Screening Methods for Isolated DC-DC Converters in High-Voltage Power Supplies for Electric Vehicles

Abstract

This invention discloses a screening method for isolated DC-DC converters for high-voltage power supplies in electric vehicles. It comprehensively considers the impact of switching frequency on isolated DC-DC converters for high-voltage power supplies, and evaluates five indicators affected by switching frequency—voltage ripple, efficiency, temperature rise, EMC, and volume—using a weighted function, and then screens them to select isolated DC-DC converters with more balanced performance across the five indicators as the isolated DC-DC converters for high-voltage power supplies in electric vehicles.

Description

Technical Field

[0001] This invention belongs to the field of high-voltage power supplies for electric vehicles, and specifically relates to a screening method for isolated DC-DC converters in high-voltage power supplies for electric vehicles. Background Technology

[0002] With the development of new energy vehicles, integration has become mainstream. Simultaneously, increasing component integration, miniaturizing component size, and reducing weight have become trends. Electric vehicle high-voltage power supply systems generally include rectifier and filter circuits, PFC, and isolated DC-DC converters. For electric vehicle high-voltage power supply systems, there are numerous inductors, capacitors, switching transistors, and transformers. High-frequency switching of the switching transistors (including IGBTs and MOSFETs) in the isolated DC-DC converter is the most direct and effective way to reduce the size parameters of circuit components. However, excessively high switching frequencies can bring a series of problems, including ripple, temperature rise, efficiency, performance, and cost. Finding a suitable isolated DC-DC converter and its corresponding switching frequency is a problem that needs to be solved in electric vehicle high-voltage power supply systems.

[0003] CN105703607A discloses a device and method for setting the switching frequency of a switching transistor. It provides a scheme for setting the switching frequency of a switching transistor in a UPS (Uninterruptible Power Supply) system. This scheme uses a load calculation module and a temperature rise calculation module to calculate the switching frequency using first and second frequencies respectively, and finally selects the smaller frequency. This scheme can improve device efficiency while meeting the junction temperature requirements of the switching transistor. However, the selected switching frequency lacks consideration for circuit voltage ripple, circuit board size, and EMC test results. Summary of the Invention

[0004] The purpose of this invention is to provide a screening method for isolated DC-DC converters in high-voltage power supplies for electric vehicles, so as to screen out isolated DC-DC converters with more balanced performance.

[0005] The method for screening isolated DC-DC converters for high-voltage power supplies in electric vehicles according to the present invention includes:

[0006] The first step is to select n different isolated DC-DC converters and n different corresponding switching frequencies.

[0007] The second step is to determine the voltage ripple, efficiency, temperature rise, EMC overshoot percentage, and total component volume percentage of the i-th isolated DC-DC converter. Here, i takes any integer from 1 to n.

[0008] Step 3: Determine the ripple measurement value X corresponding to the voltage ripple of the i-th isolated DC-DC converter. i Determine the efficiency metric Y corresponding to the efficiency of the i-th isolated DC-DC converter.i Determine the temperature rise measure Z corresponding to the temperature rise of the i-th isolated DC-DC converter. i Determine the EMC measurement value R corresponding to the percentage of EMC exceeding the baseline for the i-th isolated DC-DC converter. i Determine the volume measure S corresponding to the total volume ratio of the components in the i-th isolated DC-DC converter. i .

[0009] Step 4: Using the weighted function: f(i) = a*X i +b*Y i +c*Z i +d*R i +e*S i Calculate the evaluation value f(i) of the i-th isolated DC-DC converter to obtain n evaluation values ​​(i.e., f(1), f(2), ..., f(n)) for n isolated DC-DC converters. Here, a represents the preset ripple measurement weight, b represents the preset efficiency measurement weight, c represents the preset temperature rise measurement weight, d represents the preset EMC measurement weight, and e represents the preset volume measurement weight, a+b+c+d+e=1.

