Ground offset test circuit, method and device

Abstract

The invention discloses a ground offset test circuit, method and device, and the circuit comprises a single-chip microcomputer module which is used for controlling the operation of the circuit, including generating a control signal, adjusting the output of a voltage generation module, and controlling a switching circuit; the first voltage generation circuit is a Us end 1V voltage generation circuit, comprises an operational amplifier U1, resistors R1 and R2 and a capacitor C1, and is used for generating + 1V offset voltage and applying the + 1V offset voltage between the Us positive end and the AGND; and the second voltage generation circuit, namely a GND end 1V voltage generation circuit, comprises an operational amplifier U2 and resistors R3, R4 and R7, and is used for generating-1V offset voltage and applying the-1V offset voltage between the GND end and the AGND. According to the invention, by designing the independent Us end 1V voltage generation circuit and GND end 1V voltage generation circuit, accurate + 1V and-1V offset voltages are respectively generated, and the strict requirements of the ground offset test on positive and negative offset can be met. Compared with the prior art, the circuit provided by the invention can more accurately adjust the offset voltage, and ensures the stability of signal reference in various test scenes.

Description

Technical Field

[0001] The present invention relates to a ground offset test circuit, in particular to a ground offset test circuit, method and device, belonging to the technical field of automotive electronic and electrical testing. Background Art

[0002] In modern vehicle electronic systems, ground offset is a common phenomenon. Especially in complex electrical systems, due to the voltage difference between different devices, ground impedance and current flow, the ground potential will shift slightly, resulting in unstable signal reference in the circuit. In order to ensure the reliability of electronic equipment such as vehicle controllers and sensors in various environments, the international standard ISO 16750-1 has made corresponding provisions for ground offset testing. This test is designed to simulate the offset phenomenon caused by factors such as unstable power supply system and ground potential difference in actual vehicle environment, so as to verify the working performance of the equipment under extreme conditions.

[0003] Existing ground offset test circuits usually only have simple offset functions and are difficult to provide accurate positive and negative offset voltages. When dealing with large currents or complex offset operations, the circuit performance will be greatly reduced. In addition, existing ground offset circuits have deficiencies in dealing with power device heating, overcurrent protection, and voltage switching, and cannot meet the different requirements of 12V and 24V systems. Especially when the load current is large (over 6A), traditional test circuits are difficult to control the temperature rise of power devices while maintaining output accuracy. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a ground offset test circuit, method and device, which solves the problem that accurate positive and negative offset voltages cannot be achieved in the prior art.

[0005] The technical problem to be solved by the present invention is achieved by adopting the following technical solutions:

[0006] The present invention provides a ground offset test circuit, the ground offset test circuit comprising:

[0007] a single chip microcomputer module for controlling the operation of the circuit, including generating control signals to adjust the output of the voltage generating module and to control the switching circuit;

[0008] The first voltage generating circuit, i.e., the 1V voltage generating circuit at the Us terminal, comprises an operational amplifier U1, resistors R1, R2 and a capacitor C1, and is used to generate a +1V offset voltage, which is applied between the positive terminal of Us and AGND;

[0009] The second voltage generating circuit, i.e., the 1V voltage generating circuit at the GND terminal, comprises an operational amplifier U2, resistors R3, R4 and R7, and is used to generate a -1V offset voltage, which is applied between the GND terminal and AGND;

[0010] A Us-end power input module, used to provide power input to the Us-end, and comprising a protection circuit connected to the voltage generating circuit;

[0011] A power supply input module, including a positive power supply POW+ and a negative power supply POW-, is used to provide positive and negative power supplies required for circuit operation and is connected to a voltage generation and amplification module;

[0012] Operational amplifier circuit and power device module, including operational amplifiers U3, U4, resistors R5, R8 and Darlington power output circuit, used to further amplify the offset voltage and stabilize the high current output;

[0013] The user load module is used to receive the adjusted offset voltage to verify the performance of the device under test (DUT) under different ground offset conditions.

[0014] As a preferred technical solution of the present invention, the single chip computer module (1) is used to adjust the output offset voltage of the 1V voltage generating circuit of the Us end and the 1V voltage generating circuit of the GND end through a control signal to ensure the positive and negative offset operation of the Us end and the GND end.

