Loss testing device and method for bidirectional switch

Abstract

The invention discloses a loss test device and method for a bidirectional switch. The loss test device for the bidirectional switch comprises a power supply, an inductor, a bus capacitor, a current measurement module, a control module, a heating plate, a temperature detection module and a waveform analysis module, the bidirectional switch comprises a first end, a second end, a first driving end and a second driving end; the first end is electrically connected with one end of the inductor, the second end is electrically connected with one end of the current measurement module, and the other end of the inductor and the other end of the current measurement module are respectively connected with two ends of the power supply; the bus capacitor is connected in parallel with the power supply; the control module is electrically connected with the first driving end and the second driving end, and the heating plate is used for heating the bidirectional switch; the waveform analysis module is electrically connected with the first driving end, the second driving end, the first end, the second end, the current measurement module and the temperature detection module, and is used for obtaining a voltage signal, a current signal and a temperature signal of the bidirectional switch and forming an experimental oscillogram of the bidirectional switch according to the voltage signal, the current signal and the temperature signal.

Description

Technical Field

[0001] The present invention relates to the technical field of device testing, and in particular to a loss testing device and method for a bidirectional switch. Background Art

[0002] In power electronic circuits, MOS or IGBT devices are often connected to inductive loads. If there is no freewheeling diode in parallel across the inductive load, the high voltage and high current stored in the inductor will flow into the MOS tube every time the device is turned off. Since the gate is closed at this time, the MOS tube will be in a breakdown state for a short time. This process is called unclamped inductive switching (UIS).

[0003] Bidirectional switches contain parasitic capacitance. When the switch is in a bidirectional blocking state, energy flowing through the switch is lost in the parasitic capacitance, affecting the device's operating parameters. Calculating the loss caused by parasitic capacitance in bidirectional switches has become a pressing technical challenge. Summary of the Invention

[0004] The present invention provides a loss testing device and method for a bidirectional switch, so as to improve the reliability and accuracy of the loss testing of the bidirectional switch.

[0005] In a first aspect, the present invention provides a loss test device for a bidirectional switch, comprising: a power supply, an inductor, a bus capacitor, a current measurement module, a control module, a heating plate, a temperature detection module, and a waveform analysis module;

[0006] The bidirectional switch includes a first end, a second end, a first driving end, and a second driving end; the first end is electrically connected to one end of the inductor, the second end is electrically connected to one end of the current measuring module, and the other end of the inductor and the other end of the current measuring module are respectively connected to two ends of the power supply;

[0007] The bus capacitor is connected in parallel with the power supply;

[0008] The control module is electrically connected to the first driving end and the second driving end respectively, and is used to provide a driving signal to the bidirectional switch to control the switching state of the bidirectional switch;

[0009] The heating plate is used to heat the bidirectional switch; the temperature detection module is used to measure the temperature of the bidirectional switch;

[0010] The waveform analysis module is electrically connected to the first driving end, the second driving end, the first end, the second end, the current measurement module and the temperature detection module, respectively, and is used to obtain and form an experimental waveform diagram of the bidirectional switch based on the voltage signal, current signal and temperature signal of the bidirectional switch.

[0011] Optionally, the inductor includes an air-core inductor.

[0012] Optionally, the current measurement module includes a coaxial resistor.

[0013] Optionally, the loss test device further includes: a first chopping test port and a second chopping test port;

[0014] The first chopping test port is electrically connected to the first end, and the second chopping test port is electrically connected to the second end;

[0015] Wherein, when the first chopping test port and the second chopping test port are externally connected to a chopping test circuit, the control module is used to provide a test pulse signal to the bidirectional switch.

[0016] Optionally, the resistance of the coaxial resistor is Rs, 0.05Ω≤Rs≤0.1Ω.

[0017] In a second aspect, the present invention provides a loss testing method for a bidirectional switch, which is implemented using the loss testing device for a bidirectional switch described in the first aspect, and is characterized in that the loss testing method includes:

[0018] Controlling the bidirectional switch to be at a preset temperature;

[0019] Controlling the bidirectional switch to be in a bidirectional conduction mode within a first preset time period, so that the inductor, the bidirectional switch, and the current measurement module form an energy storage loop;

[0020] Controlling the bidirectional switch to be in a bidirectional blocking mode so that the inductor, the bidirectional switch, and the bus capacitor form a resonant circuit;

[0021] Obtaining the inductance and resistance of the inductor, the parasitic resistance of the loss test device, the resistance of the current measurement module, and the maximum current and minimum current of the bidirectional switch in the bidirectional blocking mode;

[0022] The output capacitance loss of the bidirectional switch is determined according to the inductance and resistance of the inductor, the parasitic resistance of the loss testing device, the resistance of the current measuring module, the maximum current value, and the minimum current value.

[0023] Optionally, determining the output capacitance loss of the bidirectional switch according to the inductance and resistance of the inductor, the parasitic resistance of the loss testing device, the resistance of the current measurement module, the maximum current value, and the minimum current value includes:

[0024] determining a total energy in the bidirectional off state according to the inductance value, the maximum current value, and the minimum current value;

[0025] In the bidirectional off state, a time period between the maximum current value and the minimum current value is used as a resonance duration;

[0026] determining the inductor conduction loss in the bidirectional off state according to the resistance value of the inductor, the maximum current value, and the resonance duration;

[0027] determining the loss of the test device in the bidirectional off state according to the parasitic resistance of the loss test device, the maximum current and the resonance duration;

[0028] Determining a current measurement loss in the bidirectional off state according to a resistance value of the current measurement module, the maximum current value, and the resonance duration;

[0029] An output capacitance loss of the bidirectional switch is determined based on the total energy, the inductor conduction loss, the test device loss, and the current measurement loss.

