nd side winding 121 Load 130 First static switch 130a 1st thyristor 130b Second thyristor 131 Second static switch 131a Third thyristor 131b 4th thyristor 132, 133 Current sensor 134 Controller 110 1st power supply 111 2nd power supply V1, V2, Vo voltage signals I1, I2 current signal Sc1~Sc4 control signals f1, f2, fo magnetic flux Φ max Upper limit magnetic flux -Φ max Lower limit magnetic flux Φ thz Threshold Φ LoadReal Current flux fo, Φ future Estimated Magnetic Flux Φ all Total magnetic flux k flux polarity (A)~(C) Waveform t1~t3 hours

Claims

1. 1. A dual power source switching system for selecting a first power source or a second power source to power a load connected to an inductive device, comprising: a first static switch connected to the first power source and the inductive device, the first static switch comprising a first thyristor and a second thyristor connected in anti-parallel with each other; a second static switch connected to the second power supply and the inductive device, the second static switch including a third thyristor connected in anti-parallel to each other and a fourth thyristor having a forward bias in the same sense as the first thyristor; a controller that selectively controls the first thyristor, the second thyristor, the third thyristor, and the fourth thyristor depending on whether a supply power source is the first power source or the second power source, When the power supply is switched from the first power supply to the second power supply, the controller controls the first thyristor and the second thyristor to be turned off, and determines whether a commutation enable time has been reached based on power parameters of the first static switch and the second static switch; the controller calculates a total magnetic flux based on the current magnetic flux of the inductive device and the estimated magnetic flux of the second power source, and when the commutation possible time is reached, turns on at least one of the third thyristor and the fourth thyristor in response to the total magnetic flux being less than a threshold.

2. 2. The dual power supply switching system of claim 1, wherein the power parameter includes a voltage difference, and the controller determines that the third thyristor and the fourth thyristor have reached a commutation enable time based on the voltage difference between the first voltage of the first power supply and the load voltage of the inductive device being greater than a voltage threshold.

3. 2. The dual power source switching system of claim 1, wherein the power parameters include a first current of the first power source and a second voltage of the second power source, and the controller determines that the third thyristor has reached the commutation enable time when the controller determines that the first current is greater than zero and the second voltage is greater than a load voltage of the inductive device.

4. 2. The dual power source switching system of claim 1, wherein the power parameters include a first current of the first power source and a second voltage of the second power source, and the controller determines that the fourth thyristor has reached the commutation ready time when the controller determines that the first current is less than zero and the second voltage is less than a load voltage of the inductive device.

5. 2. The dual power supply switching system of claim 1, wherein the controller calculates a polarity based on the current magnetic flux and the estimated magnetic flux, and when the commutation possible time is reached, turns on the third thyristor and forcibly turns off the first thyristor based on the polarity being reversed and the second voltage of the second power supply being greater than zero.

6. 6. The dual power supply switching system of claim 5, wherein the controller independently turns on the third thyristor and the fourth thyristor, and after turning on the third thyristor, turns on the fourth thyristor based on the second voltage being less than zero and the total magnetic flux being less than the threshold value.

7. 2. The dual power supply switching system of claim 1, wherein the controller calculates a polarity based on the current magnetic flux and the estimated magnetic flux, and when the commutation possible time is reached, turns on the fourth thyristor and forcibly turns off the second thyristor based on the polarity being reversed and the second voltage of the second power supply being less than zero.

8. 8. The dual power supply switching system of claim 7, wherein the controller independently turns on the third thyristor and the fourth thyristor, and after turning on the fourth thyristor, turns on the third thyristor based on the second voltage being greater than zero and the total magnetic flux being less than the threshold value.

9. 2. The dual power supply switching system of claim 1, wherein the controller calculates polarities based on the current magnetic flux and the estimated magnetic flux, and when the commutation possible time is reached, turns on the third thyristor and the fourth thyristor based on the polarities being the same and the total magnetic flux being less than the threshold.

10. 1. A method of operating a dual power switching system, comprising: The dual power supply switching system includes a first static switch and a second static switch connected to an inductive device, the first static switch including a first thyristor and a second thyristor connected in anti-parallel to each other, and the second static switch including a third thyristor and a fourth thyristor connected in anti-parallel to each other; The operating method includes: a step a) of controlling the first thyristor and the second thyristor to be turned off when the supply power is switched from the first power source to the second power source; b) calculating a total magnetic flux based on the current magnetic flux of the inductive device and the estimated magnetic flux of the second power source; a step c) of determining whether a commutation time has been reached based on power parameters of the first static switch and the second static switch; and (d) executing step (d1) of determining whether the total magnetic flux is smaller than a threshold value when the commutation possible time has been reached, and step (d2) of turning on at least one of the third thyristor and the fourth thyristor depending on whether the total magnetic flux is smaller than the threshold value.

11. the power parameter includes a voltage difference; The step c a step c11 of determining whether the voltage difference between the first voltage of the first power source and the load voltage of the inductive device is greater than a voltage threshold; 11. The method of claim 10, further comprising: determining that the third thyristor and the fourth thyristor have reached the commutation enable time based on the voltage difference being greater than the voltage threshold.

12. the power parameters include a first current of the first power source and a second voltage of the second power source; The step c a step c21 of determining whether the first current is greater than zero and whether the second voltage is greater than a load voltage of the inductive device; 11. The method of claim 10, further comprising: determining that the third thyristor has reached the commutation enable time based on the first current being greater than zero and the second voltage being greater than the load voltage.

13. the power parameters include a first current of the first power source and a second voltage of the second power source; The step c a step c31 of determining whether the first current is less than zero and whether the second voltage is less than a load voltage of the inductive device; 11. The method of claim 10, further comprising: determining that the fourth thyristor has reached the commutation enable time based on the first current being less than zero and the second voltage being less than the load voltage.

14. The method of claim 10 , wherein step b further comprises: calculating a polarity based on the current magnetic flux and the estimated magnetic flux.

15. When the commutation possible time is reached, a step e1 of determining whether the polarity is reversed and whether the second voltage of the second power source is greater than zero; 15. The method of claim 14, further comprising: if the polarity is reversed and the second voltage is greater than zero, turning on the third thyristor and forcing the first thyristor to be turned off.

16. After step e2, Step e3 of executing step d1 and determining whether the second voltage is less than zero; 16. The method of claim 15, further comprising: if the determination result of step d1 is positive and the second voltage is less than zero, turning on the fourth thyristor.

17. When the commutation possible time is reached, a step f1 of determining whether the polarity is reversed and whether the second voltage of the second power source is less than zero; 15. The method of claim 14, further comprising: if the polarity is reversed and the second voltage is less than zero, turning on the fourth thyristor and forcing the second thyristor to be off.

18. After step f2, Step f3 executes step d1 and determines whether the second voltage is greater than zero; 18. The method of claim 17, further comprising: a step f4 of turning on the third thyristor when the determination result of step d1 is positive and the second voltage is greater than zero.

19. When the commutation possible time is reached, Step g1 of executing step d1 and determining whether the polarities are the same; 15. The method for operating a dual power supply switching system according to claim 14, further comprising: if the determination result of step d1 is positive and the polarities are the same, step g2 of turning on the third thyristor and the fourth thyristor.

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