CN108076545B - An IGBT collector voltage protection method, system and induction cooker based on current comparison - Google Patents

Abstract

An IGBT collector voltage protection method and system based on current comparison and an induction cooker relate to the field of induction cooker protection. Aim at solves when protecting IGBT collector voltage among the electromagnetic heating system, often uses to join in marriage the pot as the standard, uses a reference voltage comparison, can sacrifice the problem of the power of other pans greatly. Firstly, connecting two comparators CMP1 and CMP2 which are connected in parallel on an IGBT collector in an electromagnetic heating system, and setting initial reference voltages of the two comparators before heating a pot; then, collecting IGBT current in an electromagnetic heating system in the heating process of the cooker to obtain the current actual current value; finally, the actual current value is compared with a preset target current value, and the reference voltage of the comparator CMP2 is controlled according to the difference between the actual current value and the target current value. The invention is suitable for protecting the IGBT collector voltage.

Description

An IGBT collector voltage protection method, system and electric circuit based on current comparison induction cooker

technical field

The invention relates to the field of induction cooker protection, in particular to the field of IGBT collector voltage protection in an induction cooker.

Background technique

In the existing electromagnetic heating system, in order to protect the IGBT collector from overvoltage breakdown, a maximum pulse width is set in the software. The inductive reactance and impedance obtained by coupling under the distance are different, the collector voltage of the same target power is different, and the reliability of the high anode IGBT is relatively poor.

Considering the above situation, a collector voltage sampling comparison is often added to the hardware in the current collector voltage protection. If the collector voltage is too high, the hardware directly limits the maximum turn-on pulse width. However, product development is often based on the matching pot. Using a reference voltage for comparison will greatly sacrifice the power of other pots.

SUMMARY OF THE INVENTION

The present invention provides an IGBT collector voltage protection method, system and induction cooker based on current comparison. The purpose of the invention is to solve the problem that when protecting the IGBT collector voltage in the electromagnetic heating system, it is often based on the matching pot, and a reference voltage comparison is used. It will greatly sacrifice the power of other pots.

The technical solution of the present invention to solve the above-mentioned technical problems is as follows: an IGBT collector voltage protection method based on current comparison, which comprises the following steps:

S1. Connect two parallel-connected comparators CMP1 and CMP2 on the IGBT collector in the electromagnetic heating system, and set the initial reference voltages of the two comparators before heating the cookware;

S2. Collect the IGBT current in the electromagnetic heating system during the heating process of the cookware, and obtain the current actual current value;

S3. Compare the actual current value with the preset target current value, and control the reference voltage of the comparator CMP2 according to the difference between the actual current value and the target current value.

The beneficial effects of the present invention are: the present invention sets a reference voltage of a comparator that can be adjusted and controlled by software to control the IGBT collector voltage protection, and on the basis of not affecting reliability, appropriately adjusts the threshold value of the reference voltage to match different cookware The protection voltage is increased, and the adaptability of the cookware is improved.

On the basis of the above technical solutions, the present invention can also be improved as follows.

Further, the initial reference voltage of the comparator CMP1 is greater than the initial reference voltage of the comparator CMP2.

The beneficial effect of adopting the above-mentioned further scheme is that: the comparator CMP1 is used as a hard protection, as long as the target voltage is reached, the maximum power is limited or the heating is suspended for a period of time. Therefore, the comparator is set to a larger initial reference voltage as a reliability factor. Mandatory protection.

Further, the process of controlling the reference voltage of the comparator CMP2 in the S3 is:

S31, compare the difference between the actual current value and the target current value, and determine whether the difference is greater than the first reference value, if so, increase the reference voltage of the comparator CMP2 from the initial reference voltage to the first reference voltage, If not, execute S32;

S32. Determine whether the difference is greater than the second reference value and smaller than the first reference value. If so, increase the reference voltage of the comparator CMP2 from the initial reference voltage to the second reference voltage. If not, increase the reference voltage of the comparator CMP2 to the second reference voltage. The reference voltage is maintained at the initial reference voltage.