[0030] Optionally, determining the total energy in the bidirectional off state according to the inductance value, the maximum current value, and the minimum current value includes:

[0031] Determining the total energy in the bidirectional off state based on the inductance value, the maximum current value, and the minimum current value based on a first calculation formula;

[0032] The first calculation formula is: Etotal = 0.5 × L × (I 2 max-I 2 min);

[0033] Wherein, Etotal is the total energy, L is the inductance value, Imax is the maximum current value, and Imin is the minimum current value.

[0034] Optionally, determining the inductor conduction loss in the bidirectional off state according to the resistance value of the inductor, the maximum current, and the resonance duration includes:

[0035] The product of the maximum current value and the integral coefficient is used as the integrated current value;

[0036] The conduction loss of the inductor is determined according to the integrated current value, the resistance value of the inductor, and the resonance duration based on a work calculation formula.

[0037] Optionally, determining the output capacitance loss of the bidirectional switch according to the total energy, the inductor conduction loss, the test device loss, and the current measurement loss includes:

[0038] The sum of the inductor conduction loss, the test device loss, and the current measurement loss is used as the device loss;

[0039] The output capacitance loss of the bidirectional switch is determined by taking the difference between the total energy and the device loss.

[0040] The technical solution provided by the present invention achieves temperature control accuracy for the bidirectional switch by providing a heating plate and a temperature detection module, ensures the reliability of current measurement of the bidirectional switch by providing a current measurement module, and obtains the operating parameters of the bidirectional switch in real time during operation by providing a waveform analysis module. Based on the various operating parameters, an experimental waveform diagram is generated, which facilitates the subsequent determination of the output capacitance loss of the bidirectional switch based on the experimental waveform diagram. In addition, the loss test device only provides an inductive load in the loop where the bidirectional switch is located to reduce energy loss in the load and improve the reliability of loss calculation for the bidirectional switch. Furthermore, by providing an inductor, the inductor and the capacitor in the bidirectional switch form a resonant circuit, allowing energy to be circulated between the inductor and the capacitor, thereby obtaining the amount of energy lost during the resonance process, and then determining the loss of the bidirectional switch, thereby improving the reliability and accuracy of the bidirectional switch loss test. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of the circuit structure of a loss testing device for a bidirectional switch provided by an embodiment of the present invention;

[0042] Figure 2 A schematic structural diagram of a loss testing device for a bidirectional switch provided by an embodiment of the present invention;

[0043] Figure 3 A schematic diagram of a partial circuit structure of a loss testing device for a bidirectional switch provided by an embodiment of the present invention;

[0044] Figure 4 An experimental waveform diagram provided by an embodiment of the present invention;

[0045] Figure 5 for Figure 4 Experimental waveform diagram of the bidirectional switch in bidirectional blocking mode;

[0046] Figure 6A schematic structural diagram of a circuit board component in a loss testing device for a bidirectional switch provided by an embodiment of the present invention;

[0047] Figure 7 A schematic diagram of a chopping test circuit provided by an embodiment of the present invention;

[0048] Figure 8 A flow chart of a loss testing method for a bidirectional switch provided in an embodiment of the present invention;

[0049] Figure 9 A flow chart of another loss testing method for a bidirectional switch provided by an embodiment of the present invention;

[0050] Figure 10 A curve diagram showing the correspondence between output capacitance loss and a first preset time length of a bidirectional switch provided by an embodiment of the present invention;

[0051] Figure 11 A graph showing the corresponding relationship between output capacitance loss, resonant frequency, and peak voltage of a bidirectional switch provided by an embodiment of the present invention;

[0052] Figure 12 A graph showing the corresponding relationship between output capacitance loss, temperature, and peak voltage of a bidirectional switch provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0053] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0054] Figure 1 A schematic diagram of the circuit structure of a loss test device for a bidirectional switch provided by an embodiment of the present invention is shown. Figure 2 A schematic diagram of a loss test device for a bidirectional switch according to an embodiment of the present invention is shown in FIG. Figure 1 and Figure 2As shown, the loss test device of the bidirectional switch includes a power supply 10, an inductor L, a bus capacitor C1, a current measurement module 20, a control module 30, a heating plate 50, a temperature detection module (not shown in the figure) and a waveform analysis module 40. The bidirectional switch DUT includes a first terminal S1, a second terminal S2, a first driving terminal G1 and a second driving terminal G2; the first terminal S1 is electrically connected to one end of the inductor L, the second terminal S2 is electrically connected to one end of the current measurement module 20, and the other end of the inductor L and the other end of the current measurement module 20 are respectively connected to the two ends of the power supply 10. The bus capacitor C1 is connected in parallel with the power supply 10. The control module 30 is electrically connected to the first driving terminal G1 and the second driving terminal G2 respectively. The control module 30 is used to provide a driving signal to the bidirectional switch DUT to control the switching state of the bidirectional switch DUT. The heating plate 50 is used to heat the bidirectional switch DUT; the temperature detection module is used to measure the temperature of the bidirectional switch DUT. The waveform analysis module 40 is electrically connected to the first driving end G1, the second driving end G2, the first end S1, the second end S2, the current measurement module 20 and the temperature detection module, respectively, and is used to obtain and form an experimental waveform diagram of the bidirectional switch DUT based on the voltage signal, current signal and temperature signal of the bidirectional switch DUT.

