Protection devices, protection methods, and testing equipment for PTC product testing

Abstract

A protection device for PTC product testing includes a microcontroller and at least one channel driver. The at least one channel driver is connected to the microcontroller. Each channel driver includes a sampling unit, a protection unit, and a protection control unit. The sampling unit collects the current flowing through the PTC product under test and outputs a sampling signal. The microcontroller compares the sampled current value flowing through the PTC product under test with a first threshold value and sends an enable signal to the protection control unit based on the comparison result. The protection control unit is connected to the sampling unit and controls the operating state of the protection unit based on the enable signal. The protection unit is connected to the sampling unit and controls the on / off state of the test channel where the protection unit is located based on the sampling signal to achieve the protection function. By monitoring the current flowing through the PTC product under test in real time, the protection function is activated only when the current is greater than or equal to the first threshold value, preventing false protection.

Description

Technical Field

[0001] This application relates to the field of electrical parameter testing technology, and in particular to a protection device, protection method and testing apparatus for testing PTC products. Background Art

[0002] PTC (Positive Temperature Coefficient) products refer to components and assemblies made with materials that have a positive temperature coefficient, such as PTC thermistors, PCT heaters, and PTC temperature sensors. Conducting withstand voltage tests on PTC products is an essential step in verifying their safety. During withstand voltage testing of PTC products, it is necessary to protect the PCT product under test or the test channel containing the PCT product for various reasons, such as preventing damage to the PCT product.

[0003] However, when testing PTC products, a "false protection" event can occur, where the protection trips before the withstand voltage test even begins, preventing the test from proceeding normally. How to avoid this "false protection" is a crucial technical problem that the field has been striving to solve. Summary of the Invention

[0004] In view of the above, this application provides a protection device, protection method and testing device for PTC product testing to solve the problems existing in the background art.

[0005] In a first aspect, one embodiment of this application provides a protection device for testing PTC products, comprising: a microcontroller and at least one channel driver; the at least one channel driver is connected to the microcontroller; the channel driver includes: a sampling unit, a protection unit, and a protection control unit; the sampling unit and the protection unit are connected; the protection control unit is connected to the microcontroller; the sampling unit is used to connect to the PTC product under test, collect the current flowing through the PTC product under test, and output a collection signal; the microcontroller is used to compare the sampled value of the current flowing through the PTC product under test with a first threshold, and send an enable signal to the protection control unit according to the comparison result; the protection control unit is connected to the microcontroller and is used to control the working state of the protection unit according to the enable signal; the protection unit is connected to the sampling unit and is used to control the on / off state of the test channel where the protection unit is located according to the collection signal, so as to realize the protection function.

[0006] In conjunction with the first aspect of this application, in an optional embodiment, the protection control unit includes a second switch module, which is connected to both the protection unit and the microcontroller. The second switch module is used to control the protection unit to turn on according to the enable signal, so that the protection unit is in a test circuit.

[0007] In conjunction with the first aspect of this application, in an optional embodiment, the second switch module includes a high-voltage relay and a second switch controller, the second switch controller controlling the operating state of the high-voltage relay according to the enable signal to control the protection unit to be in a test circuit.

[0008] In conjunction with the first aspect of this application, in an alternative embodiment, the first threshold is ≥70% max The I max This is the maximum current of the PTC product under test when it is at the Curie temperature.

[0009] In conjunction with the first aspect of this application, in an optional embodiment, the protection unit includes a drive module and a first switch module; the drive module is configured to output a first state change signal to the first switch module according to the acquired signal; the microcontroller is further configured to output a first protection control signal to the current protection unit according to the first state change signal, so as to control the channel where the protection unit is located to be closed.

[0010] In conjunction with the first aspect of this application, in an optional embodiment, the microcontroller is further configured to compare the sampled value of the current flowing through the PTC product under test with a third threshold, and output a second protection control signal to the protection unit according to the comparison result, so as to control the channel where the protection unit is located to be closed.

[0011] In conjunction with the first aspect of this application, in an optional embodiment, the sampling unit includes a signal conditioning module; the signal conditioning module is used to perform range conversion and amplification of the current flowing through the object under test, so that the microcontroller can perform analog-to-digital conversion to obtain the sampled value.

