IGBT over-temperature protection control method and device based on state machine

Abstract

The invention discloses an IGBT over-temperature protection control method and device based on a state machine, and relates to the technical field of temperature control of power electronic equipment, and the method comprises the steps: dividing an IGBT into a plurality of states; monitoring the temperature of the IGBT; and according to the temperature of the IGBT, switching between different states is automatically carried out, and a corresponding power adjustment strategy is executed. According to the invention, the temperature of the IGBT can be monitored in real time, and the power output is automatically adjusted according to the temperature change, so that the stable operation and long-term reliability of equipment are ensured. The system has real-time performance, self-adaptability, reliability, flexibility and maintenance simplicity and convenience, the fault-tolerant capability of the system is enhanced by introducing a plurality of intermediate states, it is ensured that measures are taken in time when the temperature is abnormal, and work is smoothly recovered after the temperature is recovered to be normal.

Description

Technical Field

[0001] The present invention relates to the technical field of temperature control of power electronic equipment, and in particular to an IGBT over-temperature protection control method and device based on a state machine. Background Art

[0002] The overheat protection of the IGBT (insulated gate bipolar transistor) of the PTC heater used in the air conditioning system of electric vehicles is of great significance. As the core component of power control, IGBT is responsible for regulating and controlling the current. Under the working conditions of high voltage and high current, it has a large power loss and is prone to generate a lot of heat. If the IGBT overheats without effective protection, it may cause component damage, affect the normal operation of the entire air conditioning system, and may even cause safety accidents.

[0003] Traditional IGBT overheat protection methods usually use direct temperature sampling and protection point triggering mechanisms, that is, when the temperature of the IGBT exceeds a certain preset absolute protection point, protection measures are immediately taken, such as stopping heating or intermittent heating. Although this method is simple and direct, it has the following defects:

[0004] Poor system stability: When the temperature changes, the system may switch states too suddenly due to the lack of intermediate states, causing system instability and affecting the normal operation of the equipment.

[0005] Low fault tolerance: Once the protection mechanism is triggered, fixed protection measures are usually taken, such as shutdown or intermittent heating, which may not be suitable for all situations, especially when the temperature changes rapidly.

[0006] Poor user experience: Direct shutdown or intermittent heating may affect the user experience, especially in air-conditioning application scenarios that require continuous and stable heating.

[0007] Possible over-protection: In some cases, the temperature of the IGBT may only briefly exceed the protection point and does not necessarily require immediate shutdown or intermittent heating. This protection mechanism may cause unnecessary shutdown and affect the normal operation of the equipment. Summary of the invention

[0008] In view of the defects existing in the prior art, the purpose of the present invention is to provide an IGBT over-temperature protection control method and device based on a state machine, which can monitor the temperature of the IGBT in real time and automatically adjust the power output according to the temperature change to ensure the stable operation and long-term reliability of the equipment. The present invention has real-time, adaptive, reliable, flexible and easy maintenance. By introducing multiple intermediate states, the fault tolerance of the system is enhanced, ensuring that measures are taken in time when the temperature is abnormal, and the work is smoothly resumed after the temperature returns to normal.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is: an IGBT over-temperature protection control method based on a state machine, comprising: dividing the IGBT into several states; monitoring the temperature of the IGBT; automatically switching between different states according to the temperature of the IGBT, and executing corresponding power adjustment strategies.

[0010] Based on the above technical solution, the IGBT is divided into the following states: NORMAL, normal state; NORMAL2LIMIT, an intermediate state between the normal state and the limited power state; NORMAL2FAULT, an intermediate state between the normal state and the fault state; LIMIT, a limited power state; LIMIT2NORMAL, an intermediate state between the limited power state and the normal state; FAULT, a fault state; FAULT2LIMIT, an intermediate state between the fault state and the limited power state.

