Temperature compensation circuit in aging process

Abstract

The invention discloses a temperature compensation circuit in an aging process. The temperature compensation circuit comprises a voltage stabilization filter circuit, a current conversion circuit, a threshold voltage division circuit, a control heating circuit, a voltage following circuit, a preset reference circuit and an operational amplifier circuit. According to the invention, full temperature compensation can be simultaneously carried out on a large batch of products in an aging test, each product can be uniformly heated and accords with a temperature difference range, and the defect of no temperature compensation in the prior art is overcome.

Description

Technical Field

[0001] The invention relates to the technical field of power device aging experiments, and in particular to a temperature compensation circuit in an aging process. Background Art

[0002] At present, when performing aging tests on power devices, the tested devices are usually placed in a constant temperature test chamber, and the constant temperature test chamber provides a high temperature environment for the tested devices. A constant temperature test chamber usually does not only place one DUT (Device Under Test). For the DUT close to the circulating air outlet of the constant temperature test chamber, the temperature will be slightly higher than the DUT far away from the circulating air outlet; after test comparison, when the capacity of the constant temperature chamber is less than 500L, the temperature difference is 0.5-2℃ without obstruction (no test samples are placed); if the test samples are evenly placed in the constant temperature chamber, the test samples will have a certain obstruction to the circulating air of the constant temperature chamber, and the highest temperature and the lowest temperature in the constant temperature chamber will differ by 5℃; if the capacity of the constant temperature chamber is greater than 500L, the corresponding temperature difference will be greater. At the same time, the allowable deviation of the shell temperature of the tested device during the power device aging test is generally ±3℃. When the test is carried out according to the above method, if too many devices are placed or a large-capacity constant temperature box is used for aging test, it is difficult to control the shell temperature within the required range. Therefore, how to effectively control the temperature of the tested device placed in the constant temperature box for aging test is a top priority. Summary of the invention

[0003] The object of the present invention is to overcome the above-mentioned defects and provide a temperature compensation circuit during the aging process.

[0004] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme to achieve: a temperature compensation circuit in the aging process, including a voltage stabilizing filter circuit, a current conversion circuit, a threshold voltage divider circuit, a control heating circuit, a voltage follower circuit, a preset reference circuit and an operational amplifier circuit; the current conversion circuit, the threshold voltage divider circuit and the control heating circuit are all connected to the voltage stabilizing filter circuit, the threshold voltage divider circuit is connected to the control heating circuit, the output end of the current conversion circuit is respectively connected to the control heating circuit and the voltage follower circuit, the output end of the voltage follower circuit is connected to the operational amplifier circuit, and the preset reference circuit is connected to the operational amplifier circuit.

[0005] Furthermore, the voltage stabilizing filter circuit is composed of a voltage stabilizing diode D1, a resistor R1 and a capacitor C1, the positive pole of the voltage stabilizing diode D1 is grounded, and the negative pole thereof is grounded in sequence through the resistor R1 and the capacitor C1; the connection point between the resistor R1 and the capacitor C1 is the voltage input end of the voltage stabilizing filter circuit, and the connection point between the voltage stabilizing diode D1 and the resistor R1 is the voltage output end of the voltage stabilizing filter circuit.

[0006] The current conversion circuit is used to convert the current signal into a voltage signal, which is composed of a temperature sensor AD590, a resistor R10 and a potentiometer R7. One end of the temperature sensor AD590 is connected to the voltage input end of the voltage stabilizing filter circuit, and the other end is connected to the ground through the potentiometer R7 and the resistor R10 in sequence.

[0007] The threshold voltage divider circuit 3 is composed of a resistor R2 and a potentiometer R3, wherein one end of the resistor R2 is connected to the voltage output end of the voltage stabilizing filter circuit 1, and the other end thereof is grounded after passing through the potentiometer R3; the connection point between the resistor R2 and the potentiometer R3 is the output end of the threshold voltage divider circuit 3.

