A real-time on-line protection method for preventing junction temperature of semiconductor power device from over-limit

Abstract

The application discloses a kind of real-time online protection methods for preventing semiconductor power device junction temperature over-limit, it is related to semiconductor power device junction temperature over-limit protection method field.Can guarantee under the premise of not high to CPU operation ability requirement, by fixed period t p The shell temperature and current of inner semiconductor power device are looked up to obtain corresponding time limit value t, t p / t is accumulated, whether the junction temperature of semiconductor power device is over-limit can be judged.Firstly, according to the manual parameters of semiconductor power device, the locked-rotor time limit two-dimensional table of power device under different current and shell temperature is obtained by calculation or simulation;Then, according to fixed period t p The current and shell temperature of semiconductor power device are obtained;Obtain time limit t;Finally, according to t p / t is accumulated, once the accumulated value reaches or exceeds 1, junction temperature over-limit protection is carried out, and semiconductor power device is closed.Its workload is smaller, CPU operation amount is small, and there is no parameter range limitation of mapping junction temperature of thermal sensitive parameter method.

Description

Technical Field

[0001] This invention relates to the field of methods for protecting semiconductor power devices from over-limit junction temperatures. Background Technology

[0002] In recent years, semiconductor power devices, as core components, have been widely used in industrial automation, transportation, smart grids, new energy, and other fields. Their reliability has become a research hotspot for universities, research institutions, and high-tech enterprises. The junction temperature of semiconductor power devices is one of the most critical parameters determining their reliable operation. Studies have shown that over 60% of semiconductor power device failures are caused by excessive internal junction temperatures. Therefore, it is essential to monitor and protect the junction temperature of semiconductor power devices in real time during equipment operation.

[0003] There are two main categories of methods for real-time online acquisition and protection of semiconductor power device junction temperatures during equipment operation:

[0004] One method is the online junction temperature calculation based on power consumption and thermal resistance models. US Patent No. 2016 / 0334280 A1 and Chinese Patent Application No. CN 103956887 A belong to this category. Using parameters provided by the semiconductor power device supplier and considering the switching status of the semiconductor power device during equipment operation, the real-time power consumption of the semiconductor power device is calculated online. This power consumption is then multiplied by the dynamic thermal resistance of the semiconductor power device to obtain the junction-to-case temperature rise. Adding this to the measured case temperature of the semiconductor power device yields the junction temperature. This method can obtain relatively accurate junction temperatures, but it involves a large amount of computation. Real-time online calculations require high CPU processing power. Furthermore, when the equipment's operating conditions change in real time, the dynamic junction temperature curve of the semiconductor power device cannot be obtained using this method.

[0005] The second method is the online junction temperature estimation method based on thermistor parameters. Chinese invention patent application CN 106199367 A falls into this category. It utilizes the characteristics of semiconductor power devices, selecting easily measurable parameters that have a simple linear relationship with junction temperature, and estimating the junction temperature by acquiring these parameters online in real time. This method requires minimal computation, places no demands on CPU processing power, and can obtain the dynamic junction temperature of semiconductor power devices under varying operating conditions. However, the relationship between thermistor parameters and junction temperature is often only a simple linear relationship within a certain range. Beyond this range, it is difficult to establish a corresponding mathematical model, and accuracy cannot be guaranteed. Furthermore, thermistor parameters are related not only to junction temperature but also to other parameters, necessitating the introduction of multi-dimensional data tables. This significantly increases the workload of obtaining the parameter-junction temperature relationship through testing in the early stages and increases the complexity of algorithm interpolation. Summary of the Invention

[0006] To address the above problems, this invention proposes a real-time online protection method to prevent junction temperature exceedances in semiconductor power devices. This method can achieve protection through a fixed period t, while ensuring that CPU processing power requirements are not high. p The case temperature and current of the internal semiconductor power device are obtained from a table to obtain the corresponding time limit value t. p By accumulating the values ​​of / t, it can be determined whether the junction temperature of the semiconductor power device exceeds the limit.

[0007] The technical solution of the present invention is as follows: the real-time online protection method is as follows:

[0008] First, a two-dimensional table of stall time of the power device under different currents and case temperatures is obtained by calculating or simulating the parameters in the datasheet of the semiconductor power device.

