Variable frequency drive testing device

Abstract

This invention discloses a frequency converter driver testing device that determines the initial temperature and equilibrium temperature of a power module; determines the total power module loss at the equilibrium temperature based on the IGBT's relative zero temperature coefficient parameters, current, and voltage; obtains the frequency converter driver's thermal resistance and determines the theoretical temperature based on the thermal resistance and total loss; determines the theoretical temperature rise based on the theoretical temperature and initial temperature, and determines the measured temperature rise based on the equilibrium temperature and initial temperature; determines the deviation value based on the theoretical temperature rise and measured temperature rise; obtains the standard deviation value, and compares the deviation value with the standard deviation value to determine whether the heat sink and power module assembly is qualified. The testing device determines the deviation value by comparing the theoretical temperature change estimated from the power module loss under a specific state and the thermal resistance with the actual temperature change of the power module, and compares this deviation value with a pre-determined standard deviation value to determine whether the heat sink and power module assembly is qualified. This allows for intelligent assessment of the reliability of the power module and heat sink installation.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, and in particular to a frequency converter driver detection device. Background Technology

[0002] During the manufacturing and installation of PCBA (Printed Circuit Board Assembly), it is inevitable that heat sinks need to be installed to dissipate heat from power devices in high-power inverter drives for air conditioners.

[0003] Especially with the increasing current density of power devices at present, if the heat sink and power module are not installed properly, the heat sink will not be able to dissipate heat from the power module properly, and the power module will continue to operate at high temperatures, greatly reducing its lifespan and reliability. However, checking for installation deviations and abnormalities in the heat sink is a difficult point in the industry, and there is currently no good method to confirm whether the assembly of the heat sink and power module of the frequency converter drive is reliable and in place.

[0004] The information disclosed in this background section is only intended to enhance the understanding of the background technology of this application, and therefore may include prior art that is not known to those skilled in the art. Summary of the Invention

[0005] This invention proposes a frequency converter driver testing device, which solves the technical problem that the prior art cannot confirm whether the assembly of the heat sink and power module of the frequency converter driver is qualified.

[0006] To achieve the above-mentioned objectives, the present invention employs the following technical solution:

[0007] A frequency converter driver detection device, the frequency converter driver comprising:

[0008] Power modules, including IGBTs and diodes;

[0009] Heat sink, assembled with power module;

[0010] Temperature detection module, used to detect the temperature of the power module;

[0011] The detection device includes:

[0012] The power supply provides power to the power module;

[0013] The current detection module detects the IGBT output current and the diode freewheeling current.

[0014] The voltage detection module detects the IGBT saturation voltage drop and the diode forward voltage drop.

[0015] The control module is configured as follows:

[0016] Determine the initial temperature and equilibrium temperature of the power module;

[0017] The total power module loss at equilibrium temperature is determined based on the IGBT's relative zero temperature coefficient parameters, current, and voltage.

[0018] Obtain the thermal resistance of the frequency converter driver, determine the theoretical temperature based on the thermal resistance and total loss; determine the theoretical temperature rise based on the theoretical temperature and initial temperature, determine the measured temperature rise based on the equilibrium temperature and initial temperature; determine the deviation value based on the theoretical temperature rise and the measured temperature rise.

[0019] Obtain the standard deviation value, and compare the deviation value with the standard deviation value to determine whether the heat sink and power module are assembled correctly.

[0020] The above technical solution has the following advantages or beneficial effects: the detection device determines the deviation value by the difference between the theoretical temperature change and the actual temperature change of the power module based on the power module loss estimation and thermal resistance determination under a specific state, and compares it with the predetermined standard deviation value to determine whether the heat sink and power module assembly is qualified, and can intelligently evaluate the reliability of the installation of the power module and heat sink.

[0021] In some embodiments, the total loss of the power module includes IGBT conduction loss, diode conduction loss, IGBT switching loss determined based on the relative zero temperature coefficient parameter, and diode switching loss.

[0022] The control module is configured to determine the IGBT switching loss based on the IGBT turn-on loss and the IGBT turn-off loss.

[0023] Obtain reference values ​​for the relative zero temperature coefficient current, relative zero temperature coefficient saturation voltage drop, and relative zero temperature coefficient turn-on loss of the IGBT, and determine the IGBT turn-on loss by combining the output current and saturation voltage drop.

[0024] Obtain reference values ​​for the relative zero temperature coefficient current, relative zero temperature coefficient saturation voltage drop, and relative zero temperature coefficient turn-off loss of the IGBT, and determine the IGBT turn-off loss by combining the output current and saturation voltage drop.

[0025] Determine diode switching losses based on diode reverse recovery losses;

[0026] Obtain the diode freewheeling current value under IGBT relative zero temperature coefficient current, the diode forward voltage drop under IGBT relative zero temperature coefficient current, and the reference value of reverse recovery loss under the diode freewheeling current value under IGBT relative zero temperature coefficient current. Combine the freewheeling current value and the forward voltage drop to determine the diode reverse recovery loss.

[0027] The above technical solution has the following advantages or beneficial effects: the IGBT switching loss and diode switching loss determined based on the relative zero temperature coefficient parameter can avoid the errors and uncertainties caused by temperature changes, and can make up for the instability of the temperature-sensitive saturation voltage drop detection method, so as to make the total loss of the power module more accurate, thereby ensuring the accuracy of the theoretical temperature rise, and thus more accurately judging whether the heat sink and power module are assembled.

