Dual-power-supply switchable test circuit, equipment and method

Abstract

The invention discloses a double-power-supply switchable test circuit, device and method, and the circuit comprises a main power supply network and an auxiliary power supply network which are respectively used for outputting AC power supplies VS1 and VS2 with the same frequency and phase; the first solid-state switch S1 and the second solid-state switch S2 are respectively used for controlling the on-off of the main power supply network and the auxiliary power supply network, each group of solid-state switches comprises fully-controlled power electronic elements which are reversely connected in series, and a fast recovery diode is arranged in each power electronic element; the control unit is connected to the first solid-state switch S1 and the second solid-state switch S2 and is used for controlling the on-off of the first solid-state switch S1 and the second solid-state switch S2 so as to quickly switch between the main power supply network and the auxiliary power supply network; and the load power supply end is connected to the output ends of the first solid-state switch S1 and the second solid-state switch S2 and is used for being connected with a tested load. The invention provides a double-power-supply switchable test circuit, equipment and a control method thereof, which have the characteristics of quick response, safety and reliability, and can effectively simulate the abnormal condition of instantaneous voltage drop of a power grid.

Description

Technical Field

[0001] The invention relates to a test circuit, and in particular to a dual-power supply switchable test circuit, device and method. Background Art

[0002] In the immunity test of electrical equipment, the test device needs to be able to simulate abnormal conditions of the power grid to evaluate the response ability of the electrical equipment when the power supply network fails or is abnormal. The "IEC 61000-4-11" standard issued by the International Electrotechnical Commission (IEC) clearly stipulates that the test device needs to have specific performance requirements when conducting tests such as voltage drop, short interruption and voltage gradient. These tests are widely applicable to the mains system powered by 50 / 60Hz sinusoidal AC.

[0003] In the IEC 61000-4-11 standard, voltage dips refer to a phenomenon in which the voltage at a certain phase angle (such as 90° or 270°) of the power grid suddenly drops and then returns to normal after a short period of time (ts). In order to accurately simulate this situation, the standard requires that the rise and fall time of voltage drop and recovery must be completed within 1 to 5 microseconds (μs), and that the power frequency and phase must be synchronized during the switching process.

[0004] Current technical means, such as thyristors (SCR) and mechanical switches, are difficult to complete the rapid switching of dual power supplies within microseconds. Although traditional transformer methods or power conversion technologies can achieve basic power switching, there are often long delay times and current mutations at the moment of voltage drop or recovery. The series short circuit caused by this delay and mutation will bring transient short-circuit current, increase the risk of damage to electrical equipment and test equipment, and cannot meet the requirements of the IEC 61000-4-11 standard.

[0005] Therefore, a new type of test device is needed that can quickly and safely switch dual power supplies when the voltage drops and recovers, avoid transient short circuit problems, and meet microsecond response requirements. This requirement prompted us to design a dual power switchable test device using solid-state switching technology. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a dual-power supply switchable test circuit, device and method.

[0007] The technical problem to be solved by the present invention is achieved by adopting the following technical solutions:

[0008] The present invention provides a dual-power supply switchable test circuit, comprising:

[0009] The main power supply network and the auxiliary power supply network are used to output AC power supplies VS1 and VS2 with the same frequency and phase respectively;

[0010] The first solid-state switch S1 and the second solid-state switch S2 are used to control the on and off of the main power supply network and the auxiliary power supply network respectively, and each group of solid-state switches includes fully controlled power electronic components connected in reverse series, and each power electronic component has a built-in fast recovery diode;

[0011] A control unit, connected to the first solid-state switch S1 and the second solid-state switch S2, for controlling the on and off of the two to quickly switch between the main power supply network and the secondary power supply network;

[0012] The load power supply end is connected to the output ends of the first solid-state switch S1 and the second solid-state switch S2 and is used to connect the load to be measured.

