A traction inverter multi-modulation mode loss calculation method

Abstract

The present application relates to the field of power loss calculation of traction inverter, and particularly relates to a kind of loss calculation method of multiple modulation modes of traction inverter, obtains the characteristics of power device of traction inverter;Obtain loss calculation parameters;Conventional power factor angle φ ;According to the specific modulation mode, select power loss calculation analytical expression, carry out loss calculation, obtain the on-state loss, switching loss of IGBT and the on-state loss, switching loss of FWD.The present application gives the loss calculation analytical expression of multiple modulation modes, in order to be suitable for traction and braking condition, the power factor is agreed, and the loss calculation solution in full speed range is given for two-level three-phase traction inverter, that is suitable for product loss design, and is suitable for online loss calculation, and its calculation result has higher accuracy.

Description

Technical Field

[0001] This invention relates to the field of power loss calculation for traction inverters, specifically a method for calculating the loss of traction inverters with multiple modulation modes. Background Technology

[0002] Traction inverters, as a key component of electric locomotives, have always been a focus of research. Semiconductor power devices, as the foundation and core of traction converters, directly determine the performance indicators of the traction converter. Traditional converter power device design only calculates power losses under maximum switching frequency and maximum current conditions during traction operation, assuming the junction temperature corresponding to the maximum loss meets requirements. However, with the deepening of power module reliability research, accurate loss calculations under every operating condition are crucial to obtaining accurate junction temperature curves, accurate thermal stress cycling conditions, and ultimately, reasonable remaining lifespan estimates. Therefore, the current requirement for power loss calculation has shifted to not only accurately calculating the maximum loss value but also accurately calculating the loss under every operating condition.

[0003] Research on power loss calculation and electrothermal characteristic analysis of IGBT converter modules can be broadly divided into two categories: one is the power loss calculation method for two-level inverters published in papers such as 201611255694.9 and 201511032145.0, which only provides analytical expressions for power module loss calculation under SPWM modulation and in inverter mode, but does not consider the loss calculation method under current reversal, i.e., rectification. The other category is a power consumption calculation modeling method for converters published in paper 201510344338.3 using MATLAB / Simulink simulation software. The advantage of this method is that it is not limited by the modulation method and topology circuit, and directly calculates power loss based on the modulation pulse. However, this method relies on the converter model provided by MATLAB / Simulink for offline calculations. When performing online calculations in converter product applications, the computational load is too large, requiring upgrades to the computing hardware, which is difficult to implement in practical applications. Summary of the Invention

[0004] To meet the current demand for calculating the power loss of traction inverters, this invention provides a method for calculating the loss of traction inverters with multiple modulation modes.

[0005] This invention is achieved through the following technical solution: a method for calculating the loss of a traction inverter with multiple modulation modes, comprising the following steps:

[0006] 1) Obtain the characteristics of the power devices in the traction inverter, including the IGBT saturation voltage drop V. ce Curve, turn-on loss curve E on Turn-off loss curve E offFWD saturation pressure drop curve V f Reverse recovery loss curve E rec ;

[0007] 2) Obtain loss calculation parameters, including DC bus voltage U dc Output line voltage peak U ab Phase current amplitude I, switching frequency F sw Electromagnetic sine wave frequency f, power factor

[0008] 3) Conventional power factor angle That is, the positive direction of the current is from the DC side to the load, under traction conditions. Braking conditions

[0009] 4) Select the analytical expression for power loss calculation based on the specific modulation method, perform loss calculation, and obtain the on-state loss P of the IGBT. sal_igbt Switching loss P sw_igbt And the on-state loss P of FWD sal_fwd Switching loss P sw_fwd .

[0010] In this invention, the characteristics mentioned in step 1) are basic requirements. In addition to the characteristics mentioned in step 1), gate resistance characteristics, temperature characteristics, etc. can also be taken into account.

[0011] In step 3), in order to satisfy the power loss calculation under traction and braking conditions, the power factor angle is... The following conventions are used to define the current direction: the positive direction is defined as the current flowing from the DC side to the load. Therefore, the power factor angle under traction and braking conditions is as follows: Figure 3 As shown. It should be noted that the definition of the power factor angle here is different from the definition of the power factor angle in motor applications. It adopts the definition of a four-quadrant operating power system, that is, the power factor can be positive or negative, with positive being the power flowing to the motor side and negative being the power flowing to the DC side.