[0011] On the basis of the above technical solution, in the NORMAL state, the IGBT fault status flag and the IGBT power limiting status flag are first cleared, and then it is determined whether the temperature of the IGBT is greater than the power limiting temperature threshold. If it is greater than the power limiting temperature threshold, the 1s IGBT timer flag and the timer count value are cleared, and then the NORMAL2LIMIT state is entered in the next program cycle; then it is determined whether the temperature of the IGBT is greater than the fault temperature threshold. If it is greater than the fault temperature threshold, the 1s IGBT timer flag and the timer count value are cleared, and then the NORMAL2FAULT state is entered in the next program cycle; if neither of the above two conditions is met, the current NORMAL state is entered again in the next program cycle.

[0012] On the basis of the above technical solution, in the NORMAL2LIMIT state, it is first determined whether the 1sIGBT timer flag is 1. If so, the 1sIGBT timer flag is cleared to zero, and then the LIMIT state is entered in the next program cycle; if not, it is further determined whether the IGBT temperature is greater than the limiting power temperature threshold. If it is less than the limiting power temperature threshold, the NORMAL state is entered in the next cycle, otherwise the current NORMAL2LIMIT state is maintained in the next cycle.

[0013] On the basis of the above technical solution, in the NORMAL2FAULT state, it is first determined whether the 1sIGBT timer flag is 1. If so, the 1sIGBT timer flag is cleared to zero, and then the FAULT state is entered in the next program cycle; if not, it is further determined whether the IGBT temperature is greater than 105°C. If it is less than the fault temperature threshold, the NORMAL state is entered in the next cycle, otherwise the current NORMAL2FAULT state is maintained in the next cycle.

[0014] On the basis of the above technical solution, in the LIMIT state, the IGBT power limit state flag is first set to 1, and then it is determined whether the temperature of the IGBT is greater than the normal operating temperature threshold. If it is less than the normal operating temperature threshold, the 1sIGBT timer flag is cleared and the timer count value is cleared, and then the LIMIT2NORMAL state is entered in the next program cycle; then it is determined whether the temperature of the IGBT is greater than the fault temperature threshold. If it is greater than the fault temperature threshold, the 1sIGBT timer flag is cleared and the timer count value is cleared, and then the NORMAL2LIMIT state is entered in the next program cycle; if neither of the above two conditions is met, the current LIMIT state is entered again in the next program cycle.

[0015] On the basis of the above technical solution, in the LIMIT2NORMAL state, it is first determined whether the 1sIGBT timer flag is 1. If so, the 1sIGBT timer flag is cleared to zero, and then the LIMIT state is entered in the next program cycle; if not, a further determination is made as to whether the IGBT temperature is greater than the normal operating temperature threshold. If it is greater than the normal operating temperature threshold, the LIMIT state is entered in the next cycle, otherwise the current LIMIT2NORMAL state is maintained in the next cycle.

[0016] On the basis of the above technical solution, in the FAULT state, the IGBT power limit state flag is first set to 0, and then the IGBT fault state flag is set to 1; then it is determined whether the temperature of the IGBT is greater than the normal operating temperature threshold. If it is less than the normal operating temperature threshold, the 1s IGBT timer flag and the timer count value are cleared, and then the FAULT2LIMIT state is entered in the next program cycle. Otherwise, the current FAULT state is entered again in the next program cycle.

[0017] On the basis of the above technical solution, in the FAULT2LIMIT state, it is first determined whether the 1sIGBT timer flag is 1. If so, the 1sIGBT timer flag is cleared to zero, and then the LIMIT state is entered in the next program cycle; if not, a further determination is made as to whether the IGBT temperature is less than the normal operating temperature threshold. If it is greater than the normal operating temperature threshold, the FAULT state is entered in the next cycle, otherwise the current FAULT2LIMIT state is maintained in the next cycle.