[0015] As a preferred technical solution of the present invention, the pin configuration of the operational amplifier U1 in the Us terminal 1V voltage generating circuit is as follows:

[0016] Pin 1 (OUT) and pin 2 (1IN-) of U1 are connected together to pin 2 of connector CN1;

[0017] Pin 3 (1IN+) of U1 is connected to pin 1 (OUT) of U2 and pin 2 of CN3 as the reference voltage input;

[0018] Pin 4 (GND) of U1 is connected to pin 1 of CN3 through capacitor C1 and connected to ground.

[0019] As a preferred technical solution of the present invention,

[0020] The pin configuration of the operational amplifier U2 in the GND terminal 1V voltage generation circuit is as follows:

[0021] Pin 1 (OUT) of U2 is connected to pin 2 of CN3;

[0022] Pin 2 (1IN-) of U2 is connected to reference voltage A1 through resistor R1, and is connected to CN5 through resistor R3. A fuse F1 is provided in front of CN5 to provide overcurrent protection.

[0023] Pin 3 (1IN+) of U2 is connected to the reference voltage REF+ through resistor R2, and is connected to pin 3 (1IN+) of U3 through resistors R4 and R7.

[0024] As a preferred technical solution of the present invention, the operational amplifier circuit and the power device module include:

[0025] Pin 1 (OUT) of U3 is connected to pin 2 of CN6 and pin 3 (1IN+) of U4 to provide feedback for negative offset;

[0026] Pin 2 (1IN-) of U3 is connected to CN5 (previously connected to fuse F2) through resistor R9, and is connected to reference voltage A2 through resistor R11;

[0027] Pin 1 (OUT) and pin 2 (1IN-) of U4 are connected together to pin 2 of CN8.

[0028] As a preferred technical solution of the present invention, the POW+ of the power supply input module is connected to pin 8 (VCC) of U1 and pin 1 of CN1, and POW- is connected to the GND pin (4) of U4, ensuring the stability of the positive and negative power supply of the circuit.

[0029] When the load current exceeds 6A, the heat generation of the power device increases significantly. To solve this problem, the present invention adopts a dual-path Darlington output circuit in both the positive and negative current paths to share the high current load, and at the same time cooperates with the heat sink design to effectively control the temperature rise of the power device so that it remains within a safe range under high load conditions. This design not only improves the heat resistance of the circuit, but also extends the service life of the equipment and improves the reliability of the test.

[0030] The present invention also provides a ground offset test method, which is applied to the above-mentioned ground offset test circuit and comprises the following steps:

[0031] Step S1, applying a +1V offset voltage between the Us positive terminal and AGND through a 1V voltage generating circuit at the Us terminal, and applying a -1V offset voltage between the GND terminal and AGND through a 1V voltage generating circuit at the GND terminal;

[0032] Step S2, using the operational amplifier circuit and the Darlington output circuit of the power device module to share the output current of the offset voltage, and reducing the temperature rise of the power device through a heat sink;

[0033] Step S3, dynamically switching the positive and negative offset voltages through a switching circuit to simulate different ground offset conditions;

[0034] Step S4, performing PWM fine-tuning on the output of the offset voltage through the single-chip microcomputer module to achieve precise control of the positive and negative offset voltages to meet the ground offset requirements set by the user.

[0035] The present invention also provides a ground offset test device, which has the above-mentioned ground offset test circuit, and also includes a positive and negative power supply module for providing input voltage and a display module for displaying the circuit status.

[0036] The beneficial effects of the present invention are as follows: the present invention generates accurate +1V and -1V offset voltages respectively by designing independent 1V voltage generating circuits at the Us end and 1V voltage generating circuits at the GND end, which can meet the strict requirements of the ground offset test for positive and negative offsets. Compared with the prior art, the circuit of the present invention can adjust the offset voltage more accurately to ensure the stability of the signal reference in various test scenarios; a Darlington output circuit is adopted, and the current load is effectively shared by the heat sink design, solving the heating problem of the traditional circuit under high current conditions. When the load current exceeds 6A, the circuit can still maintain the output accuracy, while controlling the temperature rise of the power device, greatly improving the reliability of the ground offset test; through the POW+ and POW- design in the power supply input module, the present invention can be applied to different power supply systems of 12V and 24V, meet the test requirements of various vehicle electronic systems, and have strong adaptability and wide applicability; by designing fuses (such as F1 and F2) in key circuit parts (such as the 1V voltage generating circuit at the Us end and the 1V voltage generating circuit at the GND end), overcurrent protection is achieved to avoid circuit damage due to excessive current. In addition, by switching the positive and negative switching of the offset voltage through the switching circuit, it is possible to simulate the working state under different ground offset conditions, providing a guarantee for the extreme condition testing of the equipment; the automatic control and precise adjustment of the offset voltage are realized through the single-chip microcomputer module, and the PWM fine-tuning function is used to ensure that the output offset voltage meets the accuracy requirements. This enables the present invention to adapt to different testing needs and provide higher accuracy and reliability in ground offset testing; it is designed according to the requirements of the international standard ISO16750-1 for ground offset, and can simulate various extreme conditions caused by ground potential offset in the vehicle environment, thereby verifying the stability of electronic equipment in a complex electrical environment. By verifying the working performance of the equipment under different ground offset conditions, the present invention provides a guarantee for the reliability of key equipment such as vehicle controllers and sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of the present invention;