[0008] The control heating circuit includes a heating subcircuit and a control switching subcircuit for controlling the on and off of the heating subcircuit. The control switching subcircuit is composed of a control comparator U1, a transistor Q1, a relay JK1 and a pull-up resistor R5. The IN- terminal of the comparator U1 is connected to the current conversion circuit, and the IN+ terminal of the comparator U1 is connected to the threshold voltage divider circuit. The positive power supply of the comparator U1 is connected to the voltage input terminal of the voltage stabilizing filter circuit, and the negative power supply of the comparator U1 is grounded; the base of the transistor Q1 is connected to the output terminal of the comparator U1, and its collector is connected to the voltage input terminal of the voltage stabilizing filter circuit. The emitter is grounded after passing through the relay JK1; the pull-up resistor R5 is connected in series between the collector and the base of the transistor Q1; the heating subcircuit includes a heating pad RH1, a mechanical switch S1, a capacitor C2, a resistor R13 and a light-emitting diode D2; the input end of the heating pad RH1 is connected to an external power supply via the normally open contact of the relay JK1 and the mechanical switch S1 in sequence, and its output end is grounded; one end of the resistor R13 is connected to the input end of the heating pad RH1, and the other end thereof is grounded after passing through the light-emitting diode D2; one end of the capacitor C2 is connected to the connection point between the normally open contact of the relay JK1 and the mechanical switch S1, and the other end thereof is grounded.

[0009] The voltage follower circuit is an operational amplifier U2, whose positive input terminal is connected to the current conversion circuit, and whose negative input terminal is connected to its output terminal.

[0010] The operational amplifier circuit includes an operational amplifier U3, a resistor R4, a resistor R6, a resistor R8, a resistor R9, a resistor R11, a capacitor C3 and a temperature display P1. The positive input terminal of the operational amplifier U3 is connected to the output terminal of the operational amplifier U2 through the resistor R6, the negative input terminal of the operational amplifier U3 is connected to the preset reference circuit through the resistor R8, and the output terminal of the operational amplifier U3 is connected to the temperature display P1; the resistor R6 is connected in series between the negative input terminal and the output terminal of the operational amplifier U3, one end of the resistor R4 is connected to the positive input terminal of the operational amplifier U3, and the other end thereof is grounded; one end of the capacitor C3 is connected to the preset reference circuit through the resistor R11, and the other end thereof is grounded; the power input terminal of the operational amplifier U3 is connected to the connection point of the capacitor C3 and the resistor R11, and the power output terminal of the operational amplifier U3 is grounded.

[0011] The preset reference circuit is a potentiometer R12, one end of which is connected to the negative input terminal of the operational amplifier U3 through a resistor R8, and the other end of which is grounded.

[0012] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0013] (1) The present invention can fully perform temperature compensation on a large number of products during aging tests, ensuring that each product is heated evenly and within the temperature difference range, thus filling the gap in the existing field of lack of temperature compensation.

[0014] (2) The present invention realizes temperature compensation during the aging process with fewer components, and because of its simple circuit structure, it can be easily replicated in batches. Its production and implementation costs are low, which can greatly reduce the cost investment of aging experiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The schematic diagram of the circuit of the present invention is shown in FIG.

[0016] The figure markings in the above figures are: 1-voltage stabilizing filter circuit, 2-current conversion circuit, 3-threshold voltage divider circuit, 4-control heating circuit, 5-voltage follower circuit, 6-preset reference circuit, 7-operational amplifier circuit. DETAILED DESCRIPTION

[0017] The specific implementation modes of the present invention are described in detail below with reference to the accompanying drawings.

[0018] like Figure 1 As shown, the circuit described in this embodiment includes seven parts: a voltage stabilizing filter circuit 1, a current conversion circuit 2, a threshold voltage dividing circuit 3, a control heating circuit 4, a voltage following circuit 5, a preset reference circuit 6 and an operational amplifier circuit. Figure 1As a whole, it can be seen that the current conversion circuit 2, the threshold voltage divider circuit 3 and the control heating circuit 4 are all connected to the voltage stabilizing filter circuit 1, the threshold voltage divider circuit 3 is connected to the control heating circuit 4, the output end of the current conversion circuit 2 is respectively connected to the control heating circuit 4 and the voltage follower circuit 5, the output end of the voltage follower circuit 5 is connected to the operational amplifier circuit 7, and the preset reference circuit 6 is connected to the operational amplifier circuit 7.