The beneficial effect of adopting the above-mentioned further scheme is: the comparator CMP2 is used as a soft protection, and the reference voltage of the comparator can be controlled by the current difference when the same cookware or different cookware is used, and the power of the cookware with low power is increased.

Further, the first reference value is 10.

Further, the second reference value is 5.

Further, the second reference voltage of the comparator CMP2 is between the first reference voltage and the initial reference voltage.

The beneficial effect of adopting the above-mentioned further scheme is: according to different current differences, the reference voltage of the comparator CMP1 is controlled layer by layer, so as to improve the power of the cookware.

Further, the initial reference voltage of the comparator CMP1 is greater than the first reference voltage of the comparator CMP2.

The beneficial effect of adopting the above-mentioned further scheme is that the comparator CMP1 is set to a larger initial reference voltage as a mandatory protection for reliability.

An IGBT collector voltage protection system based on current comparison, which includes connecting two parallel-connected comparators CMP1 and CMP2 on the IGBT collector in an electromagnetic heating system, and the system further includes:

The initial reference voltage setting module is used to set the initial reference voltage of the two comparators before heating the cookware;

The current acquisition module is used to collect the IGBT current in the electromagnetic heating system during the heating process of the cookware, and obtain the current actual current value;

The reference voltage control module is configured to compare the actual current value with the preset target current value, and control the reference voltage of the comparator CMP2 according to the difference between the actual current value and the target current value.

The beneficial effects of the present invention are: the present invention sets a reference voltage of a comparator that can be adjusted and controlled by software to control the IGBT collector voltage protection, and on the basis of not affecting reliability, appropriately adjusts the threshold value of the reference voltage to match different cookware The protection voltage is increased, and the adaptability of the cookware is improved.

Further, the initial reference voltage of the comparator CMP1 is greater than the initial reference voltage of the comparator CMP2.

The beneficial effect of adopting the above-mentioned further scheme is that: the comparator CMP1 is used as a hard protection, as long as the target voltage is reached, the maximum power is limited or the heating is suspended for a period of time. Therefore, the comparator is set to a larger initial reference voltage as a reliability factor. Mandatory protection.

Further, the reference voltage control module includes:

The first control module is used to compare the difference between the actual current value and the target current value, and determine whether the difference is greater than the first reference value, and if so, increase the reference voltage of the comparator CMP2 from the initial reference voltage to the first reference voltage, if not, start the second control module;

The second control module is used for judging whether the difference is greater than the second reference value and smaller than the first reference value, if so, the reference voltage of the comparator CMP2 is raised from the initial reference voltage to the second reference voltage, if not, then The reference voltage of the comparator CMP2 is maintained at the initial reference voltage.

The beneficial effect of adopting the above-mentioned further scheme is: the comparator CMP2 is used as a soft protection, and the reference voltage of the comparator can be controlled by the current difference when the same cookware or different cookware is used, and the power of the cookware with low power is increased.

Further, the first reference value is 10.

Further, the second reference value is 5.

Further, the second reference voltage of the comparator CMP2 is between the first reference voltage and the initial reference voltage.

The beneficial effect of adopting the above-mentioned further scheme is: according to different current differences, the reference voltage of the comparator CMP1 is controlled layer by layer, so as to improve the power of the cookware.

Further, the initial reference voltage of the comparator CMP1 is greater than the first reference voltage of the comparator CMP2.

The beneficial effect of adopting the above-mentioned further scheme is that the comparator CMP1 is set to a larger initial reference voltage as a mandatory protection for reliability.

An induction cooker includes the above-mentioned IGBT collector voltage protection system based on current comparison. On the basis of not affecting the reliability, the threshold value of the reference voltage is appropriately adjusted to match the protection voltage of different cookware and improve the adaptability of the cookware.

Description of drawings

1 is a flowchart of an IGBT collector voltage protection method based on current comparison according to an embodiment of the present invention;

2 is a flowchart of controlling the reference voltage of the comparator CMP2 according to an embodiment of the present invention;

3 is a schematic diagram of the principle of an IGBT collector voltage protection system based on current comparison according to an embodiment of the present invention;

4 is an integrated schematic diagram of the comparator CMP1 and the comparator CMP2 according to an embodiment of the present invention;

FIG. 5 is a working flowchart of the IGBT collector voltage protection system based on current comparison according to an embodiment of the present invention.

