A method and device for controlling a carrier variable of a converter

Abstract

The present invention provides a method and device for controlling a converter with variable carrier, which determine the maximum temperature rise of a device module that can be turned off under multiple carrier frequencies and different output currents; determine the design temperature rise of the device module that can be turned off under different output currents; determine the converter carrier frequency under the current heat sink temperature and the current output current based on the maximum temperature rise and the design temperature rise, and control the converter by variable carrier, taking into account the influence of the heat sink temperature of the device that can be turned off, and can avoid the phenomena of bonding wire desoldering and solder layer fatigue cracking in the device module that can be turned off as much as possible, reduce harmonic pollution when the converter is lightly loaded, and reduce the loss when the converter is heavily loaded; achieve approximately constant junction temperature of the device module that can be turned off under different output capacities, greatly reduce the number of power cycles and temperature cycles of the device module that can be turned off, and significantly extend the service life of the device module that can be turned off.

Description

Technical Field

[0001] The present invention relates to the technical field of converters, and in particular to a converter variable carrier control method and device. Background Art

[0002] A converter is a device that converts AC to DC and is composed of a single or multiple converter bridges. Converters can be divided into two categories: rectifiers and inverters. Rectifiers convert AC to DC, while inverters convert DC to AC.

[0003] In the power system, a large number of converters based on turn-off device modules are used to realize flexible direct current transmission, dynamic reactive power compensation, power system flow control, harmonic control, three-phase unbalance compensation, power routing and other functions. Due to the unstable working state of the converter based on the turn-off device module, it is sometimes lightly loaded, that is, the output capacity is small, and sometimes heavily loaded, that is, the output capacity of the converter is large, which increases the number of power cycles of the converter and the junction temperature of the turn-off device module often fluctuates greatly. The existing technology generally uses a constant carrier to control the converter. During the control process, due to the repeated impact of temperature gradient and thermal stress, the turn-off device module will have phenomena such as bond wire desoldering and solder layer fatigue cracking. The more power cycles, the shorter the life of the turn-off device module. When the converter is lightly loaded, the converter output harmonic characteristics are poor, the harmonic pollution is serious, and the loss is high when the converter is heavily loaded. Summary of the invention

[0004] In order to overcome the serious and high-loss shortcomings of the above-mentioned prior art, the present invention provides a converter variable carrier control method, comprising:

[0005] Determine the maximum temperature rise of the turnable device module under multiple carrier frequencies and different output currents based on the converter topology and the turnable device module parameters in the converter;

[0006] Determine the design temperature rise of the turn-off device module under different output currents based on the turn-off device module parameters and the current heat sink temperature;

[0007] The inverter carrier frequency at the current heat sink temperature and the current output current is determined based on the maximum temperature rise and the design temperature rise.

[0008] The method of determining the maximum temperature rise of the turnable device module under different carrier frequencies and different output currents based on the converter topology and the turnable device module parameters in the converter includes:

[0009] Calculate the total loss of the turn-off device and the total loss of the diode based on the converter topology and the module parameters of the turn-off device in the converter;

[0010] Calculate the total thermal resistance of the turn-off device junction to the heat sink and the total thermal resistance of the diode device junction to the heat sink based on the turn-off device module parameters;

[0011] The maximum temperature rise of the turn-off device module under multiple carrier frequencies and different output currents is determined based on the total loss of the turn-off device, the total loss of the diode, the total thermal resistance of the turn-off device to the heat sink, and the total thermal resistance of the diode device to the heat sink.

[0012] The method of determining the design temperature rise of the turnable device module under different output currents based on the turnable device module parameters and the current heat sink temperature includes:

[0013] Determining the maximum operating junction temperature of the turn-off device module based on the maximum allowable junction temperature in the turn-off device module parameters;

[0014] The substrate temperature of the shut-down device module is collected by a temperature probe and used as the heat sink temperature of the shut-down device module;

[0015] The difference between the highest operating junction temperature and the heat sink temperature of the turn-off device module is used as the design temperature rise of the turn-off device module under different output currents.

