Heater IGBT abnormity pre-diagnosis method and heater
By controlling the IGBT with a PWM signal and combining it with an integral control algorithm to detect current energy, the problem of fault detection before heater operation is solved, ensuring the safety and reliability of the heater.
Patent Information
- Application Number
- CN202511686043.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-18
- Publication Date
- 2026-02-10
AI Technical Summary
In the existing technology, it is difficult to effectively detect faults in heaters before operation, which may lead to system damage, energy waste and interruption of production or life activities.
By controlling the IGBT to turn on and off using PWM signals and combining the integral control algorithm to sample current energy, it is possible to determine whether the IGBT has an open circuit or short circuit fault, and the MCU controller is used for pre-diagnosis.
This enables fault detection of IGBTs before heater operation, improving the safety and reliability of the heater and avoiding damage and energy waste caused by faults.
Smart Images
Figure CN121510401A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of heater control, and more particularly to a method for pre-diagnosing abnormalities in a heater IGBT and a heater. Background Technology
[0002] In many industrial and civil sectors, heaters are a common type of equipment that typically consumes a significant amount of electrical energy during operation. Due to their high power consumption, a malfunction in a heater can have a substantial negative impact on the entire heating system, potentially leading to system damage, energy waste, and disruption of production or daily life.
[0003] Therefore, how to perform fault detection before the heater system is put into operation is a technical problem that urgently needs to be solved in this field. Summary of the Invention
[0004] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a pre-diagnosis method for IGBT anomalies in a heater and a heater, which can perform fault detection before the heater system is put into operation, thereby improving the safety and reliability of the heater.
[0005] To achieve the above objectives, one aspect of the present invention provides a method for pre-diagnosing IGBT anomalies in a heater, comprising: controlling the IGBT to turn on and off before the heater performs heating operations; wherein the IGBT is controlled to turn on via a PWM signal; In both the on and off states of the IGBT, the current is sampled using an integral control algorithm, and the total current energy is obtained based on the sampled current. Determine whether the total current energy when the IGBT is on meets the open-circuit fault condition and whether the total current energy when the IGBT is off meets the short-circuit fault condition: When the total current energy under IGBT conduction meets the open circuit fault condition or the total current energy under IGBT turn-off meets the short circuit fault condition, the heater is prohibited from performing heating action. When the total current energy under IGBT conduction does not meet the open-circuit fault condition and the total current energy under IGBT turn-off does not meet the short-circuit fault condition, the heater performs a heating action.
[0006] Furthermore, the control of IGBT turn-on and turn-off specifically includes: First, the IGBT is turned on by controlling the PWM signal. Then, when the total current energy under the IGBT's on condition does not meet the open circuit fault condition, the IGBT is turned off. Finally, it is determined whether the total current energy under the IGBT's off condition meets the short circuit fault condition.
[0007] Furthermore, the frequency of the PWM signal is between 40Hz and 60Hz, and the duty cycle is between 10% and 20%.
[0008] Furthermore, the step of sampling the current using an integral control algorithm and obtaining the total current energy based on the sampled current specifically includes: The integral control algorithm formula is as follows: Where Q is the total current energy, T is the current control period, and I(t) is the instantaneous current; Discretizing the integral control algorithm formula yields the current sampling calculation formula. Where QN represents the current energy in the Nth cycle, Ik represents the instantaneous current sampling value, and m is the ratio of the sampling frequency of the current to the frequency of the PWM signal; The current energy within one current cycle is obtained according to the current sampling calculation formula. The total current energy is the current energy accumulated over a preset number of current cycles.
[0009] Furthermore, the ratio of the current sampling frequency to the PWM signal frequency is 100.
[0010] Furthermore, the preset number of current cycles is 5.
[0011] Furthermore, determining whether the total current energy under IGBT conduction conditions meets the open-circuit fault conditions specifically includes: Determine whether the total current energy is less than the preset open-circuit current value: When the total current energy is less than the preset open-circuit current value, the open-circuit fault counter is incremented by 1 and it is determined whether the open-circuit fault counter value is less than the first preset value; when the open-circuit fault counter value is equal to the first preset value, it is determined that the open-circuit fault condition is met and the IGBT open-circuit fault is diagnosed; when the open-circuit fault counter value is less than the first preset value, the current is sampled again and a new total current energy is obtained, and it is determined whether the open-circuit fault condition is met based on the new total current energy. When the total current energy is greater than or equal to the preset open circuit current value, it is determined that the open circuit fault condition is not met, and the open circuit fault counter is cleared to zero.