[0009] Then, according to a fixed period t p Obtain the current and case temperature of semiconductor power devices;

[0010] If the current and shell temperature values ​​are within the range specified in the table, the time limit t is obtained by looking up the table. If the current and shell temperature values ​​are higher than the upper limit of the table, the time limit t is obtained by looking up the table according to the upper limit values ​​of the current and shell temperature. If the current and shell temperature values ​​are lower than the lower limit of the table, the time limit t is a negative constant. Finally, according to t... p The value is accumulated by / t. Once the accumulated value reaches or exceeds 1, junction temperature over-limit protection is activated, and the semiconductor power device is shut down.

[0011] Follow these steps:

[0012] Step 1: During a fixed interrupt period t p The three-phase current I of the motor was obtained by sampling. a I b I c And the case temperature T of semiconductor power devices c ;

[0013] Step 2, if I a If I ≥ 0, then the current I in the upper tube of phase A is... au = I a Phase A lower tube current I ad = 0; otherwise, the current I of the upper tube in phase A is 0. au = 0, Phase A lower tube current I ad = I a Similarly, the current I of the upper tube in phase B can be obtained. bu Phase B lower tube current I bd C-phase upper tube current I cu C-phase lower tube current I cd ;

[0014] Step 3: Execute the junction temperature over-limit protection algorithm for each switching transistor of the semiconductor power device in sequence; that is, execute the junction temperature over-limit protection algorithm for the upper transistor of phase A, the lower transistor of phase A, the upper transistor of phase B, the lower transistor of phase B, the upper transistor of phase C, and the lower transistor of phase C in sequence.

[0015] Furthermore, the junction temperature over-limit protection algorithm for the upper tube of phase A in step 3 is performed according to the following steps:

[0016] a. If I au > I max Then let I au = I max If I au < I min Then let t au = -t0; if I min ≤I au ≤I max If so, proceed directly to the next step;

[0017] Among them I max I represents the upper limit of the current value in the table. min The lower limit of the current in the table, t au The current in the two-dimensional table for the stall time is I. au The shell temperature is T c The corresponding stall time limit under the given conditions, t0 is taken as 100ms;

[0018] b. If T c > T max Then let T c = T max If T c < T min Then let t au = -t0; if T min ≤T c ≤T max If so, proceed directly to the next step;

[0019] Where T max T represents the upper limit of the shell temperature in the table. min The lower limit of the shell temperature is shown in the table;

[0020] c. According to I au T c Consult the two-dimensional table of stall time for power devices under different currents and case temperatures to obtain the corresponding stall time value t. au If I au T c If the value does not fall on a grid point in the table, the interpolation algorithm is applied to obtain the stall time limit t.au ;

[0021] d. Calculate the accumulation factor t p / t au Divide the two and sum them to obtain the accumulated value σ. au If σ au If σ < 0, then let σ au If the value is 0, proceed to the next step; otherwise, proceed directly to the next step.

[0022] e. If σ au If ≥ 1, an alarm will be triggered for the power device junction temperature exceeding the limit, and the equipment will stop operating; otherwise, σ will be saved. au Waiting for the next accumulation, the junction temperature over-limit protection algorithm for the upper tube of phase A has been executed.

[0023] Furthermore, following the junction temperature over-limit protection algorithm for the A-phase upper tube, I in step a can be... au Replace with the A-phase lower tube current I ad Phase B upper tube current I bu Phase B lower tube current I bd C-phase upper tube current I cu Or the C-phase lower tube current I cd Then, follow step ae to execute the junction temperature over-limit protection algorithm for phase A lower tube, phase B upper tube, phase B lower tube, phase C upper tube, and phase C lower tube in sequence.

[0024] The junction temperature over-limit protection algorithms for the upper A-phase transistor, the lower A-phase transistor, the upper B-phase transistor, the lower B-phase transistor, the upper C-phase transistor, and the lower C-phase transistor will all be executed independently. As soon as any one of them detects that the junction temperature exceeds the limit, the semiconductor power device will be shut down and the equipment will stop operating.