[0019] The voltage stabilizing filter circuit 1 is composed of a voltage stabilizing diode D1, a resistor R1 and a capacitor C1. When connected, the positive electrode of the voltage stabilizing diode D1 is grounded, and the negative electrode thereof is grounded in sequence through the resistor R1 and the capacitor C1. The connection point of the resistor R1 and the capacitor C1 is the voltage input terminal of the voltage stabilizing filter circuit 1, which is used to connect an external 9-18V AC voltage VCC. The connection point of the voltage stabilizing diode D1 and the resistor R1 is the voltage output terminal of the voltage stabilizing filter circuit 1. To ensure the use effect, the voltage stabilizing diode D1 is preferably implemented by a voltage stabilizing diode of the model BZX55C6V2.

[0020] The threshold voltage divider circuit 3 is composed of a resistor R2 and a potentiometer R3, wherein one end of the resistor R2 is connected to the voltage output end of the voltage stabilizing filter circuit 1, and the other end thereof is grounded after passing through the potentiometer R3; the connection point between the resistor R2 and the potentiometer R3 is the output end of the threshold voltage divider circuit 3.

[0021] The control heating circuit 4 includes a heating subcircuit and a control switching subcircuit for controlling the on and off of the heating subcircuit. The control switching subcircuit is composed of a control comparator U1, a transistor Q1, a relay JK1 and a pull-up resistor R5, wherein the IN- terminal of the comparator U1 is connected to the current conversion circuit 2, the IN+ terminal of the comparator U1 is connected to the threshold voltage divider circuit 3, the positive power supply of the comparator U1 is connected to the voltage input terminal of the voltage stabilizing filter circuit 1, and the negative power supply of the comparator U1 is grounded; the base of the transistor Q1 is connected to the output terminal of the comparator U1, the collector thereof is connected to the voltage input terminal of the voltage stabilizing filter circuit 1, and the emitter thereof is grounded after passing through the relay JK1; and the pull-up resistor R5 is connected in series between the collector and the base of the transistor Q1.

[0022] The heating subcircuit includes a heating pad RH1, a mechanical switch S1, a capacitor C2, a resistor R13 and a light emitting diode D2. The heating pad RH1 is arranged at the top of the test seat, and the input end of the heating pad RH1 is connected to the external power supply Vin through the normally open contact of the relay JK1 and the mechanical switch S1 in sequence, and its output end is grounded. One end of the resistor R13 is connected to the input end of the heating pad RH1, and the other end thereof is grounded after passing through the light emitting diode D2; one end of the capacitor C2 is connected to the connection point between the normally open contact of the relay JK1 and the mechanical switch S1, and the other end thereof is grounded.

[0023] During operation, the voltage stabilizing filter circuit 1 transmits the processed voltage to the threshold voltage divider circuit 3 through the voltage stabilizing diode D1, and obtains a stable voltage after voltage division by the resistor R2 and the potentiometer R3. The voltage is transmitted to the IN-terminal of the comparator U1 in the control heating circuit 4 as the threshold voltage of the control heating circuit 4. The threshold voltage can be adjusted by adjusting the resistance value of the potentiometer R3, thereby achieving the purpose of controlling the compensation temperature; the threshold voltage is set as the upper limit of the compensation temperature, that is, the upper limit of the maximum temperature allowed for the tested product during the high temperature aging test.

[0024] The current conversion circuit 2 is used to convert the current signal into a voltage signal, and is composed of a temperature sensor AD590, a resistor R10 and a potentiometer R7. The temperature sensor AD590 is arranged in the middle of the test socket. When connected, one end of the temperature sensor AD590 is connected to the voltage input end of the voltage stabilizing filter circuit 1, and the other end thereof is connected to the ground after passing through the potentiometer R7 and the resistor R10 in sequence.

[0025] The voltage follower circuit 5 is an operational amplifier U2, whose positive input terminal is connected to the current conversion circuit 2, and whose negative input terminal is connected to its output terminal.