[0028] In some embodiments,

[0029] IGBT turn-on loss = Reference value of turn-on loss with relative zero temperature coefficient * (output current / relative zero temperature coefficient current) * (saturation voltage drop / relative zero temperature coefficient saturation voltage drop);

[0030] IGBT turn-off loss = Reference value of turn-off loss with relative zero temperature coefficient * (output current / relative zero temperature coefficient current) * (saturation voltage drop / relative zero temperature coefficient saturation voltage drop);

[0031] Diode reverse recovery loss = Reference value of reverse recovery loss under diode freewheeling current value at IGBT relative zero temperature coefficient current * (Freewheeling current value / Diode freewheeling current value at IGBT zero temperature coefficient current) * (Forward voltage drop / Forward voltage drop at IGBT zero temperature coefficient current).

[0032] The above technical solution has the following advantages or beneficial effects: it provides specific methods for determining IGBT turn-on loss, IGBT turn-off loss, and diode reverse recovery loss, thereby improving the accuracy of loss determination.

[0033] In some embodiments, the control module is configured to acquire the switching frequency and duty cycle of the power module;

[0034] The IGBT conduction loss is determined based on the output current, saturation voltage drop, switching frequency, and duty cycle.

[0035] IGBT switching losses are determined based on IGBT turn-on losses, turn-off losses, and switching frequency.

[0036] The diode conduction loss is determined based on the freewheeling current value, forward voltage drop, switching frequency, and duty cycle.

[0037] The diode switching loss is determined based on the switching frequency and the diode reverse recovery loss.

[0038] The above technical solution has the following advantages or beneficial effects: the power module loss is related to the switching frequency and the duty cycle. Therefore, the switching frequency and the duty cycle are introduced to improve the accuracy of loss determination.

[0039] In some embodiments,

[0040] IGBT conduction loss = switching frequency * conduction duty cycle * output current * saturation voltage drop;

[0041] IGBT switching loss = switching frequency * (IGBT turn-on loss + IGBT turn-off loss);

[0042] Diode conduction loss = switching frequency * (1 - duty cycle) * freewheeling current * forward voltage drop;

[0043] Diode switching loss = switching frequency * diode reverse recovery loss.

[0044] The above technical solution has the following advantages or beneficial effects: it provides specific methods for determining IGBT conduction loss, IGBT switching loss, diode conduction loss, and diode switching loss, thereby improving the accuracy of loss determination.

[0045] In some embodiments, the control module is configured to determine an equilibrium temperature correction factor based on the equilibrium temperature, and to correct the reverse recovery loss of the diode using the equilibrium temperature correction factor.

[0046] The above technical solution has the following advantages or beneficial effects: Since temperature has a certain influence on the characteristics of diode, the reverse recovery loss of diode is corrected by the equilibrium temperature correction coefficient at the equilibrium temperature so that the determination of the reverse recovery loss of diode is more accurate.

[0047] In some embodiments, the power supply includes a three-phase six-pulse rectifier circuit.

[0048] The above technical solution has the following advantages or beneficial effects: the power of the three-phase six-pulse rectifier circuit is closed-loop, and the output load is easy to define; it enables the power module to heat up quickly; the bias duty cycle is a constant value, making the power module loss calculation more direct, faster and more accurate.

[0049] In some embodiments, the thermal resistance of the frequency converter driver includes the thermal resistance of the power module, the thermal resistance of the heat sink, and the assembly thermal resistance. The thermal resistance of the power module and the thermal resistance of the heat sink are the thermal resistance values ​​corresponding to their respective thermal resistance curves at the equilibrium temperature, and the assembly thermal resistance is the standard thermal resistance determined in advance based on the heat sink when it is successfully assembled with the power module.

[0050] The above technical solution has the following advantages or beneficial effects: the thermal resistance of the power module and the thermal resistance of the heat sink are stable at the equilibrium temperature and will not change; the assembly thermal resistance is a standard thermal resistance, thus enabling accurate determination of the theoretical temperature.

[0051] A frequency converter driver detection device, the frequency converter driver comprising:

[0052] Power modules, including IGBTs and diodes;

[0053] Heat sink, assembled with power module;

[0054] Temperature detection module, used to detect the temperature of the power module;

[0055] The detection device includes:

[0056] The power supply provides power to the power module;

[0057] Load, connected to power module;

[0058] The current detection module detects the IGBT output current.

[0059] The control module is configured as follows:

[0060] Determine the initial temperature and equilibrium temperature of the power module;

[0061] Controlling the load ensures that the IGBT output current has a relative zero temperature coefficient.

[0062] The total power module loss at equilibrium temperature is determined based on the IGBT's relative zero temperature coefficient parameters, current, and voltage.

[0063] Obtain the thermal resistance of the frequency converter driver, determine the theoretical temperature based on the thermal resistance and total loss; determine the theoretical temperature rise based on the theoretical temperature and initial temperature, determine the measured temperature rise based on the equilibrium temperature and initial temperature; determine the deviation value based on the theoretical temperature rise and the measured temperature rise.

[0064] Obtain the standard deviation value, and compare the deviation value with the standard deviation value to determine whether the heat sink and power module are assembled correctly.

[0065] The above technical solution has the following advantages or beneficial effects: controlling the IGBT output current to reach the relative zero temperature coefficient current, directly determining the saturation voltage drop and diode parameters based on the relative zero temperature coefficient current, eliminating the need to set up a detection module for voltage and current detection, avoiding detection errors, and improving detection speed and accuracy.