[0013] As a preferred technical solution of the present invention,

[0014] The first solid-state switch S1 includes a first power electronic component Q1 and a second power electronic component Q2, which are connected in anti-series, and each power electronic component has a built-in fast recovery diode D1 and D2;

[0015] The second solid-state switch S2 includes a third power electronic component Q3 and a fourth power electronic component Q4, which are connected in anti-series, and each power electronic component has a built-in fast recovery diode D3 and D4.

[0016] As a preferred technical solution of the present invention, the fully-controlled power electronic element includes one of an IGBT or a MOSFET tube.

[0017] As a preferred technical solution of the present invention, the control unit is configured to monitor the voltage and current of the load power supply end, and control the on and off of the first solid-state switch S1 and the second solid-state switch S2 according to the instantaneous value of the voltage and the load current.

[0018] As a preferred technical solution of the present invention, it also includes a current magnetic ring for real-time monitoring of the load current between the load power supply end and the load being measured, and feeding back the current signal to the control unit.

[0019] As a preferred technical solution of the present invention, the control unit executes a switching algorithm, which calculates the turn-on delay rise time (TdlyRise), the turn-off delay fall time (TdlyFall) and the switching compensation time (Tc) based on the parameters of the fully controlled power electronic components, the power synchronization signal, the switching phase angle Θsw, the switching phase moment Tsw, the load transient current i and the switching voltage instantaneous values ​​u1 and u2, so as to control the power output time characteristics of the switching process.

[0020] The present invention also provides a dual-power switchable test device, which has the aforementioned dual-power switchable circuit, and is used to simulate power switching under abnormal conditions of the power grid to test the anti-interference performance of the load under test;

[0021] The present invention also provides a dual-power switchable method, which can be executed in the aforementioned dual-power switchable circuit or a dual-power switchable device, comprising the following steps:

[0022] Step 1: Start the test device, the control unit enables the first solid-state switch, disables the second solid-state switch, and the main power supply network supplies power to the load under test;

[0023] Step 2: Detect the voltage and current values ​​of the load power supply end, and calculate the turn-on delay rise time (TdlyRise) and turn-off delay fall time (TdlyFall) according to the switching phase angle, transient current and voltage difference;

[0024] Step 3: According to the calculated on and off delays, switching from the main power supply network to the secondary power supply network or from the secondary power supply network to the main power supply network is performed;

[0025] in,

[0026] When performing power switching, the switching compensation time (Tc) is calculated based on the switching algorithm, where Tc = Tsw-TdlyRise+TdlyFall. When Tc is a negative value, Tc is corrected to 0; when the voltage drops, if TdlyFall>5μs, TdlyFall is set to 5μs; when the voltage recovers, if TdlyRise<1μs, Tc = Tsw+1μs, if TdlyRise>5μs, Tc = Tsw-(TdlyRise-1μs);

[0027] The opening delay rise time (TdlyRise) is calculated by the following formula:

[0028] TdlyRise=ΔTrise+TdelayON, where Δu=u2-0 when switching due to voltage drop; Δu=u1-u2 when switching due to voltage recovery, and ΔTrise=|Δu|*Krise;

[0029] The turn-off delay fall time (TdlyFall) is calculated by the following formula:

[0030] TdlyFall=ΔTfall+TdelayOFF, where Δu=u1-u2 when the voltage drops and switches; Δu=u2-0 when the voltage recovers and switches, and ΔTfall=|Δu|*Kfall;

[0031] The calculation formula of the slope K is:

[0032] Krise=(Trise-[i(Trise-Tmin) / (Id-Imin)]) / Vds or

[0033] Kfall=(Tfall-[i(Tfall-Tmin) / (Id-Imin)]) / Vds;

[0034] Among them, Trise and Tfall are the rise and fall time of the power electronic components, Vce is the CE (DS) inter-electrode withstand voltage parameter, i is the transient current, Ic is the rated current, Trisemin and Tfallmin are the minimum values ​​of the rise and fall time.