[0012] Secondly, embodiments of this application provide a protection method for PTC product testing, comprising the following steps:

[0013] The current flowing through the PTC product under test in the current test channel is collected to obtain the acquisition signal;

[0014] The current flowing through the PTC product under test in the current test channel is sampled to obtain the sampled value;

[0015] The sampled value is compared with a first threshold, and a protection control signal is output based on the comparison result.

[0016] The current test channel is controlled to be in a protected state according to the protection control signal;

[0017] When the acquired signal is greater than or equal to the second threshold, the current test channel is shut down.

[0018] In conjunction with the second aspect of this application, in an optional embodiment, the method further includes the following steps: comparing the sampled value with a third threshold, and controlling the current test channel to be closed when the sampled value is greater than or equal to the third threshold.

[0019] Thirdly, embodiments of this application provide a multi-channel testing device, including the protection device described in any of the first aspects above, and a test power supply connected to the protection device; the protection device is used to independently control whether the test channel where each channel driver is located is turned off or not.

[0020] The protection device, protection method, and testing apparatus for PTC product testing provided in this application embodiment use a microcontroller to determine whether the current flowing through the PTC product under test has reached the maximum current, thus determining whether the PTC product under test needs to activate protection. When the current of the PTC product under test reaches the maximum current, it indicates that the PTC product under test is about to enter the withstand voltage test stage, and the protection unit is activated, and the protection function takes effect. In this way, protection can be avoided before the PTC product under test enters the withstand voltage test stage, preventing "false protection" from occurring.

[0021] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0023] Figure 1a This is a schematic diagram illustrating the resistance variation of a PTC product.

[0024] Figure 1b This is a schematic diagram showing the operating current variation of a PTC product.

[0025] Figure 1c The current-voltage characteristic curve of the PTC product;

[0026] Figure 2 This is a schematic diagram of a protection device module for PTC product testing in one embodiment of this application;

[0027] Figure 3 This is a partial circuit diagram of a protection device for PTC product testing in one embodiment of this application;

[0028] Figure 4 This is a partial circuit diagram of a protection device for PTC product testing in one embodiment of this application. Figure 2 ;

[0029] Figure 5a A schematic diagram illustrating a sudden current change in a PTC product;

[0030] Figure 5b A schematic diagram showing the slow rise of current in the PTC product under test;

[0031] Figure 6 This is a partial circuit diagram of a protection device for PTC product testing in one embodiment of this application. Figure 3 ;

[0032] Figure 7 A schematic diagram of a channel controller for PTC product testing provided in another embodiment of this application;

[0033] Figure 8 This application provides an embodiment of a protection method for PTC product testing. Detailed Implementation

[0034] To make the technical solutions and beneficial effects of this application more apparent and understandable, the technical solutions in the embodiments of this application are clearly and completely described below by listing specific examples. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0036] It is understood that the terms “first,” “second,” etc., as used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor. When “first” is described, it does not imply the necessary presence of a “second”; and when “second” is discussed, it does not imply the necessary presence of a first element, component, region, layer, or portion. As used herein, the singular forms “a,” “an,” and “the” may also be intended to include the plural forms unless the context clearly indicates otherwise. “A plurality” means two or more, unless otherwise explicitly specified. It should also be understood that the term “comprising,” when used in this specification, identifies the presence of the stated feature but does not exclude the presence or addition of one or more other features. As used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0037] It is understood that in the context of this application, "connection" means that there is an electrical signal or data transmission between the connected end and the connected end, which can be understood as "electrical connection", "communication connection", etc. In the context of this application, "A and B are directly connected" means that there are no other components between A and B except for wires.

[0038] The inventors discovered through research that the main reason for "false protection" during PCT withstand voltage testing lies in the temperature characteristics of the PTC material's resistance. When a voltage is continuously applied to the PTC resistor, its resistance initially decreases around the Curie temperature and then rapidly increases, as shown in the image. Figure 1a As shown. The operating current variation of the PTC resistor is as follows. Figure 1b As shown, it reaches its maximum at the "Curie temperature". Figure 1c The figure shows the current-voltage characteristic curve of a PTC resistor. When the PTC resistor is connected to the power supply, the current increases rapidly with the increase of voltage, and the current reaches its maximum value when the Curie temperature is reached.

