CN115580126A - Thermal management method and device for power device in power converter - Google Patents
Thermal management method and device for power device in power converter Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
- H02M1/327—Means for protecting converters other than automatic disconnection against abnormal temperatures
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0003—Details of control, feedback or regulation circuits
- H02M1/0038—Circuits or arrangements for suppressing, e.g. by masking incorrect turn-on or turn-off signals, e.g. due to current spikes in current mode control
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/084—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters using a control circuit common to several phases of a multi-phase system
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
- H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
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Abstract
The embodiment of the invention relates to the technical field of power electronics and measurement thereof, in particular to a method and a device for heat management of a power device in a power converter, wherein the method comprises the following steps: acquiring a bus voltage stable value and each alternating current value of the power converter so as to obtain a working voltage value and a working current value of each power device, and acquiring a limiting value of the switching frequency of each power device according to the voltage value and the current value; calculating the real-time junction temperature of each power device according to the bus voltage stabilizing value and each alternating current value; calculating a bridge arm switching frequency value according to the junction temperature, and inputting the bridge arm switching frequency value into an amplitude limiter so as to carry out amplitude limiting according to the amplitude limiting value; and adjusting the switching frequency of the power device according to the switching frequency value output by the amplitude limiter. According to the technical scheme of the embodiment of the invention, the problems of high-frequency fluctuation inhibition of the device temperature in the converter and unbalanced temperature among devices are solved through heat management of the power devices in the power converter.
Description
Technical Field
The embodiment of the invention relates to the technical field of power electronics and measurement thereof, in particular to a method and a device for heat management of a power device in a power converter.
Background
Power converters are widely used in industry and in life. With the rapid development of power electronic technology, new energy systems with power electronic converters as the core are becoming new power for economic development and industrial revolution, and have attracted much attention. According to the reliability research report of the power electronic system, the failure rate of the power electronic converter is the highest in various application occasions such as wind power generation, photovoltaic power generation, hybrid electric vehicles, motor train unit traction converters and the like. The operational reliability of the power electronic power converter directly affects the safe and stable operation of the whole system. The power electronics are the core components of the power converter and are the most prone components of the converter to failure. Failure of the power electronics can directly lead to failure of the converter, and the reliability thereof directly affects the safe and stable operation of the converter.
Thermal stress is a major factor affecting the power electronics failure degradation and safe system operation. Among the various failure factors, about 55% of power electronic system failures are mainly induced by temperature factors, and thermal stress is the most prominent part of the stress borne by the power electronic devices. The on-state losses and switching losses that occur in practical operation of power electronics can subject the device to frequent thermal stresses.
Taking the IGBT device as an example, with the fluctuation of power and the change of external environment, the IGBT device is subjected to frequent thermal cycle impact and temperature fluctuation is an important cause of failure of the power device. The thermal stress experienced by the IGBT device mainly includes average junction temperature and junction temperature fluctuations. Research has shown that the lifetime of an IGBT device is more affected by junction temperature fluctuations. Due to the fact that the multilayer structure in the IGBT device module and the thermal expansion coefficients of different materials are not matched, alternating thermal stress can be generated, the IGBT module can be aged due to long-term stress, and the service life of the IGBT module is shortened. The larger the temperature fluctuation, the faster the device ages and there is some cumulative effect. On the other hand, a converter often contains multiple IGBT devices. For a three-phase converter, the load of each phase is relatively independent, which results in an inevitable three-phase load imbalance. In addition, the thermal resistance of the IGBT modules of the three-phase arms of the three-phase converter is difficult to be completely consistent. The difference of thermal stress of the three-phase IGBT half-bridge module is caused by unbalanced three-phase load and uneven thermal resistance, so that the thermal short plate effect of the system is caused.
Disclosure of Invention
Based on the foregoing situation in the prior art, an object of the embodiments of the present invention is to provide a method and an apparatus for thermal management of a power device in a power converter, where thermal stress of a system tends to be balanced by performing thermal management on a power electronic device, especially by suppressing junction temperature fluctuation and eliminating a thermal short plate effect in a converter system, so that a service life of the power electronic power device is prolonged, and reliability of the power converter is improved.
To achieve the above object, according to one aspect of the present invention, there is provided a method of thermal management of a power device in a power converter, the method comprising:
s102, collecting a bus voltage stable value and each alternating current value of the power converter so as to obtain a working voltage value and a working current value of each power device, and obtaining a limiting value of the switching frequency of each power device according to the voltage value and the current value;
s104, calculating the real-time junction temperature of each power device according to the bus voltage stable value and each alternating current value;
s106, judging whether the junction temperature fluctuation amplitude of each power device exceeds a first threshold value, and if so, calculating to obtain a first switching frequency value; meanwhile, judging whether the difference between the maximum junction temperature and the minimum junction temperature of the power devices of the bridge arms of each phase exceeds a second threshold value, and if so, calculating to obtain a second switching frequency value;
s108, obtaining a bridge arm switching frequency value according to the first switching frequency value and the second switching frequency value, and inputting the bridge arm switching frequency value into an amplitude limiter to limit the amplitude according to the amplitude limit value;
and S110, adjusting the switching frequency of the power device according to the switching frequency value output by the amplitude limiter.