[0025] Furthermore, step b also includes a method for protecting against overheating of the casing: if T c > T max This increments the case temperature over-limit protection counter by 1. When the counter reaches its upper limit, an over-limit case temperature protection alarm is triggered. If T... c ≤T max If the shell temperature is too high, the counter will be reset to zero.

[0026] Furthermore, the method of the present invention is applicable to all semiconductor power modules and all power topologies.

[0027] Compared with existing methods for monitoring and protecting junction temperatures of semiconductor power devices, this invention has the following advantages:

[0028] First, under certain case temperature and current, the stall time can be obtained by calculating the stall power dissipation and stall junction-case temperature rise according to the datasheet parameters of the semiconductor power device, and then finding the dynamic thermal resistance curve; or the stall time can be easily obtained using the official simulation software provided by the semiconductor power device manufacturer. Therefore, obtaining the two-dimensional stall time table of this invention requires relatively little work.

[0029] II. This invention uses a fixed period t p The case temperature and current of the internal semiconductor power device are obtained from a table to obtain the corresponding time limit value t. p By accumulating the values ​​of / t, it is possible to determine whether the junction temperature of a semiconductor power device exceeds the limit. The algorithm does not require additional hardware sampling costs, has low CPU computation requirements, and is particularly suitable for integration into a system for real-time online execution.

[0030] Third, the stall time of semiconductor power devices under certain case temperature and current is obtained through mathematical models and is accurate and effective across the entire range. This invention does not have the parameter range limitation of the thermistor parameter method for mapping junction temperature. Attached Figure Description

[0031] Figure 1 This is the workflow diagram for this case;

[0032] Figure 2 This is a flowchart illustrating the process of the protection method for excessive junction temperature of phase A in this case. Detailed Implementation

[0033] To clearly illustrate the technical features of this patent, the following detailed description is provided through specific embodiments and in conjunction with the accompanying drawings.

[0034] The following example uses the semiconductor power device FP35R12W2T7 to illustrate the specific implementation of this invention. This is an IGBT power module mass-produced by Infineon Technologies, with a rated voltage of 1200V and a rated current of 35A. For example, this power module is used in a 2kW servo drive, driving a 2kW motor with a rated current of 6.8 Arms and a stall current of 29A.

[0035] According to the FP35R12W2T7 datasheet, by calculating the locked-rotor power dissipation and locked-rotor junction-case temperature rise, and referring to the dynamic thermal resistance curve, the locked-rotor time limit of this power device under a certain case temperature and current can be obtained. Alternatively, the official simulation software provided by the semiconductor power device manufacturer, specifically IPOSIM for Infineon, can be used to more conveniently obtain the locked-rotor time limit of the power device under a certain case temperature and current. Repeating this process, an example of the locked-rotor time limit table for FP35R12W2T7 is finally obtained, as shown in Table 1 below. min – I max It is the current value flowing through the IGBT chip, Tmin – T max It is the case temperature of the power module, t 11 -t nn It refers to the stall time of an IGBT chip under a certain case temperature and current.

[0036] Table 1. Stall Time Limits for FP35R12W2T7

[0037]

[0038] Based on the aforementioned stall time limit table, the flowchart of this invention is as follows: Figure 1 As shown, its working process is as follows:

[0039] Step 1: During a fixed interrupt period t p For example, during the current loop interruption period, the three-phase current I of the motor is sampled and obtained. a I b I c And the temperature of the NTC inside the semiconductor power device FP35R12W2T7, i.e., the case temperature T. c I a I b I c T is a necessary parameter for closed-loop control of the motor. c These are essential parameters for the device to perform overheat protection of power devices. Therefore, this invention does not require additional hardware sampling circuits, and does not incur additional hardware costs.

[0040] Step 2, if I a If I ≥ 0, then the current I in the upper tube of phase A is... au = I a Phase A lower tube current I ad = 0; otherwise, the current I of the upper tube in phase A is 0. au = 0, Phase A lower tube current I ad = I a Similarly, the current I of the upper tube in phase B can be obtained. bu Phase B lower tube current I bd C-phase upper tube current I cu C-phase lower tube current I cd .