[0012] As a further improvement to the technical solution of this invention, when the modulation method is SPWM, the analytical expression for calculating power loss in both traction and braking conditions is as follows:

[0013] Adjustment system: IGBT on-state loss: FWD through-state loss: IGBT switching losses: FWD switching losses:

[0014] Where I is the phase current amplitude; V ce0 rce These are the IGBT saturation voltage drops V ce Regarding the current I c The constant term and coefficient of the first-order approximation of the curve; V f0 r f The saturation voltage drop V of FWD is respectively f Regarding the current I f The constant term and coefficient of the first-order approximation of the curve; U dcon_test Test E in the device datasheet on Regarding the current I c The DC-side voltage used when plotting the curve; U dcoff_test Test E in the device datasheet off Regarding the current I c The DC-side voltage used when plotting the curve; U dcrec_test Test E in the device datasheet rec Regarding the current I f DC side voltage used when plotting the curve; k ron To test E according to the device datasheet on Regarding the gate resistor R on Gate correction factor for curve calculation; k roff To test E according to the device datasheet off Regarding the gate turn-off resistor R off Gate correction factor, k, calculated from the curve ron k roff The calculation methods are as follows:

[0015]

[0016]

[0017] Among them, E on_r E is the function expression for the relationship between the gate resistance and current as shown in the device datasheet. off_r R is the function expression for the relationship between the gate resistance and current from the device datasheet. on R is the actual gate resistor used for turn-on. on_test For E on Regarding the gate resistor R used in the current curve measurement... off R is the actual gate resistor used for shutdown. off_test For E off The gate resistor used in the measurement of the current curve.

[0018] As a further improvement to the technical solution of this invention, when the modulation method is third harmonic injection SPWM modulation, the analytical expression for calculating power loss in both traction and braking conditions is as follows:

[0019] Adjustment system: IGBT on-state loss:

[0020]

[0021] FWD through-state loss:

[0022]

[0023] IGBT switching losses: FWD switching losses:

[0024] As a further improvement to the technical solution of this invention, when the modulation method is the middle 60° SPWM modulation, the analytical expression for calculating power loss in both traction and braking conditions is as follows:

[0025] Adjustment system: IGBT on-state loss:

[0026]

[0027] FWD through-state loss:

[0028]

[0029] IGBT switching losses:

[0030]

[0031] FWD switching losses:

[0032] Where k is the parameter for 2k+1 frequency division for the middle 60° modulation. For example, in a 7-frequency division with 60° modulation in the middle, k is 3; in a 3-frequency division with 60° modulation in the middle, k is 1.

[0033] As a further improvement to the technical solution of this invention, when the modulation method is square wave modulation, the analytical expression for calculating power loss in both traction and braking conditions is as follows:

[0034] IGBT on-state loss: FWD through-state loss: IGBT switching losses: FWD switching losses:

[0035] Among them, the square wave modulation switching frequency F sw It is equal to the frequency f of the sine wave.

[0036] In the above technical solution, the IGBT saturation voltage drop V ce FWD saturation pressure drop curve V fThe curve at a single junction temperature is used, but linear interpolation can be performed based on the actual junction temperature.

[0037] The SVPWM modulation method commonly used in inverters can be approximated by the third harmonic injection SPWM modulation described in this invention when the carrier ratio is greater than or equal to 10.

[0038] Regarding the calculation method for the modulation index, the peak output line voltage U used in this invention is... ab It can also be transformed into the effective value of line voltage or the peak or effective value of phase voltage.

[0039] The multi-modulation loss calculation method for traction inverters described in this invention provides analytical expressions for loss calculation of various modulation modes. To be applicable to both traction and braking conditions, the power factor is defined, and a loss calculation solution for two-level three-phase traction inverters across the entire speed range is provided. This solution is suitable for both product loss design and online loss calculation, and its calculation results have higher accuracy. In particular, specific formulas are given for calculating the modulation parameters, using only the DC side voltage and output line voltage. Since traction systems are generally equipped with sensors for measurement, this solution can be implemented without adding any sensors to the existing traction system, demonstrating good economic efficiency. Attached Figure Description

[0040] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific 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 from these drawings without creative effort.

[0041] Figure 1 This is a topology diagram of a two-level three-phase inverter.

[0042] Figure 2 This is a flowchart of the loss calculation method for multi-modulation mode traction inverters described in this invention.

[0043] Figure 3 This is a convention for the power factor angle under different operating conditions. Detailed Implementation

[0044] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Example

[0046] For traction converters in the rail transit industry, multiple modulation methods are typically employed across the entire speed range. In the low-speed region where the carrier ratio is greater than 10, SPWM or third harmonic injection SPWM modulation is commonly used. In the medium-speed region where the carrier ratio is less than 10, a 60° intermediate modulation SPWM modulation method is typically used. In the high-speed region, square wave modulation with a 50% duty cycle is employed. This invention's embodiments illustrate the loss calculation methods for these four modulation methods under traction and braking conditions. Given... Figure 1 The topology is symmetrical, and each IGBT module (including IGBT and FWD) has the same average power loss during the sine wave period. The following calculation is for the average power loss of a power module.