In the accompanying drawings, the list of components represented by each number is as follows:

1. Initial reference voltage setting module, 2. Current acquisition module, 3. Reference voltage control module, 4. First control module, 5. Second control module.

Detailed ways

The principles and features of the present invention will be described below with reference to the accompanying drawings. The examples are only used to explain the present invention, but not to limit the scope of the present invention.

Example 1

As shown in FIG. 1 , this embodiment proposes an IGBT collector voltage protection method based on current comparison, which includes the following steps:

S1. Connect two parallel-connected comparators CMP1 and CMP2 on the IGBT collector in the electromagnetic heating system, and set the initial reference voltages of the two comparators before heating the cookware;

S2. Collect the IGBT current in the electromagnetic heating system during the heating process of the cookware, and obtain the current actual current value;

S3, compare the actual current value with the preset target current value, and control the reference voltage of the comparator CMP2 according to the difference between the actual current value and the target current value;

Among them, as shown in FIG. 2, the specific process of controlling the reference voltage of the comparator CMP2 is as follows:

S31. Compare the difference between the actual current value and the target current value, and determine whether the difference is greater than 10. If so, increase the reference voltage of the comparator CMP2 from the initial reference voltage to the first reference voltage. If not, Then execute S32;

S32. Determine whether the difference is greater than 5 and less than 10. If so, increase the reference voltage of the comparator CMP2 from the initial reference voltage to the second reference voltage. If not, maintain the reference voltage of the comparator CMP2 at the initial reference voltage Voltage.

The above process of comparing the difference between the actual current value and the target current value is as follows: first, the current signals of the actual current value and the target current value are converted into voltage signals respectively, and then the converted voltage signals are passed through a 5V voltage comparison circuit. After conversion, it is sent to the single-chip microcomputer for difference calculation to obtain the binary value, and then the difference between the actual current value and the target current value can be obtained after the binary value is converted into decimal.

In the method described in this embodiment, the comparator CMP1 is used as a hard protection. As long as the target voltage is reached, the maximum power is limited or the heating is suspended for a period of time, which can be used as a mandatory protection for reliability. Therefore, the initial reference voltage of the comparator CMP1 should be larger. Some, preferably, the initial reference voltage of the comparator CMP1 is greater than the initial reference voltage of the comparator CMP2 and greater than the first reference voltage of the comparator CMP2.

The comparator CMP2 is used as a soft protection. When the collector voltage of the IGBT reaches a threshold, there are two situations:

1. When using cookware of different materials, under the same target power, due to the limitation of the protection voltage, the cookware with poor material cannot reach the target power, that is, there is a current difference. In this way, the threshold value of the comparison voltage is adjusted, the threshold value of the comparison voltage is selected, and the power of the low-power cookware is increased as much as possible while ensuring the reliability of the performance;

2. For the same type of pot, such as a matching pot, in the case of different pan spacing and pan deformation, although the pan spacing and pan deformation cannot be detected, when the pan spacing is too large and the pan is protruding, the same Under the target power, the collector voltage becomes higher, so that the actual current cannot reach the target current. However, by using the method described in this embodiment, the power can also reach the target value by adjusting the voltage threshold.

Example 2

As shown in FIG. 3 , this embodiment proposes an IGBT collector voltage protection system based on current comparison, which includes two parallel-connected comparators CMP1 and CMP2 connected to the IGBT collector in the electromagnetic heating system. The system also includes:

The initial reference voltage setting module 1 is used to set the initial reference voltages of the two comparators before heating the cookware;

The current acquisition module 2 is used to collect the IGBT current in the electromagnetic heating system during the heating process of the cookware, and obtain the current actual current value;

The reference voltage control module 3 is configured to compare the actual current value with the preset target current value, and control the reference voltage of the comparator CMP2 according to the difference between the actual current value and the target current value.