[0016] The method of determining the converter carrier frequency at the current heat sink temperature and the current output current based on the maximum temperature rise and the design temperature rise includes:

[0017] Obtaining the temperature rise of the turn-off device module at different carrier frequencies and the same output current from the maximum temperature rise;

[0018] Selecting the temperature rise closest to the design temperature rise from the obtained temperature rises;

[0019] The carrier frequency corresponding to the selected temperature rise is used as the converter carrier frequency at the current heat sink temperature and the current output current.

[0020] The method of calculating the total loss of the turnable device and the total loss of the diode based on the converter topology and the turnable device module parameters in the converter includes:

[0021] Divide the output current of the converter into multiple current segments at equal intervals, and obtain the current at the midpoint of each current segment;

[0022] Different carrier frequencies of the converter are set, and the current and carrier frequency at the midpoint of each current segment are input into the simulation model of the converter for calculation, so as to obtain the conduction loss and switching loss of the turnable device and the conduction loss and turn-off loss of the diode device;

[0023] The sum of the conduction loss and the switching loss of the turnable device is taken as the total loss of the turnable device, and the sum of the conduction loss and the turn-off loss of the diode device is taken as the total loss of the diode;

[0024] The simulation model is determined based on the converter topology and switchable device module parameters.

[0025] The method of calculating the total thermal resistance of the turnable device junction to the heat sink and the total thermal resistance of the diode device junction to the heat sink based on the turnable device module parameters includes:

[0026] Obtain the turn-off device junction-to-case thermal resistance and the case-to-heat sink thermal resistance from the turn-off device module parameters, and use the sum of the turn-off device junction-to-case thermal resistance and the case-to-heat sink thermal resistance as the turn-off device junction-to-heat sink total thermal resistance;

[0027] The device module parameters can be turned off to obtain the diode junction-to-case thermal resistance and the case-to-heat sink thermal resistance, and the sum of the diode junction-to-case thermal resistance and the case-to-heat sink thermal resistance is used as the total diode device junction-to-heat sink thermal resistance.

[0028] The method of determining the maximum temperature rise of the turnable device module under different carrier frequencies and different output currents based on the total loss of the turnable device, the total loss of the diode, the total thermal resistance of the turnable device to the heat sink, and the total thermal resistance of the diode device to the heat sink comprises:

[0029] The product of the total loss of the turn-off device and the total thermal resistance of the turn-off device to the heat sink is taken as the temperature rise of the turn-off device;

[0030] The product of the total loss of the diode and the total thermal resistance of the diode device junction to the heat sink is taken as the temperature rise of the diode;

[0031] The maximum value of the temperature rise of the turn-off device and the temperature rise of the diode is selected as the maximum temperature rise of the turn-off device module under different carrier frequencies and different output currents.

[0032] The current segments are [I min ,I min +(I max -I min ) / N]、[I min +(I max -I min ) / N,I min +2(I max -I min ) / N], ..., [I max -(I max -I min ) / N,I max ], where I min is the lower limit of the converter output current, I max is the upper limit of the converter output current, and N is the number of current segments.

[0033] The carrier frequency of the converter is set to f0, 2f0, 3f0...kf0, where f0 is the power frequency, kf0 is the maximum switching frequency of the switchable device module, and k is a natural number.

[0034] In another aspect, the present invention provides a converter variable carrier control device, comprising:

[0035] A first determination module is used to determine the maximum temperature rise of the turnable device module under multiple carrier frequencies and different output currents based on the converter topology and the turnable device module parameters in the converter;

[0036] A second determination module is used to determine the design temperature rise of the turnable device module under different output currents based on the turnable device module parameters and the current heat sink temperature;

[0037] The third determination module is used to determine the converter carrier frequency under the current heat sink temperature and the current output current based on the maximum temperature rise and the design temperature rise.

[0038] The first determining module is specifically used for:

[0039] Calculate the total loss of the turn-off device and the total loss of the diode based on the converter topology and the module parameters of the turn-off device in the converter;

[0040] Calculate the total thermal resistance of the turn-off device junction to the heat sink and the total thermal resistance of the diode device junction to the heat sink based on the turn-off device module parameters;

[0041] The maximum temperature rise of the turn-off device module under multiple carrier frequencies and different output currents is determined based on the total loss of the turn-off device, the total loss of the diode, the total thermal resistance of the turn-off device to the heat sink, and the total thermal resistance of the diode device to the heat sink.