[0055] Among them, the power supply 10 includes a DC power supply, the inductor L includes a plug-in inductor or a chip inductor, etc., the bus capacitor C1 includes an electrolytic capacitor, a ceramic capacitor or a film capacitor, etc., the current measurement module 20 includes a device or a sampling circuit that can measure the current signal, etc., the temperature detection module includes a thermocouple or a thermistor sensor, etc., which can be set according to actual needs and is not specifically limited here.

[0056] The control module 30 may include a main controller, a digital signal-to-analog signal converter, a first drive unit, a second drive unit, etc. The main controller is used to output a first digital signal for controlling the first drive unit to output a first drive signal, and output a second digital signal for controlling the second drive unit to output a second drive signal. The digital signal-to-analog signal converter is used to convert the first digital signal into a first analog signal, and convert the second digital signal into a second analog signal, and then transmit the first analog signal to the first drive end G1, and transmit the second analog signal to the second drive end G2. The specific structure of the control module 30 is not limited to the above description and can be set according to actual needs.

[0057] The heating plate 50 includes a heating plate made of metal material or heat-insulating material such as an iron plate, and the waveform analysis module 40 includes an oscilloscope, etc., which can be set according to actual needs and is not specifically limited here.

[0058] The bidirectional switch DUT is a switching device with bidirectional control function. The bidirectional switch DUT includes two driving ends. When the driving signals received by the two driving ends are both signals for controlling the bidirectional switch DUT to be turned on, the bidirectional switch DNU is in a bidirectional conduction mode. When the driving signals received by the two driving ends are both signals for controlling the bidirectional switch DUT to be turned off, the bidirectional switch DNU is in a bidirectional blocking mode. When the driving signal received by one of the driving ends is for controlling the bidirectional switch DUT to be turned on and the driving signal received by the other driving end is for controlling the bidirectional switch DUT to be turned off, the bidirectional switch DUT is in a forward diode mode or a reverse diode mode.

[0059] It should be noted that Figure 1 In addition to the waveform analysis module 40, all other circuit components and the control module 30 are located in Figure 2 In the circuit board component 01. In this way, all circuit components can be integrated into the circuit board component 01. When it is necessary to perform a loss test on the bidirectional switch DUT to be tested, the bidirectional switch DUT to be tested can be set at a corresponding position in the circuit board component 01, so that the bidirectional switch DUT to be tested is located in the test circuit loop, and then the loss test of the bidirectional switch DUT is performed, thereby improving the ease of testing. In addition, after the bidirectional switch DUT is set in the circuit test loop, the bidirectional switch DUT can be completely wrapped with silicone grease, so that the silicone grease is in contact with the heating plate 50. The silicone grease has good thermal conductivity, and the heating temperature provided by the heating plate 50 can be transmitted to the bidirectional switch DUT through the silicone grease. A temperature measuring device can be set in the silicone grease to detect the current temperature of the bidirectional switch DUT.

[0060] Specifically, the heating plate 50 is provided to meet the temperature requirements of the bidirectional switch loss test. While the heating plate 50 heats the bidirectional switch DUT, the temperature detection module can obtain the current temperature of the bidirectional switch DUT in real time. When the current temperature of the bidirectional switch DUT after thermal equilibrium is detected to be slightly different from or equal to the temperature provided by the heating plate 50, the bidirectional switch DUT is subjected to the loss test.

[0061] The loss test process is as follows: the control module 30 provides a driving signal to the first driving end G1 and the second driving end G2 in the first time period to control the bidirectional switch DUT to be in a bidirectional conduction mode, so that the bidirectional switch DUT maintains a bidirectional conduction mode in the first time period, and the power supply 10 charges the bus capacitor C1 in the first time period, so that the bus capacitor C1 plays a role in stabilizing the voltage in the subsequent process. Afterwards, the control module 30 provides a driving signal to the first driving end G1 and the second driving end G2 to control the bidirectional switch DUT to be in a bidirectional disconnection mode, so that the bidirectional switch DUT is in a bidirectional blocking mode. The waveform analysis module 40 charges the inductor L in the first time period. When the bidirectional switch DUT is in the bidirectional blocking mode, the equivalent circuit diagram of the loss test device is as follows: Figure 3 The experimental waveform obtained by the waveform analysis module 40 is shown as follows. Figure 4 shown. Figure 5 for Figure 4 The experimental waveform of the bidirectional switch in bidirectional blocking mode is shown in Figure 2. Figures 1 to 5 , Figure 4 The waveform of stage I corresponds to the period when the bidirectional switch DUT is in bidirectional conduction mode. In this period, the control module 30 provides a 6V driving signal to both the first driving terminal G1 and the second driving terminal G2, so that V G1S1 =V G2S2 =6V, the bidirectional switch DUT plays the role of conducting the electrical signal during this stage, so the voltage V between the first terminal S1 and the second terminal S2 of the bidirectional switch DUT S1S2 is zero, and the power supply continues to charge the inductor L during this stage, so that the current I flowing through the bidirectional switch DUT S1S2 Continues to increase; when the control module 30 provides a -3V drive signal to both the first drive terminal G1 and the second drive terminal G2, V G1S1 =V G2S2 =-3V. In this stage, the bidirectional switch DUT is in bidirectional blocking mode. However, there are equivalent resistance Rd, parasitic resistances Rs1, Rs2, Rc, and parasitic capacitance Coss inside the bidirectional switch DUT. At this time, the inductor L charges the parasitic capacitance Coss, and the voltage V S1S2 Gradually increases, and then the parasitic capacitance Coss charges the inductor L, and the voltage V S1S2 Gradually decrease to zero, and by calculating the loss caused by the parasitic capacitance Coss of the bidirectional switch DUT in the bidirectional blocking mode, the output capacitance loss of the bidirectional switch DUT can be obtained. In this way, the loss test device for the bidirectional switch provided by the present invention has a simple structure, convenient temperature control, and is easy to use.