Further, obtaining a clipping value of the switching frequency of the power device according to the voltage value and the current value includes:
and obtaining the amplitude limit value of the switching frequency of the power device through a table look-up according to the voltage value and the current value.
Further, the real-time junction temperature of each power device is calculated by the following steps:
determining junction temperature monitoring time according to the direction of each phase current and the initial state and the secondary state of the half bridge arm;
monitoring the voltage of the direct current bus at the junction temperature monitoring moment as the ringing peak voltage of the direct current bus corresponding to the power device;
and determining the junction temperature of the power device based on the ringing peak voltage of the direct current bus, the voltage stabilizing value of the direct current bus and the phase current.
Further, the junction temperature fluctuation amplitude of the power device is calculated by the following method:
obtaining the junction temperature fluctuation range of the power device by making a difference between the maximum junction temperature value and the minimum junction temperature value of the power device in a preset period; and the number of the first and second groups,
and comparing the difference between the maximum junction temperature and the minimum junction temperature of the power devices of the bridge arms of each phase by adopting hysteresis loops.
Further, the step S106 further includes:
if the junction temperature fluctuation range of each power device exceeds a first threshold value, calculating switching frequency values under different load currents by adopting a PID (proportion integration differentiation) method to serve as first switching frequency values;
and if the junction temperature fluctuation amplitude of each power device does not exceed the first threshold, returning to the step S104 to continue the calculation.
Further, the step S106 further includes:
if the difference between the maximum junction temperature and the minimum junction temperature of the power device of each phase of bridge arm exceeds a second threshold value, calculating the switching frequency value of each phase of bridge arm by adopting a PID (proportion integration differentiation) method to serve as a second switching frequency value;
and if the difference between the maximum junction temperature and the minimum junction temperature of the power devices of the bridge arms of each phase does not exceed the second threshold value, returning to the step S104 to continue calculating.
Further, the bridge arm switching frequency value is calculated according to the following formula
：
Wherein,
is a relative multiple of the first switching frequency value,
is a relative multiple of the value of the second switching frequency,
is the fundamental frequency.
Further, adjusting the switching frequency of the power device according to the switching frequency value output by the limiter, further includes:
when the junction temperature difference of the power devices exceeds a second threshold value, the switching frequency of the high-temperature power devices is reduced preferentially;
and when the switching frequency of the high-temperature power device is reduced so that the Total Harmonic Distortion (THD) of the output current is greater than a third threshold value, the switching frequency of the low-temperature power device is increased.
According to a second aspect of the present invention, there is provided an apparatus for thermal management of a power device in a power converter, comprising:
the voltage and current acquisition module is used for acquiring a bus voltage stable value and each alternating current value of the power converter so as to obtain a working voltage value and a working current value of each power device;
the amplitude limiting value calculation module is used for calculating the amplitude limiting value of the switching frequency of the power device according to the voltage value and the current value;
the real-time junction temperature calculation module is used for obtaining the real-time junction temperature of each power device according to the bus voltage stabilizing value and each alternating current value;
the switching frequency value calculation module is used for judging whether the junction temperature fluctuation amplitude of each power device exceeds a first threshold value or not, and if so, calculating to obtain a first switching frequency value; meanwhile, whether the difference between the maximum junction temperature and the minimum junction temperature of the power devices of the bridge arms of each phase exceeds a second threshold value or not is judged, and if the difference exceeds the second threshold value, a second switching frequency value is obtained through calculation;
the amplitude limiting module is used for obtaining a bridge arm switching frequency value according to the first switching frequency value and the second switching frequency value, and inputting the bridge arm switching frequency value into an amplitude limiter so as to carry out amplitude limiting according to the amplitude limiting value;
and the switching frequency adjusting module is used for adjusting the switching frequency of the power device according to the switching frequency value output by the amplitude limiter.
According to a third aspect of the present invention, there is provided an electronic apparatus comprising:
a processor; and
a memory having stored thereon executable code which, when executed by the processor, performs the method according to the first aspect of the invention.