[0042] The second determining module is specifically used for:

[0043] Determining the maximum operating junction temperature of the turn-off device module based on the maximum allowable junction temperature in the turn-off device module parameters;

[0044] The substrate temperature of the shut-down device module is collected by a temperature probe and used as the heat sink temperature of the shut-down device module;

[0045] The difference between the highest operating junction temperature and the heat sink temperature of the turn-off device module is used as the design temperature rise of the turn-off device module under different output currents.

[0046] The third determination module is specifically used for:

[0047] Obtaining the temperature rise of the turn-off device module at different carrier frequencies and the same output current from the maximum temperature rise;

[0048] Selecting the temperature rise closest to the design temperature rise from the obtained temperature rises;

[0049] The carrier frequency corresponding to the selected temperature rise is used as the converter carrier frequency at the current heat sink temperature and the current output current.

[0050] The technical solution provided by the present invention has the following beneficial effects:

[0051] In the inverter variable carrier control method provided by the present invention, multiple carrier frequencies and the maximum temperature rise of the turnable device module under different output currents are determined based on the inverter topology structure and the turnable device module parameters in the inverter; the design temperature rise of the turnable device module under different output currents is determined based on the turnable device module parameters and the current heat sink temperature; the converter carrier frequency under the current heat sink temperature and the current output current is determined based on the maximum temperature rise and the design temperature rise, and the converter is controlled by the variable carrier, thereby reducing the harmonic pollution of the converter when the converter is lightly loaded and reducing the loss of the converter when the converter is heavily loaded;

[0052] The present invention takes into account the influence of the temperature of the heat sink of the turnable device, and can avoid the phenomenon of bonding wire desoldering and solder layer fatigue cracking in the turnable device module as much as possible;

[0053] The present invention dynamically changes the carrier frequency of the converter, realizes that the junction temperature of the turn-off device module is approximately constant under different output capacities, greatly reduces the number of power cycles and temperature cycles of the turn-off device module, and significantly prolongs the service life of the turn-off device module;

[0054] The technical solution provided by the present invention dynamically adjusts the carrier frequency, so that the carrier frequency is greatly increased when the converter is lightly loaded, the output harmonic characteristics of the converter are improved, and the carrier frequency is reduced when the converter is heavily loaded, thereby reducing the loss of the converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 is a flow chart of a method for controlling a carrier frequency conversion of a converter according to an embodiment of the present invention;

[0056] Figure 2 It is a structural diagram of a converter variable carrier control device in an embodiment of the present invention. DETAILED DESCRIPTION

[0057] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0058] Example 1

[0059] Embodiment 1 of the present invention provides a method for controlling a variable carrier of a converter, and the specific flow chart is as follows: Figure 1 As shown, the specific process is as follows:

[0060] S101: determining a maximum temperature rise of a turnable device module at multiple carrier frequencies and different output currents based on a converter topology and parameters of a turnable device module in the converter;

[0061] S102: Determine the design temperature rise of the turnable device module under different output currents based on the turnable device module parameters and the current heat sink temperature;

[0062] S103: Determine the converter carrier frequency at the current heat sink temperature and the current output current based on the maximum temperature rise and the design temperature rise.

[0063] In S101, based on the converter topology and the parameters of the switchable device modules in the converter, the maximum temperature rise of the switchable device modules under multiple carrier frequencies and different output currents is determined, including:

[0064] Calculate the total loss of the turn-off device and the total loss of the diode based on the converter topology and the module parameters of the turn-off device in the converter;

[0065] Calculate the total thermal resistance of the turn-off device junction to the heat sink and the total thermal resistance of the diode device junction to the heat sink based on the turn-off device module parameters;

[0066] The maximum temperature rise of the turn-off device module under multiple carrier frequencies and different output currents is determined based on the total loss of the turn-off device, the total loss of the diode, the total thermal resistance of the turn-off device to the heat sink, and the total thermal resistance of the diode device to the heat sink.