[0018] The present invention also provides a device for implementing the above method, comprising:

[0019] A temperature monitoring unit, used to monitor the temperature of the IGBT;

[0020] Power adjustment unit, when the IGBT power limit flag is 1, the adjusted power is 800W;

[0021] The state machine control unit is used to determine the current state of the IGBT;

[0022] PWM duty cycle adjustment unit, when the IGBT fault flag is 1, the PWM duty cycle is set to 0 to turn off the IGBT; when the IGBT fault flag and the power limit flag are both 0, the PWM duty cycle is adjusted to the specified power according to the host computer instruction;

[0023] The status information reporting unit reports the status information according to the corresponding flag bit.

[0024] The beneficial effects of the present invention are:

[0025] Enhanced fault tolerance: By setting multiple intermediate states, such as NORMAL2LIMIT, NORMAL2FAULT, LIMIT2NORMAL, FAULT2LIMIT, etc., smooth transition is achieved and system instability is reduced.

[0026] Flexibility: Allows PWM duty cycle to be adjusted according to host computer instructions to adapt to different working requirements.

[0027] Easy maintenance: The state machine is clearly designed to simplify fault diagnosis and system maintenance.

[0028] Improved user experience: Provides a more continuous and stable heating experience by avoiding unnecessary downtime or intermittent heating. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the IGBT over-temperature protection control method based on the state machine in the present invention;

[0030] Figure 2This is a flow chart of the IGBT in the normal working state of the present invention;

[0031] Figure 3 It is a flow chart of the intermediate state from the normal state to the power limiting state of the IGBT in the present invention;

[0032] Figure 4 It is a flow chart of the intermediate state from the normal state to the fault state of the IGBT in the present invention;

[0033] Figure 5 This is a flow chart of the IGBT power limiting state in the present invention;

[0034] Figure 6 It is a flow chart of the intermediate state of the IGBT limiting power state to the normal state in the present invention;

[0035] Figure 7 This is a flow chart of the IGBT under fault condition in the present invention;

[0036] Figure 8 It is a flow chart of the intermediate state from the IGBT fault state to the power limiting state in the present invention. DETAILED DESCRIPTION

[0037] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions.

[0038] In the description of the present invention, it should be noted that directional words, such as the terms "center", "lateral (X)", "longitudinal (Y)", "vertical (Z)", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating directions and positional relationships are based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of narrating the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and cannot be understood as limiting the specific scope of protection of the present invention.

[0039] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. Therefore, the definition of "first" and "second" features can explicitly or implicitly include one or more of the features. In the description of the present invention, "several" and "a number" mean two or more, unless otherwise clearly and specifically defined.

[0040] In the present invention, unless otherwise specified and limited, the terms "assemble", "connect", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can also be a mechanical connection; it can be directly connected, or it can be connected through an intermediate medium, or the two elements can be internally connected. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] In the invention, unless otherwise specified and limited, a first feature being “above” or “below” a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being “above”, “below”, and “above” a second feature includes that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “above”, “below”, and “below” a second feature includes that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0042] The following is a further description of the specific embodiments of the present invention in conjunction with the drawings of the specification, so that the technical solution and its beneficial effects of the present invention are clearer and more explicit. The following description of the embodiments with reference to the drawings is exemplary and intended to explain the present invention, but cannot be understood as limiting the present invention.

[0043] See also Figure 1 As shown, an embodiment of the present invention provides an IGBT over-temperature protection control method based on a state machine, characterized in that it includes: dividing the IGBT into several states; monitoring the temperature of the IGBT; automatically switching between different states according to the temperature of the IGBT, and executing the corresponding power adjustment strategy. When the IGBT temperature exceeds the fault temperature threshold for a certain period of time (for example, when the IGBT temperature exceeds 105°C for more than 1 second), the power output is stopped. When the IGBT temperature exceeds the power limiting temperature threshold for a certain period of time (for example, when the IGBT temperature exceeds 90°C for more than 1 second), the power is reduced to 800W. When the IGBT temperature returns to below the normal operating temperature threshold and maintains for a certain period of time (for example, when the IGBT temperature returns to below 80°C and maintains for 1 second), the fault is eliminated and the operation can be attempted to be started. The controller software adjusts the PWM duty cycle according to the IGBT fault flag and the power limiting flag to achieve precise control of the PTC.