In summary, embodiments of the present invention provide a method and an apparatus for thermal management of a power device in a power converter, where the method includes: acquiring a bus voltage stable value and each alternating current value of the power converter so as to obtain a working voltage value and a working current value of each power device, and acquiring a limiting value of the switching frequency of each power device according to the voltage value and the current value; calculating the real-time junction temperature of each power device according to the bus voltage stabilizing value and each alternating current value; judging whether the junction temperature fluctuation amplitude of each power device exceeds a first threshold value or not, and if so, obtaining a first switching frequency value through calculation; meanwhile, judging whether the difference between the maximum junction temperature and the minimum junction temperature of the power devices of the bridge arms of each phase exceeds a second threshold value, and if so, calculating to obtain a second switching frequency value; obtaining a bridge arm switching frequency value according to the first switching frequency value and the second switching frequency value, and inputting the bridge arm switching frequency value into an amplitude limiter to limit the amplitude according to the amplitude limit value; and adjusting the switching frequency of the power device according to the switching frequency value output by the amplitude limiter. According to the technical scheme of the embodiment of the invention, the problems of high-frequency fluctuation inhibition of the device temperature in the converter and unbalanced temperature among devices are solved through heat management of the power devices in the power converter. The temperature of each power device in the converter is comprehensively monitored, and then the thermal stress condition in the converter is evaluated based on the temperature information of all the power devices. The temperature of the power device is adjusted by adjusting the switching frequency of the power device, namely, an active heat management method, so that the high-frequency suppression of the temperature fluctuation of the power device is realized, the temperature of each power device is balanced, the thermal stress short plate effect is improved, and the reliability of a converter system is improved.
Drawings
FIG. 1 is a schematic of a topology of a three-phase half-bridge inverter;
FIG. 2 is an IGBT power loss schematic diagram of an IGBT module under different switching frequencies;
FIG. 3 is a flow chart of a method for thermal management of a power device in a power converter provided by an embodiment of the present invention;
FIG. 4 is the SPWM carrier waveform after being regulated to suppress junction temperature high frequency fluctuation;
FIG. 5 is the SPWM carrier waveform after adjustment for improving temperature uniformity of each phase bridge arm;
FIG. 6 is a block diagram of an apparatus for thermal management of a power device in a power converter according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of an electronic device according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the accompanying drawings in combination with the embodiments. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.
It is to be understood that unless otherwise defined, technical or scientific terms used in one or more embodiments of the present invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The use of "first," "second," and similar terms in one or more embodiments of the invention are not intended to indicate any order, quantity, or importance, but rather are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect.
The thermal management method is mainly divided into internal thermal management and external thermal management according to the control object. Taking an IGBT power device as an example, the main idea of internal thermal management is to actively change the loss of an IGBT module to adjust the junction temperature of the IGBT. Typical methods of thermal management are by changing the switching frequency, adjusting the IGBT dynamics, and changing the system modulation. The control method of adjusting the junction temperature by changing the switching frequency is usually used for suppressing the junction temperature fluctuation, but the second-level fluctuation is mainly considered, and the technical scheme for the temperature fluctuation with higher frequency is lacked. The dynamic process of adjusting the IGBT mainly refers to controlling the switching loss through the process of adjusting the switching, and further controlling the junction temperature of the device. However, this method requires a complicated gate driving circuit and has an influence on electromagnetic interference of the circuit. The thermal management method for changing the modulation scheme of the system mainly aims at the converter with a redundancy control strategy and is not suitable for all converters. The main idea of the external thermal management method is to control the junction temperature of the IGBT by adjusting the external heat dissipation conditions. The low-frequency junction temperature fluctuation caused by load fluctuation when the IGBT operates is smoothed by adjusting external heat dissipation conditions, and the result shows that when the load current fluctuates within the range of 60% -100% of the rated value, the service life of the IGBT can be prolonged by about 69 times by reducing the junction temperature fluctuation of about 60%. However, it is difficult to suppress high-frequency temperature fluctuations of the system by the method of achieving thermal management by controlling the heat dissipation conditions.
Existing thermal management methods still have some drawbacks. In the aspect of junction temperature fluctuation smoothing of the IGBT, most of current researches stay at a low-frequency fluctuation suppression level, and the researches on the suppression of high-frequency temperature fluctuation are insufficient. In a practical converter, the frequency of temperature fluctuations of the device module during operation is influenced by the load current. For example, when the load current with fluctuation of power frequency is processed, the junction temperature fluctuation frequency is consistent with the power frequency. The prior art does not restrain junction temperature fluctuation of power frequency (50 Hz). In addition, for practical transducers, it is difficult to ensure that the thermal stresses of the individual components are exactly the same. On the one hand, the processing power of each device is difficult to be completely the same in a full period, such as the operation condition under unbalanced load. On the other hand, the heat dissipation conditions of different devices of the same converter cannot be completely consistent, and particularly, the liquid cooling radiator has the defect of poor temperature equalization performance obviously. If the temperature difference between the IGBTs is large, the stress of the whole converter is unbalanced, the aging of parts of devices is accelerated, the overload capacity of the whole converter is reduced, the fault risk is increased, the reliability is reduced, and the like. However, currently, there are few thermal management studies on the thermal stress imbalance of each IGBT. The thermal management method provided by the embodiment of the invention solves the problems of high-frequency fluctuation inhibition of device temperature in the converter and unbalanced temperature among devices.
