Dual-power-supply switchable test circuit and equipment

Abstract

The utility model discloses a double-power-supply switchable test circuit and equipment, and the test 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 double-power-supply switchable test circuit and equipment provided by the utility model 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 utility model relates to a test circuit, especially in a kind of two-way power switchable test circuit and equipment. BACKGROUND

[0002] In the immunity test of electrical equipment, test device needs to be able to simulate power grid abnormal situation, to evaluate the response capability of electrical equipment when power supply network appears fault or abnormality. The standard of IEC 61000-4-11 published by International Electrotechnical Commission (IEC) clearly stipulates that when voltage transient dip, short-time interruption and voltage gradual change test is carried out, test device needs to have specific performance requirements. These tests are widely applicable to 50 / 60Hz sinusoidal ac power supply of mains system.

[0003] Under the standard of IEC 61000-4-11, voltage transient dip (Voltage Dips) refers to the phenomenon that the voltage at a certain phase angle (such as 90° or 270°) of power grid suddenly drops and then restores to normal after a short time (ts). In order to accurately simulate this situation, the standard requires that the rise and fall time of voltage dip and recovery needs to be completed within 1 to 5 microseconds (μs), and requires that the power frequency and phase remain synchronous during switching process.

[0004] Current technical means, such as thyristor (SCR) and mechanical switch, are difficult to complete the rapid switching of two-way power supply within microsecond level time. Although the traditional transformation mode or power conversion technology can realize basic power switching, there is often a long delay time and current mutation phenomenon in the moment of voltage dip or recovery. The delay and mutation caused by the short circuit in series will bring transient short-circuit current, increase the damage risk of electrical equipment and test device, and cannot meet the requirements of IEC 61000-4-11 standard.

[0005] Therefore, a new type of test device is needed, which can quickly and safely switch two-way power supply when voltage transient dip and recovery, avoid transient short-circuit problem, and meet the response requirement of microsecond level. This demand prompts us to design a two-way power switchable test device using solid-state switching technology. UTILITY MODEL CONTENT

[0006] The technical problem to be solved by the utility model lies in: provide a two-way power switchable test circuit and equipment.

[0007] The technical problem to be solved by the utility model adopts the following technical scheme to realize:

[0008] The utility model provides a two-way power switchable test circuit, comprising:

[0009] A main power supply network and a secondary power supply network are respectively used for outputting alternating current power VS1 and VS2 of the same frequency and phase;

[0010] A first solid-state switch S1 and a second solid-state switch S2 are respectively used for controlling the on-off of the main power supply network and the secondary power supply network, each group of solid-state switches comprises full-controlled power electronic elements in anti-series connection, and each power electronic element is internally provided with a fast recovery diode;

[0011] A 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 two to quickly switch between the main power supply network and the secondary power supply network;

[0012] A 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 connecting a measured load.

[0013] As a preferred technical scheme of the utility model,

[0014] The first solid-state switch S1 comprises a first power electronic element Q1 and a second power electronic element Q2, which are connected in anti-series connection, and each power electronic element is internally provided with a fast recovery diode D1 and D2;

[0015] The second solid-state switch S2 comprises a third power electronic element Q3 and a fourth power electronic element Q4, which are connected in anti-series connection, and each power electronic element is internally provided with a fast recovery diode D3 and D4.

[0016] As a preferred technical scheme of the utility model, the full-controlled power electronic element comprises one of IGBT or MOSFET tube.

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

[0018] As a preferred technical scheme of the utility model, it further comprises a current magnetic ring, which is used for monitoring the load current between the load power supply end and the measured load in real time, and feeding back the current signal to the control unit.

[0019] As a preferred technical scheme of the utility model, the control unit executes a switching algorithm, which is based on the full-controlled power electronic element parameters, the power supply synchronization signal, the switching phase angle Θsw, the switching phase moment Tsw, the load transient current i and the switching voltage instantaneous value u1 and u2, calculates the turn-on delay rise time (TdlyRise), the turn-off delay fall time (TdlyFall) and the switching compensation duration (Tc), so as to control the power output time characteristic of the switching process.