[0010] Step 5: If there is only one maximum value among the n evaluation values, then the isolated DC-DC converter corresponding to the maximum value among the n evaluation values ​​shall be used as the isolated DC-DC converter for the high-voltage power supply of the electric vehicle; if there are j maximum values ​​among the n evaluation values ​​and j≥2 (that is, the maximum values ​​among the n evaluation values ​​are j equal values ​​and j≥2), then according to the requirements of the high-voltage power supply of the electric vehicle, one isolated DC-DC converter shall be selected from the j isolated DC-DC converters corresponding to the j maximum values ​​among the n evaluation values ​​as the isolated DC-DC converter for the high-voltage power supply of the electric vehicle.

[0011] Preferably, based on the requirements of the high-voltage power supply for electric vehicles, the method for selecting one isolated DC-DC converter from the j isolated DC-DC converters corresponding to the j maximum values ​​of n evaluation values ​​as the isolated DC-DC converter for the high-voltage power supply of electric vehicles is as follows: the selection is based on the following priority: the largest volume value is the first priority, the largest efficiency value is the second priority, the largest ripple value is the third priority, the largest temperature rise value is the fourth priority, and the largest EMC value is the fifth priority.

[0012] Using the largest volume metric as the first priority for further screening yields isolated DC-DC converters with the highest evaluation value and smallest size. If no converter can be found based on the largest volume metric (i.e., there are two or more maximum volume metric values), then screening based on the largest efficiency metric yields isolated DC-DC converters with the highest evaluation value, smallest size, and high efficiency. If no converter can be found based on the largest efficiency metric (i.e., there are two or more maximum efficiency metric values), then screening based on the largest ripple metric yields isolated DC-DC converters with the highest evaluation value, smallest size, high efficiency, and low voltage ripple. If no converter can be found based on the largest ripple metric (i.e., there are two or more maximum ripple metric values), then screening based on the largest temperature rise metric yields isolated DC-DC converters with the highest evaluation value, smallest size, high efficiency, low voltage ripple, and low temperature rise. If no suitable DC-DC converter can be found by using the maximum temperature rise value (i.e., there are two or more maximum temperature rise values), then filter by the maximum EMC value. This will yield an isolated DC-DC converter with the highest evaluation value, smaller size, higher efficiency, lower voltage ripple, lower temperature rise, and a smaller percentage of EMC values ​​exceeding the baseline.

[0013] Preferably, there are two ways to determine the voltage ripple of the i-th isolated DC-DC converter.

[0014] The first method is to make the i-th isolated DC-DC converter operate at the corresponding i-th switching frequency f. i Even if the i-th isolated DC-DC converter is working, and the switching frequency of each switch of the i-th isolated DC-DC converter is the corresponding i-th switching frequency f. i ), Measure the input voltage U of the i-th isolated DC-DC converter. 0i Output voltage U 1i Then, using the formula: The voltage ripple ΔU of the i-th isolated DC-DC converter is calculated. i ; where f i L represents the i-th switching frequency corresponding to the i-th isolated DC-DC converter. i Let C represent the resonant inductance of the i-th isolated DC-DC converter. i L represents the resonant capacitance of the i-th isolated DC-DC converter. i C i All parameters are known.

[0015] The second method is to make the i-th isolated DC-DC converter operate at the corresponding i-th switching frequency f. iTo perform the operation, an oscilloscope is connected to the output terminal of the i-th isolated DC-DC converter. The voltage ripple ΔU of the i-th isolated DC-DC converter is measured using the oscilloscope. i This method is relatively simple, but it requires the use of an oscilloscope.

[0016] Preferably, the efficiency of the i-th isolated DC-DC converter is determined by setting the i-th isolated DC-DC converter to operate at the corresponding i-th switching frequency f. i Work to measure the input voltage U of the i-th isolated DC-DC converter. 0i Input current I 0i Output voltage U 1i Output current I 1i Then, using the formula: The efficiency η of the i-th isolated DC-DC converter is calculated. i .

[0017] Preferably, the method for determining the temperature rise of the i-th isolated DC-DC converter is as follows:

[0018] First, select multiple acquisition points in the i-th isolated DC-DC converter, and place a temperature sensor at each acquisition point.

[0019] Secondly, the i-th isolated DC-DC converter is switched at the corresponding i-th switching frequency f. i Work.

[0020] Then, based on the temperature values ​​collected by the temperature sensors at each collection point, the temperature rise value at each collection point is calculated.