[0041] Step 3: Execute the junction temperature over-limit protection algorithm for each switching transistor of the semiconductor power device in sequence.

[0042] The following explanation uses the junction temperature over-limit protection algorithm of the A-phase upper tube as an example. The junction temperature over-limit protection algorithm of other switching tubes is the same and will not be repeated here.

[0043] a. If I au > I maxThen let I au = I max If I au < I min Then let t au = -t0; if I min ≤I au ≤I max If so, proceed directly to the next step;

[0044] Among them I max I represents the upper limit of the current value in the table. min The lower limit of the current in the table, t au The current in the two-dimensional table for the stall time is I. au The shell temperature is T c The corresponding stall time limit under the given conditions is t0 = 100ms in this embodiment.

[0045] b. If T c > T max Then let T c = T max If T c < T min Then let t au = -t0; if T min ≤T c ≤T max If so, proceed directly to the next step;

[0046] Where T max T represents the upper limit of the shell temperature in the table. min The lower limit of the shell temperature is shown in the table.

[0047] In addition, step b also includes a method for protecting against overheating of the casing. Specifically, if T c > T max If this continues for more than a certain period of time, an overheat protection alarm for the power devices will be triggered, and the equipment will stop operating. Therefore, if T... c > T max This increments the case temperature over-limit protection counter by 1. When the counter reaches its upper limit, an over-limit case temperature protection alarm is triggered. If T... c ≤T max If the shell temperature is too high, the counter will be reset to zero.

[0048] c. According to I au T c Refer to Table 1 to obtain the corresponding stall time limit value t. au If I au T c If the value does not fall on a grid point in the table, the interpolation algorithm is applied to obtain the stall time limit t. auThere are many interpolation algorithms available in the prior art. In this case, a conventional interpolation algorithm, such as linear interpolation, can be selected.

[0049] d. Calculate the accumulation factor t p / t au Divide the two and sum them to obtain the accumulated value σ. au If σ au If σ < 0, then let σ au If the value is 0, proceed to the next step; otherwise, proceed directly to the next step.

[0050] e. If σ au If ≥ 1, an alarm will be triggered for the power device junction temperature exceeding the limit, and the equipment will stop operating; otherwise, σ will be saved. au Waiting for the next accumulation, the junction temperature over-limit protection algorithm for the upper tube of phase A has been executed.

[0051] Following the junction temperature over-limit protection algorithm for the upper A-phase tube, the same algorithm can be applied sequentially to the lower A-phase tube, upper B-phase tube, lower B-phase tube, upper C-phase tube, and lower C-phase tube. The only difference is the replacement of I in step a. au Then, proceed with step a. For example, when performing the junction temperature over-limit protection algorithm for the A-phase lower tube, step a will be performed with I... au Replace with I ad , to obtain t ad Calculate the accumulation factor t p / t ad And accumulate them to obtain the accumulated value σ. ad Once step ae is completed, the algorithm for over-limit junction temperature protection of the lower A-phase tube is finished.

[0052] As time progresses, the junction temperature over-limit protection algorithms for the upper A-phase transistor, the lower A-phase transistor, the upper B-phase transistor, the lower B-phase transistor, the upper C-phase transistor, and the lower C-phase transistor will all be executed independently. As soon as any one of them detects that the junction temperature exceeds the limit, the semiconductor power device will be shut down and the equipment will stop operating.

[0053] There are many specific ways to implement this invention. The above description is only a preferred embodiment of this invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of this invention, and these improvements should also be considered within the scope of protection of this invention.