[0066] In some embodiments, the control module determines that the IGBT turn-on loss is a reference value for turn-on loss with a relative zero temperature coefficient; the IGBT turn-off loss is a reference value for turn-off loss with a relative zero temperature coefficient; and the diode reverse recovery loss is a reference value for reverse recovery loss.

[0067] The control module determines the IGBT conduction loss by using the IGBT's relative zero temperature coefficient current, relative zero temperature coefficient saturation voltage drop, switching frequency, and conduction duty cycle.

[0068] The control module determines the diode conduction loss by using the diode freewheeling current value under IGBT relative zero temperature coefficient current, the diode forward conduction voltage drop under IGBT relative zero temperature coefficient current, the switching frequency, and the conduction duty cycle.

[0069] The above technical solution has the following advantages or beneficial effects: by controlling the IGBT output current to achieve a relative zero temperature coefficient current, the determination of total loss is simplified. Specifically, the determination of IGBT turn-on loss, IGBT turn-off loss, IGBT conduction loss, diode reverse recovery loss, and diode conduction loss is simplified, thereby improving detection accuracy and speed.

[0070] Other features and advantages of the present invention will become clearer after reading the detailed embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0071] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0072] Figure 1 This is a schematic diagram of the inverter driver assembly process;

[0073] Figure 2 This is a schematic diagram according to an embodiment;

[0074] Figure 3 This is a flowchart of the detection process according to an embodiment;

[0075] Figure 4 This is a flowchart illustrating the total loss estimation process according to an embodiment.

[0076] Figure 5 This is a schematic diagram according to another embodiment;

[0077] Figure 6 This is a flowchart of the detection process according to another embodiment;

[0078] Figure 7 A flowchart for estimating total loss according to another embodiment;

[0079] Figure 8 A graph showing the relative zero temperature coefficient according to an embodiment;

[0080] Figure 9 This is a diagram showing the correspondence between thermal resistance and frequency converter according to an embodiment;

[0081] Figure 10The thermal resistance curves of the IGBT and diode according to the embodiment are shown. Detailed Implementation

[0082] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0083] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0084] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0085] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0086] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0087] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0088] The air conditioning unit disclosed in this application performs a refrigeration cycle by using a compressor, a condenser, a throttling device, and an evaporator. The refrigeration cycle includes a series of processes involving compression, condensation, expansion, and evaporation to cool or heat an indoor space.

[0089] Low-temperature, low-pressure refrigerant enters the compressor, which compresses it into a high-temperature, high-pressure refrigerant gas and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and the heat is released to the surrounding environment through the condensation process.

[0090] The throttling device expands the high-temperature, high-pressure liquid refrigerant that condenses in the condenser into a low-pressure liquid refrigerant. The evaporator evaporates the expanded refrigerant in the throttling device, returning the low-temperature, low-pressure refrigerant gas to the compressor. The evaporator achieves its cooling effect by utilizing the latent heat of refrigerant evaporation to exchange heat with the material being cooled. Throughout the cycle, the air conditioner regulates the temperature of the indoor space.

[0091] The outdoor unit of an air conditioning unit refers to the part of the refrigeration cycle that includes the compressor and the outdoor heat exchanger. The throttling device is located in the outdoor unit.

[0092] The indoor and outdoor heat exchangers function as either condensers or evaporators. When the indoor heat exchanger is used as a condenser, the air conditioner functions as a heater in heating mode; when the indoor heat exchanger is used as an evaporator, the air conditioner functions as a cooler in cooling mode.

[0093] Air conditioning units include variable frequency drive units.

[0094] In some embodiments, the air conditioning unit drives the compressor to operate via a variable frequency drive.

[0095] In some embodiments, the variable frequency drive detection device drives the compressor and fan to operate via the variable frequency drive device.

[0096] Since the variable frequency drive device includes a power module, the power module generates a lot of heat when the variable frequency drive device is running. It is necessary to dissipate heat from the power module to ensure its normal operation. Therefore, a heat sink needs to be installed on the power module to dissipate heat.

[0097] The proper assembly of the heat sink and power module is crucial to whether the heat sink can meet heat dissipation standards. If the heat sink and power module are not properly assembled, and there are discrepancies between them, the heat sink's heat dissipation effect will be significantly reduced, leading to excessively high temperatures in the power module and affecting its lifespan. Therefore, ensuring that the assembly relationship between the heat sink and power module meets the heat dissipation requirements of the power module is a problem that the testing device needs to solve.

[0098] The variable frequency drive testing device is used to test the variable frequency drive.

[0099] First, let's explain the variable frequency drive:

[0100] The variable frequency drive includes: a power module, a heat sink, and a temperature detection module.

[0101] The power module includes IGBTs and diodes.

[0102] Heat sink and power module assembly.

[0103] The temperature detection module is used to detect the temperature of the power module.

[0104] exist Figure 1 In this example, the installation process for the variable frequency drive is as follows:

[0105] We provide PCB circuit boards.

[0106] Power devices are mounted on a PCB circuit board to form a PCBA, which is also known as a power module.

[0107] Assemble the heat sink by using brackets, screws, and other fixing methods to press and install the heat sink and power module together to complete the assembly.

[0108] In some embodiments, a thermally conductive layer or structure may be added between the heat sink and the power module to improve heat dissipation.

[0109] Since the heat generation performance of the power module and the heat dissipation performance of the radiator itself are determined under specific conditions, the assembly relationship between the radiator and the power module plays a crucial role in the heat dissipation performance of the radiator under these specific conditions, and it is necessary to test whether the assembly of the radiator and the power module is qualified.