[0021] Finally, the average temperature rise values ​​at all sampling points are calculated, and the resulting average value is taken as the temperature rise T of the i-th isolated DC-DC converter. i Alternatively, the maximum value among all temperature rise values ​​collected can be used as the temperature rise T of the i-th isolated DC-DC converter. i .

[0022] Preferably, the method for determining the EMC overshoot ratio of the i-th isolated DC-DC converter is as follows:

[0023] First, the i-th isolated DC-DC converter is switched at the corresponding i-th switching frequency f. i Work.

[0024] Secondly, EMC tests are performed on the i-th isolated DC-DC converter under the preset overall frequency band to obtain the EMC noise-frequency curve of the i-th isolated DC-DC converter.

[0025] Then, based on the EMC noise-frequency curve of the i-th isolated DC-DC converter, the bandwidth Δf corresponding to the EMC exceeding the baseline is analyzed. i .

[0026] Finally, using the formula: The EMC over-baseline ratio pe of the i-th isolated DC-DC converter was calculated. i ;wherein, Δf all This indicates the bandwidth corresponding to the preset overall frequency band.

[0027] Preferably, the method for determining the total volume percentage of components in the i-th isolated DC-DC converter is as follows:

[0028] First, a 3D model of all components of the i-th isolated DC-DC converter is created.

[0029] Then, the total volume V of the components is calculated based on the 3D model. i .

[0030] Finally, using the formula: The total component volume ratio (pv) of the i-th isolated DC-DC converter was calculated. i Among them, V all This indicates the preset total volume of the high-voltage power supply, which is the volume corresponding to the allowable space of the high-voltage power supply on the electric vehicle.

[0031] Preferably, the preset weights for ripple measurement (a), efficiency measurement (b), temperature rise measurement (c), EMC measurement (d), and volume measurement (e) also satisfy the following condition: e > b > a > c > d. Setting the volume measurement weight to the maximum slightly emphasizes the small size of the selected isolated DC-DC converters for electric vehicle high-voltage power supplies.

[0032] Preferably, the ripple measurement value X corresponding to the voltage ripple of the i-th isolated DC-DC converter is determined. i The method is as follows: based on the voltage ripple of the i-th isolated DC-DC converter, look up the preset ripple measurement value table to obtain the corresponding ripple measurement value X. i The preset ripple measurement table is a table showing the correspondence between voltage ripple and ripple measurement values. The smaller the voltage ripple, the larger the ripple measurement value.

[0033] Preferably, the efficiency measure Y corresponding to the efficiency of the i-th isolated DC-DC converter is determined. i The method is as follows: based on the efficiency of the i-th isolated DC-DC converter, look up the preset efficiency measurement table to obtain the corresponding efficiency measurement value Y. iAmong them, the preset efficiency measurement value table is a correspondence table between efficiency and efficiency measurement value. The higher the efficiency, the larger the efficiency measurement value.

[0034] Preferably, the temperature rise measurement value Z corresponding to the temperature rise of the i-th isolated DC-DC converter is determined. i The method is as follows: based on the temperature rise of the i-th isolated DC-DC converter, look up the preset temperature rise measurement table to obtain the corresponding temperature rise measurement value Z. i The preset temperature rise measurement table is a table showing the correspondence between temperature rise and temperature rise measurement value. The smaller the temperature rise, the larger the temperature rise measurement value.

[0035] Preferably, the EMC measurement value R corresponding to the percentage of EMC exceeding the baseline for the i-th isolated DC-DC converter is determined. i The method is as follows: based on the percentage of EMC exceeding the baseline of the i-th isolated DC-DC converter, query the preset EMC measurement value table to obtain the corresponding EMC measurement value R. i The preset EMC measurement value table is a table showing the correspondence between the percentage of EMC exceeding the baseline and the EMC measurement value. The smaller the percentage of EMC exceeding the baseline, the larger the EMC measurement value.

[0036] Preferably, the volume measurement value S corresponding to the total volume ratio of the components in the i-th isolated DC-DC converter is determined. i The method is as follows: based on the total volume ratio of the components in the i-th isolated DC-DC converter, a preset volume measurement value table is consulted to obtain the corresponding volume measurement value S. i The preset volume measurement value table is a table showing the correspondence between the total volume ratio of components and the volume measurement value. The smaller the total volume ratio of components, the larger the volume measurement value.