[0044] Specifically, the IGBT is divided into the following states: NORMAL, normal state; NORMAL2LIMIT, intermediate state from normal state to limited power state; NORMAL2FAULT, intermediate state from normal state to fault state; LIMIT, limited power state; LIMIT2NORMAL, intermediate state from limited power state to normal state; FAULT, fault state; FAULT2LIMIT, intermediate state from fault state to limited power state.

[0045] See also Figure 2 As shown, in the NORMAL state, the IGBT fault status flag and the IGBT power limit status flag are first cleared, and then it is determined whether the temperature of the IGBT is greater than the power limit temperature threshold. If it is greater than the power limit temperature threshold, the 1s IGBT timer flag and the timer count value are cleared, and then the NORMAL2LIMIT state is entered in the next program cycle; then it is determined whether the temperature of the IGBT is greater than the fault temperature threshold. If it is greater than the fault temperature threshold, the 1s IGBT timer flag and the timer count value are cleared, and then the NORMAL2FAULT state is entered in the next program cycle; if neither of the above two conditions is met, the current NORMAL state is entered again in the next program cycle.

[0046] See also Figure 3 As shown, in the NORMAL2LIMIT state, it is first determined whether the 1sIGBT timer flag is 1. If so, the 1sIGBT timer flag is cleared to zero, and then the LIMIT state is entered in the next program cycle; if not, a further determination is made as to whether the IGBT temperature is greater than the power limiting temperature threshold. If it is less than the power limiting temperature threshold, the NORMAL state is entered in the next cycle, otherwise the current NORMAL2LIMIT state is maintained in the next cycle.

[0047] See also Figure 4 As shown, in the NORMAL2FAULT state, it is first determined whether the 1sIGBT timer flag is 1. If so, the 1sIGBT timer flag is cleared to zero, and then the FAULT state is entered in the next program cycle; if not, a further determination is made as to whether the IGBT temperature is greater than 105°C. If it is less than the fault temperature threshold, the NORMAL state is entered in the next cycle, otherwise the current NORMAL2FAULT state is maintained in the next cycle.

[0048] See also Figure 5As shown, in the LIMIT state, the IGBT power limit state flag is first set to 1, and then it is determined whether the temperature of the IGBT is greater than the normal operating temperature threshold. If it is less than the normal operating temperature threshold, the 1s IGBT timer flag is cleared and the timer count value is cleared, and then the LIMIT2NORMAL state is entered in the next program cycle; then it is determined whether the temperature of the IGBT is greater than the fault temperature threshold. If it is greater than the fault temperature threshold, the 1s IGBT timer flag is cleared and the timer count value is cleared, and then the NORMAL2LIMIT state is entered in the next program cycle; if neither of the above two conditions is met, the current LIMIT state is entered again in the next program cycle.

[0049] See also Figure 6 As shown, in the LIMIT2NORMAL state, it is first determined whether the 1sIGBT timer flag is 1. If so, the 1sIGBT timer flag is cleared to zero, and then the LIMIT state is entered in the next program cycle; if not, a further determination is made as to whether the IGBT temperature is greater than the normal operating temperature threshold. If so, the LIMIT state is entered in the next cycle, otherwise, the current LIMIT2NORMAL state is maintained in the next cycle.

[0050] See also Figure 7 As shown, in the FAULT state, the IGBT power limit state flag is first set to 0, and then the IGBT fault state flag is set to 1; then it is determined whether the temperature of the IGBT is greater than the normal operating temperature threshold. If it is less than the normal operating temperature threshold, the 1s IGBT timer flag and the timer count value are cleared, and then the FAULT2LIMIT state is entered in the next program cycle. Otherwise, the current FAULT state is entered again in the next program cycle.