[0110] The variable frequency drive testing device is used to test whether the assembly of the heat sink and power module is qualified and meets the heat dissipation requirements.

[0111] The detection device is described below:

[0112] exist Figure 2 In one example, the detection device includes:

[0113] The power supply provides power to the power module;

[0114] The current detection module detects the IGBT output current and the diode freewheeling current.

[0115] The voltage detection module detects the IGBT saturation voltage drop and the diode forward voltage drop.

[0116] The control module is configured as follows:

[0117] Determine the initial temperature and equilibrium temperature of the power module;

[0118] The total power module loss at equilibrium temperature is determined based on the IGBT's relative zero temperature coefficient parameters, current, and voltage.

[0119] Obtain the thermal resistance of the frequency converter driver, determine the theoretical temperature based on the thermal resistance and total loss; determine the theoretical temperature rise based on the theoretical temperature and initial temperature, determine the measured temperature rise based on the equilibrium temperature and initial temperature; determine the deviation value based on the theoretical temperature rise and the measured temperature rise.

[0120] Obtain the standard deviation value, and compare the deviation value with the standard deviation value to determine whether the heat sink and power module are assembled correctly.

[0121] The initial temperature represents the ambient temperature, which remains constant throughout the entire testing process.

[0122] The equilibrium temperature is the temperature at which the power module reaches a stable state after being heated for a period of time, that is, the temperature at which the temperature remains constant.

[0123] In some embodiments, the equilibrium temperature is the temperature at which the real-time temperature detected by the temperature detection module remains constant within a set time period.

[0124] The equilibrium temperature varies under different testing conditions.

[0125] The thermal resistance of the frequency converter driver is constant at equilibrium temperature.

[0126] Since the relative zero temperature coefficient parameter of IGBT is an inherent parameter of IGBT, it can be obtained through... Figure 8 Curve acquisition.

[0127] In some embodiments, the relative zero temperature coefficient parameter of the IGBT is stored in a storage module.

[0128] In some embodiments, the thermal resistance of the frequency converter driver is stored in a storage module.

[0129] The standard deviation is a deviation value that meets the requirements and is determined in advance through experiments.

[0130] In some embodiments, the standard deviation value is stored in a storage module.

[0131] In some embodiments, the output module outputs information on whether the heat sink and power module are properly assembled.

[0132] In some embodiments, theoretical temperature = thermal resistance * total loss.

[0133] The testing device determines the deviation value by comparing the theoretical temperature change based on the power module loss estimation and thermal resistance determination under thermal equilibrium conditions with the actual temperature change of the power module. It then compares this deviation value with a pre-determined standard deviation value to determine whether the heat sink and power module assembly is qualified. This allows for intelligent assessment of the reliability of the power module and heat sink installation.

[0134] By testing the inverter driver, the heat sink can ensure the normal operation of the power module and extend its service life. The testing device is simple, reliable, easy to implement, and convenient and quick to use.

[0135] exist Figure 3 In this example, the process for detecting a frequency converter drive is as follows:

[0136] S1, Begin.

[0137] S2, Detect the initial temperature of the power module.

[0138] S3 controls the power supply to power the power module, which generates heat and dissipates it through a heat sink.

[0139] S4. Detect the real-time temperature of the power module.

[0140] S5. If the real-time temperature remains unchanged within the set time, proceed to step S6; otherwise, proceed to step S4.

[0141] S6. Determine the real-time temperature as the equilibrium temperature.

[0142] S7. Determine the total power module loss at equilibrium temperature based on the IGBT relative zero temperature coefficient parameters, current, and voltage.

[0143] S8. Obtain the thermal resistance of the frequency converter driver, determine the theoretical temperature based on the thermal resistance and total loss, determine the theoretical temperature rise based on the theoretical temperature and initial temperature, determine the measured temperature rise based on the equilibrium temperature and initial temperature, determine the deviation value based on the theoretical temperature rise and measured temperature rise, and obtain the standard deviation value.

[0144] S9. If the deviation value is within the standard deviation threshold range, proceed to step S10; otherwise, proceed to step S11.

[0145] S10, The heat sink and power module are assembled successfully.

[0146] S11. The heat sink and power module are not assembled properly.

[0147] In some embodiments, the total loss of the power module includes IGBT conduction loss, diode conduction loss, IGBT switching loss determined based on the relative zero temperature coefficient parameter, and diode switching loss.

[0148] IGBT switching losses and diode switching losses determined based on the relative zero temperature coefficient parameter can avoid errors and uncertainties caused by temperature changes. It can also compensate for the instability of temperature-sensitive saturation voltage drop detection methods, making the total loss of the power module more accurate. This ensures the accuracy of the theoretical temperature rise and allows for a more precise judgment on whether the heat sink and power module assembly is qualified.