[0020] The utility model also provides a kind of double-path power supply switchable test equipment, with the double-path power supply switchable circuit of preceding, for being equipped with the double-path power supply switching component under the condition of simulating abnormal power grid;

[0021] The utility model has the advantages that:

[0022] The utility model provides a kind of double-path power supply switchable test circuit and equipment, with the characteristics of fast response, safe and reliable, can effectively simulate voltage transient drop, short-time interruption and voltage gradual change phenomenon under abnormal power grid condition.The specific beneficial effects of the utility model include the following points:

[0023] Efficient switching meets microsecond-level response requirements: by adopting reverse series full-controlled power electronic components (such as IGBT), the fast switching of main and auxiliary power supply networks is realized.The control unit can complete voltage rise or drop within 1-5 microseconds, fully meets the requirements of IEC 61000-4-11 standard, and ensures to simulate real voltage fluctuation under abnormal power grid condition.

[0024] Prevent transient short circuit and improve safety: the utility model calculates turn-on delay and turn-off delay through unique control algorithm, and automatically adjusts compensation duration (Tc) when switching, effectively avoids transient short circuit phenomenon when two-way power supply switches.The design of reverse-parallel fast recovery diode also enhances the protection function when power supply switches, so that the circuit does not appear current mutation while fast switching.

[0025] Real-time monitoring of load state ensures test accuracy: current magnetic ring is connected in series at load end, load current and voltage instantaneous value are monitored in real time by control unit, switching phase angle and transient current are combined to accurately control on-off of solid-state switch, ensure smooth switching process, and load voltage waveform meets standard requirements.

[0026] Intelligent delay adjustment adapts to various test scenarios: control algorithm can calculate slope K according to switching phase angle and transient current, and further calculate turn-on and turn-off delay.By setting upper and lower limits of delay (such as limiting TdlyRise and TdlyFall when voltage drops and recovers), ensure accurate switching under different load current conditions, effectively improve the adaptability of system.

[0027] Simple structure, easy to implement: modular design is adopted, main power supply network, auxiliary power supply network, solid-state switch and control unit are integrated in test circuit, and control method is simple and efficient.Compared with traditional mechanical switch or thyristor scheme, the structure of the utility model is more compact, response speed is faster, and can be better applied in immunity test device.

[0028] This invention enables rapid and safe power switching while effectively improving the reliability and adaptability of the testing device, providing an efficient and accurate testing solution for the immunity testing of electrical equipment. Attached Figure Description

[0029] Figure 1 This is a circuit diagram of the present invention;

[0030] Figure 2 This is a flowchart illustrating the present invention.

[0031] Figure 3 This is a dynamic characteristic diagram (load-time characteristic).

[0032] In the diagram: 1. Main power supply network; 2. Secondary power supply network; 3. First solid-state switch S1; 4. Second solid-state switch S2; 5. Control unit; 6. Load power supply terminal; 7. Load under test; 8. Current magnetic ring. Detailed Implementation

[0033] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0034] Example 1

[0035] like Figure 1 As shown, this embodiment provides a dual-power switchable test circuit, including:

[0036] 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;

[0037] The first solid-state switch S1 (labeled 3) and the second solid-state switch S2 (labeled 4) are used to control the on / off state of the main power supply network 1 and the auxiliary power supply network 2, respectively. Each set of solid-state switches includes anti-series fully controlled power electronic components, and each power electronic component has a built-in fast recovery diode.

[0038] Control unit 5 is connected to the first solid-state switch S1 and the second solid-state switch S2 to control the on / off state of the two switches, so as to quickly switch between the main power supply network 1 and the auxiliary power supply network 2.

[0039] 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 the load under test 7.

[0040] Specifically, the first solid-state switch S1 includes a first power electronic element Q1 and a second power electronic element Q2, which are connected in anti-series, and each of which is internally provided with a fast recovery diode D1 and D2; the second solid-state switch S2 includes a third power electronic element Q3 and a fourth power electronic element Q4, which are connected in anti-series, and each of which is internally provided with a fast recovery diode D3 and D4.

[0041] The fully-controlled power electronic element includes one of an IGBT or a MOSFET tube; specifically, the fully-controlled power electronic element includes one of an IGBT or a MOSFET tube. These elements have good switching characteristics and high switching speed, and are suitable for fast switching control of an alternating current power supply. In the utility model, the purpose of selecting a fully-controlled power electronic element is to ensure microsecond-level fast switching between the main power supply network and the auxiliary power supply network, and to avoid the shortcomings of traditional switching devices in response speed. The IGBT (Insulated Gate Bipolar Transistor) has low conduction loss and high voltage resistance characteristics, and is suitable for higher voltage application scenarios; the MOSFET tube (Metal Oxide Semiconductor Field Effect Transistor) is suitable for occasions requiring frequent switching due to its higher switching frequency, so the utility model can select an IGBT or a MOSFET tube as a fully-controlled power electronic element according to different application requirements, to realize efficient and safe switching of a dual-path power supply.