[0047] 1. Device characteristic input

[0048] Power device model: ABB 5SNA 1500E330305

[0049] IGBT saturation on-state voltage drop (first-order approximation): V ce =r ce I c +V ce0 =0.00129I c +1.239

[0050] Diode saturation forward voltage drop (first-order approximation): V f =r f I c +V f0 =0.0007I c +1.1

[0051] Gate resistance correction factor: k ron =1.34;

[0052] Gate turn-off resistance correction factor: k roff =1.01;

[0053] Energy loss during activation E on E on (I c )=1.2616e-10I c 3 -2.66e-7I c 2 +1.6021e-3I c +0.1514 Turn-off energy loss E off :

[0054] E off (I c )=1.4315e-10*I c3 -5.6495e-7I c 2 +2.41e-3I c +0.2166

[0055] Reverse recovery loss energy E rec :

[0056] E rec (I f ) = 1.047e-10I f 3 -7.4605e-7I f 2 +2.1938e-3I f +0.277

[0057] U dcon_test =1800V

[0058] U dcoff_test =1800V

[0059] U dcrec_test =1800V

[0060] 2. SPWM modulation and traction loss calculation

[0061] 2.1 Parameter Input: Electromagnetic sine wave frequency f: 11.72Hz

[0062] Switching frequency F sw 550Hz

[0063] Power factor 0.84

[0064] Phase current amplitude I: 1117.2A

[0065] DC bus voltage U dc 1800V

[0066] Output line voltage peak U ab 696.8V

[0067] 2.2 Loss Calculation:

[0068] Adjustment system IGBT on-state loss: FWD through-state loss: IGBT switching losses:

[0069]

[0070] FWD switching losses:

[0071] 3. SPWM modulation and braking loss calculation

[0072] 3.1 Parameter Input: Electromagnetic sine wave frequency f: 11.72Hz

[0073] Switching frequency F sw 550Hz

[0074] Power factor -0.84

[0075] Phase current amplitude I: 761.8A

[0076] DC bus voltage U dc 1800V

[0077] Output line voltage peak U ab 576.8V

[0078] 3.2 Loss Calculation

[0079] Adjustment system IGBT on-state loss: FWD through-state loss: IGBT switching losses:

[0080]

[0081] FWD switching losses: 4. Third Harmonic Injection SPWM Modulation and Traction Loss Calculation 4.1 Parameter Input Electromagnetic Sine Wave Frequency f: 28.65Hz

[0082] Switching frequency F sw 344Hz

[0083] Power factor 0.86

[0084] Phase current amplitude I: 922.6A

[0085] DC bus voltage U dc 1800V

[0086] Output line voltage peak U ab :1566V

[0087] 4.2 Loss Calculation

[0088] Adjustment system: IGBT on-state loss:

[0089]

[0090] FWD through-state loss:

[0091]

[0092] IGBT switching losses:

[0093]

[0094] FWD switching losses: 5. Third Harmonic Injection SPWM Modulation and Braking Loss Calculation 5.1 Parameter Input Electromagnetic Sine Wave Frequency f: 28.65Hz

[0095] Switching frequency F sw 344Hz

[0096] Power factor -0.86

[0097] Phase current amplitude I: 764.4A

[0098] DC bus voltage U dc 1800V

[0099] Output line voltage peak U ab 1448V

[0100] 5.2 Loss Calculation

[0101] Adjustment system: IGBT on-state loss:

[0102]

[0103] FWD through-state loss:

[0104]

[0105] IGBT switching losses:

[0106]

[0107] FWD switching losses: 6. Calculation of traction loss under 60° SPWM 7-way frequency division modulation and traction conditions. 6.1 Parameter Input: Electromagnetic sine wave frequency f: 31.4Hz

[0108] Frequency division number: 7, corresponding to k = 3

[0109] Power factor 0.865

[0110] Phase current amplitude I: 892.4A

[0111] DC bus voltage U dc 1800V

[0112] Output line voltage peak Uab :1683V

[0113] 6.2 Loss Calculation

[0114] Adjustment system: IGBT on-state loss:

[0115]

[0116] FWD through-state loss:

[0117]

[0118] IGBT switching losses:

[0119]

[0120] FWD switching losses: 7. Calculation of losses during braking operation using 60° SPWM 7-way frequency division modulation. 7.1 Parameter Input: Electromagnetic sine wave frequency f: 31.4Hz

[0121] Frequency division number: 7, corresponding to k = 3

[0122] Power factor -0.865

[0123] Phase current amplitude I: 768.2A

[0124] DC bus voltage U dc 1800V

[0125] Output line voltage peak U ab 1585V

[0126] 7.2 Loss Calculation

[0127] Adjustment system: IGBT on-state loss:

[0128]

[0129] FWD through-state loss:

[0130]

[0131] IGBT switching losses:

[0132]

[0133] FWD switching losses:

[0134] 8. Square wave modulation and traction loss calculation

[0135] 8.1 Parameter Input: Electromagnetic sine wave frequency f: 70.63Hz

[0136] Switching frequency F sw 70.63Hz

[0137] Power factor 0.932

[0138] Phase current amplitude I: 775.7A

[0139] DC bus voltage U dc 1800V

[0140] 8.2 Loss Calculation:

[0141] IGBT on-state loss: FWD through-state loss: IGBT switching losses: FWD switching losses:

[0142] 9. Calculation of losses under square wave modulation and braking conditions

[0143] 9.1 Parameter Input: Electromagnetic sine wave frequency f: 70.63Hz

[0144] Switching frequency F sw 70.63Hz

[0145] Power factor -0.96

[0146] Phase current amplitude I: 742A

[0147] DC bus voltage U dc 1800V

[0148] 9.2 Loss Calculation:

[0149] IGBT on-state loss: FWD through-state loss: IGBT switching losses: FWD switching losses:

[0150] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating the losses of a traction inverter with multiple modulation modes, characterized in that, Includes the following steps: 1) Obtain the characteristics of the power devices in the traction inverter, including the IGBT saturation voltage drop. Curve, turn-on loss Curve, turn-off loss Curve, FWD saturation pressure drop Curve, reverse recovery loss curve; 2) Obtain loss calculation parameters, including DC bus voltage. Peak output line voltage Phase current amplitude Switching frequency Electromagnetic sine wave frequency Power factor ; 3) Conventional power factor angle That is, the positive direction of the current is from the DC side to the load, under traction conditions. Under braking conditions ; 4) Select the analytical expression for power loss calculation based on the specific modulation method, perform loss calculation, and obtain the on-state loss of the IGBT. Switching losses and the on-state loss of FWD Switching losses ; When the modulation method is third harmonic injection SPWM modulation, the analytical expression for calculating power loss in both traction and braking conditions is as follows: Adjustment system: ; IGBT on-state loss: ; FWD through-state loss: ; IGBT switching losses: ; FWD switching losses: ; in, This refers to the phase current amplitude. , IGBT saturation voltage drop Regarding current The constant term and coefficients of the first-order approximation of the curve; , FWD saturation pressure drop Regarding current The constant term and coefficients of the first-order approximation of the curve; Test for the device datasheet Regarding current The DC-side voltage used when plotting the curve; Test for the device datasheet Regarding current The DC-side voltage used when plotting the curve; Test for the device datasheet Regarding current The DC-side voltage used when plotting the curve; To test according to the device datasheet Regarding the gate resistor Gate correction factor for curve calculation; To test according to the device datasheet Regarding the gate turn-off resistor Gate correction factor for curve calculation.

2. A method for calculating the losses of a traction inverter with multiple modulation modes, characterized in that, Includes the following steps: 1) Obtain the characteristics of the power devices in the traction inverter, including the IGBT saturation voltage drop. Curve, turn-on loss Curve, turn-off loss Curve, FWD saturation pressure drop Curve, reverse recovery loss curve; 2) Obtain loss calculation parameters, including DC bus voltage. Peak output line voltage Phase current amplitude Switching frequency Electromagnetic sine wave frequency Power factor ; 3) Conventional power factor angle That is, the positive direction of the current is from the DC side to the load, under traction conditions. Under braking conditions ; 4) Select the analytical expression for power loss calculation based on the specific modulation method, perform loss calculation, and obtain the on-state loss of the IGBT. Switching losses and the on-state loss of FWD Switching losses ; When the modulation method is square wave modulation, the analytical expression for calculating power loss in both traction and braking conditions is as follows: IGBT on-state loss: ; FWD through-state loss: ; IGBT switching losses: ; FWD switching losses: ; Among them, the square wave modulation switching frequency Equal to the frequency of a sine wave ; This refers to the phase current amplitude. , IGBT saturation voltage drop Regarding current The constant term and coefficients of the first-order approximation of the curve; , FWD saturation pressure drop Regarding current The constant term and coefficients of the first-order approximation of the curve; Test for the device datasheet Regarding current The DC-side voltage used when plotting the curve; Test for the device datasheet Regarding current The DC-side voltage used when plotting the curve; To test according to the device datasheet Regarding the gate resistor Gate correction factor for curve calculation; This indicates that the current of the IGBT is The corresponding activation loss at that time; The current of FWD is The corresponding reverse recovery loss.

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