[0038] Figure 2 is a circuit diagram of the present invention;

[0039] In the figure: 1. single chip microcomputer module; 2. first voltage generating circuit; 3. second voltage generating circuit; 4. Us end power input module; 5. power supply input module; 6. operational amplifier circuit and power device module; 7. user load module. DETAILED DESCRIPTION

[0040] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0041] Example 1

[0042] like Figure 1-2 As shown, this embodiment provides a ground offset test circuit for applying an offset voltage between a positive terminal Us of an input voltage and a ground terminal AGND. The ground offset test circuit includes:

[0043] The single chip microcomputer module 1 is used to control the operation of the circuit, including generating control signals to adjust the output of the voltage generation module and control the switching circuit, such as PWM output, generating 1V voltage generation control, switching circuit control, and realizing overvoltage protection. The typical implementation process is:

[0044] The single-chip microcomputer module 1 first receives the control parameters input by the user, such as the required offset voltage value and offset direction. Based on these parameters, the single-chip microcomputer generates a PWM (pulse width modulation) signal to accurately control the output offset voltage of the 1V voltage generating circuit (module 2) at the Us end and the 1V voltage generating circuit (module 3) at the GND end, applying +1V and -1V offset signals respectively. The single-chip microcomputer also realizes the positive and negative conversion of the offset voltage by controlling the switching circuit, ensuring that the voltage switching between the positive end of the Us and the GND end is smooth and impact-free.

[0045] During the implementation process, the single-chip microcomputer module 1 will monitor the output voltage status of each module in real time, and fine-tune the output voltage by adjusting the duty cycle of the PWM signal to ensure the stability and accuracy of the offset voltage. At the same time, the single-chip microcomputer module 1 dynamically adjusts the working state of the Darlington output circuit according to the load conditions to avoid overheating of the power device, thereby ensuring the normal operation of the ground offset test under various load conditions;

[0046] The first voltage generating circuit 2, i.e., the 1V voltage generating circuit at the Us end, includes an operational amplifier U1, resistors R1, R2, and a capacitor C1, which is used to generate a +1V offset voltage, which is applied between the positive end of Us and AGND to simulate a positive ground offset. During operation, when the single-chip microcomputer module 1 receives an instruction requiring a positive offset, the single-chip microcomputer controls the input signal of the operational amplifier U1 to output a stable +1V offset voltage. This voltage is appropriately divided and adjusted through resistors R1 and R2, and capacitor C1 is used to filter out high-frequency noise in the voltage to ensure smoothness and stability of the offset voltage;

[0047] The second voltage generating circuit 3, i.e., the 1V voltage generating circuit at the GND terminal, includes an operational amplifier U2, resistors R3, R4 and R7, which are used to generate a -1V offset voltage, which is applied between the GND terminal and AGND; the circuit is used to generate a negative offset voltage of -1V, and applied between the GND terminal and AGND to simulate a reverse ground offset. When the single-chip microcomputer module 1 sends a control signal that requires a negative offset, the operational amplifier U2 receives the instruction and outputs a stable -1V offset voltage. The voltage is divided and adjusted by resistors R3 and R4, and further adjusted by resistor R7 to ensure the accuracy and stability of the voltage. This negative offset voltage is finally applied between the GND terminal and AGND, thereby realizing a reverse ground offset test.