[0051] See also Figure 8 As shown, in the FAULT2LIMIT state, it is first determined whether the 1sIGBT timer flag is 1. If so, the 1sIGBT timer flag is cleared to zero, and then the LIMIT state is entered in the next program cycle; if not, a further determination is made as to whether the IGBT temperature is less than the normal operating temperature threshold. If it is greater than the normal operating temperature threshold, the FAULT state is entered in the next cycle, otherwise the current FAULT2LIMIT state is maintained in the next cycle.

[0052] The embodiment of the present invention also provides a device for implementing the above method, including a temperature monitoring unit, which is used to monitor the temperature of the IGBT; a power adjustment unit, which adjusts the power to 800W when the IGBT power limit flag is 1; a state machine control unit, which is used to determine the current state of the IGBT; a PWM duty cycle adjustment unit, which sets the PWM duty cycle to 0 to turn off the IGBT when the IGBT fault flag is 1; when the IGBT fault flag and the power limit flag are both 0, adjusts the PWM duty cycle to a specified power according to the host computer instruction; and a status information reporting unit, which reports the status information according to the corresponding flag.

[0053] The overheat protection mechanism usually includes temperature monitoring and corresponding heat dissipation measures. The NTC temperature sensor will monitor the operating temperature of the IGBT in real time. Once it detects that the temperature exceeds the preset safety threshold, the protection circuit will start, and the IGBT will reduce the load or stop working through the control signal. In the present invention, when the IGBT temperature reaches the power limit temperature threshold for a certain period of time, the system will reduce the power to 800W. When the temperature reaches the fault temperature threshold for a certain period of time, the PWM (pulse width modulation) signal will be turned off through a specific control signal, blocking the switch output of the IGBT for shutdown protection.

[0054] IGBT overheat protection for electric vehicle air conditioner PTC heaters is crucial to ensuring vehicle safety, improving system reliability and extending equipment life. Effective overheat protection measures can ensure that the IGBT operates within a safe temperature range, avoiding performance degradation or damage caused by overheating, while also ensuring passenger comfort and vehicle energy efficiency.

[0055] In the description of the specification, the description with reference to the terms "one embodiment", "preferably", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention, and the schematic expressions of the above terms in this specification do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0056] The present invention is not limited to the above-mentioned embodiments. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention. The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A state machine-based IGBT over-temperature protection control method, characterized in that: include: Divide the IGBT into several states; Monitoring the temperature of the IGBT; According to the temperature of the IGBT, it automatically switches between different states and executes the corresponding power adjustment strategy.

2. The IGBT over-temperature protection control method based on a state machine according to claim 1, characterized in that: The IGBT is divided into the following states: NORMAL, normal state; NORMAL2LIMIT, the intermediate state from the normal state to the power-limited state; NORMAL2FAULT, the intermediate state from normal state to fault state; LIMIT, limited power state; LIMIT2NORMAL, limits the power state to the intermediate state of the normal state; FAULT, fault status; FAULT2LIMIT, the intermediate state from the fault state to the limited power state.

3. The IGBT over-temperature protection control method based on a state machine according to claim 2, characterized in that: In the NORMAL state, the IGBT fault status flag and the IGBT power limit status flag are first cleared, and then it is determined whether the temperature of the IGBT is greater than the power limit temperature threshold. If it is greater than the power limit temperature threshold, the 1s IGBT timer flag and the timer count value are cleared, and then the NORMAL2LIMIT state is entered in the next program cycle; then it is determined whether the temperature of the IGBT is greater than the fault temperature threshold. If it is greater than the fault temperature threshold, the 1s IGBT timer flag and the timer count value are cleared, and then the NORMAL2FAULT state is entered in the next program cycle; if neither of the above two conditions is met, the current NORMAL state is entered again in the next program cycle.