[0149] The calculation method for IGBT switching losses and diode switching losses adopts the Vcesat (IGBT saturation voltage drop) detection method under the relatively zero temperature coefficient system current of the IGBT. The so-called relatively zero temperature coefficient current Vcesat (IGBT saturation voltage drop) detection method is based on the fact that when the IGBT power device in the frequency converter drive power module is turned on, it can be equivalent to a diode and MOSFET in series conduction mode. Temperature changes affect the intrinsic carrier concentration and the bipolar diffusion coefficient, hence diodes have a negative temperature coefficient (NTC) characteristic. However, for MOSFETs, temperature affects the threshold voltage Vth and mobility μ, thus exhibiting a typical positive temperature coefficient (PTC) characteristic. Therefore, the IGBT in the frequency converter drive module exhibits a negative temperature coefficient characteristic at low conduction currents and a positive temperature coefficient characteristic at high conduction currents. Therefore, the point where these characteristics diverge is considered the relatively zero temperature coefficient point. Figure 8 As shown, its advantage is that this point is insensitive to temperature changes, corresponding to a specific conducting current value of the IGBT in the frequency converter power module. Therefore, under this specific current, Vcesat (IGBT saturation voltage drop) is a fixed value. This eliminates errors caused by temperature and many uncertain factors. Thus, it can compensate for the instability of temperature-sensitive Vcesat detection methods. Based on the IGBT switching losses and diode switching losses determined by the relative zero temperature coefficient parameter, the switching losses of the power module can be estimated more accurately.

[0150] The control module is configured to operate based on the IGBT turn-on loss E. on and IGBT turn-off loss E off Determine the IGBT switching loss Esw.

[0151] Obtain the relative zero temperature coefficient current I of the IGBT CZERO , relative zero temperature coefficient saturation pressure drop V cezero and the reference value E for turn-on loss with relative zero temperature coefficient ONREF And combined with the output current I c and saturation pressure drop V cesat Determine the IGBT turn-on loss E on .

[0152] Relative zero temperature coefficient current I CZERO , relative zero temperature coefficient saturation pressure drop V cezero To pass Figure 8 The curve is obtained.

[0153] Reference value for turn-on loss with relative zero temperature coefficient E ONREF This was obtained through prior experimental testing under corresponding conditions.

[0154] In some embodiments, the IGBT turn-on loss E on =Reference value for turn-on loss with relative zero temperature coefficient E ONREF *(Output current I) c / Relative zero temperature coefficient current I CZERO )*(saturation pressure drop V cesat / Saturation pressure drop relative to zero temperature coefficient V cezero ).

[0155] Obtain the relative zero temperature coefficient current I of the IGBT CZERO , relative zero temperature coefficient saturation pressure drop V cezero and the reference value E for the relative zero temperature coefficient turn-off loss OFFREF And combined with the output current I c and saturation pressure drop V cesat Determine the IGBT turn-off loss E off .

[0156] Reference value for turn-on loss with relative zero temperature coefficient E OFFREF This was obtained through prior experimental testing under corresponding conditions.

[0157] In some embodiments, the IGBT turn-off loss E off =Relative zero temperature coefficient turn-off loss reference value E OFFREF *(Output current I) c / Relative zero temperature coefficient current I CZERO )*(saturation pressure drop V cesat / Saturation pressure drop relative to zero temperature coefficient V cezero ).

[0158] The control module is configured to determine the diode switching loss E based on the diode reverse recovery loss Err. Dsw .

[0159] Obtain the diode freewheeling current value I under the IGBT relative zero temperature coefficient current. Fref IGBT diode forward voltage drop V under relative zero temperature coefficient current Fref The reference value for reverse recovery loss E of diode freewheeling current under IGBT relative zero temperature coefficient current. rr-REF And combined with the freewheeling current value I f and forward conduction voltage drop V r Determine the reverse recovery loss Err of the diode.

[0160] IGBT diode freewheeling current value at relative zero temperature coefficient current. Fref IGBT diode forward voltage drop V under relative zero temperature coefficient current Fref Reference value of reverse recovery loss E under diode freewheeling current at relative zero temperature coefficient current. rr-REF This was obtained through prior experimental testing under corresponding conditions.

[0161] In some embodiments, the diode reverse recovery loss Err = the reference value of reverse recovery loss E under the diode freewheeling current value at the IGBT relative zero temperature coefficient current. rr-REF *(Freewheeling current value I) f / IGBT diode freewheeling current value I under zero temperature coefficient current Fref Forward conduction voltage drop V r / IGBT forward voltage drop V under zero temperature coefficient current Fref ).

[0162] The above provides specific methods for determining IGBT turn-on losses, IGBT turn-off losses, and diode reverse recovery losses, in order to improve the accuracy of loss determination.

[0163] In some embodiments, the control module is configured to determine an equilibrium temperature correction factor based on the equilibrium temperature, and to correct the reverse recovery loss of the diode using the equilibrium temperature correction factor.

[0164] Since temperature has a certain impact on diode characteristics, the reverse recovery loss of the diode is corrected by the equilibrium temperature correction factor at the equilibrium temperature to make the determination of the reverse recovery loss of the diode more accurate.

[0165] Considering the influence of temperature on diode characteristics, a correction factor is used to verify the loss during loss calculation. For example, the temperature correction factor is a and b when the diode's equilibrium temperature is determined in advance.

[0166] Err0 = E rr-REF ×(a*I f / I Fref +b)×(a*V r / V Fref +b).

[0167] In some embodiments, the control module is configured to acquire the switching frequency fsw and the duty cycle d of the power module.

[0168] Based on the output current I c , saturation pressure drop V cesat The switching frequency fsw and the duty cycle d determine the IGBT conduction loss E. con .

[0169] In some embodiments, the IGBT conduction loss E con = Switching frequency fsw * Duty cycle d * Output current I c *Saturation pressure drop V cesat .

[0170] The control module is configured to operate based on the IGBT turn-on loss E. on Turn-off loss E off The switching frequency fsw determines the IGBT switching loss E. sw .