[0012] Furthermore, determining whether the total current energy meets the short-circuit fault conditions when the IGBT is turned off specifically includes: Determine whether the total current energy is greater than the preset shutdown current value: When the total current energy is greater than the preset shutdown current value, the short-circuit fault counter is incremented by 1, and it is determined whether the short-circuit fault counter value is less than a second preset value; when the short-circuit fault counter value is equal to the second preset value, it is determined that the short-circuit fault condition is met, and the IGBT short-circuit fault is diagnosed; when the short-circuit fault counter value is less than the second preset value, the current is sampled again to obtain a new total current energy, and it is determined whether the short-circuit fault condition is met based on the new total current energy. When the total current energy is less than or equal to the preset shutdown current value, it is determined that the short-circuit fault condition is not met, and the short-circuit fault counter is cleared to zero.
[0013] In one aspect, the present invention also provides a heater, comprising an MCU controller, a power interface, an IGBT, and a heater core: wherein the power interface, the IGBT, and the heater core constitute a heating circuit; the MCU controller performs an abnormality pre-diagnosis of the IGBT by executing the heater IGBT abnormality pre-diagnosis method according to any one of claims 1 to 8.
[0014] Furthermore, the heater includes multiple heating circuits; the MCU controller performs pre-diagnosis of anomalies in each of the IGBTs in the heating circuit.
[0015] This invention uses PWM to control IGBT conduction, sampling current energy according to an integral control algorithm to determine if an IGBT open-circuit fault has occurred. Similarly, it controls IGBT turn-off, sampling current energy according to the integral control algorithm to determine if an IGBT short-circuit fault has occurred. The entire diagnostic process requires no additional detection circuitry, saving product costs. It features a simple control flow, high detection accuracy, and short processing time. It can pre-diagnose IGBT device performance for faults before the heater product performs its heating action, effectively ensuring the safety and reliability of the heater product. Attached Figure Description
[0016] Figure 1 The flowchart is a pre-diagnosis method for heater IGBT abnormalities provided by the present invention;
[0017] Figure 2 This is a schematic diagram of the heater provided by the present invention. Detailed Implementation
[0018] The heater IGBT anomaly pre-diagnosis method provided by this invention mainly uses PWM (Pulse Width Modulation) to control the IGBT conduction, samples the current energy according to an integral control algorithm, and determines whether an IGBT open-circuit fault has occurred. Similarly, the IGBT is controlled to turn off, and the current energy is then sampled according to the integral control algorithm to determine whether an IGBT short-circuit fault has occurred. If the pre-diagnosis result is normal, the product can perform the heating action; if the pre-diagnosis result is abnormal, the product will be locked and unable to perform the heating action.
[0019] The technical content of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0020] like Figure 1 As shown, an embodiment of the present invention provides a pre-diagnosis method for heater IGBT anomalies, which is performed before the heater performs heating operations, and includes the following steps:
[0021] Step S11: Control the IGBT to turn on using the PWM signal.
[0022] In this step, the frequency of the PWM signal is preferably controlled between 40Hz and 60Hz, and the duty cycle is controlled between 10% and 20%, which can reduce the energy demand of the heater on the battery during the pre-diagnosis process.
[0023] For example, if the PWM signal frequency CF1 is 50Hz, the duty cycle CD1 is 10%, and the heating power of the heating core is set to 3000W, then if all IGBTs are turned on for heating, the heating core will consume 3000W of battery energy. In scenarios where the battery pack charge is below 3000W but the heater still needs to operate, if all IGBTs are turned on for heating, the battery pack will enter protection mode the instant heating is activated, preventing power output. The heater will also fail to pass the IGBT anomaly pre-diagnosis and will not be able to operate. However, if a 10% duty cycle PWM method is used for heating, the heater only needs to consume 300W of battery energy, allowing the battery pack to output power normally, and the heater can pass the IGBT anomaly pre-diagnosis and operate normally.
[0024] Step S12: Sample the current according to the integral control algorithm and obtain the total current energy based on the sampled current.
[0025] This step specifically includes two sub-steps: step S121 sampling of the current and step S122 obtaining the total current energy.