[0067] The above-mentioned calculation of the total loss of the turn-off device and the total loss of the diode based on the converter topology and the turn-off device module parameters in the converter includes:

[0068] The output current of the converter is divided into multiple current segments at equal intervals, and the current at the midpoint of each current segment is obtained; the current segments are [I min ,I min +(I max -I min ) / N]、[I min +(I max -I min ) / N,I min +2(I max -I min ) / N], ..., [I max -(I max -I min ) / N,I max ], I min is the lower limit of the converter output current, I max is the upper limit of the converter output current, N is the number of current segments, the more current segments there are, the finer the control; the current at the midpoint of each current segment is Imin +(I max -I min ) / 2N、I min +3(I max -I min ) / 2N, ..., I max -(I max -I min ) / 2N;

[0069] Set different carrier frequencies of the converter (i.e. set f s , f s f0, 2f0, 3f0...kf0, f0 is the power frequency, kf0 is the maximum switching frequency of the switchable device module, and k is a natural number), and the current at the midpoint of each current segment and the carrier frequency are input into the simulation model of the converter for calculation, and the conduction loss and switching loss of the switchable device and the conduction loss and turn-off loss of the diode device are obtained; among which, the conduction loss of the switchable device is expressed by P cond,TOD (i) indicates that the switching loss of the turn-off device is P SW,TOD (i,f s ) represents the conduction loss of the diode device, and P cond,Diode (i) indicates that the turn-off loss of the diode device is represented by P SW,Diode (i,f s )express;

[0070] The conduction loss P of the device that can be turned off cond,TOD (i) and switching loss P SW,TOD (i,f s ) is taken as the total loss of the turn-off device, and the total loss of the turn-off device is expressed as P TOD (i,f s ) means that P TOD (i,f s )=P cond,TOD (i)+P SW,TOD (i,f s ), and the conduction loss of the diode device P cond,Diode (i) and turn-off loss P SW,Diode (i,f s ) is the total loss of the diode, and the total loss of the diode is expressed as P Diode (i,f s ) means that P Diode (i,f s )=P cond,Diode (i)+P SW,Diode (i,f s ).

[0071] The simulation model is determined based on the converter topology and switchable device module parameters.

[0072] In the first embodiment of the present invention, not only the conduction loss P of the turnable device can be obtained by the above simulation model, but also the conduction loss P of the turnable device can be obtained by the above simulation model. cond,TOD (i) and switching loss P SW,TOD (i,f s ) and the conduction loss P of the diode device cond,Diode (i) and turn-off loss P SW,Diode (i,f s ), the conduction loss and switching loss of the turn-off device can also be calculated by the following formula:

[0073]

[0074]

[0075] Where: V CEO is the turn-on voltage of the device that can be turned off; I P is the peak value of the converter output current; r CE is the on-state resistance of the turn-off device; E on (I nom ,V nom ) is the turn-on loss of the switchable device at rated voltage and rated current; E off (I nom ,V nom ) is the rated voltage V nom , Rated current I nom Turn-off loss under V dc is the DC voltage of the converter;

[0076] The on-state loss and turn-off loss of the diode device are calculated by the following formula:

[0077]

[0078]

[0079] Where: I P is the peak value of the converter output current; V FO is the turn-on voltage of the diode; r F is the on-state resistance of the diode, E rec (I nom1 ) is the diode at rated current I nom1 Reverse recovery loss under V nom1 is the rated voltage of the diode.

[0080] The total thermal resistance of the turn-off device junction to the heat sink and the total thermal resistance of the diode device junction to the heat sink are calculated based on the turn-off device module parameters, including:

[0081] Get the turn-off device junction-to-case thermal resistance R from the turn-off device module parameters thJC,TOD Thermal resistance R thCH,TOD The thermal resistance of the device to the case R thJC,TOD Thermal resistance R thCH,TOD The total thermal resistance R of the turn-off device to the heat sink th,TOD , that is, R th,TOD =R thJC,TOD +R thCH,TOD ;

[0082] The diode junction-to-case thermal resistance R can be obtained from the shutdown device module parameters. thJC,Diode Thermal resistance R thCH,Diode The diode junction to case thermal resistance R thJC,Diode Thermal resistance R thCH,Diode The total thermal resistance of the diode device to the heat sink is R th,Diode , that is, R th,Diode =R thJC,Diode +R thCH,Diode .