[0062] The technical solution provided by the embodiment of the present invention achieves temperature control accuracy for the bidirectional switch by providing a heating plate and a temperature detection module, ensures the reliability of current measurement of the bidirectional switch by providing a current measurement module, and obtains the operating parameters of the bidirectional switch in real time during operation by providing a waveform analysis module. Based on the various operating parameters, an experimental waveform diagram is generated, which facilitates the subsequent determination of the output capacitance loss of the bidirectional switch based on the experimental waveform diagram. In addition, the loss test device only provides an inductive load in the loop where the bidirectional switch is located to reduce energy loss in the load and improve the reliability of loss calculation for the bidirectional switch. Furthermore, by providing an inductor, the inductor and the capacitor in the bidirectional switch form a resonant circuit, allowing energy to be circulated between the inductor and the capacitor, thereby obtaining the amount of energy lost during the resonance process, and then determining the loss of the bidirectional switch, thereby improving the reliability and accuracy of the loss test of the bidirectional switch.

[0063] Optionally, the inductor L includes an air-core inductor.

[0064] Specifically, the frequency and impedance of air-core inductors vary linearly, making them suitable for high-frequency scenarios. They can maintain minimal signal distortion while also exhibiting low loss characteristics, reducing energy loss in the inductor L. Air-core inductors can include hand-wound Litz wire, which is composed of multiple strands of insulated fine wire twisted together. Each wire alternates between the outer and inner layers of the conductor, making the current distribution more uniform. This can effectively reduce the increase in resistance caused by the skin effect at high frequencies, thereby reducing energy loss in the inductor L. This, in turn, reduces energy loss in loads other than the bidirectional switch DUT, improving the accuracy and reliability of loss measurements of the bidirectional switch.

[0065] Optionally, the current measurement module 20 includes a coaxial resistor.

[0066] The resistance of the coaxial resistor can be set according to actual needs. In an optional embodiment, the resistance of the coaxial resistor is Rs, and 0.05Ω≤Rs≤0.1Ω. In this way, by setting a coaxial resistor with a smaller resistance, energy loss in the coaxial resistor is reduced, thereby improving the loss calculation accuracy of the bidirectional switch DUT.

[0067] Specifically, the symmetrical current paths of coaxial resistors can offset magnetic fields and effectively reduce parasitic inductance, making them suitable for current measurement in high-frequency scenarios such as bidirectional switch DUTs, avoiding interference with high-frequency signals. The outer conductor of a coaxial resistor acts as a shield, reducing the impact of external electromagnetic fields on measurements while also lowering the noise radiated by the resistor itself. The coaxial design of a coaxial resistor forces current to flow along the center conductor, eliminating the shunting effect and improving current measurement accuracy, thereby enhancing loss measurement accuracy.

[0068] Optional, Figure 6A schematic structural diagram of a circuit board component in a loss testing device for a bidirectional switch provided by an embodiment of the present invention. Figure 7 A schematic diagram of a chopping test circuit provided by an embodiment of the present invention, referring to Figure 6 and Figure 7 The loss test device further includes a first chopping test port F6 and a second chopping test port F7; the first chopping test port F6 is electrically connected to the first end S1, and the second chopping test port F7 is electrically connected to the second end S2. When the first chopping test port F6 and the second chopping test port F7 are externally connected to the chopping test circuit, the control module 30 is configured to provide a test pulse signal to the bidirectional switch DUT.

[0069] Specifically, by providing a first chopping test port F6 electrically connected to the first end S1 of the bidirectional switch DUT and a second chopping test port F7 electrically connected to the second end S2 of the bidirectional switch DUT in the circuit board component of the loss test device, after the bidirectional switch DUT is fixedly connected to the circuit board component 01, the first chopping test port F6 and the second chopping port F7 can be electrically connected to an external chopping test circuit through an external circuit, and a pulse signal is provided to the bidirectional switch DUT through the control module 30 in the circuit board component 01 to control the bidirectional switch DUT to be in a bidirectional conduction mode or a bidirectional blocking mode, thereby testing the chopping function of the bidirectional switch DUT.