The reference voltage control module 3 includes:

The first control module 4 is used to compare the difference between the actual current value and the target current value, and determine whether the difference is greater than 10, and if so, increase the reference voltage of the comparator CMP2 from the initial reference voltage to the first reference voltage, if not, start the second control module 5;

The second control module 5 is used for judging whether the difference is greater than the second reference value and smaller than the first reference value, and judging whether the difference is greater than 5, and if so, raising the reference voltage of the comparator CMP2 from the initial reference voltage to the second reference voltage, if not, the reference voltage of the comparator CMP2 is maintained at the initial reference voltage.

The above process of comparing the difference between the actual current value and the target current value is as follows: first, the current signals of the actual current value and the target current value are converted into voltage signals respectively, and then the converted voltage signals are passed through a 5V voltage comparison circuit. After conversion, it is sent to the single-chip microcomputer for difference calculation to obtain the binary value, and then the difference between the actual current value and the target current value can be obtained after the binary value is converted into decimal.

In the system described in this embodiment, the comparator CMP1 is used as a hard protection. As long as the target voltage is reached, the maximum power is limited or the heating is suspended for a period of time, which can be used as a mandatory protection for reliability. Therefore, the initial reference voltage of the comparator CMP1 should be larger. Some, preferably, the initial reference voltage of the comparator CMP1 is greater than the initial reference voltage of the comparator CMP2 and greater than the first reference voltage of the comparator CMP2.

The comparator CMP2 is used as a soft protection. When the collector voltage of the IGBT reaches a threshold, there are two situations:

1. When using cookware of different materials, under the same target power, due to the limitation of the protection voltage, the cookware with poor material cannot reach the target power, that is, there is a current difference. In this way, the threshold value of the comparison voltage is adjusted, the threshold value of the comparison voltage is selected, and the power of the low-power cookware is increased as much as possible while ensuring the reliability of the performance;

2. For the same type of pot, such as a matching pot, in the case of different pan spacing and pan deformation, although the pan spacing and pan deformation cannot be detected, when the pan spacing is too large and the pan is protruding, the same Under the target power, the collector voltage becomes higher, so that the actual current cannot reach the target current, but the system described in this embodiment can also adjust the voltage threshold to make the power reach the target value.

Example 3

Figure 4 shows the integrated schematic diagram of the comparator CMP1 and the comparator CMP2. The comparator CMP1 is used as a hard protection. Generally, the reliability program is only configured once. For example, the configuration is 8/12VDD; the comparator CMP2 is used as a soft protection. The reference voltage can be adjusted by software. After being identified as different pots, pots with a large distance current difference can directly use 7/12VDD as the reference voltage, for example, 6/12 as the reference voltage for larger ones, otherwise use 5/12VDD as the reference voltage to satisfy power requirements.

The specific control flow is shown in Figure 5:

First power on and initialize, configure the reference voltage of the comparator CMP1 to be 8/12VDD, configure the reference voltage of the comparator CMP2 to be 5/12VDD, then heat the cookware, collect the current in the heating system during the heating process, and judge The difference between the detected actual current value and the preset target current value, when the current difference is greater than 10, change the reference voltage of the comparator CMP2 to 7/12VDD and continue heating, when the current difference is less than 10 And when it is greater than 5, the reference voltage of the comparator CMP2 is changed to 6/12VDD, and when the current difference is less than 5, the initial reference voltage of the comparator CMP2 is maintained at 5/12VDD.

In the above manner, the protection voltage of different cookware can be matched by adjusting the threshold value of the reference voltage of the soft protection comparator CMP2 on the basis of not affecting the reliability, and the adaptability of the cookware can be improved.

Example 4

This embodiment proposes an induction cooker. The induction cooker includes the above-mentioned IGBT collector voltage protection system based on current comparison. By adding a soft protection comparator CMP2 to compare the collector voltage, the software can adjust the reference voltage of the comparator. , Under the premise of not affecting the reliability, it can improve the power consistency of different cookware.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection of the present invention. within the range.