[0035] Preferably, during the switching process, when calculating the switching compensation time Tc, if TdlyFall>5μs when the voltage drops, TdlyFall is reset to 5μs;

[0036] When the voltage recovers, if TdlyRise<1μs, Tc is set to Tsw+1μs; if TdlyRise>5μs, Tc is set to Tsw-(TdlyRise-1μs).

[0037] Further preferably, the switching phase moment Tsw is calculated by the following formula:

[0038] Where Θsw is the switching phase angle, and f is the frequency of the AC power supply;

[0039] The monitoring time of the transient current i is Tsw-1 / f, that is, the time Tsw of the power cycle before the current switching.

[0040] The beneficial effects of the present invention are:

[0041] The present invention provides a dual-power switchable test circuit, device and control method thereof, which has the characteristics of fast response, safety and reliability, and can effectively simulate the abnormal situation of instantaneous voltage drop of the power grid. The specific beneficial effects of the invention include the following points:

[0042] Efficient switching to meet microsecond response requirements: By using fully controlled power electronic components (such as IGBT) in reverse series, fast switching of the main and auxiliary power supply networks is achieved. The control unit can complete voltage rise or fall within 1-5 microseconds, fully complying with the requirements of the IEC 61000-4-11 standard, ensuring simulation of real voltage fluctuations under abnormal grid conditions.

[0043] Prevent transient short circuit and improve safety: The present invention calculates the turn-on delay and turn-off delay through a unique control algorithm, and automatically adjusts the compensation time (Tc) during switching, effectively avoiding transient short circuit when switching between two power supplies. The design of the anti-parallel fast recovery diode also enhances the protection function during power switching, so that the circuit does not experience current mutations during rapid switching.

[0044] Monitor the load status in real time to ensure test accuracy: connect a current magnetic ring in series at the load end, monitor the instantaneous values ​​of the load current and voltage in real time through the control unit, and accurately control the on and off of the solid-state switch by combining the switching phase angle and transient current to ensure a smooth switching process and that the load voltage waveform meets standard requirements.

[0045] Intelligent delay adjustment to adapt to various test scenarios: The control algorithm can calculate the slope K based on parameters such as the switching phase angle and transient current, and further calculate the turn-on and turn-off delays. By setting the upper and lower limits of the delay (such as limiting TdlyRise and TdlyFall when the voltage drops and recovers), accurate switching can be achieved under different load current conditions, effectively improving the adaptability of the system.

[0046] Simple structure and easy implementation: The modular design is adopted to integrate the main power supply network, the auxiliary power supply network, the solid-state switch and the control unit into the test circuit, and the control method is simple and efficient. Compared with the traditional mechanical switch or thyristor solution, the structure of the present invention is more compact and has a faster response speed, and can be better applied to the anti-interference test device.

[0047] The present invention not only realizes fast and safe switching of power supply, but also effectively improves the reliability and adaptability of the test device, and provides an efficient and accurate test solution for the immunity test of electrical equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is a circuit diagram of the present invention;

[0049] Figure 2 It is a schematic diagram of the process of the present invention; Figure 3 It is a schematic diagram of dynamic characteristics (load-time characteristics);

[0050] In the figure: 1. main power supply network; 2. auxiliary power supply network; 3. first solid-state switch S1; 4. second solid-state switch S2; 5. control unit; 6. load power supply terminal; 7. measured load; 8. current magnetic ring. DETAILED DESCRIPTION

[0051] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0052] Example 1

[0053] like Figure 1-3 As shown, this embodiment provides a dual-power switchable test circuit, including:

[0054] The main power supply network 1 and the auxiliary power supply network 2 are used to output AC power supplies VS1 and VS2 with the same frequency and phase respectively;