[0048] The Us-end power input module 4 is used to provide power input to the Us-end, and includes a protection circuit connected to the voltage generation circuit; it is used to provide a stable power input to the Us-end to ensure the reference voltage of the test. At the same time, overvoltage and overcurrent protection circuits are designed in the module. When the input voltage exceeds the safe range, the protection circuit will respond quickly to prevent circuit damage. In actual operation, the Us-end power input module 4 transmits a stable voltage to the Us-end 1V voltage generation circuit, and ensures that during the offset voltage superposition process, the reference voltage is always kept within the preset range, thereby providing reliable power support for the entire ground offset test.

[0049] A power supply input module 5, including a positive power supply POW+ and a negative power supply POW-, is used to provide positive and negative power supplies required for circuit operation and is connected to the voltage generation and amplification module;

[0050] Operational amplifier circuit and power device module 6, including operational amplifiers U3, U4, resistors R5, R8 and Darlington power output circuit, for further amplifying the offset voltage and stabilizing the high current output;

[0051] The design purpose of the operational amplifier circuit and power device module 6 is to further amplify the offset voltage signal in the ground offset test and provide a stable high current output to meet the requirements of the test under high current load conditions. The module is mainly composed of operational amplifiers U3 and U4, resistors R5 and R8, and Darlington power output circuit. Among them, operational amplifiers U3 and U4 receive the offset voltage signal from the first voltage generating circuit and the second voltage generating circuit, and perform preliminary voltage amplification on it. The amplified signal is current-limited and stabilized by resistors R5 and R8 to ensure that the signal will not be attenuated or distorted during transmission.

[0052] The Darlington power output circuit plays a key role in current amplification in this module. The Darlington circuit is a current amplifier consisting of two transistors connected in series (in this circuit, shown by connectors CN7 and CN9). Specifically, the Darlington circuit is designed to connect the collector of the first transistor to the base of the second transistor so that the current can be cascaded between the two transistors. The small current of the first transistor is amplified and enters the base of the second transistor, where it is further amplified into a larger current output. This dual-transistor Darlington circuit has a high current gain and can achieve higher output current than a single transistor.

[0053] In the operational amplifier circuit and power device module 6 of the present invention, the Darlington circuit is responsible for current amplification of the offset voltage signal amplified by the operational amplifier to ensure that a stable high current output can still be provided when the load is large. This configuration enables the circuit to not only output an accurate offset voltage in the ground offset test, but also maintain output stability when the current demand is high. In addition, the high gain characteristic of the Darlington circuit reduces the dependence on the output capacity of the operational amplifier and reduces the heating of the power device, thereby extending the working life of the equipment and improving the reliability of the overall test circuit.

[0054] The user load module 7 is used to receive the adjusted offset voltage and connect it to the user load through the output interface to verify the performance of the device under test (DUT) under different offset conditions.

[0055] Furthermore, the single chip computer module 1 is used to adjust the output offset voltage of the 1V voltage generating circuit of the Us terminal and the 1V voltage generating circuit of the GND terminal through the control signal to ensure the positive and negative offset operation of the Us terminal and the GND terminal.

[0056] Specifically, the pin configuration of the operational amplifier U1 in the 1V voltage generating circuit of the Us terminal is as follows:

[0057] Pin 1 (OUT) and pin 2 (1IN-) of U1 are connected together to pin 2 of connector CN1;

[0058] Pin 3 (1IN+) of U1 is connected to pin 1 (OUT) of U2 and pin 2 of CN3 as the reference voltage input;

[0059] Pin 4 (GND) of U1 is connected to pin 1 of CN3 through capacitor C1 and connected to ground.

[0060] The pin configuration of the operational amplifier U2 in the GND terminal 1V voltage generation circuit is as follows:

[0061] Pin 1 (OUT) of U2 is connected to pin 2 of CN3;

[0062] Pin 2 (1IN-) of U2 is connected to reference voltage A1 through resistor R1, and is connected to CN5 through resistor R3. A fuse F1 is provided in front of CN5 to provide overcurrent protection.