The technical solution of the present invention will be described in detail below with reference to the accompanying drawings. In the embodiment of the present invention, a three-phase half-bridge inverter including 6 IGBT devices is taken as an example for explanation, and a schematic topology structure diagram of the three-phase half-bridge inverter is shown in fig. 1. While this exemplary embodiment is merely illustrative or illustrative of the principles of the present invention, the present invention is also applicable to other forms of power converters and power devices including, but not limited to, single or three phase PWM rectifiers, single or three phase PWM inverters, half bridge topologies, full bridge topologies, triode power devices, MOSFET power devices, etc.
As shown in fig. 1, a three-phase half-bridge formed by 6 IGBTsAnd the inverter inputs direct current, adopts SPWM to control the driving signals of all IGBTs to generate three-phase alternating current and is connected with the load of the induction motor. For an IGBT device, its losses mainly include turn-on loss, turn-off loss, and on-state loss. When the power device is in an on state, the current of tens of amperes or even hundreds of amperes flows, and the on-state loss is extremely large. The voltage and current during switching are overlapped to represent that the voltage and current passes through the amplification region, certain switching loss can be formed, and the IGBT switching loss working in a hard switching mode is more prominent. Therefore, the higher the switching frequency is, the larger the corresponding IGBT switching loss is, which in turn leads to the larger total loss; the lower the switching frequency, the smaller the corresponding IGBT switching losses, which in turn leads to smaller total losses. Loss of power device
Can be expressed as:
wherein,
is the frequency of the switching of the switch,
is the loss of each turn-on process,
is the loss of each turn-off process.
Is the on-state power loss of the device. Wherein
Mainly affected by the load current.
Can be expressed as:
wherein
Indicating the start time of the turn-on process of the device,
representing the end time of the device turn-on process;
indicating the start time of the device turn-off process,
indicating the end time of the device turn-off process.
For a three-phase converter, the switching frequency is adjusted. Frequency scanning simulation is carried out through thermal simulation software, and the bus voltage is set to be 400V under the set working condition, and the effective value of the line current is set to be 100A. The resulting IGBT power losses for the IGBT module at different switching frequencies are shown in fig. 2. As can be seen from fig. 2, the turn-on loss, the turn-off loss and the switching frequency of the IGBT have a linear relationship, and the on-state loss is not affected by the switching frequency. Therefore, the switching loss power of the device can be changed by changing the switching frequency of the device, and the linear control of the power loss of the device is further realized. The linear relationship of the power loss and the switching frequency enables the thermal management method based on the switching frequency regulation to have stronger robustness.
Based on the above analysis, the present invention provides a method for thermal management of an inverter based on switching frequency regulation, and fig. 3 is a flowchart of a method 100 for thermal management of a power device in a power inverter according to an embodiment of the present invention, as shown in fig. 3, the method includes the following steps:
s102, collecting a bus voltage stable value and each phase alternating current value of the power converter so as to obtain a working voltage value and a working current value of each power device, and calculating a limiting value of the switching frequency of each power device according to the voltage value and the current value. Firstly, the voltage value and the current value of the power converter and the power device thereof are monitored. Since the adjustment of the switching frequency of the bridge arm affects Total Harmonic Distortion (THD) output by the converter, and the degree of the effect is closely related to the voltage and current of the converter, after the voltage and current values of the power converter and its power devices are obtained, the amplitude limit value of the switching frequency is obtained first, and the result can be reserved for subsequent switching frequency adjustment. The computational expression for the clipping values can be expressed as:
wherein,
represents the allowed maximum value of the switching frequency,
representing the allowed minimum value of the switching frequency. The allowed minimum value of the switching frequency depends on the cut-off frequency setting of the filter and the output performance of the system (spectrum of the output signal); the allowable maximum value of the switching frequency depends on the IGBT device performance, stray parameters of the circuit, and the like. Because the working voltage and working current of the power device can affect the loss of the device, on the premise of ensuring that the device works in a safe working area, the working voltage and working current of the general power device are larger, and the allowable maximum working voltage and working current are largerThe smaller the upper clipping value (e.g., inversely proportional to the product of the operating voltage and current), the specific clipping value may be obtained by a table lookup.
And S104, calculating the real-time junction temperature of each power device according to the bus voltage stable value and each alternating current value. The following steps may be used for the calculation:
determining junction temperature monitoring time according to the direction of each phase current and the initial state and the secondary state of the half bridge arm;
monitoring the voltage of the direct current bus at the junction temperature monitoring moment to be used as the ringing peak voltage of the direct current bus corresponding to the power device;
and determining the junction temperature of the power device based on the ringing peak voltage of the direct current bus, the voltage stabilizing value of the direct current bus and the phase current.