[0055] The first solid-state switch S1 (labeled 3) and the second solid-state switch S2 (labeled 4) are used to control the on and off of the main power supply network 1 and the auxiliary power supply network 2 respectively. Each group of solid-state switches includes fully controlled power electronic components connected in reverse series, and each power electronic component has a built-in fast recovery diode;

[0056] A control unit 5, connected to the first solid-state switch S1 and the second solid-state switch S2, for controlling the on and off of the first solid-state switch S1 and the second solid-state switch S2, so as to quickly switch between the main power supply network 1 and the secondary power supply network 2;

[0057] The load power supply terminal 6 is connected to the output terminals of the first solid-state switch S1 and the second solid-state switch S2 and is used to connect to the load 7 under test.

[0058] Specifically, the first solid-state switch S1 includes a first power electronic component Q1 and a second power electronic component Q2, which are connected in anti-series, and each power electronic component has built-in fast recovery diodes D1 and D2; the second solid-state switch S2 includes a third power electronic component Q3 and a fourth power electronic component Q4, which are connected in anti-series, and each power electronic component has built-in fast recovery diodes D3 and D4.

[0059] The fully controlled power electronic component includes one of an IGBT or a MOSFET tube; specifically, the fully controlled power electronic component includes one of an IGBT or a MOSFET tube. These components have good switching characteristics and high switching speeds, and are suitable for fast switching control of AC power supplies. In the present invention, the purpose of selecting fully controlled power electronic components is to ensure fast switching between the main power supply network and the auxiliary power supply network in microseconds, avoiding the shortcomings of traditional switching devices in response speed. IGBT (insulated gate bipolar transistor) has low conduction loss and high withstand voltage characteristics, and is suitable for higher voltage application scenarios; MOSFET tube (metal oxide semiconductor field effect transistor) is suitable for occasions that require frequent switching due to its higher switching frequency. Therefore, the present invention can select IGBT or MOSFET tube as a fully controlled power electronic component according to different application requirements to achieve efficient and safe switching of dual power supplies.

[0060] The control unit 5 is configured to monitor the voltage and current of the load power supply terminal 6, and control the on and off of the first solid-state switch S1 and the second solid-state switch S2 according to the instantaneous value of the voltage and the load current.

[0061] It also includes a current magnetic ring 8 for real-time monitoring of the load current between the load power supply terminal 6 and the load under test 7 and feeding back the current signal to the control unit 5 .

[0062] Preferably, the control unit 5 executes a switching algorithm, which calculates the turn-on delay rise time (TdlyRise), the turn-off delay fall time (TdlyFall) and the switching compensation time (Tc) based on the parameters of the fully controlled power electronic components, the power synchronization signal, the switching phase angle Θsw, the switching phase moment Tsw, the load transient current i and the switching voltage instantaneous values ​​u1 and u2, so as to control the power output time characteristics of the switching process.

[0063] Specifically, in the circuit implementation process of the present invention, the main power supply network and the auxiliary power supply network respectively output AC power supplies (VS1 and VS2) of the same frequency and phase, and the two power supplies are quickly switched by the control unit. The output ends of the main power supply network and the auxiliary power supply network are respectively connected to the first solid-state switch (S1) and the second solid-state switch (S2), wherein each solid-state switch is composed of a fully controlled power electronic element (such as an IGBT or MOSFET tube) connected in reverse series, and a fast recovery diode is built in to provide a fast response and short-circuit protection function during the power switching process. The control unit monitors the voltage and current signals at the load end in real time, and dynamically calculates the opening delay and the closing delay through the switching algorithm according to the parameters such as the instantaneous value of the voltage, the switching phase angle and the transient current, so as to accurately control the on and off of the solid-state switch. The load power supply end is connected to the load to be measured. When the voltage of the main power supply network or the auxiliary power supply network drops or recovers, the control unit performs a smooth switching of the power supply according to the calculated delay compensation time (Tc), ensuring that the voltage waveform at the load end meets the requirements of the IEC 61000-4-11 standard. Through the circuit design, the present invention can realize the safe switching of dual power supplies within microseconds, avoid transient short circuits and meet the strict standards of anti-interference testing.