[0070] It should be noted that before performing a loss test on a bidirectional switch DUT, it is necessary to verify whether the bidirectional switch DUT can operate normally. Usually, the bidirectional switch DUT is inserted into a chopping test circuit board for verification testing. After that, the bidirectional switch DUT is removed from the chopping test circuit and fixed in the circuit board component 01 in the loss test device, and then the loss test is performed on the bidirectional switch. However, the above process requires the bidirectional switch DUT to be moved multiple times, which is cumbersome to operate. The present invention has realized the chopping test verification of the bidirectional switch by reserving a first chopping test port F6 and a second chopping test port F7 for chopping test in the loss test device, and externally connecting the chopping test ports to the chopping test circuit. In this way, the number of times the bidirectional switch DUT is moved can be reduced, thereby improving the test efficiency.

[0071] Based on the same inventive concept, an embodiment of the present invention further provides a loss test method for a bidirectional switch, which is suitable for measuring the output capacitance loss of the bidirectional switch. The method can be implemented using the loss test device for a bidirectional switch provided by any embodiment of the present invention. Figure 8 A flow chart of a loss test method for a bidirectional switch provided by an embodiment of the present invention is shown in FIG. Figure 8 As shown, the loss test method for bidirectional switches includes:

[0072] S101, controlling the bidirectional switch to be at a preset temperature.

[0073] Among them, the preset temperature can be set according to actual test requirements. For example, the preset temperature can be 25°C, 50°C, 75°C, 100°C or 125°C, etc., and can also be other, which is not specifically limited here.

[0074] Specifically, the current temperature of the bidirectional switch DUT can be obtained through the temperature detection module. If the current temperature does not reach the preset temperature, the heating plate is controlled to continue heating the bidirectional switch DUT until the temperature detection module detects that the current temperature of the bidirectional switch DUT is constant and maintained at the preset temperature, so as to subsequently detect the loss of the bidirectional switch DUT at the preset temperature.

[0075] S102: Control the bidirectional switch to be in a bidirectional conduction mode within a first preset time period, so that the inductor, the bidirectional switch, and the current measurement module form an energy storage loop.

[0076] The first preset time length can be adjusted according to actual needs. For example, the first preset time length is 130ns, and can also be other values, which are not specifically limited here.

[0077] Specifically, a first driving signal for controlling the bidirectional switch DUT to be turned on is provided to the first driving end and the second driving end of the bidirectional switch DUT through the control module, so that the bidirectional switch DUT is in a bidirectional conduction mode, thereby forming an energy storage loop with the inductor, the bidirectional switch and the current measurement module, and the power supply can charge the inductor through the bidirectional switch DUT.

[0078] S103 , controlling the bidirectional switch to be in a bidirectional blocking mode, so that the inductor, the bidirectional switch, and the bus capacitor form a resonant circuit.

[0079] Specifically, the control module provides a second driving signal to the first driving end and the second driving end of the bidirectional switch DUT to control the bidirectional switch DUT to be disconnected, so that the bidirectional switch DUT is in a bidirectional conduction mode, thereby forming an energy storage loop among the inductor, the bidirectional switch and the current measurement module, and the power supply can charge the inductor through the bidirectional switch DUT.

[0080] Exemplarily, the first driving signal is at a high level, the second driving signal is at a low level, the voltage of the first driving signal is 6V, and the voltage of the second driving signal is -3V.

[0081] S104 , obtaining the inductance and resistance of the inductor, the parasitic resistance of the loss test device, the resistance of the current measurement module, and the maximum current and minimum current of the bidirectional switch in the bidirectional blocking mode.

[0082] Specifically, the resistance value of the inductor can be measured by a Wheatstone bridge, the parasitic resistance Rp of the loss test device can be obtained from the setting parameters of the loss test device, and the resistance value of the current measurement module can be obtained from the setting parameters of the current measurement module. Figure 5 , the maximum current I of the bidirectional switch in bidirectional blocking mode S1S2(max) and the minimum current I S1S2(min) Can be obtained through the waveform analysis module.

[0083] For example, the inductor L has a value range of 0.2 μH to 6.5 μH, the resistance of the current measurement module is 0.1 Ω, the parasitic resistance of the loss test device is 0.1 Ω, and the resistance of the inductor is 0.1 Ω. Other values are also possible and are not specifically limited here.

[0084] S105 , determining the output capacitance loss of the bidirectional switch according to the inductance and resistance of the inductor, the parasitic resistance of the loss test device, the resistance of the current measurement module, the maximum current value, and the minimum current value.

[0085] Specifically, the total energy generated by the system can be determined based on the maximum current, minimum current, and inductance value. The test device loss of the system in the loss test device can be determined based on the parasitic resistance, maximum current, and minimum current of the loss test device. The current measurement loss of the system in the current measurement module can be determined based on the resistance value, maximum current, and minimum current of the current measurement module. The difference between the total energy and the test device loss and current measurement loss is used as the output capacitance loss of the bidirectional switch. In this way, the output capacitance loss of the bidirectional switch can be obtained through the loss test device, improving the ease and reliability of measuring the output capacitance loss of the bidirectional switch.