[0026] In step S121, when sampling the current, the sampling frequency SF1 needs to be set according to the frequency CF1 of the PWM signal. Here, the two parameter values follow the relationship SF1 = m * CF1. Preferably, the value of m is 100. This is because if the sampling frequency is set to 100 times the PWM frequency, then 100 data points can be sampled from the signal of one PWM cycle, which is equivalent to being able to sample and identify 1% of the duty cycle accuracy of the PWM signal, effectively improving the detection accuracy of current energy.
[0027] The formula for the integral control algorithm is: Where Q is the total current energy, T is the current control period, and I(t) is the instantaneous current.
[0028] After discretizing the integral control algorithm, the current sampling calculation formula is obtained: Among them, Q N I represents the current energy in the Nth cycle. k This represents the instantaneous current sample value; m is the ratio of the current sampling frequency to the PWM signal frequency.
[0029] As mentioned above, the current sampling frequency SF1 is 100 times the PWM control frequency CF1, meaning m is 100. Therefore, the time to accumulate 100 instantaneous current sampling values is exactly one current cycle, which is also the signal cycle of the PWM signal. Accumulating 100 instantaneous current sampling values yields the current energy within that cycle.
[0030] Next, the current energy for 5 cycles is accumulated using the accumulation formula. Where Qtotal is the total current energy, also denoted as the IGBT turn-on self-test current value Ion (used below).
[0031] In one embodiment, a total current energy of 5 cycles is preferred. This is because, taking a 50Hz signal as an example, a single cycle lasts 20ms, so 5 cycles total 100ms. This not only eliminates random interference, increasing detection accuracy and reliability, but also allows for rapid self-testing, increasing product response speed. The PWM signal in this application is 40Hz~60Hz, and the 5-cycle signal balances both detection accuracy and response speed.
[0032] Step S13: Determine if the self-test current value Ion is less than the open-circuit current value. If Ion is less than 5A, increment the open-circuit fault counter Cnt_IGBT_Open by 1 and proceed to step S14. Otherwise, clear the open-circuit fault counter Cnt_IGBT_Open, record that the IGBT has no open-circuit fault, and proceed to step S15. In this step, the open-circuit current value needs to be preset to 5A. The open-circuit current value is only for illustrative purposes and can be adjusted as needed. Step S14: Determine if the open-circuit fault counter Cnt_IGBT_Open is less than the preset number of times 3. If Cnt_IGBT_Open is less than 3, repeat steps S11 to S13, obtain the new total current energy based on the new sampling current, and determine whether the open-circuit fault condition is met based on the new total current energy. If Cnt_IGBT_Open is equal to 3, diagnose an IGBT open-circuit fault and proceed to step S19.
[0033] In this step, the preset number of attempts can be adjusted according to actual needs. The example of 3 attempts provided here is merely illustrative and not intended to limit the scope of the invention. Therefore, it can be understood that determining whether the total current energy Qtotal under IGBT conduction meets the open-circuit fault condition requires both the determination of the open-circuit current value and the determination of the preset number of attempts. By combining these two methods, the possibility of misjudging an open-circuit fault due to limited sampling data can be effectively avoided.
[0034] Step S15: Control the IGBT to turn off.
[0035] Step S16: Sample the current according to the integral control algorithm and obtain the total current energy based on the sampled current.
[0036] The specific implementation process in this step can be found in the description of step S12, and will not be repeated here. Similarly, according to the preset integral control algorithm, the total current energy Q is accumulated and calculated. total This is denoted as the IGBT turn-off self-test current value, Ioff. The current sampling frequency is the same as the sampling frequency when the IGBT is on, and is 100 times the PWM signal frequency.
[0037] Step S17: Determine whether the turn-off self-test current value Ioff is greater than the turn-off current value: If Ioff is greater than 2A, increment the short-circuit fault counter Cnt_IGBT_Short by 1 and execute step S18; otherwise, clear Cnt_IGBT_Short to zero, determine that there is no short-circuit fault in the IGBT, and execute step S19.
[0038] In this step, the preset shutdown current value needs to be 2A. The shutdown current value is only for illustrative purposes and can be adjusted as needed.
[0039] Step S18: Determine whether Cnt_IGBT_Short is less than the preset number of times 3; if Cnt_IGBT_Short is less than 3, repeat steps S15 to S17, obtain the new total current energy based on the new sampling current, and determine whether the turn-off fault condition is met based on the new total current energy; if Cnt_IGBT_Short is equal to 3, diagnose the IGBT short circuit fault and execute step S19.