[0042] The control unit 5 is configured to monitor the voltage and current of the load power supply end 6, and control the on-off of the first solid-state switch S1 and the second solid-state switch S2 according to the voltage instantaneous value and the load current.

[0043] It also includes a current magnetic ring 8 for monitoring the load current between the load power supply end 6 and the measured load 7 in real time, and feeding back the current signal to the control unit 5.

[0044] Preferably, the control unit 5 executes a switching algorithm based on the fully-controlled power electronic element parameters, the power supply synchronization signal, the switching phase angle Θsw, the switching phase time Tsw, the load transient current i, and the switching voltage instantaneous values u1 and u2, to calculate the turn-on delay rise time (TdlyRise), the turn-off delay fall time (TdlyFall), and the switching compensation duration (Tc), so as to control the power supply output time characteristics of the switching process.

[0045] Specifically, in the circuit implementation process of the utility model, the main power supply network and the auxiliary power supply network output the same frequency and same phase alternating current power (VS1 and VS2) respectively, and the control unit is used to realize the quick switching of the two power supplies. The output ends of the main power supply network and the auxiliary power supply network are connected to the first solid state switch (S1) and the second solid state switch (S2) respectively, wherein each solid state switch is composed of anti-series full control type power electronic elements (such as IGBT or MOSFET tube), and a fast recovery diode is built-in, so as to provide a quick response and a short circuit protection function in the power supply switching process. The control unit monitors the voltage and current signals of the load end in real time, and according to the voltage instantaneous value, the switching phase angle and the transient current and other parameters, the switching algorithm is used to dynamically calculate the turn-on delay and the turn-off delay, so as to accurately control the on-off of the solid state switch. The load power supply end is connected to the measured load, when the voltage of the main power supply network or the auxiliary power supply network drops or recovers, the control unit carries out the smooth switching of the power supply according to the calculated delay compensation time (Tc), and ensures that the voltage waveform of the load end meets the requirements of the IEC 61000-4-11 standard. Through the circuit design, the utility model can realize the safe switching of the double power supply in the microsecond level, avoid the transient short circuit and meet the strict standard of the interference test.

[0046] Embodiment 2

[0047] The embodiment provides a double power supply switchable test device with the double power supply switchable test circuit in embodiment 1.

[0048] Specifically, the double power supply switching assembly is used for simulating abnormal conditions of the power grid.

[0049] Embodiment 3

[0050] The embodiment provides a double power supply switchable test method, which can be executed on the double power supply switchable test circuit in embodiment 1 or the double power supply switchable test device in embodiment 2, and includes the following steps.

[0051] Step 1: start the test device, the control unit 5 enables the first solid state switch S1 and disables the second solid state switch S2, and the main power supply network 1 supplies power to the measured load 7;

[0052] Step 2: detect the voltage and current values of the load power supply end 6, calculate 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;

[0053] Step 3: according to the calculated turn-on and turn-off delay, execute the switching from the main power supply network 1 to the auxiliary power supply network 2 or the switching from the auxiliary power supply network 2 to the main power supply network 1;

[0054] Among them,

[0055] In the execution of power switching, the switching compensation duration (Tc) is calculated based on the switching algorithm, wherein Tc = Tsw - TdlyRise + TdlyFall, when Tc is negative, Tc is corrected to 0; in voltage drop, if TdlyFall > 5us, TdlyFall is set to 5us; in voltage recovery, if TdlyRise < 1us, Tc = Tsw + 1us, if TdlyRise > 5us, Tc = Tsw - (TdlyRise - 1us);

[0056] The opening delay rise time (TdlyRise) is calculated by the following formula:

[0057] TdlyRise = ΔTrise + TdelayON, wherein, when voltage drop switching, Δu = u2 - 0; when voltage recovery switching, Δu = u1 - u2, and ΔTrise = |Δu| Krise;

[0058] The closing delay fall time (TdlyFall) is calculated by the following formula:

[0059] TdlyFall = ΔTfall + TdelayOFF, wherein, when voltage drop switching, Δu = u1 - u2; when voltage recovery switching, Δu = u2 - 0, and ΔTfall = |Δu| Kfall;

[0060] The calculation formula of the slope K is:

[0061] Or ;

[0062] Wherein, Trise and Tfall are the rise and fall times of power electronic elements, Vds is the DS (ce) inter-electrode test voltage parameter, i is the transient current, Trisemin and Tfallmin are the minimum working current Id corresponding values of the rise and fall times.