The specific calculation method of the real-time junction temperature in this step has been published in the previous chinese patent of the applicant (CN 202110373619.7), with the publication number of CN113098314B, and the repeated description thereof will be omitted here.
S106, judging whether the junction temperature fluctuation amplitude of each power device exceeds a first threshold value, and if so, calculating to obtain a first switching frequency value; and simultaneously judging whether the difference between the maximum junction temperature and the minimum junction temperature of the power devices of the bridge arms of each phase exceeds a second threshold value or not, and if so, calculating to obtain a second switching frequency value. If the junction temperature fluctuation range of each power device exceeds a first threshold value, calculating switching frequency values under different load currents by adopting a PID (proportion integration differentiation) method to serve as first switching frequency values; and if the junction temperature fluctuation amplitude of each power device does not exceed the first threshold, returning to the step S104 to continue the calculation. If the difference between the maximum junction temperature and the minimum junction temperature of the power device of each phase of the bridge arm exceeds a second threshold value, calculating the switching frequency value of each phase of the bridge arm by adopting a PID method to serve as a second switching frequency value; and if the difference between the maximum junction temperature and the minimum junction temperature of the power devices of the bridge arms of each phase does not exceed the second threshold value, returning to the step S104 to continue calculating.
After the junction temperature of each device in the power converter is obtained, two thermal stresses are calculated, wherein one thermal stress is the temperature fluctuation range of a single IGBT; the other is the difference between the maximum junction temperature and the minimum junction temperature in the temperature of each phase bridge arm device. By introducing hysteresis loop for comparison, the temperature fluctuation amplitude of a single IGBT can be calculated by adopting the following method: the junction temperature fluctuation range of the power device is obtained by making a difference between the maximum junction temperature value and the minimum junction temperature value of the power device in a preset period, and the preset period can be set according to actual requirements. And comparing the difference between the maximum junction temperature and the minimum junction temperature of the power devices of the bridge arms of each phase by using hysteresis loops. The problem of frequent switching of the switching frequency can be reduced by introducing hysteresis comparison, and the stability of the system is improved.
On one hand, if the temperature fluctuation amplitude of the single IGBT does not exceed a preset first threshold value, the junction temperature monitoring is continued; when the temperature fluctuation amplitude of the single IGBT exceeds a preset first threshold value, calculating the switching frequency values (in relative multiple) under different load currents through a PID algorithm
Indicative), a switching frequency adjustment corresponding to the load current fluctuation is achieved. The regulation principle is that the larger the load current is, the lower the switching frequency is; the smaller the load current is, the higher the switching frequency is, thereby achieving suppression of junction temperature fluctuation. The switching frequency is adjusted by adjusting the SPWM triangular carrier frequency, and the SPWM carrier waveform after adjustment is shown in fig. 4, where in fig. 4, the sinusoidal curve represents a modulated wave having a frequency identical to the output fundamental wave frequency, and the triangular curve represents a carrier having a frequency identical to the switching frequency. On the other hand, the maximum and minimum junction temperatures of the IGBTs are compared, hysteresis loops are introduced for comparison, and if the difference between the maximum junction temperature and the minimum junction temperature of each phase of bridge arm power device does not exceed a preset second threshold, junction temperature monitoring is continued; if the difference between the maximum junction temperature and the minimum junction temperature of each phase bridge arm power device exceeds a preset second threshold value, calculating the switching frequency value of each phase bridge arm through a PID algorithm (by relative multiple)
Indicative), temperature uniformity improvement based on switching frequency adjustment is achieved. Wherein the first threshold value and the second threshold value can be determined by the switching frequency of the switching frequency,for example, it may be set to 5% of the maximum difference in system temperature. For example, the temperature of the IGBT of phase B is lower than that of the IGBT of phase A and phase C, and the switching frequency of the phase B is adjusted to improve the temperature consistency of bridge arms of each phase
The adjusted SPWM carrier waveform is shown in fig. 5.
And S108, obtaining a bridge arm switching frequency value according to the first switching frequency value and the second switching frequency value, inputting the bridge arm switching frequency value into an amplitude limiter to carry out amplitude limiting according to the amplitude limiting value, wherein the amplitude limiting value of the amplitude limiter is obtained by calculation in the step S102. The switching frequency of each bridge arm is a relative multiple regulated by suppressing junction temperature fluctuation
And improving relative multiple of bridge arm temperature consistency
Co-determined, relative multiple
May be obtained by dividing the first switching frequency value by the fundamental frequency; relative multiple of
May be obtained by dividing the second switching frequency value by the fundamental frequency; where the base frequency is the carrier frequency without thermal management and switching frequency adjustment, such as typically 10kHz. The bridge arm switching frequency value can therefore be calculated according to the following formula:
wherein,
is a relative multiple of the first switching frequency value,
is a relative multiple of the second switching frequency value,
is the fundamental frequency.