[0083] Based on the total loss P of the turn-off device TOD (i,f s ), the total loss of the diode P Diode (i,f s ), the total thermal resistance of the turn-off device to the heat sink R th,TOD The total thermal resistance R of the diode device to the heat sink th,Diode Determine the maximum temperature rise of the device module that can be turned off at different carrier frequencies and different output currents, including:

[0084] The total loss of the turn-off device P TOD (i,f s ) and the total thermal resistance of the heat sink connected to the turn-off device R th,TOD The product of is the temperature rise ΔT of the turn-off device. TOD (i,f s ), that is, ΔT TOD (i,f s )=R th,TOD ×P TOD (i,f s );

[0085] The temperature rise of the diode is calculated by multiplying the total loss of the diode by the total thermal resistance of the diode device to the heat sink. The temperature rise of the diode is expressed by ΔT Diode (i,f s ) means, that is, ΔT Diode (i,f s )=R th,Diode ×P Diode (i,f s);

[0086] The maximum value of the temperature rise of the turn-off device and the temperature rise of the diode is selected as the maximum temperature rise of the turn-off device module under different carrier frequencies and different output currents. The maximum temperature rise of the turn-off device module under different carrier frequencies and different output currents is expressed by ΔT(i,f s ) means, that is, ΔT(i,f s )=max{ΔT TOD (i,f s ),ΔT Diode (i,f s )}.

[0087] In S102, the design temperature rise of the turnable device module under different output currents is determined based on the turnable device module parameters and the current heat sink temperature, including:

[0088] The maximum operating junction temperature of the shutdown device module is determined based on the maximum allowable junction temperature in the shutdown device module parameters. The maximum operating junction temperature of the shutdown device module is expressed as T op Indicates that T op Generally, it is a certain temperature lower than the maximum allowable junction temperature, leaving a certain safety margin;

[0089] The temperature probe is used to collect the substrate temperature of the shutdown device module and use it as the heat sink temperature of the shutdown device module. h express;

[0090] The difference between the maximum operating junction temperature and the heat sink temperature of the turn-off device module is taken as the design temperature rise of the turn-off device module under the current heat sink temperature and different output currents. The design temperature rise is represented by ΔT(i), that is, ΔT(i) = T op -T h .

[0091] In S103, determining the converter carrier frequency at the current heat sink temperature and the current output current based on the maximum temperature rise and the design temperature rise includes:

[0092] The temperature rise of the turn-off device module under different carrier frequencies and the same output current is obtained from the maximum temperature rise;

[0093] Select the temperature rise closest to the design temperature rise from the obtained temperature rises;

[0094] The carrier frequency corresponding to the selected temperature rise is used as the converter carrier frequency at the current heat sink temperature and the current output current.

[0095] Example 2

[0096] Based on the same inventive concept, Embodiment 2 of the present invention further provides a converter variable carrier control device, such as Figure 2 As shown, it includes:

[0097] A first determination module is used to determine the maximum temperature rise of the turnable device module under multiple carrier frequencies and different output currents based on the converter topology and the turnable device module parameters in the converter;

[0098] A second determination module is used to determine the design temperature rise of the turnable device module under different output currents based on the turnable device module parameters and the current heat sink temperature;

[0099] The third determination module is used to determine the converter carrier frequency under the current heat sink temperature and the current output current based on the maximum temperature rise and the design temperature rise.

[0100] The first determination module is specifically used for:

[0101] Calculate the total loss of the turn-off device and the total loss of the diode based on the converter topology and the module parameters of the turn-off device in the converter;

[0102] Calculate the total thermal resistance of the turn-off device junction to the heat sink and the total thermal resistance of the diode device junction to the heat sink based on the turn-off device module parameters;

[0103] The maximum temperature rise of the turn-off device module under multiple carrier frequencies and different output currents is determined based on the total loss of the turn-off device, the total loss of the diode, the total thermal resistance of the turn-off device to the heat sink, and the total thermal resistance of the diode device to the heat sink.