[0039] Withstand voltage testing includes rated withstand voltage testing and ultimate withstand voltage testing. Rated withstand voltage testing uses a DC power supply to apply the rated voltage to the PTC under test, and determines whether the PTC is damaged by measuring the current value within a specified time. Ultimate withstand voltage testing uses a DC power supply to gradually increase the voltage applied to the PTC under test until the PTC is damaged, often manifesting as explosion or short circuit. A sudden increase in current will occur before explosion. Figure 1cAs can be seen, the rated voltage and breakdown voltage of a PTC occur after the current reaches its maximum value. This means both tests are performed after the PTC has exceeded its Curie temperature. Therefore, when the PTC effect occurs, the current reaches its maximum value, exceeding the protection current threshold and triggering protection, thus terminating the test. This application uses a microcontroller to determine whether the current flowing through the PTC under test has reached its maximum current, thus determining whether protection needs to be activated. When the current of the PTC under test reaches its maximum current, it indicates that the PTC is about to enter the withstand voltage test stage, activating the protection unit and making the protection function effective. This avoids triggering protection before the PTC under test enters the withstand voltage test stage, preventing false protection.

[0040] This application provides a protection device for PTC product testing, such as... Figure 2 As shown, the system includes a microcontroller and at least one channel driver. The at least one channel driver is connected to the microcontroller. The figure shows N channel drivers, each connected to the microcontroller, where N is greater than or equal to 2. A single microcontroller controls all N channel drivers simultaneously, enabling simultaneous testing of multiple channels and improving the testing efficiency of PTC products.

[0041] The channel driver includes a sampling unit, a protection unit, and a protection control unit. The sampling unit is connected to the PTC product under test and is used to acquire the current flowing through the PTC product and output the acquisition signal. Optionally, the sampling unit includes a first sampling module for acquiring the current flowing through the PTC product, converting the acquired current signal into a voltage signal, and outputting the voltage signal as the acquisition signal.

[0042] The microcontroller, connected to the sampling unit and the protection control unit, determines whether to activate the protection unit based on the current flowing through the PTC product under test. It sends an activation signal to the protection control unit to control the protection unit's operating status. When the current flowing through the PTC product under test has not reached its maximum value, it indicates that the PTC product has not yet reached its Curie temperature and has not yet entered the withstand voltage test stage; therefore, the protection unit does not need to be activated. The protection unit is in an inactive state. When the current flowing through the PTC product under test has reached its maximum value, or has exceeded its maximum value, it indicates that the PTC product has entered the withstand voltage test stage, and the protection unit needs to be activated. The protection unit is in an activated state.

[0043] The microcontroller compares the sampled value of the acquired signal with a first threshold, and sends an enable signal to the protection control unit based on the comparison result. When the sampled value is greater than the first threshold, the enable signal is sent to control the protection unit to enter the working state. The sampled value of the current flowing through the PTC product under test is obtained by sampling the acquired signal of the current flowing through the PTC product under test. The microcontroller includes signal conditioning and analog-to-digital conversion to sample the acquired signal and obtain the sampled value.

[0044] Optionally, the first threshold is the maximum current I of the PTC product under test when it is at the Curie temperature. max The microcontroller determines whether the PTC product under test needs protection by judging whether the current flowing through it has reached the maximum current. When the current of the PTC product under test reaches the maximum current, it indicates that the PTC product is about to enter the withstand voltage test stage, the protection unit is activated, and the protection function takes effect.

[0045] Optionally, the first threshold is the maximum current I. max More than 70%, that is, the first threshold ≥ 70% max Optionally, the first threshold is ≥80% of Imax. Optionally, the first threshold is ≥90% of Imax. The first threshold is related to the maximum current I. max The greater the difference, the more sufficient the protection action time. The microcontroller determines whether the PTC product under test has reached its maximum current by counting the number of times the current flowing through it reaches the first threshold. When the current flowing through the PTC product under test reaches the first threshold for the second time, it is determined that the PTC product under test has reached its maximum current, and the protection unit is activated for protection.

[0046] The protection unit is connected to the sampling unit and is used to control the on / off state of the test channel where the protection unit is located based on the acquisition signal from the sampling unit. When the acquisition signal is greater than or equal to a second threshold, the protection unit will be triggered to shut down its test channel, thereby protecting the PTC product under test in that test channel from damage. Alternatively, shutting down its test channel will prevent other test channels from being affected.