[0026] The temperature sensor AD590 converts the real-time current signal into a voltage signal according to a certain ratio through the resistor R10 and the potentiometer R7; the voltage signal is transmitted to the IN+ terminal of the comparator U1 and the IN+ terminal of the operational amplifier U2 in the control heating circuit 4. By changing the resistance value of the potentiometer R7, the voltage signal converted by the temperature sensor AD590 can be adjusted, so that the output signal is more accurate; according to the detailed specifications of the temperature sensor AD590, its output current is 273μA at absolute temperature, so in this embodiment, the resistor R10 and the potentiometer R7 are adjusted to 10K, and its output voltage is 10K×273μA=2.73V.

[0027] The control heating circuit 4 compares the two voltage signals of the IN- and IN+ terminals of the comparator U1 to determine whether the output terminal of the comparator U1 outputs a high level or a low level. When IN+ of the comparator U1 is greater than IN-, the comparator U1 outputs a high level, and the transistor Q1 is turned on through the pull-up resistor R5, the relay JK1 coil is energized, the contacts are attracted, the heating pad RH1 starts to heat, and R13 and D2 form a working indication of the heating state. When IN- of the comparator U1 is greater than IN+, the comparator U1 outputs a low level, and the transistor Q1 is cut off; that is: when the product needs to be subjected to a high temperature aging test at 125°C, the threshold voltage is set to 3.98V (2.73V+1.25V, where 2.73V is the initial voltage of AD590, and 1.25V is the aging temperature of the aging product), when the output current of the temperature sensor AD590 is less than 0.398μA, the heating compensation works, and when the output current of the AD590 is greater than 0.398μA, the heating compensation stops working.

[0028] The voltage follower circuit 5 copies the signal output by the current conversion circuit 2 to the output end of the operational amplifier U2 through the operational amplifier U2, thereby avoiding signal loss and distortion and ensuring the stability of the output signal.

[0029] The preset reference circuit 6 is a potentiometer R12. When connected, one end of the preset reference circuit 6 is connected to the negative input terminal of the operational amplifier U3 through the resistor R8, and the other end is grounded. The preset reference circuit 6 divides the voltage to a stable 2.73V through the resistor R11 and the potentiometer R12, and the voltage is transmitted to the IN-terminal of the operational amplifier U3 as the reference voltage of the operational amplifier circuit 7. The operational amplifier circuit 7 performs differential operation amplification on the signals transmitted by the voltage follower circuit 5 and the preset reference circuit 6, and finally outputs the voltage Vo, and the voltage value of Vo is: Vo=R9 / R8(V1-V3); that is, when the output current of the temperature sensor AD590 is less than 0.398μA, the corresponding output voltage is 3.98V. According to the above formula, Vo=200 / 20(3.98-2.73)=12.5V; the corresponding temperature T at this time is: 125℃.

[0030] As described above, the present invention can be implemented better.

Claims

1. A temperature compensation circuit in an aging process, characterized in that: The invention comprises a voltage stabilizing filter circuit (1), a current conversion circuit (2), a threshold voltage divider circuit (3), a control heating circuit (4), a voltage follower circuit (5), a preset reference circuit (6) and an operational amplifier circuit (7); the current conversion circuit (2), the threshold voltage divider circuit (3) and the control heating circuit (4) are all connected to the voltage stabilizing filter circuit (1), the threshold voltage divider circuit (3) is connected to the control heating circuit (4), the output end of the current conversion circuit (2) is respectively connected to the control heating circuit (4) and the voltage follower circuit (5), the output end of the voltage follower circuit (5) is connected to the operational amplifier circuit (7), and the preset reference circuit (6) is connected to the operational amplifier circuit (7).

2. A temperature compensation circuit in an aging process according to claim 1, characterized in that: The voltage stabilizing filter circuit (1) is composed of a voltage stabilizing diode D1, a resistor R1 and a capacitor C1. The positive electrode of the voltage stabilizing diode D1 is grounded, and the negative electrode thereof is grounded in sequence through the resistor R1 and the capacitor C1. The connection point between the resistor R1 and the capacitor C1 is the voltage input end of the voltage stabilizing filter circuit (1), and the connection point between the voltage stabilizing diode D1 and the resistor R1 is the voltage output end of the voltage stabilizing filter circuit (1).