[0040] In this step, the preset number of attempts is also adjusted according to actual needs and may differ from the preset number of attempts in step S14. Here, a preset number of 3 is provided only as an example. As can be seen above, determining whether the total energy of the IGBT turn-off current Qtotal meets the short-circuit fault condition requires considering both the turn-off current value and the preset number of attempts. By using the results of both, the possibility of misjudging a short-circuit fault due to limited sampling data can be effectively avoided.
[0041] Step S19, pre-diagnosis ends.
[0042] When the diagnosis ends due to an IGBT open-circuit fault or short-circuit fault, the heater should not be started. When the IGBT has no open-circuit fault or short-circuit fault, it indicates that the IGBT pre-diagnosis result is normal, and the heater can be started.
[0043] In the above embodiment, open-circuit fault diagnosis (S11~S14) is performed first, followed by short-circuit fault diagnosis (S15~S18). That is, if no open-circuit fault is diagnosed in the IGBT, the IGBT is then turned off for short-circuit fault diagnosis. In practical applications, short-circuit fault diagnosis can also be performed first (i.e., steps S15~S18 are adjusted to S11~S14). If no short-circuit fault is found in the IGBT (when no short-circuit fault is found in step 17), the IGBT is then turned on for open-circuit fault diagnosis (steps S11~S14 are adjusted to S15~S18). The specific execution process is not detailed here. This invention does not restrict the order of open-circuit and short-circuit fault diagnosis. However, the preferred order is open-circuit fault diagnosis followed by short-circuit fault diagnosis. This is because after the entire pre-diagnosis process ends, the product is still in the IGBT-off state, returning to the state before self-testing. Therefore, processing the pre-diagnosis self-test process as an independent module is more convenient for system strategy. However, for detecting short-circuit faults followed by open-circuit faults, after the pre-diagnosis self-test is completed, the IGBT is in the open state, and the IGBT needs to be turned off again to restore the product to the initial IGBT-off state, which is a relatively complicated process.
[0044] As can be seen from the above, before the heater performs the heating action, the present invention can pre-diagnose the performance of the IGBT device through a simple control process, confirm in advance whether there is a fault in the product, effectively avoid the occurrence of explosion or safety accidents caused by device problems, and ensure the safety and reliability of the heater product.
[0045] like Figure 2 As shown, one embodiment of the present invention also provides a heater, comprising an MCU controller 21, a first power interface 22, a communication interface 23, a voltage, current and temperature detection circuit 24, a second power interface 25, an IGBT 26, and a heater core 27. The IGBT 26 is electrically connected to both the second power interface 25 and the heater core 27, forming a heating circuit. The MCU controller 21 controls the heating function by turning on the IGBT 26 and controls the heating function by turning off the IGBT 26. Before controlling the heating function to start, the MCU controller 21 also performs the aforementioned IGBT anomaly pre-diagnosis method to diagnose any anomalies in the IGBT 26. The IGBT 26 anomaly pre-diagnosis method is described above and will not be repeated here. The first power interface 22 supplies power to the entire heater, providing low-voltage power to the MCU controller 21. The communication interface 23 is responsible for communication between the MCU controller 21 and external control devices. The MCU controller 21 obtains the voltage, current and temperature parameters of the product's operation through the voltage, current and temperature detection circuit 24.
[0046] Figure 2 The heater shown in the image only has a single heating circuit. However, heater products typically use two or more heater cores 27 connected in parallel, with each heater core 27 connected in series with an IGBT 26 for independent control. Therefore, when multiple heating circuits exist, the MCU controller 21 needs to repeat the above IGBT 26 anomaly pre-diagnosis process steps S11~S19 to perform anomaly pre-diagnosis for each IGBT 26 individually.
[0047] As can be seen, the heater provided by the present invention does not add any additional circuitry compared to existing heaters. It only adds a control process to the MCU to achieve pre-diagnosis of IGBT26 abnormalities before operation, thus ensuring the safety and reliability of the product.
[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.