[0047] The protection control unit is connected to the microcontroller, the protection unit, and the PTC product under test, respectively. It receives an enable signal and controls the operating state of the protection unit based on this signal. When the protection control unit does not receive an enable signal, it and the PTC product under test are in the same test circuit, and the protection unit is not connected to this circuit. In this case, the protection unit is not conductive and does not operate because it is not connected to the test circuit. When the protection control unit receives an enable signal, it connects the protection unit to the test circuit, putting the protection unit into operation. At this time, the protection unit and the PTC product under test are electrically connected and in the same test circuit, and the protection function is activated, thereby protecting the PTC product under test.

[0048] Figure 3 This is a partial circuit diagram of the channel driver. (Example) Figure 3 As shown, HV is connected to the positive terminal of the DC power supply. The object under test is connected between LJ1 and LJ2. The sampling unit includes a sampling resistor R15, used to convert the operating current flowing through the PTC product under test into a voltage signal. The sampling unit also includes an acquisition module. The acquisition module includes resistors R13 and R7 connected in series. The first input terminal SD of the protection unit is connected between resistors R13 and R7. Resistors R13 and R7 are used to divide the voltage across R15 to obtain the acquisition signal, which is then input to the driver module IC3 through the first input terminal. The second threshold value for triggering the protection unit to perform "hardware protection" is set by setting the resistance values ​​of resistors R13 and R7.

[0049] Optionally, the protection control unit includes a second switch module connected to the microcontroller, used to change its own state according to the enable signal, thereby controlling whether the protection unit is in the working state. When no enable signal is received, the second switch module is turned on, making the protection control unit and the PTC product under test in the same test circuit; the protection unit is short-circuited or not selected, and is in a non-working state. When an enable signal is received, the second switch module is turned off, making the protection control unit inactive. At this time, the protection unit is selected and in the working state, and the protection unit and the PTC product under test are in the same test circuit, thereby realizing the protection of the PTC product under test.

[0050] Optionally, the protection control unit includes a second switch and a second switch controller. The second switch controller is connected to the microcontroller and the second switch respectively, and is used to control the second switch to change its own state according to the enable signal, so as to control the protection unit to be in the working state.

[0051] like Figure 4 As shown, the second switching module includes a high-voltage relay and a second switching controller BG2. J1A is the coil of the high-voltage relay, and J1B is the contact of the high-voltage relay. Initially, the relay coil is energized, and the DC power supply, the PTC under test, and the protection control unit form a circuit. The protection unit is not connected to the test circuit, and the protection function is not active. The microcontroller samples the current flowing through the PTC under test in real time through the second acquisition module of the sampling unit to obtain its sampled value. This sampled value is compared with a second threshold to determine whether the current flowing through the PTC under test has reached the maximum current Imax at the Curie temperature. When the current flowing through the PTC under test has not reached the maximum value, it indicates that the PTC under test has not yet reached the Curie temperature point and has not yet reached the withstand voltage test stage; therefore, the protection unit does not need to be activated.

[0052] When the current flowing through the PTC product under test reaches its maximum value, or has exceeded its maximum value, it indicates that the PTC product under test has entered the withstand voltage test stage, and the protection unit needs to be activated. The microcontroller sends an activation signal to the protection control unit. The JEX terminal of the protection control unit receives this activation signal and is at a low level. At this time, the second switch controller BG2 is cut off due to the low base level, and the high-voltage relay coil changes from the energized state to the non-energized state. The protection control unit is disconnected, and the protection unit is connected to the test circuit. At this time, the DC power supply, the PTC under test, and the protection unit form a loop, and the protection function is activated.