3. A temperature compensation circuit in an aging process according to claim 2, characterized in that: The current conversion circuit (2) is used to convert the current signal into a voltage signal, and is composed of a temperature sensor AD590, a resistor R10 and a potentiometer R7. One end of the temperature sensor AD590 is connected to the voltage input end of the voltage stabilizing filter circuit (1), and the other end is connected to the ground via the potentiometer R7 and the resistor R10 in sequence.

4. A temperature compensation circuit in an aging process according to claim 3, characterized in that: The threshold voltage divider circuit (3) is composed of a resistor R2 and a potentiometer R3, wherein one end of the resistor R2 is connected to the voltage output end of the voltage stabilizing filter circuit (1), and the other end is grounded after passing through the potentiometer R3; the connection point between the resistor R2 and the potentiometer R3 is the output end of the threshold voltage divider circuit (3).

5. A temperature compensation circuit in an aging process according to claim 4, characterized in that: The control heating circuit (4) comprises a heating subcircuit and a control switching subcircuit for controlling the on and off of the heating subcircuit. The control switching subcircuit is composed of a control comparator U1, a transistor Q1, a relay JK1 and a pull-up resistor R5. The IN- terminal of the comparator U1 is connected to the current conversion circuit (2), and the IN+ terminal of the comparator U1 is connected to the threshold voltage divider circuit (3). The positive pole of the power supply of the comparator U1 is connected to the voltage input terminal of the voltage stabilizing filter circuit (1), and the negative pole of the power supply of the comparator U1 is grounded. The base of the transistor Q1 is connected to the output terminal of the comparator U1, and its collector is connected to the voltage input terminal of the voltage stabilizing filter circuit (1). The end is connected, and its emitter is grounded after passing through the relay JK1; the pull-up resistor R5 is connected in series between the collector and the base of the transistor Q1; the heating subcircuit includes a heating pad RH1, a mechanical switch S1, a capacitor C2, a resistor R13 and a light-emitting diode D2; the input end of the heating pad RH1 is connected to an external power supply via the normally open contact of the relay JK1 and the mechanical switch S1 in sequence, and its output end is grounded; one end of the resistor R13 is connected to the input end of the heating pad RH1, and the other end thereof is grounded after passing through the light-emitting diode D2; one end of the capacitor C2 is connected to the connection point between the normally open contact of the relay JK1 and the mechanical switch S1, and the other end thereof is grounded.

6. A temperature compensation circuit in an aging process according to claim 5, characterized in that: The voltage follower circuit (5) is an operational amplifier U2, whose positive input terminal is connected to the current conversion circuit (2), and whose negative input terminal is connected to its output terminal.

7. A temperature compensation circuit in an aging process according to claim 6, characterized in that: The operational amplifier circuit (7) comprises an operational amplifier U3, a resistor R4, a resistor R6, a resistor R8, a resistor R9, a resistor R11, a capacitor C3 and a temperature display P1. The positive input terminal of the operational amplifier U3 is connected to the output terminal of the operational amplifier U2 via the resistor R6, the negative input terminal of the operational amplifier U3 is connected to the preset reference circuit (6) via the resistor R8, and the output terminal of the operational amplifier U3 is connected to the temperature display P1; the resistor R6 is connected in series between the negative input terminal and the output terminal of the operational amplifier U3, one end of the resistor R4 is connected to the positive input terminal of the operational amplifier U3, and the other end thereof is grounded; one end of the capacitor C3 is connected to the preset reference circuit (6) via the resistor R11, and the other end thereof is grounded; the power input terminal of the operational amplifier U3 is connected to the connection point of the capacitor C3 and the resistor R11, and the power output terminal of the operational amplifier U3 is grounded.

8. A temperature compensation circuit in an aging process according to claim 7, characterized in that: The preset reference circuit (6) is a potentiometer R12, one end of which is connected to the negative input terminal of the operational amplifier U3 through a resistor R8, and the other end of which is grounded.

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