[0064] Example 2

[0065] This embodiment provides a dual-power switchable test device, which has a dual-power switchable test circuit in Embodiment 1.

[0066] Specifically, the device is used to simulate power switching under abnormal conditions of the power grid to test the anti-interference ability of the load 7 under test.

[0067] Example 3

[0068] This embodiment provides a dual-power switchable test method, which can be executed in a dual-power switchable test circuit in Embodiment 1 or a dual-power switchable test device in Embodiment 2, including the following steps:

[0069] Step 1: Start the test device, the control unit 5 enables the first solid-state switch S1, disables the second solid-state switch S2, and the main power supply network 1 supplies power to the load 7 under test;

[0070] Step 2: Detect the voltage and current values ​​of the load power supply terminal 6, and calculate the turn-on delay rise time (TdlyRise) and the turn-off delay fall time (TdlyFall) according to the switching phase angle, transient current and voltage difference;

[0071] Step 3: According to the calculated on and off delays, switching from the main power supply network 1 to the secondary power supply network 2 or switching from the secondary power supply network 2 to the main power supply network 1 is performed;

[0072] in,

[0073] When performing power switching, the switching compensation time (Tc) is calculated based on the switching algorithm, where Tc = Tsw-TdlyRise+TdlyFall. When Tc is a negative value, Tc is corrected to 0; when the voltage drops, if TdlyFall>5μs, TdlyFall is set to 5μs; when the voltage recovers, if TdlyRise<1μs, Tc = Tsw+1μs, if TdlyRise>5μs, Tc = Tsw-(TdlyRise-1μs);

[0074] The opening delay rise time (TdlyRise) is calculated by the following formula:

[0075] TdlyRise=ΔTrise+TdelayON, where Δu=u2-0 when switching due to voltage drop; Δu=u1-u2 when switching due to voltage recovery, and ΔTrise=|Δu|*Krise;

[0076] The turn-off delay fall time (TdlyFall) is calculated by the following formula:

[0077] TdlyFall=ΔTfall+TdelayOFF, where Δu=u1-u2 when the voltage drops and switches; Δu=u2-0 when the voltage recovers and switches, and ΔTfall=|Δu|*Kfall;

[0078] The calculation formula of the slope K is:

[0079] Krise=(Trise-[i(Trise-Tmin) / (Id-Imin)]) / Vds or

[0080] Kfall=(Tfall-[i(Tfall-Tmin) / (Id-Imin)]) / Vds;

[0081] Among them, Trise and Tfall are the rise and fall time of the power electronic components, Vds is the DS(ce) inter-electrode test voltage parameter, i is the transient current, Trisemin and Tfallmin are the corresponding values ​​of the minimum operating current Id of the rise and fall time.

[0082] Furthermore, during the switching process, when calculating the switching compensation time Tc, if TdlyFall>5μs when the voltage drops, TdlyFall is reset to 5μs;

[0083] When the voltage recovers, if TdlyRise<1μs, Tc is set to Tsw+1μs; if TdlyRise>5μs, Tc is set to Tsw-(TdlyRise-1μs).

[0084] Specifically, the switching phase moment Tsw is calculated by the following formula:

[0085] Where Θsw is the switching phase angle, and f is the frequency of the AC power supply;

[0086] The monitoring time of the transient current i is Tsw-1 / f, that is, the time Tsw of the power cycle before the current switching.

[0087] Regarding the above formulas and calculations, ΔTrise represents the change in voltage rise time, Δu is the voltage difference, Krise is the slope related to the characteristics of the power electronic component, TdelayON represents the turn-on delay of the power electronic component, which is the time required for the component to actually turn on from receiving the turn-on signal; u1 represents the instantaneous value of the voltage of the main power supply network, and u2 represents the instantaneous value of the voltage of the secondary power supply network; ΔTfall represents the change in voltage fall time; TdelayOFF represents the turn-off delay of the power electronic component, which is the time required for the component to actually turn off from receiving the turn-off signal; Kfall represents the slope parameter related to the voltage drop process, which is used to calculate the change in voltage drop time, and the specific value is determined according to the characteristics of the power electronic component.