[0063] Further, in the switching process, when calculating the switching compensation duration Tc, if TdlyFall > 5us in voltage drop, TdlyFall is reset to 5us;

[0064] In voltage recovery, if TdlyRise < 1us, Tc is set to Tsw + 1us; if TdlyRise > 5us, Tc is set to Tsw - (TdlyRise - 1us).

[0065] Specifically, the switching phase moment Tsw is calculated by the following formula:

[0066] wherein Θsw is the switching phase angle, and f is the frequency of the alternating power supply;

[0067] The monitoring moment of the transient current i is Tsw - 1 / f, that is, the moment Tsw of the previous power supply cycle before the current switching.

[0068] Regarding the above formula and calculation, wherein ΔTrise represents the change amount of the voltage rise time, Δu is the voltage difference, Krise is the slope related to the characteristics of the power electronic element, TdelayON represents the turn-on delay of the power electronic element, which is the time required for the element to actually turn on after receiving the turn-on signal; u1 represents the voltage instantaneous value of the main power supply network, and u2 represents the voltage instantaneous value of the auxiliary power supply network; ΔTfall represents the change amount of the voltage fall time; TdelayOFF represents the turn-off delay of the power electronic element, which is the time required for the element to actually turn off after receiving the turn-off signal; Kfall represents the slope parameter related to the voltage drop process, which is used to calculate the voltage fall time change amount, and the specific value is determined according to the characteristics of the power electronic element.

[0069] The typical implementation process is as follows:

[0070] First, start the test device, and the control unit enables the first solid-state switch of the main power supply, disables the second solid-state switch of the auxiliary power supply, and enables the main power supply network to supply power to the measured load. Then, the control unit detects the voltage and current values of the load power supply end, calculates the turn-on delay (TdlyRise) and the turn-off delay (TdlyFall) according to the switching phase angle, the transient current and the voltage difference. According to the calculated turn-on and turn-off delays, the switching 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 duration Tc is calculated based on the switching algorithm, and if Tc is negative, it is corrected to 0; when the voltage drops, TdlyFall is limited to 5 μs, and when the voltage recovers, Tc is adjusted to 1 μs or subtracted from the excess part according to the conditions. The turn-on delay and the turn-off delay are calculated according to the slope K of the voltage difference Δu and the transient current i, wherein K is determined by the parameters of the power electronic element. The switching phase moment Tsw is calculated from 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.

[0071] A typical calculation process is as follows:

[0072] Known conditions:

[0073] According to the datasheet of a certain transistor, under the conditions of Tj=25℃, the main control output driving signal (Vgs=13V) to the gate, continuous current Id=47A, and Vds=380V, the typical value of the dynamic characteristics is obtained as follows:

[0074] The turn-on delay time (tdon) is 18ns; the rise time (tr) is 27ns; the turn-off delay time (tdoff) is 111ns; and the fall time (tf) is 8ns.

[0075] The dynamic characteristic graph (load-time characteristic) is shown in Figure 3 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);

[0076] Tf(i<20A) is approximately 40-[i(40-10 / 20)]=40-1.5 i(ns); Tf(i>20A) is approximately constant at 9ns.

[0077] The following is a calculation example:

[0078] The measured load is a resistor of 10 ohms, the main power supply network peak is 300V, and the auxiliary power supply network peak is 100V; it is assumed that the drop phase angle is 90°, and the recovery phase angle is 150°; the drop maintenance time is 1 second.

[0079] The device starts, and the calculation process is as follows:

[0080] I. When the main power supply network voltage phase is 90°, the instantaneous current i=30A is measured.

[0081] II. Δu=200V;

[0082] III. Kfall=9 / 380=0.02ns / V;

[0083] IV. ΔTfall=200 0.02=4ns;

[0084] V. Tdlyfall=ΔTfall+TdelayOFF=4+(215-1.9 30)=162ns;

[0085] VI. Δu=100V;

[0086] Seven, Krise = (27 / 380) (40-0) = 2.85ns / V;

[0087] Eight, Delta Trise = 100 2.85 = 285ns;

[0088] Nine, TdlyRise = Delta Trise + TdelayON = 285 + 17 = 302ns;

[0089] Ten, since TdlyRise < 1us, Tc = Tsw + 1 = 5001us;

[0090] The recovery voltage trigger time is calculated according to the above principle.