Claims
1. A method for pre-diagnosing abnormalities in a heater IGBT, characterized in that, include: Before the heater performs heating, the IGBT is controlled to turn on and off; the IGBT is turned on by a PWM signal. In both the on and off states of the IGBT, the current is sampled using an integral control algorithm, and the total current energy is obtained based on the sampled current. Determine whether the total current energy when the IGBT is on meets the open-circuit fault condition and whether the total current energy when the IGBT is off meets the short-circuit fault condition: When the total current energy under IGBT conduction meets the open circuit fault condition or the total current energy under IGBT turn-off meets the short circuit fault condition, the heater is prohibited from performing heating action. When the total current energy under IGBT conduction does not meet the open-circuit fault condition and the total current energy under IGBT turn-off does not meet the short-circuit fault condition, the heater performs a heating action.
2. The heater IGBT anomaly pre-diagnosis method according to claim 1, characterized in that, The control of IGBT turn-on and turn-off specifically includes: First, the IGBT is turned on by controlling the PWM signal. Then, when the total current energy under the IGBT's on condition does not meet the open circuit fault condition, the IGBT is turned off. Finally, it is determined whether the total current energy under the IGBT's off condition meets the short circuit fault condition.
3. The heater IGBT anomaly pre-diagnosis method according to claim 2, characterized in that, The frequency of the PWM signal is between 40Hz and 60Hz, and the duty cycle is between 10% and 20%.
4. The heater IGBT abnormality pre-diagnosis method according to claim 3, wherein sampling the current using an integral control algorithm and obtaining the total current energy based on the sampled current specifically includes: The integral control algorithm formula is as follows: Where Q is the total current energy, T is the current control period, and I(t) is the instantaneous current; Discretizing the integral control algorithm formula yields the current sampling calculation formula. Where QN represents the current energy in the Nth cycle, Ik represents the instantaneous current sampling value, and m is the ratio of the sampling frequency of the current to the frequency of the PWM signal; The current energy within one current cycle is obtained according to the current sampling calculation formula. The total current energy is the current energy accumulated over a preset number of current cycles.
5. The heater IGBT abnormality pre-diagnosis method according to claim 4, characterized in that, The ratio of the current sampling frequency to the PWM signal frequency is 100.
6. The heater IGBT anomaly pre-diagnosis method according to claim 4, characterized in that, The preset number of current cycles is 5.
7. The method for pre-diagnostic abnormalities of heater IGBTs according to any one of claims 1 to 6, characterized in that, The determination of whether the total current energy under IGBT conduction meets the open-circuit fault conditions specifically includes: Determine whether the total current energy is less than the preset open-circuit current value: When the total current energy is less than the preset open-circuit current value, the open-circuit fault counter is incremented by 1 and it is determined whether the open-circuit fault counter value is less than the first preset value; when the open-circuit fault counter value is equal to the first preset value, it is determined that the open-circuit fault condition is met and the IGBT open-circuit fault is diagnosed; when the open-circuit fault counter value is less than the first preset value, the current is sampled again and a new total current energy is obtained, and it is determined whether the open-circuit fault condition is met based on the new total current energy. When the total current energy is greater than or equal to the preset open circuit current value, it is determined that the open circuit fault condition is not met, and the open circuit fault counter is cleared to zero.
8. The method for pre-diagnosing heater IGBT anomalies according to any one of claims 1 to 6, characterized in that, The determination of whether the total current energy meets the short-circuit fault conditions when the IGBT is turned off specifically includes: Determine whether the total current energy is greater than the preset shutdown current value: When the total current energy is greater than the preset shutdown current value, the short-circuit fault counter is incremented by 1, and it is determined whether the short-circuit fault counter value is less than a second preset value; when the short-circuit fault counter value is equal to the second preset value, it is determined that the short-circuit fault condition is met, and the IGBT short-circuit fault is diagnosed; when the short-circuit fault counter value is less than the second preset value, the current is sampled again to obtain a new total current energy, and it is determined whether the short-circuit fault condition is met based on the new total current energy. When the total current energy is less than or equal to the preset shutdown current value, it is determined that the short-circuit fault condition is not met, and the short-circuit fault counter is cleared to zero.
9. A heater, characterized in that, The device includes an MCU controller, a power interface, an IGBT, and a heater core; wherein the power interface, the IGBT, and the heater core constitute a heating circuit; the MCU controller performs an abnormality pre-diagnosis of the IGBT by executing the heater IGBT abnormality pre-diagnosis method according to any one of claims 1 to 8.
10. The heater according to claim 9, characterized in that, The heater includes multiple heating circuits; the MCU controller performs pre-diagnosis of anomalies in each of the IGBTs in the heating circuit.