[0088] The typical implementation process is as follows:

[0089] First, the test device is started, and the control unit enables the first solid-state switch of the main power supply and disables the second solid-state switch of the auxiliary power supply, so that the main power supply network supplies power to the load under test. Then, the control unit detects the voltage and current values ​​of the load power supply end, and calculates the turn-on delay (TdlyRise) and the turn-off delay (TdlyFall) according to the switching phase angle, transient current and voltage difference. According to the calculated turn-on and turn-off delays, the switch from the main power supply network to the auxiliary power supply network or from the auxiliary power supply network to the main power supply network is performed. During the switching process, the switching compensation time Tc is calculated based on the switching algorithm, and if Tc is a negative value, it is corrected to 0; when the voltage drops, TdlyFall is limited to 5μs, and when the voltage recovers, Tc is adjusted to 1μs or the excess part is subtracted according to the conditions. The turn-on delay and the turn-off delay are calculated according to the voltage difference Δu and the slope K of the transient current i, respectively, where K is determined by the parameters of the power electronic components. The switching phase moment Tsw is calculated by the switching phase angle and the power supply frequency, and the transient current is collected at the Tsw moment of the previous cycle to ensure the accuracy and stability of the switching.

[0090] A typical calculation process is as follows:

[0091] Known conditions:

[0092] According to a transistor data sheet, under the conditions of Tj = 25°C, main control output drive signal (Vgs = 13V) to gate, continuous current Id = 47A, Vds = 380V, the typical values ​​of dynamic characteristics are:

[0093] Turn-on delay time (tdon delay channel opening) is 18ns; Rise time (tr turn-on current rise time) is 27ns; Turn-off delay time (tdoff delay channel pinch-off) is 111ns; Fall time (tf pinch-off current fall time) is 8ns;

[0094] Its dynamic characteristic diagram (load-time characteristic) is as follows Figure 3 As shown, specifically, Td(on) is approximately constant at 17ns; Td(off) is approximately 215-[i(215-130) / (50-5)]=215-1.9*i(ns); Tr is approximately 2+[i(10-2) / (50-5)]=2+0.17*i(ns);

[0095] Tf(i<20A) is approximately 40-[i(40-10 / 20)]=40-1.5*i(ns); Tf(i>20A) is approximately constant at 9ns;

[0096] The following is a calculation example:

[0097] The load under test is a 10 ohm resistor, the peak value of the main power supply network is 300V, and the peak value of the auxiliary power supply network is 100V; the drop phase angle is set to 90°, the recovery phase angle is 150°; the drop duration is 1 second;

[0098] The device starts and the calculation process is as follows:

[0099] 1. Measure the instantaneous current i=30A when the voltage phase of the main power supply network is 90°.

[0100] 2. Δu = 200V;

[0101] 3. Kfall = 9 / 380 = 0.02ns / V;

[0102] 4. ΔTfall = 200*0.02 = 4ns;

[0103] 5. Tdlyfall = ΔTfall + TdelayOFF = 4 + (215-1.9*30) = 162ns;

[0104] 6. Δu = 100V;

[0105] 7. Krise = (27 / 380) * (40-0) = 2.85ns / V;

[0106] 8. ΔTrise = 100*2.85 = 285ns;

[0107] 9. TdlyRise = ΔTrise + TdelayON = 285 + 17 = 302ns;

[0108] 10. Because TdlyRise<1us, Tc=Tsw+1=5001us;

[0109] The recovery voltage triggering time is calculated according to the above principle.