[0104] The second determination module is specifically used for:

[0105] Determining the maximum operating junction temperature of the turn-off device module based on the maximum allowable junction temperature in the turn-off device module parameters;

[0106] The substrate temperature of the shut-down device module is collected by a temperature probe and used as the heat sink temperature of the shut-down device module;

[0107] The difference between the maximum operating junction temperature and the heat sink temperature of the turn-off device module is used as the design temperature rise of the turn-off device module under different output currents.

[0108] The third determination module is specifically used for:

[0109] The temperature rise of the turn-off device module under different carrier frequencies and the same output current is obtained from the maximum temperature rise;

[0110] Select the temperature rise closest to the design temperature rise from the obtained temperature rises;

[0111] The carrier frequency corresponding to the selected temperature rise is used as the converter carrier frequency at the current heat sink temperature and the current output current.

[0112] For the convenience of description, the various parts of the above device are divided into various modules or units according to their functions and described separately. Of course, when implementing the present application, the functions of each module or unit can be implemented in the same or multiple software or hardware.

[0113] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0114] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0115] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0116] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Ordinary technicians in the relevant field can still modify or make equivalent substitutions to the specific implementation methods of the present invention with reference to the above embodiments. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the present invention to be approved.

Claims

1. A method for controlling a variable carrier of a converter, characterized in that: include: Determine the maximum temperature rise of the turnable device module under multiple carrier frequencies and different output currents based on the converter topology and the turnable device module parameters in the converter; Determine the design temperature rise of the turn-off device module under different output currents based on the turn-off device module parameters and the current heat sink temperature; Determine the converter carrier frequency at the current heat sink temperature and the current output current based on the maximum temperature rise and the design temperature rise; The method of determining the maximum temperature rise of the turnable device module under multiple carrier frequencies and different output currents based on the converter topology structure and the turnable device module parameters in the converter includes: Calculate the total loss of the turn-off device and the total loss of the diode based on the converter topology and the module parameters of the turn-off device in the converter; Calculate the total thermal resistance of the turn-off device junction to the heat sink and the total thermal resistance of the diode device junction to the heat sink based on the turn-off device module parameters; Determine the maximum temperature rise of the turnable device module under multiple carrier frequencies and different output currents based on the total loss of the turnable device, the total loss of the diode, the total thermal resistance of the turnable device to the heat sink, and the total thermal resistance of the diode device to the heat sink; The method of determining the design temperature rise of the turnable device module under different output currents based on the turnable device module parameters and the current heat sink temperature includes: Determining the maximum operating junction temperature of the turn-off device module based on the maximum allowable junction temperature in the turn-off device module parameters; The substrate temperature of the shut-down device module is collected by a temperature probe and used as the heat sink temperature of the shut-down device module; The difference between the highest operating junction temperature and the heat sink temperature of the turn-off device module is used as the design temperature rise of the turn-off device module under different output currents; The method of determining the converter carrier frequency at the current heat sink temperature and the current output current based on the maximum temperature rise and the design temperature rise includes: Obtaining the temperature rise of the turn-off device module at different carrier frequencies and the same output current from the maximum temperature rise; Selecting the temperature rise closest to the design temperature rise from the obtained temperature rises; The carrier frequency corresponding to the selected temperature rise is used as the converter carrier frequency at the current heat sink temperature and the current output current.

2. The inverter variable carrier control method according to claim 1, characterized in that: The method of calculating the total loss of the turnable device and the total loss of the diode based on the converter topology and the turnable device module parameters in the converter includes: Divide the output current of the converter into multiple current segments at equal intervals, and obtain the current at the midpoint of each current segment; Set different carrier frequencies of the converter, and calculate the current at the midpoint of each current segment and the carrier frequency input to the simulation model of the converter to obtain the conduction loss and switching loss of the turnable device and the conduction loss and turn-off loss of the diode device; The sum of the conduction loss and the switching loss of the turnable device is taken as the total loss of the turnable device, and the sum of the conduction loss and the turn-off loss of the diode device is taken as the total loss of the diode; The simulation model is determined based on the converter topology and switchable device module parameters.