And S110, adjusting the switching frequency of the power device according to the switching frequency value output by the amplitude limiter. The actual switching frequency of the power device is adjusted to the switching frequency value after amplitude limiting, so that junction temperature fluctuation suppression of a single power device and improvement of temperature consistency of power devices of different phases are realized. In the adjusting process, when the IGBT has temperature difference, the switching frequency of the high-temperature IGBT is reduced preferentially, so that the power loss of the whole converter can be reduced; when lowering the switching frequency of the high-temperature IGBT deteriorates the system output performance, it is considered to raise the switching frequency of the low-temperature IGBT. "deterioration of output performance" means that the total harmonic distortion THD of the output current becomes large, and for example, when the total harmonic distortion THD of the output current is larger than a third threshold, it is considered that the output performance is deteriorated. Generally, the total harmonic distortion THD is required to be no more than 10%.
And then, returning to the step S102 to continue monitoring data such as the voltage value and the current value of the power converter, and performing the next round of thermal management.
An embodiment of the present invention further provides a thermal management apparatus for a power device in a power converter, and a block diagram of the thermal management apparatus is shown in fig. 6, where the apparatus includes:
the voltage and current acquisition module 601 is used for acquiring a bus voltage stable value and each phase of alternating current values of the power converter so as to obtain a working voltage value and a working current value of each power device;
a clipping value calculating module 602, configured to obtain a clipping value of the switching frequency of the power device according to the voltage value and the current value;
a real-time junction temperature calculation module 603, which calculates the real-time junction temperature of each power device according to the bus voltage stabilizing value and each ac current value;
a switching frequency value calculation module 604, configured to determine whether the junction temperature fluctuation range of each power device exceeds a first threshold, and if so, obtain a first switching frequency value through calculation; meanwhile, whether the difference between the maximum junction temperature and the minimum junction temperature of the power devices of the bridge arms of each phase exceeds a second threshold value or not is judged, and if the difference exceeds the second threshold value, a second switching frequency value is obtained through calculation;
the amplitude limiting module 605 is configured to obtain a bridge arm switching frequency value according to the first switching frequency value and the second switching frequency value, and input the bridge arm switching frequency value into an amplitude limiter to limit amplitude according to the amplitude limiting value;
and a switching frequency adjusting module 606, configured to adjust the switching frequency of the power device according to the switching frequency value output by the limiter.
The specific process of each module in the thermal management device provided by this embodiment of the present invention to implement its function is the same as each step of the thermal management method provided by the above-mentioned embodiment of the present invention, and therefore, repeated descriptions thereof will be omitted here.
Fig. 7 is a schematic structural diagram of an electronic device according to an embodiment of the present invention. As shown in fig. 7, the electronic device 700 includes: one or more processors 701 and memory 702; and computer program instructions stored in the memory 702 which, when executed by the processor 701, cause the processor 701 to perform a thermal management method as in any of the embodiments described above. The processor 701 may be a Central Processing Unit (CPU) or other form of processing unit having data processing capabilities and/or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.
Memory 702 may include one or more computer program products that may include various forms of computer-readable storage media, such as volatile memory and/or non-volatile memory. Volatile memory can include, for example, random Access Memory (RAM), cache memory (or the like). The non-volatile memory may include, for example, read Only Memory (ROM), a hard disk, flash memory, and the like. One or more computer program instructions may be stored on a computer-readable storage medium and executed by processor 701 to implement the steps of the thermal management methods of the various embodiments of the present invention described above and/or other desired functions.
In some embodiments, the electronic device 700 may further include: an input device 703 and an output device 704, which are interconnected by a bus system and/or other form of connection mechanism (not shown in fig. 7). For example, when the electronic device is a stand-alone device, the input means 703 may be a communication network connector for receiving the acquired input signal from an external removable device. The input device 703 may also include, for example, a keyboard, a mouse, a microphone, and the like. The output device 704 may output various information to the outside, and may include, for example, a display, speakers, a printer, and a communication network and its connected remote output devices.
In addition to the above-described methods and apparatus, embodiments of the invention may also be a computer program product comprising computer program instructions which, when executed by a processor, cause the processor to perform the steps of the thermal management method of any of the above-described embodiments.
The computer program product may include program code for carrying out operations for embodiments of the present invention in any combination of one or more programming languages, including an object oriented programming language such as Java, C + + or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computing device, partly on the user's device, as a stand-alone software package, partly on the user's computing device and partly on a remote computing device, or entirely on the remote computing device or server.
Furthermore, embodiments of the invention may also be a computer readable storage medium having stored thereon computer program instructions which, when executed by a processor, cause the processor to perform the steps in the thermal management methods of the various embodiments of the invention.