[0110] The present invention provides a dual-power switchable test circuit, device and control method thereof, which has the characteristics of fast response, safety and reliability, and can effectively simulate the voltage instantaneous drop, short-term interruption and voltage gradient phenomenon under abnormal conditions of the power grid. The specific beneficial effects of the invention include the following points:

[0111] Efficient switching to meet microsecond response requirements: By using fully controlled power electronic components (such as IGBT) in reverse series, fast switching of the main and auxiliary power supply networks is achieved. The control unit can complete voltage rise or fall within 1-5 microseconds, fully complying with the requirements of the IEC 61000-4-11 standard, ensuring simulation of real voltage fluctuations under abnormal grid conditions.

[0112] Prevent transient short circuit and improve safety: The present invention calculates the turn-on delay and turn-off delay through a unique control algorithm, and automatically adjusts the compensation time (Tc) during switching, effectively avoiding transient short circuit when switching between two power supplies. The design of the anti-parallel fast recovery diode also enhances the protection function during power switching, so that the circuit does not experience current mutations during rapid switching.

[0113] Monitor the load status in real time to ensure test accuracy: connect a current magnetic ring in series at the load end, monitor the instantaneous values ​​of the load current and voltage in real time through the control unit, and accurately control the on and off of the solid-state switch by combining the switching phase angle and transient current to ensure a smooth switching process and that the load voltage waveform meets standard requirements.

[0114] Intelligent delay adjustment to adapt to various test scenarios: The control algorithm can calculate the slope K based on parameters such as the switching phase angle and transient current, and further calculate the turn-on and turn-off delays. By setting the upper and lower limits of the delay (such as limiting TdlyRise and TdlyFall when the voltage drops and recovers), accurate switching can be achieved under different load current conditions, effectively improving the adaptability of the system.

[0115] Simple structure and easy implementation: The modular design is adopted to integrate the main power supply network, the auxiliary power supply network, the solid-state switch and the control unit into the test circuit, and the control method is simple and efficient. Compared with the traditional mechanical switch or thyristor solution, the structure of the present invention is more compact and has a faster response speed, and can be better applied to the anti-interference test device.

[0116] The present invention not only realizes fast and safe switching of power supply, but also effectively improves the reliability and adaptability of the test device, and provides an efficient and accurate test solution for the immunity test of electrical equipment.

[0117] The basic principles, main features and advantages of the present invention are shown and described above. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A dual-power switchable test circuit, characterized in that: include: The main power supply network (1) and the auxiliary power supply network (2) are used to output AC power supplies VS1 and VS2 with the same frequency and phase, respectively; A first solid-state switch S1 (3) and a second solid-state switch S2 (4), respectively used to control the on and off of the main power supply network (1) and the secondary power supply network (2), each group of solid-state switches comprises fully controlled power electronic components connected in reverse series, and each power electronic component has a built-in fast recovery diode; A control unit (5), connected to the first solid-state switch S1 (3) and the second solid-state switch S2 (4), for controlling the on and off of the two solid-state switches, so as to quickly switch between the main power supply network (1) and the secondary power supply network (2); The load power supply terminal (6) is connected to the output terminals of the first solid-state switch S1 (4) and the second solid-state switch S2 (5), and is used to connect to the load to be measured (7).

2. A dual-power switchable test circuit according to claim 1, characterized in that: The first solid-state switch S1 (3) comprises a first power electronic component Q1 and a second power electronic component Q2, which are connected in anti-series, and each power electronic component has a built-in fast recovery diode D1 and D2; The second solid-state switch S2 (4) includes a third power electronic component Q3 and a fourth power electronic component Q4, which are connected in anti-series, and each power electronic component has a built-in fast recovery diode D3 and D4.

3. A dual-power switchable test circuit according to claim 1, characterized in that: The fully controlled power electronic element includes one of an IGBT or a MOSFET tube.