[0171] In some embodiments, the IGBT switching loss E sw = Switching frequency fsw * (IGBT turn-on loss E) on +IGBT turn-off loss E off ).

[0172] The control module is configured to operate based on the freewheeling current value I. f Forward conduction voltage drop V r The switching frequency fsw and the duty cycle d determine the diode's conduction loss E. Dcon .

[0173] In some embodiments, the diode conduction loss E Dcon = Switching frequency fsw * (1 - Duty cycle d) * Freewheeling current value I f *Forward conduction voltage drop V r .

[0174] The control module is configured to operate based on the switching frequency fsw and the diode reverse recovery loss E. rr Determine the diode switching loss E Dsw .

[0175] In some embodiments, the diode switching loss E Dsw = Switching frequency fsw * Diode reverse recovery loss Err .

[0176] Power module losses are related to switching frequency and duty cycle. Therefore, the switching frequency and duty cycle are introduced to improve the accuracy of loss determination.

[0177] Meanwhile, specific methods for determining IGBT conduction loss, IGBT switching loss, diode conduction loss, and diode switching loss are given to improve the accuracy of loss determination.

[0178] IGBT loss E IGBT-toal Including IGBT conduction loss E con With IGBT switching loss E sw .

[0179] E IGBT-toal =E con +E sw .

[0180] Diode loss E DIODE-Total Including diode conduction loss E Dcon With diode switching loss E Dsw .

[0181] E DIODE-Total =E Dcon +E Dsw .

[0182] Total losses include IGBT losses E IGBT-toal and diode loss E DIODE-Total .

[0183] Total loss P toal =6*E IGBT-toal +6*E DIODE-Total .

[0184] The process for determining the total loss is as follows: Figure 4 As shown.

[0185] exist Figure 5 In one example, the detection device includes:

[0186] The power supply provides power to the power module.

[0187] The load is connected to the power module and is used to regulate the output current of the power module.

[0188] The current detection module detects the output current of the IGBT.

[0189] The control module is configured as follows:

[0190] Determine the initial temperature and equilibrium temperature of the power module;

[0191] Controlling the load ensures that the IGBT output current has a relative zero temperature coefficient.

[0192] The total power module loss at equilibrium temperature is determined based on the IGBT's relative zero temperature coefficient parameters, current, and voltage.

[0193] Obtain the thermal resistance of the frequency converter driver, determine the theoretical temperature based on the thermal resistance and total loss; determine the theoretical temperature rise based on the theoretical temperature and initial temperature, determine the measured temperature rise based on the equilibrium temperature and initial temperature; determine the deviation value based on the theoretical temperature rise and the measured temperature rise.

[0194] Obtain the standard deviation value, and compare the deviation value with the standard deviation value to determine whether the heat sink and power module are assembled correctly.

[0195] Controlling the IGBT output current to achieve a relative zero temperature coefficient current I CZERO You can directly access Figure 8 The relative zero temperature is determined by the relative zero temperature coefficient current, and the saturation voltage drop V is determined by the relative zero temperature. cezero And the diode freewheeling current value I at this time Fref and the forward voltage drop V of the diode Fref There is no need to set up a detection module for voltage and current detection, avoiding detection errors and improving detection speed and accuracy.

[0196] exist Figure 6 In this example, the process for detecting a frequency converter drive is as follows:

[0197] S1, Begin.

[0198] S2, Detect the initial temperature of the power module.

[0199] S3 controls the power supply to power the power module, which generates heat and dissipates it through a heat sink.

[0200] S4. Determine the IGBT's relative zero temperature coefficient current.

[0201] S5. Adjust the load to regulate the output current of the IGBT.

[0202] S6. Detect the output current of the IGBT.

[0203] S7. Is the output current of the IGBT a relative zero temperature coefficient current? If yes, proceed to step S8; otherwise, proceed to step S6.

[0204] S8, Detect the real-time temperature of the power module.

[0205] S9. If the real-time temperature remains unchanged within the set time, proceed to step S10; otherwise, proceed to step S8.

[0206] S10. Determine the real-time temperature as the equilibrium temperature.

[0207] S11. Determine the total power module loss at equilibrium temperature based on the IGBT relative zero temperature coefficient parameter.

[0208] S12. Obtain the thermal resistance of the frequency converter driver, determine the theoretical temperature based on the thermal resistance and total loss, determine the theoretical temperature rise based on the theoretical temperature and initial temperature, determine the measured temperature rise based on the equilibrium temperature and initial temperature, determine the deviation value based on the theoretical temperature rise and measured temperature rise, and obtain the standard deviation value.

[0209] S13. If the deviation value is within the standard deviation threshold range, proceed to step S14; otherwise, proceed to step S15.

[0210] S14. The heat sink and power module are assembled successfully.

[0211] S15. The heat sink and power module are not assembled properly.

[0212] In some embodiments, the control module is configured to determine the IGBT turn-on loss as a reference value for turn-on loss with a relative zero temperature coefficient.

[0213] The control module determines the IGBT turn-on loss E. on E is the reference value for turn-on loss with a relative zero temperature coefficient. ONREF .

[0214] E on =E ONREF .

[0215] In some embodiments, the control module is configured to determine the IGBT turn-off loss as a reference value for a relatively zero temperature coefficient turn-off loss; and the diode reverse recovery loss as a reference value for a reverse recovery loss.

[0216] The control module determines the IGBT turn-off loss E. off E is the reference value for the turn-off loss with a relative zero temperature coefficient. OFFRE .

[0217] E off =E OFFRE .