[0086] The technical solution of the embodiment of the present invention is to obtain the corresponding loss of the bidirectional switch at the preset temperature by controlling the bidirectional switch to be at a preset temperature. The bidirectional switch is controlled to be in a bidirectional conduction mode for a first preset time period, so that the inductor, the bidirectional switch and the current measurement module form an energy storage circuit, so that the power supply can charge the inductor through the bidirectional switch; the bidirectional switch is controlled to be in a bidirectional blocking mode, so that the inductor, the bidirectional switch and the bus capacitor form a resonant circuit, and the inductance and resistance values of the inductor, the parasitic resistance of the loss test device, the resistance value of the current measurement module, and the maximum and minimum current values of the bidirectional switch in the bidirectional blocking mode are obtained. When the bidirectional switch is in the bidirectional blocking mode, the electric energy stored in the inductor is circulated between the bidirectional switch and the inductor. Then, the output capacitance loss generated by the bidirectional switch during the resonance process is determined based on the inductance and resistance values of the inductor, the parasitic resistance of the loss test device, the resistance value of the current measurement module, the maximum and minimum current values. In this way, the reliability and accuracy of the output capacitance loss of the bidirectional switch can be improved.

[0087] Optionally, an embodiment of the present invention describes a case where the output capacitance loss of a bidirectional switch is determined based on the inductance and resistance of the inductor, the parasitic resistance of the loss testing device, the resistance of the current measurement module, the maximum current value, and the minimum current value. Figure 9 A flow chart of another loss testing method for a bidirectional switch provided by an embodiment of the present invention is shown in FIG. Figure 9 As shown, the loss test method of the bidirectional switch includes:

[0088] S201 , controlling the bidirectional switch to be at a preset temperature.

[0089] S202: Control the bidirectional switch to be in a bidirectional conduction mode within a first preset time period, so that the inductor, the bidirectional switch, and the current measurement module form an energy storage loop.

[0090] S203 : Control the bidirectional switch to be in a bidirectional blocking mode, so that the inductor, the bidirectional switch, and the bus capacitor form a resonant circuit.

[0091] S204 , obtaining the inductance and resistance of the inductor, the parasitic impedance of the loss test device, the impedance of the current measurement module, and the maximum current and minimum current of the bidirectional switch in the bidirectional blocking mode.

[0092] S205 : Determine the total energy in the bidirectional off state according to the inductance value, the maximum current value, and the minimum current value.

[0093] Specifically, when the bidirectional switch is in bidirectional conduction mode, the power supply, inductor, and bidirectional switch form a conductive path. The power supply transfers energy to the inductor, charging it. After a time tc, the current in the conductive loop reaches its maximum value, Imax. This indicates that the total energy reaches its maximum before the inductor resonates with the capacitance within the bidirectional switch. Therefore, the total energy provided by the power supply to the inductor can be determined by the inductor and the maximum and minimum currents during the conduction process.

[0094] It should be noted that when the bidirectional switch is in bidirectional blocking mode, the inductor, bidirectional switch, and bus capacitor form a resonant circuit. The inductor resonates with the bus capacitor and the parasitic capacitance in the bidirectional switch. As an inductive energy storage element, the inductor can exchange energy with the bus capacitor and the parasitic capacitance in the bidirectional switch to produce LC resonance. At the completion of a resonant cycle, the parasitic capacitance in the bidirectional switch has undergone a passive charge and active discharge. Ideally, the bidirectional switch has no parasitic resistance or capacitance, so the inductor, bidirectional switch, and bus capacitor do not lose energy during the resonance process, allowing for an infinite number of resonant cycles. However, parasitic resistance and capacitance exist in the bidirectional switch, so the total energy stored in the inductor is lost during a resonant cycle. Calculating the total energy stored in the inductor facilitates the subsequent calculation of the energy lost in the bidirectional switch.

[0095] Optionally, determining the total energy in the bidirectional off state according to the inductance value, the maximum current value, and the minimum current value includes determining the total energy in the bidirectional off state based on a first calculation formula according to the inductance value, the maximum current value, and the minimum current value; the first calculation formula is: Etotal = 0.5 × L × (I 2 max-I 2 min).

[0096] Where Etotal is the total energy, L is the inductance, Imax is the maximum current, and Imin is the minimum current.

[0097] Specifically, the inductance value L, the maximum current value Imax and the minimum current value Imin obtained in the waveform analysis module are substituted into the first calculation formula for calculation to obtain the total energy Etotal.

[0098] S206 : In the bidirectional off state, the time period between the maximum current value and the minimum current value is used as the resonance time period.

[0099] Specifically, refer to Figure 4 and Figure 5 During a first preset duration (stage I), the power supply continuously charges the inductor, and the current flowing through the bidirectional switch gradually increases. When the bidirectional switch is in a bidirectional blocking mode, the electric energy stored in the inductor circulates through the parasitic capacitance and inductance of the bidirectional switch, causing the current to gradually decrease from a maximum value to a minimum value in the bidirectional blocking mode. During this process, the bidirectional switch and the inductor resonate. Thus, the time period between the maximum and minimum current values is used as the time period for subsequent output capacitor loss calculations, thereby improving the accuracy of loss calculations.

[0100] S207 : Determine the conduction loss of the inductor in the bidirectional off state according to the resistance value, the maximum current, and the resonance duration of the inductor.