[0063] Pin 3 (1IN+) of U2 is connected to the reference voltage REF+ through resistor R2, and is connected to pin 3 (1IN+) of U3 through resistors R4 and R7;

[0064] The operational amplifier circuit and power device module include:

[0065] Pin 1 (OUT) of U3 is connected to pin 2 of CN6 and pin 3 (1IN+) of U4 to provide feedback for negative offset;

[0066] Pin 2 (1IN-) of U3 is connected to CN5 (previously connected to fuse F2) through resistor R9, and is connected to reference voltage A2 through resistor R11;

[0067] Pin 1 (OUT) and pin 2 (1IN-) of U4 are connected together to pin 2 of CN8;

[0068] The POW+ of the power input module is connected to pin 8 (VCC) of U1 and pin 1 of CN1, and POW- is connected to the GND pin (4) of U4 to ensure the stability of the positive and negative power supply of the circuit.

[0069] Specifically, the Us-end 1V voltage generating module 2 generates a 1V bias voltage through a single-chip microcomputer and a 1V generating circuit. The ground-end 1V voltage generating module 3 generates a 1V bias voltage through a single-chip microcomputer and a 1V generating circuit.

[0070] The Us-end power supply 4, as a reference voltage, is directly connected to the operational amplifier circuit; the power supply input module 5, as an energy provider, is directly connected to the operational amplifier circuit;

[0071] The operational amplifier circuit and power device module 6, as shown in the figure, includes operational amplifiers U1, U2, U3, U4, resistors R1, R2, R3, R4, R5, R7, R8, R9, R10, R11 and a Darlington power output circuit, which are used to achieve a positive or negative 1V offset between the user's Us voltage and the ground voltage; and provide the required maximum current of 10A.

[0072] Specifically, the present invention implements ground offset testing by designing a first voltage generating circuit and a second voltage generating circuit, and is particularly suitable for ground offset simulation in automotive electronic systems. In automotive electrical systems, the ground potential between different components may produce slight offsets due to current flow and ground impedance, and these offsets may affect the normal operation of controllers, sensors and other equipment. To this end, the ground offset test circuit of the present invention simulates the positive and negative ground offsets in an actual use environment by applying a +1V offset voltage between the positive terminal of Us and AGND, and applying a -1V offset voltage between the GND terminal and AGND.

[0073] When the automotive electronic system needs to perform a ground offset test, the single-chip microcomputer module controls the first voltage generation circuit to output a +1V offset voltage, which is applied between the positive end of Us and AGND to simulate a positive offset. At the same time, the second voltage generation circuit outputs a -1V offset voltage, which is applied between the GND end and AGND to simulate a negative offset. This combination of positive and negative offsets can truly restore the ground potential changes in the automotive electrical system. The offset voltage signal is further amplified by the operational amplifier circuit and the power device module 6, and the high current driving capability of the Darlington power output circuit is utilized to ensure the stable output of the offset voltage under high current loads, thereby verifying the working reliability of automotive electronic equipment under various ground offset conditions.

[0074] The working principle includes:

[0075] An offset voltage is generated by a single chip microcomputer, a 1V voltage generating circuit at the Us terminal, and a 1V voltage generating circuit at the GND terminal;

[0076] Through the operational amplifier circuit, under the switching control of the single-chip microcomputer, the offset voltage of +1V or -1V is added to the positive and negative ends of Us; and the high current power output required by the device output is provided;

[0077] User voltage Us, directly connected to REF+ and REF-;

[0078] Two sets of Darlington tubes are used at the positive end and the ground end respectively, which solves the problem of overheating under high power conditions;

[0079] And the power supply voltage input is controlled by overvoltage protection.

[0080] During operation, when the single-chip microcomputer module 1 receives an instruction to perform a positive shift, the single-chip microcomputer generates a corresponding PWM output, so that the 1V voltage generation circuit accurately generates a 1V voltage. Then the single-chip microcomputer switches the positive and negative 1V, and then connects to the A1 and A2 ports of the operational amplifier module. In the operational amplifier module, the formula V0 = (R3 / R1)(V REF+ -(±V A1 ));

[0081] The present invention realizes the separate adjustment of US and GND by independent control of positive and negative power supplies, and in particular, utilizes the design of negative power supply so that the offset voltage can be added or subtracted under negative conditions. Figure 2 As shown, the positive end of the Us input voltage is connected to REF+, and the negative end is connected to REF-, and the +1V and -1V offset voltages are generated through the operational amplifier. Specifically, the +1V voltage at the positive end is added between A1 and AGND through the operational amplifier, and this independent voltage is controlled by the switching circuit to achieve switching in the positive and negative directions; the -1V voltage at the negative end is also added between A2 and AGND through the operational amplifier, and is also connected in the positive and negative directions through the switching circuit.