4. The IGBT over-temperature protection control method based on a state machine according to claim 2, characterized in that: In the NORMAL2LIMIT state, first determine whether the 1sIGBT timer flag is 1. If so, clear the 1sIGBT timer flag to zero, and then enter the LIMIT state in the next program cycle; if not, further determine whether the IGBT temperature is greater than the power limit temperature threshold. If it is less than the power limit temperature threshold, enter the NORMAL state in the next cycle, otherwise maintain the current NORMAL2LIMIT state in the next cycle.

5. The IGBT over-temperature protection control method based on a state machine according to claim 2, characterized in that: In the NORMAL2FAULT state, first determine whether the 1sIGBT timer flag is 1. If so, clear the 1sIGBT timer flag to zero, and then enter the FAULT state in the next program cycle; if not, further determine whether the IGBT temperature is greater than 105°C. If it is less than the fault temperature threshold, enter the NORMAL state in the next cycle, otherwise maintain the current NORMAL2FAULT state in the next cycle.

6. The IGBT over-temperature protection control method based on a state machine according to claim 2, characterized in that: In the LIMIT state, the IGBT power limit state flag is first set to 1, and then it is determined whether the temperature of the IGBT is greater than the normal operating temperature threshold. If it is less than the normal operating temperature threshold, the 1s IGBT timer flag and the timer count value are cleared, and then the LIMIT2NORMAL state is entered in the next program cycle; then it is determined whether the temperature of the IGBT is greater than the fault temperature threshold. If it is greater than the fault temperature threshold, the 1s IGBT timer flag and the timer count value are cleared, and then the NORMAL2LIMIT state is entered in the next program cycle; if neither of the above two conditions is met, the current LIMIT state is entered again in the next program cycle.

7. The IGBT over-temperature protection control method based on a state machine according to claim 2, characterized in that: In the LIMIT2NORMAL state, first determine whether the 1sIGBT timer flag is 1. If so, clear the 1sIGBT timer flag to zero, and then enter the LIMIT state in the next program cycle; if not, further determine whether the IGBT temperature is greater than the normal operating temperature threshold. If so, enter the LIMIT state in the next cycle, otherwise maintain the current LIMIT2NORMAL state in the next cycle.

8. The IGBT over-temperature protection control method based on a state machine according to claim 2, characterized in that: In the FAULT state, the IGBT power limit state flag is first set to 0, and then the IGBT fault state flag is set to 1; then it is determined whether the temperature of the IGBT is greater than the normal operating temperature threshold. If it is less than the normal operating temperature threshold, the 1s IGBT timer flag and the timer count value are cleared, and then the FAULT2LIMIT state is entered in the next program cycle. Otherwise, the current FAULT state is entered again in the next program cycle.

9. The IGBT over-temperature protection control method based on a state machine according to claim 2, characterized in that: In the FAULT2LIMIT state, first determine whether the 1sIGBT timer flag is 1. If so, clear the 1sIGBT timer flag to zero, and then enter the LIMIT state in the next program cycle. If not, further determine whether the IGBT temperature is lower than the normal operating temperature threshold. If it is higher than the normal operating temperature threshold, enter the FAULT state in the next cycle. Otherwise, maintain the current FAULT2LIMIT state in the next cycle.

10. A device for implementing the method according to any one of claims 1 to 9, characterized in that: include A temperature monitoring unit, used to monitor the temperature of the IGBT; Power adjustment unit, when the IGBT power limit flag is 1, the adjusted power is 800W; The state machine control unit is used to determine the current state of the IGBT; PWM duty cycle adjustment unit, when the IGBT fault flag is 1, the PWM duty cycle is set to 0 to turn off the IGBT; When the IGBT fault flag and the power limit flag are both 0, the PWM duty cycle is adjusted to the specified power according to the host computer command; The status information reporting unit reports the status information according to the corresponding flag bit.

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