[0218] The control module determines the diode reverse recovery loss E. rr The reverse recovery loss reference value E rr-REF .

[0219] E rr =E rr-REF .

[0220] In some embodiments, the control module is configured to determine the IGBT conduction loss by means of the IGBT's relative zero temperature coefficient current, relative zero temperature coefficient saturation voltage drop, switching frequency, and conduction duty cycle.

[0221] The control module is configured to use a relative zero temperature coefficient current I through the IGBT. CZERO , relative zero temperature coefficient saturation pressure drop V cezero The switching frequency fsw and the duty cycle d determine the IGBT conduction loss E. con .

[0222] E con =fsw*(d*V cezero ×I CZERO ).

[0223] In some embodiments, the control module is configured to determine the diode conduction loss by the diode freewheeling current value under IGBT relative zero temperature coefficient current, the diode forward conduction voltage drop under IGBT relative zero temperature coefficient current, the switching frequency, and the conduction duty cycle.

[0224] The control module is configured to control the diode freewheeling current value I under the IGBT relative zero temperature coefficient current. Fref IGBT diode forward voltage drop V under relative zero temperature coefficient current Fref The switching frequency fsw and the duty cycle d determine the diode's conduction loss E. Dcon .

[0225] E Dcon =fsw*((1-d)*V Fref ×I Fref ).

[0226] By controlling the IGBT output current to achieve a relative zero temperature coefficient current, the determination of total losses is simplified. Specifically, the determination of IGBT turn-on losses, IGBT turn-off losses, IGBT conduction losses, diode reverse recovery losses, and diode conduction losses is simplified, thereby improving detection accuracy and speed.

[0227] The process for determining the total loss is as follows: Figure 7 As shown.

[0228] In some embodiments, the power supply includes a three-phase six-pulse rectifier circuit.

[0229] The three-phase six-pulse rectifier circuit has a closed-loop power supply, making the output load easy to define; it enables the power module to heat up quickly; and the bias duty cycle is a constant value, making the calculation of power module losses more direct, faster, and more accurate.

[0230] The three-phase six-pulse rectifier circuit utilizes a constant-power six-pulse IGBT rapid heating technology. It employs six-pulse electromagnetic heating asymmetric PWM control technology, enabling a large DC bias current even with a small output AC current. This is achieved for several reasons: First, its control mode uses a bias current closed-loop control mode, thus its power is also closed-loop, making the output load easy to define. Second, the high-frequency carrier frequency reaches 15kHz, more than twice the frequency of ordinary compressor inverter drive control, which increases dynamic losses and allows for rapid heating of the IGBT power devices. Third, the constant-power six-pulse control current uses a bias current control mode, resulting in a fixed bias duty cycle, which makes IGBT loss estimation more direct, faster, and more accurate, avoiding estimation errors.

[0231] The six-pulse rapid heat source generates a load with rated output circuit power through a frequency converter driving the load. Its feature is that it can output load current arbitrarily while keeping the input power relatively small, avoiding the problem of test fixtures being too large to install due to excessive input power.

[0232] exist Figure 9 In this example, the thermal resistance of the frequency converter driver includes the thermal resistance R of the power module. th1 Radiator thermal resistance R th3 and assembly thermal resistance R th2 thermal resistance R of power module th1 and heat sink thermal resistance R th3 The thermal resistance values ​​corresponding to the respective thermal resistance curves at the equilibrium temperature are given. The assembly thermal resistance is the standard thermal resistance R determined in advance based on the heat sink's successful assembly with the power module. th2 .

[0233] The thermal resistance of the power module and the thermal resistance of the heat sink are stable at the equilibrium temperature and will not change. The assembly thermal resistance is a standard thermal resistance, thus the theoretical temperature can be accurately determined.

[0234] exist Figure 10 In the example, the thermal resistance curves of the IGBT and diode of the power module are shown.

[0235] The testing device can evaluate the quality of the heat sink and power module assembly by analyzing the rapid heat source generation, heat transfer path, and driver loss of the designed variable frequency drive. This prevents defective products from leaving the product line and improves the online automated testing rate, ensuring product reliability.

[0236] The detection device can prevent potential damage and abnormal alarms to power devices in the market caused by unreliable or inadequate installation of heat sinks and power modules, thus avoiding customer complaints.

[0237] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0238] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A frequency converter driver detection device, wherein the frequency converter driver comprises: Power modules, including IGBTs and diodes; Heat sink, assembled with power module; Temperature detection module, used to detect the temperature of the power module; The detection device is characterized by comprising: The power supply provides power to the power module; The current detection module detects the IGBT output current and the diode freewheeling current. The voltage detection module detects the IGBT saturation voltage drop and the diode forward voltage drop. The control module is configured as follows: Determine the initial temperature and equilibrium temperature of the power module; The total power module loss at equilibrium temperature is determined based on the IGBT's relative zero temperature coefficient parameters, current, and voltage. Obtain the thermal resistance of the frequency converter driver, determine the theoretical temperature based on the thermal resistance and total loss; determine the theoretical temperature rise based on the theoretical temperature and initial temperature, determine the measured temperature rise based on the equilibrium temperature and initial temperature; determine the deviation value based on the theoretical temperature rise and the measured temperature rise. Obtain the standard deviation value, and compare the deviation value with the standard deviation value to determine whether the heat sink and power module are assembled correctly.