[0082] In this circuit, the resistance values ​​satisfy the relationship of R1=R2, R3=R4, and the output voltage is calculated by the formula V0=(R3 / R1)(V REF+ -(±V A1 )) is achieved by precisely controlling the output offset voltage through the resistance ratio relationship to ensure the accuracy and stability of the offset voltage.

[0083] The present invention uses the user's 12VDC or 24VDC Us voltage as input, uses the voltage midpoint as the reference ground AGND, applies offset voltages of +1V and -1V respectively, and then outputs;

[0084] The ground offset test circuit of the present invention is also equipped with overcurrent and overvoltage protection mechanisms to cope with abnormal current and voltage fluctuations that may occur in the automotive electrical system. Through these designs, the ground offset test can ensure the safety and stability of the test process on the basis of simulating actual working conditions, and effectively evaluate the performance of automotive electronic systems in complex electrical environments.

[0085] Example 2

[0086] This embodiment provides a ground offset test method, which is applied to the ground offset test circuit in Embodiment 1, and includes the following steps:

[0087] Step S1, applying a +1V offset voltage between the Us positive terminal and AGND through a 1V voltage generating circuit at the Us terminal, and applying a -1V offset voltage between the GND terminal and AGND through a 1V voltage generating circuit at the GND terminal;

[0088] Step S2, using the operational amplifier circuit and the Darlington output circuit of the power device module to share the output current of the offset voltage, and reducing the temperature rise of the power device through a heat sink;

[0089] Step S3, dynamically switching the positive and negative offset voltages through a switching circuit to simulate different ground offset conditions;

[0090] Step S4, performing PWM fine-tuning on the output of the offset voltage through the single-chip microcomputer module to achieve precise control of the positive and negative offset voltages to meet the ground offset requirements set by the user.

[0091] Example 3

[0092] This embodiment provides a ground offset test device, which has the ground offset test circuit in Embodiment 1 and can execute the ground offset test method in Embodiment 2, and also includes a positive and negative power supply module for providing input voltage and a display module for displaying circuit status.

[0093] The present invention generates accurate +1V and -1V offset voltages respectively by designing independent 1V voltage generating circuits at the Us end and 1V voltage generating circuits at the GND end, which can meet the strict requirements of the ground offset test for positive and negative offsets. Compared with the prior art, the circuit of the present invention can adjust the offset voltage more accurately to ensure the stability of the signal reference in various test scenarios; a Darlington output circuit is adopted, and the current load is effectively shared by the heat sink design, solving the heating problem of the traditional circuit under high current conditions. When the load current exceeds 6A, the circuit can still maintain the output accuracy, while controlling the temperature rise of the power device, greatly improving the reliability of the ground offset test; through the POW+ and POW- design in the power supply input module, the present invention can be applied to different power supply systems of 12V and 24V, meet the test requirements of various vehicle electronic systems, and has strong adaptability and wide applicability; by designing fuses (such as F1 and F2) in key circuit parts (such as the 1V voltage generating circuit at the Us end and the 1V voltage generating circuit at the GND end), overcurrent protection is achieved to avoid circuit damage due to excessive current. In addition, by switching the positive and negative switching of the offset voltage through the switching circuit, it is possible to simulate the working state under different ground offset conditions, providing a guarantee for the extreme condition testing of the equipment; the automatic control and precise adjustment of the offset voltage are realized through the single-chip microcomputer module, and the PWM fine-tuning function is used to ensure that the output offset voltage meets the accuracy requirements. This enables the present invention to adapt to different testing needs and provide higher accuracy and reliability in ground offset testing; it is designed according to the requirements of the international standard ISO 16750-1 for ground offset, and can simulate various extreme conditions caused by ground potential offset in the vehicle environment, thereby verifying the stability of electronic equipment in a complex electrical environment. By verifying the working performance of the equipment under different ground offset conditions, the present invention provides a guarantee for the reliability of key equipment such as vehicle controllers and sensors.