[0091] The utility model provides a kind of double-path power supply switchable test circuit and equipment, with the characteristics of fast response, safe and reliable, can effectively simulate voltage transient drop, short-time interruption and voltage gradual change phenomenon under abnormal situation of power grid.The specific beneficial effects of the utility model include the following points:

[0092] High-efficiency switching meets microsecond-level response requirements: by adopting reverse series full-controlled power electronic components (such as IGBT), the fast switching of main and auxiliary power supply networks is realized.The control unit can complete voltage rise or drop within 1-5 microseconds, fully meets the requirements of IEC 61000-4-11 standard, and ensures to simulate real voltage fluctuation under abnormal situation of power grid.

[0093] Its control method can prevent transient short circuit and improve safety: the utility model calculates turn-on delay and turn-off delay by unique control algorithm, and automatically adjusts compensation duration (Tc) when switching, effectively avoids transient short circuit phenomenon when two-way power supply switches.The design of reverse parallel fast recovery diode also enhances the protection function when power supply switches, so that the circuit does not appear current mutation while fast switching.

[0094] Real-time monitoring of load state ensures test accuracy: current magnetic ring is connected in series at load end, load current and voltage instantaneous value are monitored in real time by control unit, switching phase angle and transient current are combined to accurately control on-off of solid-state switch, to ensure smooth switching process, and load voltage waveform meets standard requirements.

[0095] Intelligent delay adjustment adapts to various test scenarios: control algorithm can calculate slope K according to switching phase angle and transient current and further calculate turn-on and turn-off delay.By setting upper and lower limits of delay (such as limiting TdlyRise and TdlyFall when voltage drops and recovers), accurate switching can be achieved under different load current conditions, effectively improving the adaptability of system.

[0096] Simple structure, easy to implement: using modular design, the main power supply network, auxiliary power supply network, solid state switch and control unit are integrated in the test circuit, and the control method is simple and efficient. Compared with the traditional mechanical switch or thyristor scheme, the structure of the utility model is more compact, the response speed is faster, and it can be better applied to the anti-interference test device.

[0097] The utility model realizes the power supply fast, safe switching, effectively improves the reliability and adaptability of test device, provides a kind of efficient, accurate test solution for electrical equipment anti-interference test.

[0098] The basic principle, main features and advantages of the utility model are shown and described above.The skilled person in the art should understand that the utility model is not limited by the above examples, various changes and improvements can be made without departing from the spirit and scope of the utility model, and these changes and improvements all fall within the scope of the utility model claimed.The scope of protection of the utility model is defined by the appended claims and their equivalents.

Claims

1. A dual power supply switchable test circuit, characterized by, Comprise: A main power supply network (1) and a secondary power supply network (2) for outputting alternating current power VS1 and VS2 of the same frequency and phase respectively; A first solid-state switch S1 (3) and a second solid-state switch S2 (4) for controlling the on-off of the main power supply network (1) and the secondary power supply network (2) respectively, each group of solid-state switches comprising anti-series full-controlled power electronic elements, and each power electronic element is internally provided with a 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-off of the two to quickly switch between the main power supply network (1) and the secondary power supply network (2); A load power supply end (6) connected to the output end of the first solid-state switch S1 (3) and the second solid-state switch S2 (4) for connecting the measured load (7); The full-controlled power electronic element comprises one of IGBT or MOSFET tube.

2. The double-path power supply switchable test circuit according to claim 1, wherein: The first solid-state switch S1 (3) comprises a first power electronic element Q1 and a second power electronic element Q2 connected in anti-series, and each power electronic element is internally provided with a fast recovery diode D1 and D2; The second solid-state switch S2 (4) comprises a third power electronic element Q3 and a fourth power electronic element Q4 connected in anti-series, and each power electronic element is internally provided with a fast recovery diode D3 and D4.

3. The dual power supply switchable test circuit of claim 1, wherein, The control unit (5) is configured to monitor the voltage and current of the load power supply end (6).

4. The dual power supply switchable test circuit of claim 1, wherein, Further comprising a current magnetic ring (8) for monitoring the load current between the load power supply end (6) and the measured load (7) in real time, and feeding back the current signal to the control unit (5).

5. A dual supply switchable test apparatus having a dual supply switchable test circuit as claimed in any one of claims 1 to 4, characterised by, For equipping with double-path power supply switching assembly under the condition of analog power grid abnormality.

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