4. A dual-power switchable test circuit according to claim 1, characterized in that: The control unit (5) is configured to monitor the voltage and current of the load power supply terminal (6), and control the on and off of the first solid-state switch S1 (3) and the second solid-state switch S2 (4) according to the instantaneous value of the voltage and the load current.

5. A dual-power switchable test circuit according to claim 1, characterized in that: It also includes a current magnetic ring (8) for real-time monitoring of the load current between the load power supply terminal (6) and the measured load (7), and feeding back the current signal to the control unit (5).

6. A dual-power switchable test circuit according to claim 1, characterized in that: The control unit (5) executes a switching algorithm, which calculates a turn-on delay rise time (TdlyRise), a turn-off delay fall time (TdlyFall) and a switching compensation time (Tc) based on the parameters of the fully controlled power electronic components, the power synchronization signal, the switching phase angle Θsw, the switching phase moment Tsw, the load transient current i and the switching voltage instantaneous values ​​u1 and u2, so as to control the power output time characteristics of the switching process.

7. A dual-power switchable test device, comprising a dual-power switchable test circuit as claimed in any one of claims 1 to 6, characterized in that: The device is used to simulate power switching under abnormal power grid conditions to test the anti-interference ability of the load under test (7).

8. A dual-power switchable test method, which can be executed in a dual-power switchable test circuit or a dual-power switchable test device as claimed in any one of claims 1 to 7, characterized in that: The steps include: Step 1: Start the test device, the control unit (5) enables the first solid-state switch S1 (3), disables the second solid-state switch S2 (4), and supplies power to the load under test (7) from the main power supply network (1); Step 2: Detecting the voltage and current values ​​of the load power supply terminal (6), and calculating the turn-on delay rise time (TdlyRise) and the turn-off delay fall time (TdlyFall) according to the switching phase angle, the transient current and the voltage difference; Step 3: According to the calculated on and off delays, switching from the main power supply network (1) to the secondary power supply network (2) or switching from the secondary power supply network (2) to the main power supply network (1) is performed; in, When performing power switching, the switching compensation time (Tc) is calculated based on the switching algorithm, where Tc = Tsw-TdlyRise+TdlyFall. When Tc is a negative value, Tc is corrected to 0; During the switching process, when calculating the switching compensation time Tc, when the voltage drops, if TdlyFall>5μs, TdlyFall is set to 5μs; when the voltage recovers, if TdlyRise<1μs, Tc=Tsw+1μs, if TdlyRise>5μs, Tc=Tsw-(TdlyRise-1μs).

9. A dual-power switchable test method according to claim 8, characterized in that: The opening delay rise time (TdlyRise) is calculated by the following formula: TdlyRise=ΔTrise+TdelayON, where Δu=u2-0 when switching due to voltage drop; Δu=u1-u2 when switching due to voltage recovery, and ΔTrise=|Δu|*Krise; The turn-off delay fall time (TdlyFall) is calculated by the following formula: TdlyFall=ΔTfall+TdelayOFF, where Δu=u1-u2 when the voltage drops and switches; Δu=u2-0 when the voltage recovers and switches, and ΔTfall=|Δu|*Kfall; The calculation formula of the slope K is: Krise=(Trise-[i(Trise-Tmin) / (Id-Imin)]) / Vds or Kfall=(Tfall-[i(Tfall-Tmin) / (Id-Imin)]) / Vds; Among them, Trise and Tfall are the rise and fall time of the power electronic components, Vce is the CE (DS) inter-electrode withstand voltage parameter, i is the transient current, Ic is the rated current, Trisemin and Tfallmin are the minimum values ​​of the rise and fall time.

10. A dual-power switchable test method according to claim 8, characterized in that: The switching phase moment Tsw is calculated by the following formula: Where Θsw is the switching phase angle, and f is the frequency of the AC power supply; The monitoring time of the transient current i is Tsw-1 / f, that is, the time Tsw of the power cycle before the current switching.

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