The computer-readable storage medium may take any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may include, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or a combination of any of the foregoing. More specific examples (a non-exhaustive list) of the readable storage medium include: an electrical connection having one or more wires, a portable disk, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.
It should be understood that the Processor in the embodiments of the present invention may be a Central Processing Unit (CPU), and the Processor may also be other general purpose processors, digital Signal Processors (DSPs), application Specific Integrated Circuits (ASICs), field Programmable Gate Arrays (FPGAs) or other Programmable logic devices, discrete Gate or transistor logic devices, discrete hardware components, and the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
In summary, the embodiments of the present invention relate to a method and an apparatus for thermal management of a power device in a power converter, where the method includes: acquiring a bus voltage stable value and each alternating current value of the power converter so as to obtain a working voltage value and a working current value of each power device, and acquiring a limiting value of the switching frequency of each power device according to the voltage value and the current value; calculating the real-time junction temperature of each power device according to the bus voltage stable value and each alternating current value; judging whether the junction temperature fluctuation amplitude of each power device exceeds a first threshold value or not, and if so, calculating to obtain a first switching frequency value; meanwhile, whether the difference between the maximum junction temperature and the minimum junction temperature of the power devices of the bridge arms of each phase exceeds a second threshold value or not is judged, and if the difference exceeds the second threshold value, a second switching frequency value is obtained through calculation; obtaining a bridge arm switching frequency value according to the first switching frequency value and the second switching frequency value, and inputting the bridge arm switching frequency value into an amplitude limiter to limit the amplitude according to the amplitude limit value; and adjusting the switching frequency of the power device according to the switching frequency value output by the amplitude limiter. The technical scheme of the embodiment of the invention solves the problem of junction temperature high-frequency fluctuation of devices in the power converter, in particular to junction temperature fluctuation of power frequency 50 Hz; in addition, the problem of unbalanced thermal stress of the power device of the whole power converter is solved, the fault risk of the converter is reduced, the service lives of the converter and the device are verified, and the reliability of the converter is enhanced. According to the technical scheme of the embodiment of the invention, when the switching frequency is switched, the influence on the performance of the output current of the system is very small, and the output current has no ringing or obvious transition process at the switching frequency switching moment, so that the system is very smooth and natural. The adoption of asynchronous switching frequency has little influence on the steady-state output THD of the system.
It should be understood that the discussion of any embodiment above is merely exemplary, and is not intended to intimate that the scope of the disclosure, including the claims, is limited to those examples; features from the above embodiments or from different embodiments may also be combined within the inventive idea, steps may be implemented in any order, and there are many other variations of different aspects of one or more embodiments of the invention as described above, which are not provided in detail for the sake of brevity. The foregoing detailed description of the invention is merely exemplary in nature and is not intended to limit the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.
Claims (10)
1. A method of thermal management of a power device in a power converter, the method comprising:
s102, collecting a bus voltage stabilizing value and each phase alternating current value of the power converter to obtain a working voltage value and a working current value of each power device, and obtaining a limiting value of the switching frequency of each power device according to the voltage value and the current value;
s104, calculating the real-time junction temperature of each power device according to the bus voltage stable value and each alternating current value;
s106, judging whether the junction temperature fluctuation amplitude of each power device exceeds a first threshold value, and if so, obtaining a first switching frequency value through calculation; meanwhile, whether the difference between the maximum junction temperature and the minimum junction temperature of the power devices of the bridge arms of each phase exceeds a second threshold value or not is judged, and if the difference exceeds the second threshold value, a second switching frequency value is obtained through calculation;
s108, obtaining a bridge arm switching frequency value according to the first switching frequency value and the second switching frequency value, and inputting the bridge arm switching frequency value into an amplitude limiter to limit amplitude according to the amplitude limiting value;
and S110, adjusting the switching frequency of the power device according to the switching frequency value output by the amplitude limiter.
2. The method of claim 1, wherein obtaining the clipping value of the switching frequency of the power device according to the voltage value and the current value comprises:
and obtaining the amplitude limit value of the switching frequency of the power device by looking up a table according to the voltage value and the current value.
3. The method of claim 1, wherein the real-time junction temperature of each power device is calculated by:
determining junction temperature monitoring time according to the direction of each phase current and the initial state and the secondary state of the half bridge arm;
monitoring the voltage of the direct current bus at the junction temperature monitoring moment to be used as the ringing peak voltage of the direct current bus corresponding to the power device;
and determining the junction temperature of the power device based on the ringing peak voltage of the direct current bus, the voltage stabilizing value of the direct current bus and the phase current.
4. A method according to claim 2 or 3, wherein the amplitude of the junction temperature fluctuation of the power device is calculated by:
obtaining the junction temperature fluctuation range of the power device by making a difference between the maximum junction temperature value and the minimum junction temperature value of the power device in a preset period; and the number of the first and second groups,
and comparing the difference between the maximum junction temperature and the minimum junction temperature of the power devices of the bridge arms of each phase by using hysteresis loops.