[0094] The basic principles, main features and advantages of the present invention are shown and described above. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A ground offset test circuit, used for applying an offset voltage between a positive terminal Us of an input voltage and a ground terminal AGND, characterized in that: The ground offset test circuit includes: A single chip microcomputer module (1) is used to control the operation of the circuit, including generating a control signal to adjust the output of the voltage generating module and control the switching circuit; A first voltage generating circuit (2), namely a 1V voltage generating circuit at the Us terminal, comprises an operational amplifier U1, resistors R1, R2 and a capacitor C1, and is used to generate a +1V offset voltage, which is applied between the Us positive terminal and AGND; The second voltage generating circuit (3), i.e., the 1V voltage generating circuit at the GND terminal, comprises an operational amplifier U2, resistors R3, R4 and R7, and is used to generate a -1V offset voltage, which is applied between the GND terminal and AGND; A Us-end power input module (4), used for providing power input to the Us-end, and comprising a protection circuit connected to the voltage generating circuit; A power supply input module (5), including a positive power supply POW+ and a negative power supply POW-, used to provide positive and negative power supplies required for circuit operation, connected to the voltage generation and amplification module; An operational amplifier circuit and power device module (6), including operational amplifiers U3, U4, resistors R5, R8 and a Darlington power output circuit, for further amplifying the offset voltage and stabilizing the high current output; The user load module (7) is used to receive the adjusted offset voltage to verify the performance of the device under test (DUT) under different offset conditions.

2. A ground offset test circuit according to claim 1, characterized in that: The single chip computer module (1) is used to adjust the output offset voltage of the 1V voltage generating circuit of the Us terminal and the 1V voltage generating circuit of the GND terminal through a control signal, thereby ensuring the positive and negative offset operation of the Us terminal and the GND terminal.

3. A ground offset test circuit according to claim 1, characterized in that: The pin configuration of the operational amplifier U1 in the Us terminal 1V voltage generating circuit is as follows: Pin 1 (OUT) and pin 2 (1IN-) of U1 are connected together to pin 2 of connector CN1; Pin 3 (1IN+) of U1 is connected to pin 1 (OUT) of U2 and pin 2 of CN3 as the reference voltage input; Pin 4 (GND) of U1 is connected to pin 1 of CN3 through capacitor C1 and connected to ground.

4. A ground offset test circuit according to claim 1, characterized in that: The pin configuration of the operational amplifier U2 in the GND terminal 1V voltage generation circuit is as follows: Pin 1 (OUT) of U2 is connected to pin 2 of CN3; Pin 2 (1IN-) of U2 is connected to reference voltage A1 through resistor R1, and is connected to CN5 through resistor R3. A fuse F1 is provided in front of CN5 to provide overcurrent protection. Pin 3 (1IN+) of U2 is connected to the reference voltage REF+ through resistor R2, and is connected to pin 3 (1IN+) of U3 through resistors R4 and R7.

5. The ground offset test circuit according to claim 1, characterized in that: The operational amplifier circuit and power device module include: Pin 1 (OUT) of U3 is connected to pin 2 of CN6 and pin 3 (1IN+) of U4 to provide feedback for negative offset; Pin 2 (1IN-) of U3 is connected to CN5 (previously connected to fuse F2) through resistor R9, and is connected to reference voltage A2 through resistor R11; Pin 1 (OUT) and pin 2 (1IN-) of U4 are connected together to pin 2 of CN8.

6. A ground offset test circuit according to claim 1, characterized in that: The POW+ of the power supply input module is connected to pin 8 (VCC) of U1 and pin 1 of CN1, and the POW- is connected to the GND pin (4) of U4, to ensure the stability of the positive and negative power supply of the circuit.

7. A ground offset test method, applied to a ground offset test circuit as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: Step S1, applying a +1V offset voltage between the Us positive terminal and AGND through a 1V voltage generating circuit at the Us terminal, and applying a -1V offset voltage between the GND terminal and AGND through a 1V voltage generating circuit at the GND terminal; Step S2, using the operational amplifier circuit and the Darlington output circuit of the power device module to share the output current of the offset voltage, and reducing the temperature rise of the power device through a heat sink; Step S3, dynamically switching the positive and negative offset voltages through a switching circuit to simulate different ground offset conditions; Step S4, performing PWM fine-tuning on the output of the offset voltage through the single-chip microcomputer module to achieve precise control of the positive and negative offset voltages to meet the ground offset requirements set by the user.

8. A ground offset test device, comprising a ground offset test circuit as claimed in any one of claims 1 to 7, characterized in that: It also includes positive and negative power supply modules for providing input voltage and a display module for displaying circuit status.

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