3. The inverter variable carrier control method according to claim 2, characterized in that: The method of calculating the total thermal resistance of the turnable device junction to the heat sink and the total thermal resistance of the diode device junction to the heat sink based on the turnable device module parameters includes: Obtain the turn-off device junction-to-case thermal resistance and the case-to-heat sink thermal resistance from the turn-off device module parameters, and use the sum of the turn-off device junction-to-case thermal resistance and the case-to-heat sink thermal resistance as the turn-off device junction-to-heat sink total thermal resistance; The diode junction-to-case thermal resistance and the case-to-heat sink thermal resistance are obtained from the turn-off device module parameters, and the sum of the diode junction-to-case thermal resistance and the case-to-heat sink thermal resistance is taken as the total diode device junction-to-heat sink thermal resistance.

4. The inverter variable carrier control method according to claim 2, characterized in that: The method of determining the maximum temperature rise of the turnable device module under different carrier frequencies and different output currents based on the total loss of the turnable device, the total loss of the diode, the total thermal resistance of the turnable device to the heat sink, and the total thermal resistance of the diode device to the heat sink comprises: The product of the total loss of the turn-off device and the total thermal resistance of the turn-off device to the heat sink is taken as the temperature rise of the turn-off device; The product of the total loss of the diode and the total thermal resistance of the diode device junction to the heat sink is taken as the temperature rise of the diode; The maximum value of the temperature rise of the turn-off device and the temperature rise of the diode is selected as the maximum temperature rise of the turn-off device module under different carrier frequencies and different output currents.

5. The inverter variable carrier control method according to claim 2, characterized in that: The current segments are , ,……, ,in, I min is the lower limit of the converter output current, I max is the upper limit of the converter output current, and N is the number of current segments.

6. The inverter variable carrier control method according to claim 5, characterized in that: The carrier frequency of the converter is set to f 0, 2 f 0,3 f 0...... kf 0, where f 0 is the power frequency, kf 0 is the maximum switching frequency of the device module that can be turned off. k is a natural number.

7. A converter variable carrier control device, characterized in that: include: A first determination module is used to determine the maximum temperature rise of the turnable device module under multiple carrier frequencies and different output currents based on the converter topology and the turnable device module parameters in the converter; A second determination module is used to determine the design temperature rise of the turnable device module under different output currents based on the turnable device module parameters and the current heat sink temperature; A third determination module is used to determine the converter carrier frequency at the current heat sink temperature and the current output current based on the maximum temperature rise and the design temperature rise; The first determining module is specifically used for: Calculate the total loss of the turn-off device and the total loss of the diode based on the converter topology and the module parameters of the turn-off device in the converter; Calculate the total thermal resistance of the turn-off device junction to the heat sink and the total thermal resistance of the diode device junction to the heat sink based on the turn-off device module parameters; Determine the maximum temperature rise of the turnable device module under multiple carrier frequencies and different output currents based on the total loss of the turnable device, the total loss of the diode, the total thermal resistance of the turnable device to the heat sink, and the total thermal resistance of the diode device to the heat sink; The second determining module is specifically used for: Determining the maximum operating junction temperature of the turn-off device module based on the maximum allowable junction temperature in the turn-off device module parameters; The substrate temperature of the shut-down device module is collected by a temperature probe and used as the heat sink temperature of the shut-down device module; The difference between the highest operating junction temperature and the heat sink temperature of the turn-off device module is used as the design temperature rise of the turn-off device module under different output currents; The third determination module is specifically used for: Obtaining the temperature rise of the turn-off device module at different carrier frequencies and the same output current from the maximum temperature rise; Selecting the temperature rise closest to the design temperature rise from the obtained temperature rises; The carrier frequency corresponding to the selected temperature rise is used as the converter carrier frequency at the current heat sink temperature and the current output current.

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