5. The method according to claim 4, wherein the step S106 further comprises:
if the junction temperature fluctuation range of each power device exceeds a first threshold value, calculating switching frequency values under different load currents by adopting a PID (proportion integration differentiation) method to serve as first switching frequency values;
and if the junction temperature fluctuation amplitude of each power device does not exceed the first threshold, returning to the step S104 to continue the calculation.
6. The method according to claim 5, wherein the step S106 further comprises:
if the difference between the maximum junction temperature and the minimum junction temperature of the power device of each phase of the bridge arm exceeds a second threshold value, calculating the switching frequency value of each phase of the bridge arm by adopting a PID method to serve as a second switching frequency value;
and if the difference between the maximum junction temperature and the minimum junction temperature of the power device of each phase bridge arm does not exceed the second threshold value, returning to the step S104 to continue calculating.
7. The method of claim 6, wherein the bridge arm switching frequency value is calculated according to the following formula
：
Wherein,
at a first switching frequencyThe relative multiple of the value of the one or more,
is a relative multiple of the second switching frequency value,
is the fundamental frequency.
8. The method of claim 7, wherein adjusting the switching frequency of the power device according to the switching frequency value output by the limiter, further comprises:
when the junction temperature difference of the power devices exceeds a second threshold value, the switching frequency of the high-temperature power devices is reduced preferentially;
and when the switching frequency of the high-temperature power device is reduced so that the Total Harmonic Distortion (THD) of the output current is greater than a third threshold value, the switching frequency of the low-temperature power device is increased.
9. An apparatus for thermal management of a power device in a power converter, comprising:
the voltage and current acquisition module is used for acquiring a bus voltage stable value and each alternating current value of the power converter so as to obtain a working voltage value and a working current value of each power device;
the amplitude limiting value calculation module is used for calculating the amplitude limiting value of the switching frequency of the power device according to the voltage value and the current value;
the real-time junction temperature calculation module is used for obtaining the real-time junction temperature of each power device according to the bus voltage stabilizing value and each alternating current value;
the switching frequency value calculation module is used for judging whether the junction temperature fluctuation amplitude of each power device exceeds a first threshold value or not, and if so, calculating to obtain a first switching frequency value; meanwhile, whether the difference between the maximum junction temperature and the minimum junction temperature of the power devices of the bridge arms of each phase exceeds a second threshold value or not is judged, and if the difference exceeds the second threshold value, a second switching frequency value is obtained through calculation;
the amplitude limiting module is used for obtaining a bridge arm switching frequency value according to the first switching frequency value and the second switching frequency value, and inputting the bridge arm switching frequency value into an amplitude limiter so as to carry out amplitude limiting according to the amplitude limiting value;
and the switching frequency adjusting module is used for adjusting the switching frequency of the power device according to the switching frequency value output by the amplitude limiter.
10. An electronic device, comprising:
a processor; and
memory having stored thereon executable code which, when executed by a processor, performs the method of any one of claims 1-8.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117134588A (en) * | 2023-10-27 | 2023-11-28 | 国网浙江省电力有限公司杭州供电公司 | Switching frequency control method and device and electronic equipment |
| CN117155135A (en) * | 2023-10-27 | 2023-12-01 | 国网湖北省电力有限公司经济技术研究院 | Junction temperature control method, device and equipment for isolated DC/DC converter |
| CN117559787A (en) * | 2024-01-10 | 2024-02-13 | 致瞻科技(上海)有限公司 | Active control method and system for junction temperature of power device under locked-rotor working condition |
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2022
- 2022-10-31 CN CN202211343062.3A patent/CN115580126A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117134588A (en) * | 2023-10-27 | 2023-11-28 | 国网浙江省电力有限公司杭州供电公司 | Switching frequency control method and device and electronic equipment |
| CN117155135A (en) * | 2023-10-27 | 2023-12-01 | 国网湖北省电力有限公司经济技术研究院 | Junction temperature control method, device and equipment for isolated DC/DC converter |
| CN117155135B (en) * | 2023-10-27 | 2024-01-30 | 国网湖北省电力有限公司经济技术研究院 | Junction temperature control method, device and equipment for isolated DC/DC converter |
| CN117134588B (en) * | 2023-10-27 | 2024-02-06 | 国网浙江省电力有限公司杭州供电公司 | Switching frequency control method and device and electronic equipment |
| CN117559787A (en) * | 2024-01-10 | 2024-02-13 | 致瞻科技(上海)有限公司 | Active control method and system for junction temperature of power device under locked-rotor working condition |
| CN117559787B (en) * | 2024-01-10 | 2024-03-22 | 致瞻科技(上海)有限公司 | Active control method and system for junction temperature of power device under locked-rotor working condition |
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