[0101] Specifically, the calculation formula for inductor conduction loss is E L =(I L ) 2 ×R L ×T,I L is the integrated current flowing through the bidirectional switch during the resonant time, R L is the resistance value of the inductor, T is the resonance time, and I is determined by integral calculation. L It is related to the maximum current Imax, so I L Substitute the relationship between Imax and inductor into the above formula to calculate the inductor conduction loss.

[0102] Optionally, the inductor conduction loss in the bidirectional off state is determined based on the resistance value of the inductor, the maximum current and the resonance time, including taking the product of the maximum current and the integral coefficient as the integral current value; and the inductor conduction loss is determined based on the work calculation formula according to the integral current value, the resistance value of the inductor and the resonance time.

[0103] The integral current value represents the integral value of the current flowing through the bidirectional switch during the resonance time. The integral current value can accurately calculate the loss of the inductor resistance during the resonance time.

[0104] Specifically, the integral coefficient can be obtained by integrating the current. For example, the integral coefficient is 1 / 2, I L =Imax / 2, substitute Imax into the work calculation formula E L =(Imax / 2) 2 ×R L ×T to determine the inductor conduction loss.

[0105] S208 : Determine the loss of the test device in a bidirectional off state according to the parasitic resistance, maximum current, and resonance duration of the loss test device.

[0106] Specifically, the parasitic resistance, maximum current and resonance duration can be substituted into the calculation formula E of the test device loss. P =(Imax / 2) 2 ×R P ×T is calculated to determine the test device loss. Where Imax is the maximum current, R P is the parasitic resistance of the loss test device, T is the resonance time, E P is the test device loss.

[0107] S209 : Determine the current measurement loss in the bidirectional off state according to the resistance value, the maximum current value, and the resonance duration of the current measurement module.

[0108] Specifically, the resistance value, maximum current and resonance duration of the current measurement module can be substituted into the calculation formula E of the current measurement loss. s =(Imax / 2) 2 ×R s ×T is calculated to determine the test device loss. Where Imax is the maximum current, R s is the parasitic resistance of the current measurement module, T is the resonance time, E s Measure the loss for current.

[0109] S210 , determining the output capacitance loss of the bidirectional switch according to the total energy, the inductor conduction loss, the test device loss, and the current measurement loss.

[0110] Specifically, since the total energy includes the energy lost in the inductor resistance, the energy lost in the output capacitance (parasitic capacitance) of the bidirectional switch, the energy lost in the resistance of the loss test device, and the energy lost in the resistance of the current measurement module, the value after subtracting the inductor conduction loss, the test device loss and the current measurement loss from the total energy can be used as the output capacitance loss.

[0111] Optionally, the output capacitance loss of the bidirectional switch is determined based on the total energy, inductor conduction loss, test device loss and current measurement loss, including taking the sum of the inductor conduction loss, test device loss and current measurement loss as the device loss; and taking the difference between the total energy and the device loss to determine the output capacitance loss of the bidirectional switch.

[0112] Specifically, by calculating the inductor conduction loss E L , test equipment loss E P and current measurement loss E s The sum of the total energy Etotal and the device loss E is taken as the device loss E, and the difference between the total energy Etotal and the device loss E is taken as the output capacitance loss Ed of the bidirectional switch, that is, Ed = Etotal - E, E = E L +E P +E s , execute two calculation steps to improve the calculation efficiency.

[0113] The technical solution of the present invention determines the total energy in a bidirectional off-state based on the inductance value, the maximum current value, and the minimum current value, and calculates the inductor conduction loss generated on the resistance value of the inductor, the test device loss generated on the loss test device, and the current measurement loss generated on the current measurement module in the bidirectional off-state, so as to use the portion of the total energy after deducting the inductor conduction loss, the test device loss, and the current measurement loss as the output capacitance loss of the bidirectional switch, thereby improving the calculation accuracy of the output capacitance loss of the bidirectional switch.

[0114] It should be noted that the parameters provided in the embodiment of the present invention, such as the preset temperature, the peak voltage of the bidirectional switch within the resonant time, the first preset time and the resonant frequency, can all be changed to obtain the output capacitance loss of the bidirectional switch under different working conditions. Figure 10 A curve diagram showing the relationship between the output capacitance loss of a bidirectional switch and the first preset time duration is provided in an embodiment of the present invention. Figure 10 As shown, the test results are as follows: when the inductance L is 0.2μH, the peak voltage V S1S2 =1V, preset temperature T = 25℃, output capacitor loss Ed (E in the figure) DISS ) and the corresponding curve diagram of the first preset time length. Figure 11 A graph showing the output capacitance loss of a bidirectional switch, the resonant frequency, and the peak voltage is provided in accordance with an embodiment of the present invention. Figure 11 As shown, an air-core inductor of 0.2μH to 6.5μH is used to achieve a resonant frequency f of 2.92MHz to 10.54MHz. R For each inductance value, the peak voltage V is adjusted by controlling the first preset time S1S2 , so that the peak voltage range is between 10V and 80V, in order to study the output capacitance loss corresponding to the bidirectional switch under different resonant frequencies and different peak voltages. Figure 12 A graph showing the corresponding relationship between output capacitance loss, temperature and peak voltage of a bidirectional switch provided by an embodiment of the present invention is shown in FIG. Figure 12 As shown, the bidirectional switch is heated by the heating plate to place the bidirectional switch under different preset temperature conditions, and the peak voltage V is adjusted by controlling the first preset time. S1S2 , to study the output capacitance loss of the bidirectional switch corresponding to different peak voltages and temperatures. When testing the output capacitance loss at different temperatures, after each test is completed, a preset interval is required. After the preset interval, the bidirectional switch temperature stabilizes before entering the next test process. This prevents the experimental parameters of the previous test process from affecting the next test process, thereby improving test accuracy.