2. The variable frequency drive detection apparatus of claim 1, wherein, The total losses of the power module include IGBT conduction losses, diode conduction losses, IGBT switching losses and diode switching losses determined based on the relative zero temperature coefficient parameter; The control module is configured to determine the IGBT switching loss based on the IGBT turn-on loss and the IGBT turn-off loss. Obtain reference values ​​for the relative zero temperature coefficient current, relative zero temperature coefficient saturation voltage drop, and relative zero temperature coefficient turn-on loss of the IGBT, and determine the IGBT turn-on loss by combining the output current and saturation voltage drop. Obtain reference values ​​for the relative zero temperature coefficient current, relative zero temperature coefficient saturation voltage drop, and relative zero temperature coefficient turn-off loss of the IGBT, and determine the IGBT turn-off loss by combining the output current and saturation voltage drop. Determine diode switching losses based on diode reverse recovery losses; Obtain the diode freewheeling current value under IGBT relative zero temperature coefficient current, the diode forward voltage drop under IGBT relative zero temperature coefficient current, and the reference value of reverse recovery loss under the diode freewheeling current value under IGBT relative zero temperature coefficient current. Combine the freewheeling current value and the forward voltage drop to determine the diode reverse recovery loss.

3. The frequency converter driver detection device according to claim 2, characterized in that, IGBT turn-on loss = Reference value of turn-on loss with relative zero temperature coefficient * (output current / current with relative zero temperature coefficient) * (saturation voltage drop / saturation voltage drop with relative zero temperature coefficient). IGBT turn-off loss = Reference value of turn-off loss with relative zero temperature coefficient * (output current / current with relative zero temperature coefficient) * (saturation voltage drop / saturation voltage drop with relative zero temperature coefficient). Diode reverse recovery loss = Reference value of reverse recovery loss under diode freewheeling current value at IGBT relative zero temperature coefficient current * (Freewheeling current value / Diode freewheeling current value at IGBT zero temperature coefficient current) * (Forward voltage drop / Forward voltage drop at IGBT zero temperature coefficient current).

4. The frequency converter driver detection device according to claim 2, characterized in that, The control module is configured to acquire the switching frequency and duty cycle of the power module; The IGBT conduction loss is determined based on the output current, saturation voltage drop, switching frequency, and duty cycle. IGBT switching losses are determined based on IGBT turn-on losses, turn-off losses, and switching frequency. The diode conduction loss is determined based on the freewheeling current value, forward voltage drop, switching frequency, and duty cycle. The diode switching loss is determined based on the switching frequency and the diode reverse recovery loss.

5. The frequency converter driver detection device according to claim 4, characterized in that, IGBT conduction loss = switching frequency * conduction duty cycle * output current * saturation voltage drop; IGBT switching loss = switching frequency * (IGBT turn-on loss + IGBT turn-off loss); Diode conduction loss = switching frequency * (1 - duty cycle) * freewheeling current * forward voltage drop; Diode switching loss = switching frequency * diode reverse recovery loss.

6. The frequency converter driver detection device according to claim 2, characterized in that, The control module is configured to determine the equilibrium temperature correction factor based on the equilibrium temperature, and then use the equilibrium temperature correction factor to correct the reverse recovery loss of the diode.

7. The frequency converter driver detection device according to claim 1, characterized in that, The power supply includes a three-phase six-pulse rectifier circuit.

8. The frequency converter driver detection device according to claim 1, characterized in that, The thermal resistance of a frequency converter driver includes the thermal resistance of the power module, the thermal resistance of the heat sink, and the assembly thermal resistance. The thermal resistance of the power module and the thermal resistance of the heat sink are the thermal resistance values ​​corresponding to their respective thermal resistance curves at the equilibrium temperature. The assembly thermal resistance is the standard thermal resistance determined in advance based on the heat sink's qualified assembly with the power module.

9. A frequency converter driver detection device, wherein the frequency converter driver comprises: Power modules, including IGBTs and diodes; Heat sink, assembled with power module; Temperature detection module, used to detect the temperature of the power module; The detection device is characterized by comprising: The power supply provides power to the power module; Load, connected to power module; The current detection module detects the IGBT output current. The control module is configured as follows: Determine the initial temperature and equilibrium temperature of the power module; Controlling the load ensures that the IGBT output current has a relative zero temperature coefficient. Determine the total power module loss at equilibrium temperature based on the IGBT's relative zero temperature coefficient parameter; Obtain the thermal resistance of the frequency converter driver, determine the theoretical temperature based on the thermal resistance and total loss; determine the theoretical temperature rise based on the theoretical temperature and initial temperature, determine the measured temperature rise based on the equilibrium temperature and initial temperature; determine the deviation value based on the theoretical temperature rise and the measured temperature rise. Obtain the standard deviation value, and compare the deviation value with the standard deviation value to determine whether the heat sink and power module are assembled correctly.

10. The frequency converter driver detection device according to claim 9, characterized in that, The control module determines the IGBT turn-on loss to be a reference value for turn-on loss with a relative zero temperature coefficient; the IGBT turn-off loss to be a reference value for turn-off loss with a relative zero temperature coefficient. The reverse recovery loss of the diode is a reference value for reverse recovery loss; The control module determines the IGBT conduction loss by using the IGBT's relative zero temperature coefficient current, relative zero temperature coefficient saturation voltage drop, switching frequency, and conduction duty cycle. The control module determines the diode conduction loss by using the diode freewheeling current value under IGBT relative zero temperature coefficient current, the diode forward conduction voltage drop under IGBT relative zero temperature coefficient current, the switching frequency, and the conduction duty cycle.

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