[0053] like Figure 3 As shown, the protection unit includes a driver module IC3 and a first switch module Q1. The first switch module Q1 uses a high-voltage transistor. The driver module IC3 uses a driver chip. IC3 includes a first input terminal 3, a second input terminal 2, a first output terminal 6, and a second output terminal 7. The first input terminal SD of the protection unit is connected between resistors R13 and R7. Resistors R13 and R7 are used to divide the voltage across R15 to obtain the acquisition signal, which is then input into the driver module IC3 through the first input terminal. The first output terminal 6 is connected to the base of Q1. The second output terminal 7 is connected to the base of Q1 through resistor R14. IC3 receives the input signal from the sampling unit through the first input terminal. The second control terminal 2 of the driver module IC3 is connected to the output of the microcontroller and is used to receive the first protection control signal output by the microcontroller. The base level of Q1 is introduced to the IN input terminal of the microcontroller. The microcontroller determines whether Q1 is cut off by acquiring the base level of Q1.

[0054] By using a microcontroller to determine whether the current flowing through the PTC product under test has reached its maximum current, the system can determine whether the PTC product needs to activate its protection. When the current of the PTC product under test reaches its maximum current, it indicates that the PTC product is about to enter the withstand voltage test stage, and the protection unit is activated, and the protection function takes effect. In this way, the protection is prevented from being triggered before the PTC product under test enters the withstand voltage test stage, thus preventing "false protection".

[0055] When using a single DC power supply to test multiple different PTC products, if one product fails during testing, causing a short circuit in that test channel, the DC power supply will enter constant current mode. At this time, due to the load short circuit, according to Ohm's law, the output voltage of the DC power supply will be very low. This will cause the PTC products under test in other test channels to be unable to maintain their conduction state and quickly return to their pre-Curie temperature, rendering the test meaningless and ultimately interrupting the testing process for all products. By using a microcontroller to detect and quickly protect the current during the testing process of each channel, when a short circuit is detected in a PTC product under test in a certain test channel, the power supply to that channel is quickly cut off without affecting other channels. This achieves the purpose of multi-channel testing and allows for maximum channel expansion based on the configured DC power supply power.

[0056] Optionally, the protection unit includes a first protection mode for rapid protection of the test channel, suitable for situations where a sudden current change occurs during the test of the PTC product under test. Figure 5a This diagram illustrates a sudden current surge in the PTC product under test. The horizontal axis represents time T, and the vertical axis represents the current I flowing through the PTC product and the voltage V applied to it. I is the steady-state operating current of the PTC, V is the voltage applied across the PTC, I2 is the first protection value that triggers the "hardware protection," and I1 is the preset second protection value. When the PTC product under test reaches its ultimate withstand voltage or experiences damage or other abnormalities leading to a short circuit during the withstand voltage test, the operating current flowing through the PTC product experiences a sudden increase, rapidly reaching I2, which will directly trigger the "hardware protection."

[0057] When the operating current flowing through the PTC product under test suddenly increases, the acquisition signal received at the SD terminal also suddenly increases, and the SD terminal inputs a "1 high level". This triggers the first output terminal 6 of the driver module IC3 to turn off Q1 due to the sinking current. The first switch module Q1 is then briefly turned off.

[0058] Meanwhile, the microcontroller monitors the base level of switch module Q1 in real time to determine whether Q1 is cut off. When Q1 is cut off, the microcontroller continuously outputs a low level to the second input terminal 2 of the driver unit IC3, i.e., the "K mark" terminal, so that the first output terminal OUTS6 of the driver unit IC3 continuously "drives in" current, causing Q1 to be cut off, thereby closing the test channel. "Drives in" means that the first output terminal OUTS6 of the driver unit IC3 can receive sinking current, thereby outputting a low level to the base of Q1.

[0059] Optionally, the protection unit also includes a delay module for reducing the rate of change of the current flowing through the first switching module, so that the first switching module has sufficient time to change its state.

[0060] Optionally, the protection unit also includes an inductor L1, connected in series with the PCT under test in the test circuit. The PCT under test is connected to the collector C of the first switching module Q1 via inductor L1. Inductor L1 is used to slow down the rise rate of the current flowing through the PCT under test, giving the first switching module Q1 sufficient time to change from the on state to the off state. Utilizing the characteristic that the current flowing through the inductor cannot change instantaneously, this provides time for Q1 to cut off when a sudden change in the damage current of the PTC under test occurs. The measured operating time is 1μs.

[0061] When the tested PTC reaches its maximum withstand voltage, or when the PTC is damaged and short-circuited, causing a sudden increase in current, the corresponding line current will also increase abruptly. The signal is transmitted to the SD pin of the driver chip via the current sampling voltage divider resistor composed of R13 and R7. By changing the level of the SD pin, the output is turned on and off, thereby driving the high-voltage transistor to shut off the circuit, thus achieving the purpose of turning off the voltage applied across the PTC.