[0115] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations, and substitutions are possible for those skilled in the art without departing from the scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the scope of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A loss test device for a bidirectional switch, characterized in that: include: Power supply, inductor, busbar capacitor, current measurement module, control module, heating plate, temperature detection module and waveform analysis module; The bidirectional switch includes a first end, a second end, a first driving end, and a second driving end; the first end is electrically connected to one end of the inductor, the second end is electrically connected to one end of the current measuring module, and the other end of the inductor and the other end of the current measuring module are respectively connected to two ends of the power supply; The bus capacitor is connected in parallel with the power supply; The control module is electrically connected to the first driving end and the second driving end respectively, and is used to provide a driving signal to the bidirectional switch to control the switching state of the bidirectional switch; The heating plate is used to heat the bidirectional switch; the temperature detection module is used to measure the temperature of the bidirectional switch; The waveform analysis module is electrically connected to the first driving end, the second driving end, the first end, the second end, the current measurement module and the temperature detection module, respectively, and is used to obtain and form an experimental waveform diagram of the bidirectional switch based on the voltage signal, current signal and temperature signal of the bidirectional switch.

2. The loss testing device according to claim 1, characterized in that: The inductor comprises an air-core inductor.

3. The loss testing device according to claim 1, characterized in that: The current measurement module includes a coaxial resistor.

4. The loss testing device according to claim 1, wherein: Also includes: a first chopping test port and a second chopping test port; The first chopping test port is electrically connected to the first end, and the second chopping test port is electrically connected to the second end; Wherein, when the first chopping test port and the second chopping test port are externally connected to a chopping test circuit, the control module is used to provide a test pulse signal to the bidirectional switch.

5. The loss testing device according to claim 3, characterized in that: The resistance of the coaxial resistor is Rs, 0.05Ω≤Rs≤0.1Ω.

6. A loss test method for a bidirectional switch, implemented using the loss test device for a bidirectional switch according to any one of claims 1 to 5, characterized in that: The loss testing method includes: Controlling the bidirectional switch to be at a preset temperature; Controlling the bidirectional switch to be in a bidirectional conduction mode within a first preset time period, so that the inductor, the bidirectional switch, and the current measurement module form an energy storage loop; Controlling the bidirectional switch to be in a bidirectional blocking mode so that the inductor, the bidirectional switch, and the bus capacitor form a resonant circuit; Obtaining the inductance and resistance of the inductor, the parasitic resistance of the loss test device, the resistance of the current measurement module, and the maximum current and minimum current of the bidirectional switch in the bidirectional blocking mode; The output capacitance loss of the bidirectional switch is determined according to the inductance and resistance of the inductor, the parasitic resistance of the loss testing device, the resistance of the current measuring module, the maximum current value, and the minimum current value.

7. The loss testing method according to claim 6, wherein: Determining the output capacitance loss of the bidirectional switch according to the inductance and resistance of the inductor, the parasitic resistance of the loss testing device, the resistance of the current measuring module, the maximum current value, and the minimum current value, including: determining a total energy in the bidirectional off state according to the inductance value, the maximum current value, and the minimum current value; In the bidirectional off state, a time period between the maximum current value and the minimum current value is used as a resonance duration; determining the inductor conduction loss in the bidirectional off state according to the resistance value of the inductor, the maximum current value, and the resonance duration; determining the loss of the test device in the bidirectional off state according to the parasitic resistance of the loss test device, the maximum current and the resonance duration; Determining a current measurement loss in the bidirectional off state according to a resistance value of the current measurement module, the maximum current value, and the resonance duration; An output capacitance loss of the bidirectional switch is determined based on the total energy, the inductor conduction loss, the test device loss, and the current measurement loss.

8. The loss testing method according to claim 7, characterized in that: Determining the total energy in the bidirectional off state according to the inductance value, the maximum current value, and the minimum current value includes: Determining the total energy in the bidirectional off state based on the inductance value, the maximum current value, and the minimum current value based on a first calculation formula; The first calculation formula is: Etotal = 0.5 × L × (I 2 max-I 2 min); Wherein, Etotal is the total energy, L is the inductance value, Imax is the maximum current value, and Imin is the minimum current value.

9. The loss testing method according to claim 7, characterized in that: Determining the inductor conduction loss in the bidirectional off state according to the resistance value of the inductor, the maximum current, and the resonance duration includes: The product of the maximum current value and the integral coefficient is used as the integrated current value; The conduction loss of the inductor is determined according to the integrated current value, the resistance value of the inductor, and the resonance duration based on a work calculation formula.

10. The loss testing method according to claim 7, wherein: Determining the output capacitance loss of the bidirectional switch according to the total energy, the inductor conduction loss, the test device loss, and the current measurement loss includes: The sum of the inductor conduction loss, the test device loss, and the current measurement loss is used as the device loss; The output capacitance loss of the bidirectional switch is determined by taking the difference between the total energy and the device loss.

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