Claims

1. A real-time online protection method for preventing junction temperature exceeding limits in semiconductor power devices, characterized in that, The real-time online protection method is as follows: First, a two-dimensional table of stall time of the power device under different currents and case temperatures is obtained by calculating or simulating the parameters in the datasheet of the semiconductor power device. Then, according to a fixed period t p Obtain the current and case temperature of semiconductor power devices; If the current and shell temperature values ​​are within the range specified in the table, the time limit t is obtained by looking up the table. If the current and shell temperature values ​​are higher than the upper limit of the table, the time limit t is obtained by looking up the table according to the upper limit values ​​of the current and shell temperature. If the current and shell temperature values ​​are lower than the lower limit of the table, the time limit t is a negative constant. Finally, according to t... p The value is accumulated by / t. Once the accumulated value reaches or exceeds 1, junction temperature over-limit protection is activated, and the semiconductor power device is shut down. Follow these steps: Step 1: During a fixed interrupt period t p The three-phase current I of the motor was obtained by sampling. a I b I c And the case temperature T of semiconductor power devices c ; Step 2, if I a If I ≥ 0, then the current I in the upper tube of phase A is... au =I a Phase A lower tube current I ad =0; Otherwise, the current I in phase A will be... au =0, A-phase lower tube current I ad =I a Similarly, the current I of the upper tube in phase B can be obtained. bu Phase B lower tube current I bd C-phase upper tube current I cu C-phase lower tube current I cd ; Step 3: Execute the junction temperature over-limit protection algorithm for each switching transistor of the semiconductor power device in sequence; that is, execute the junction temperature over-limit protection algorithm for the upper transistor of phase A, the junction temperature over-limit protection algorithm for the lower transistor of phase A, the junction temperature over-limit protection algorithm for the upper transistor of phase B, the junction temperature over-limit protection algorithm for the lower transistor of phase B, the junction temperature over-limit protection algorithm for the upper transistor of phase C, and the junction temperature over-limit protection algorithm for the lower transistor of phase C in sequence. The junction temperature over-limit protection algorithm for the upper tube of phase A in step 3 is performed according to the following steps: a. If I au >I max Then let I au =I max If I au min Then let t au =-t0; if I min ≤I au ≤I max If so, proceed directly to the next step;​ Where I max I represents the upper limit of the current value in the table. min The lower limit of the current in the table, t au The current in the two-dimensional table for the stall time is I. au The shell temperature is T c The corresponding stall time limit under the given conditions, t0 is taken as 100ms; b. If T c >T max Then let T c =T max If T c <T min Then let t au =-t0; if T min ≤T c ≤T max If so, proceed directly to the next step; Where T max T represents the upper limit of the shell temperature in the table. min The lower limit of the shell temperature is shown in the table; c. According to I au T c Consult the two-dimensional table of stall time for power devices under different currents and case temperatures to obtain the corresponding stall time value t. au If I au T c If the value does not fall on a grid point in the table, the interpolation algorithm is applied to obtain the stall time limit t. au ; d. Calculate the accumulation factor t p / t au Divide the two and sum them to obtain the accumulated value σ. au If σ au If σ < 0, then let σ au If the result is 0, proceed to the next step; otherwise, proceed directly to the next step. e. If σ au If ≥1, an alarm will be triggered for the junction temperature of the power device exceeding the limit, and the equipment will stop operating; otherwise, σ will be saved. au Waiting for the next accumulation, the junction temperature over-limit protection algorithm for the upper tube of phase A has been executed.

2. The real-time online protection method for preventing junction temperature exceedance of semiconductor power devices according to claim 1, characterized in that, After the junction temperature over-limit protection algorithm for the A-phase upper tube, I in step a can be... au Replace with the A-phase lower tube current I ad Phase B upper tube current I bu Phase B lower tube current I bd C-phase upper tube current I cu Or the C-phase lower tube current I cd Then, follow step ae to execute the junction temperature over-limit protection algorithm for phase A lower tube, phase B upper tube, phase B lower tube, phase C upper tube, and phase C lower tube in sequence. The junction temperature over-limit protection algorithms for the A-phase lower transistor, B-phase upper transistor, B-phase lower transistor, C-phase upper transistor, and C-phase lower transistor will all be executed independently. As soon as any one of them detects that the junction temperature exceeds the limit, the semiconductor power device will be shut down and the equipment will stop operating.

3. A real-time online protection method for preventing junction temperature exceedance of semiconductor power devices according to claim 1 or 2, characterized in that, Step b also includes a method for protecting against overheating of the casing: if T c >T max This increments the case temperature over-limit protection counter by 1. When the counter reaches its upper limit, an over-limit case temperature protection alarm is triggered. If T... c ≤T max If the shell temperature is too high, the counter will be reset to zero.

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