[0062] Understandably, if the response speed of the first switching module Q1 is fast enough, there is no need to use inductor L1.

[0063] In another embodiment, the protection unit further includes a second protection mode, also known as "software protection." During the withstand voltage test of the PCT product under test, the current flowing through the PTC product exhibits a slow, non-abrupt increase. For example... Figure 5b As shown, I is the steady-state operating current of the PTC, V is the voltage applied across the PTC, I1 is the user-set protection current value, and I2 is the hardware threshold protection current. When the PTC fails and the current rises slowly, the channel controller has enough time to respond. The response time is T2-T1, and the second protection mode of "software protection" will be adopted.

[0064] The first protection mode and the second protection mode operate in parallel. Because the second protection mode requires sampling the current flowing through the PCT product under test to obtain a sample value, its protection speed is slower than the first protection mode, making it suitable for situations where the current changes slowly. The sampling includes range conversion, amplification, and analog-to-digital conversion after current acquisition.

[0065] like Figure 4 As shown, the microcontroller is also connected to the sampling unit. The sampling unit further includes a signal conditioning module for range conversion and amplification of the current flowing through the measured object, so that the microcontroller can perform analog-to-digital conversion to obtain the sampled value. Figure 6As shown, the signal conditioning module includes a second acquisition module and an amplification module IC2A. The second acquisition module includes sampling resistors R2 and R3, which are connected in series to the emitter E of the first switch module Q1 for sampling the current flowing through the PTC under test. IC1 is an analog switch chip. The non-inverting input of the operational amplifier IC2A is connected between resistors R2 and R3. It receives the signal acquired by the second acquisition module, amplifies it after input to the non-inverting input of IC2A, and then inputs the amplified signal from the output terminal 1 of IC2A into the microcontroller for A / D conversion to obtain the sampled value of the current flowing through the PTC under test.

[0066] The microcontroller compares the sampled value with a third threshold. When the sampled value exceeds the third threshold, it triggers the second protection mode, i.e., "software protection." The third threshold is the current threshold corresponding to triggering "software protection." The microcontroller outputs a second protection control signal to the IN2 terminal of the drive module IC3, causing the first switch module Q1 to remain off, thereby controlling the channel containing the protection unit to close. The method of continuously turning off the first switch module Q1 is the same as that of the first protection mode described above.

[0067] Another embodiment of this application also provides a channel controller for PTC product testing, such as... Figure 7 As shown in the diagram. The difference from other embodiments is that the microcontroller is integrated within the channel controllers; that is, each channel controller includes a microcontroller, allowing one microcontroller to control one channel controller independently. With this configuration, the number of channel controllers is not limited by the number of channels in the microprocessor, resulting in greater scalability.

[0068] This application also provides a channel control method for PTC product testing, including the following steps:

[0069] S10: The current flowing through the PTC product under test in the current test channel is collected to obtain a collection signal. Step S10 is implemented using a sampling unit. The sampling unit includes a first acquisition module. The first acquisition module includes a sampling resistor, which converts the current flowing through the PTC product under test into a voltage, which is used as the acquisition signal.

[0070] S20: Sample the current flowing through the PTC product under test in the current test channel to obtain a sampled value; step S10 is implemented using a sampling unit. The sampling unit includes a second acquisition module that samples the current flowing through the PTC product under test. The sampling unit also includes a signal conditioning module that performs range conversion and amplification on the sampled current, and then inputs it to the microcontroller for analog-to-digital conversion to obtain the sampled value.

[0071] S30, compare the sampled value with a first threshold, and output a protection function enable signal based on the comparison result. The microcontroller compares the sampled value with the first threshold. When the sampled value is greater than the first threshold, it indicates that the PTC product under test is in the testing phase, and sends an enable signal to the protection control unit to control the protection unit to enter the working state, and the protection function takes effect. First threshold ≥ 70% max The I max This is the maximum current of the PTC product under test when it is at the Curie temperature.

[0072] S40, the current test channel is controlled to be in a protected state according to the protection control signal. The protection control unit connects the protection unit to the test circuit according to the enable signal, the protection function is activated, and the current test channel is in a protected state.