Claims (13)

1. an IGBT collector voltage protection method based on current comparison, is characterized in that, it comprises the following steps: S1. Connect two parallel-connected comparators CMP1 and CMP2 on the IGBT collector in the electromagnetic heating system, and set the initial reference voltages of the two comparators before heating the cookware; S2. Collect the IGBT current in the electromagnetic heating system during the heating process of the cookware, and obtain the current actual current value; S3, compare the actual current value with the preset target current value, and control the reference voltage of the comparator CMP2 according to the difference between the actual current value and the target current value; The process of controlling the reference voltage of the comparator CMP2 in the S3 is: S31, compare the difference between the actual current value and the target current value, and determine whether the difference is greater than the first reference value, if so, increase the reference voltage of the comparator CMP2 from the initial reference voltage to the first reference voltage, If not, execute S32; S32. Determine whether the difference is greater than the second reference value and smaller than the first reference value. If so, increase the reference voltage of the comparator CMP2 from the initial reference voltage to the second reference voltage. If not, increase the reference voltage of the comparator CMP2 to the second reference voltage. The reference voltage is maintained at the initial reference voltage. 2 . The IGBT collector voltage protection method based on current comparison according to claim 1 , wherein the initial reference voltage of the comparator CMP1 is greater than the initial reference voltage of the comparator CMP2 . 3 . 3 . The IGBT collector voltage protection method based on current comparison according to claim 1 , wherein the first reference value is 10. 4 . 4 . The IGBT collector voltage protection method based on current comparison according to claim 1 or 3 , wherein the second reference value is 5. 5 . 5 . The IGBT collector voltage protection method based on current comparison according to claim 1 , wherein the second reference voltage of the comparator CMP2 is between the first reference voltage and the initial reference voltage. 6 . 6. The IGBT collector voltage protection method based on current comparison according to claim 1 or 5, wherein the initial reference voltage of the comparator CMP1 is greater than the first reference voltage of the comparator CMP2. 7. An IGBT collector voltage protection system based on current comparison, characterized in that the system comprises two parallel-connected comparators CMP1 and CMP2 connected to the IGBT collector in the electromagnetic heating system, and the system further comprises : an initial reference voltage setting module (1) for setting the initial reference voltages of the two comparators before heating the cookware; The current acquisition module (2) is used to collect the IGBT current in the electromagnetic heating system during the heating process of the cookware, so as to obtain the current actual current value; a reference voltage control module (3) for comparing the actual current value with a preset target current value, and controlling the reference voltage of the comparator CMP2 according to the difference between the actual current value and the target current value; The reference voltage control module (3) includes: A first control module (4) for comparing the difference between the actual current value and the target current value, and judging whether the difference is greater than the first reference value, and if so, changing the reference voltage of the comparator CMP2 from the initial reference value The voltage is raised to the first reference voltage, and if not, the second control module (5) is activated; A second control module (5) for judging whether the difference is larger than the second reference value and smaller than the first reference value, if so, raising the reference voltage of the comparator CMP2 from the initial reference voltage to the second reference voltage, if If not, the reference voltage of the comparator CMP2 is maintained at the initial reference voltage. 8 . The IGBT collector voltage protection system based on current comparison according to claim 7 , wherein the initial reference voltage of the comparator CMP1 is greater than the initial reference voltage of the comparator CMP2 . 9 . The IGBT collector voltage protection system based on current comparison according to claim 7 , wherein the first reference value is 10. 10 . 10 . The IGBT collector voltage protection system based on current comparison according to claim 7 , wherein the second reference value is 5. 11 . 11 . The IGBT collector voltage protection system based on current comparison according to claim 7 , wherein the second reference voltage of the comparator CMP2 is between the first reference voltage and the initial reference voltage. 12 . 12. The IGBT collector voltage protection system based on current comparison according to claim 7 or 11, wherein the initial reference voltage of the comparator CMP1 is greater than the first reference voltage of the comparator CMP2. 13. An induction cooker, characterized in that the induction cooker comprises the IGBT collector voltage protection system based on current comparison according to claims 7 to 12.

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