[0073] S50, when the acquired signal is greater than or equal to the second threshold, the current test channel is shut down. The protection unit performs protection actions based on the acquired signal. When the acquired signal is greater than the second threshold, hardware protection is triggered, and the test channel is quickly shut down. The second threshold is a preset threshold for triggering hardware protection.

[0074] Optionally, the method further includes the following steps: S21, comparing the sampled value with a third threshold, and controlling the current test channel to be closed when the sampled value is greater than or equal to the third threshold.

[0075] The microcontroller monitors the sampled values ​​in real time and compares them with a third threshold. When the sampled value is greater than or equal to the third threshold, the control protection unit shuts down the current test channel. The third threshold is a preset threshold that triggers software protection.

[0076] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0077] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A protection device for PTC product testing, characterized in that, Includes a microcontroller and at least one channel driver; The at least one channel driver is connected to the microcontroller; The channel driver includes: a sampling unit, a protection unit, and a protection control unit; the sampling unit and the protection unit are connected; the protection control unit is connected to the microcontroller; The sampling unit is used to connect to the PTC product under test, collect the current flowing through the PTC product under test, and output the collection signal; The microcontroller is used to compare the sampled value of the current flowing through the PTC product under test with a first threshold, and send an enable signal to the protection control unit according to the comparison result; wherein, the first threshold is a current value related to the maximum current of the PTC product under test when it is at the Curie temperature; The protection control unit is connected to the microcontroller and is used to control the working state of the protection unit according to the enable signal; The protection unit is connected to the sampling unit and is used to control the on / off state of the test channel where the protection unit is located based on the acquired signal, so as to realize the protection function.

2. The protection device for PTC product testing according to claim 1, characterized in that, The protection control unit includes a second switch module, which is connected to the protection unit and the microcontroller respectively. The second switch module is used to control the protection unit to be turned on according to the enable signal, so that the protection unit is in the test circuit.

3. The protection device for PTC product testing according to claim 2, characterized in that, The second switch module includes a high-voltage relay and a second switch controller. The second switch controller controls the operating state of the high-voltage relay according to the enable signal, so as to control the protection unit to be in the test circuit.

4. The protection device for PTC product testing according to claim 1, characterized in that, The first threshold ≥70% max The I max This is the maximum current of the PTC product under test when it is at the Curie temperature.

5. The protection device for PTC product testing according to claim 1, characterized in that, The protection unit includes a drive module and a first switch module; the drive module is used to output a first state change signal to the first switch module according to the acquired signal; the microcontroller is also used to output a first protection control signal to the current protection unit according to the first state change signal, so as to control the channel where the protection unit is located to be closed.

6. The protection device for PTC product testing according to claim 1, characterized in that, The microcontroller is also used to compare the sampled value of the current flowing through the PTC product under test with a third threshold, and output a second protection control signal to the protection unit according to the comparison result, so as to control the channel where the protection unit is located to be closed.

7. The protection device for PTC product testing according to claim 1, characterized in that, The sampling unit includes a signal conditioning module; the signal conditioning module is used to perform range conversion and amplification of the current flowing through the measured object so that the microcontroller can perform analog-to-digital conversion to obtain the sampled value.

8. A protection method for testing PTC products, characterized in that, The following steps are involved: The current flowing through the PTC product under test in the current test channel is collected to obtain the acquisition signal; The current flowing through the PTC product under test in the current test channel is sampled to obtain the sampled value; The sampled value is compared with a first threshold, and a protection function enable signal is output based on the comparison result; wherein, the first threshold is a current value related to the maximum current of the PTC product under test when it is at the Curie temperature; The protection function activation signal controls the current test channel to be in a protected state. When the acquired signal is greater than or equal to the second threshold, the current test channel is shut down.

9. The protection method for PTC product testing according to claim 8, characterized in that, It also includes the following steps: The sampled value is compared with a third threshold. When the sampled value is greater than or equal to the third threshold, the current test channel is shut down.

10. A multi-channel testing device, characterized in that, The device includes the protection device as described in any one of claims 1-7, and a test power supply connected to the protection device; the protection device is used to independently control whether the test channel where each channel driver is located is turned off.

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