[0037] This invention comprehensively considers the impact of switching frequency on isolated DC-DC converters for high-voltage power supplies. It evaluates five performance indicators affected by switching frequency—voltage ripple, efficiency, temperature rise, EMC, and size—using a weighted function, and then filters them to select isolated DC-DC converters with a more balanced performance across these five indicators for use in electric vehicle high-voltage power supplies. Furthermore, in practical applications, the weighting coefficients can be adjusted according to specific product requirements, making product design more targeted; it can also achieve a balance between product performance and economy, or emphasize a particular aspect. This invention has significant implications for the design of the entire high-voltage power supply system. Attached Figure Description

[0038] Figure 1 This is the circuit schematic of the isolated DC-DC converter selected in this embodiment.

[0039] Figure 2This is a flowchart illustrating the screening method for isolated DC-DC converters in the high-voltage power supply of electric vehicles in this embodiment.

[0040] Figure 3 This is a flowchart for determining the temperature rise of the i-th isolated DC-DC converter in this embodiment.

[0041] Figure 4 This is a flowchart for determining the EMC over-baseline percentage of the i-th isolated DC-DC converter in this embodiment.

[0042] Figure 5 This is a flowchart for determining the total volume percentage of components in the i-th isolated DC-DC converter in this embodiment. Detailed Implementation

[0043] like Figures 1 to 5 As shown, the screening method for isolated DC-DC converters in the high-voltage power supply of electric vehicles in this embodiment includes:

[0044] Step 1: Select n different isolated DC-DC converters and n different corresponding switching frequencies, and then proceed to Step 2.

[0045] Step 2: Determine the voltage ripple, efficiency, temperature rise, EMC over-baseline percentage, and total component volume percentage of the i-th isolated DC-DC converter, and then proceed to Step 3. Here, i takes any integer from 1 to n.

[0046] Switching frequency affects the voltage ripple of isolated DC-DC converters, and voltage ripple affects the stability of high-voltage power supplies. Therefore, voltage ripple must be considered during the selection process.

[0047] The voltage ripple of the i-th isolated DC-DC converter is determined by setting the i-th isolated DC-DC converter to the corresponding i-th switching frequency f. i Work (i.e.) Figure 1 The switching frequencies of transistors Q1 to Q8 are f i Using an oscilloscope connected to the output of the i-th isolated DC-DC converter, the voltage ripple ΔU of the i-th isolated DC-DC converter is measured using the oscilloscope. i .

[0048] Alternatively, as another embodiment, the voltage ripple of the i-th isolated DC-DC converter can also be determined by making the i-th isolated DC-DC converter operate at the corresponding i-th switching frequency f. i Work (i.e.) Figure 1 The switching frequencies of transistors Q1 to Q8 are f i ), Measure the input voltage U of the i-th isolated DC-DC converter. 0i Output voltage U1i Using the formula: The voltage ripple ΔU of the i-th isolated DC-DC converter is calculated. i ; where f i L represents the i-th switching frequency corresponding to the i-th isolated DC-DC converter. i This represents the resonant inductance of the i-th isolated DC-DC converter (i.e., Figure 1 Lr1), C i This represents the resonant capacitance of the i-th isolated DC-DC converter (i.e., Figure 1 Cr1), L i C i All parameters are known.

[0049] Switching frequency affects the efficiency of isolated DC-DC converters, so efficiency should be considered during the selection process.

[0050] The efficiency of the i-th isolated DC-DC converter is determined by setting the i-th isolated DC-DC converter to operate at the corresponding i-th switching frequency f. i Work to measure the input voltage U of the i-th isolated DC-DC converter. 0i Input current I 0i Output voltage U 1i Output current I 1i Then, using the formula: The efficiency η of the i-th isolated DC-DC converter is calculated. i .

[0051] Switching frequency affects the temperature rise of isolated DC-DC converters, so temperature rise should be considered during screening.

[0052] like Figure 3 As shown, the method for determining the temperature rise of the i-th isolated DC-DC converter is as follows:

[0053] First, select multiple acquisition points in the i-th isolated DC-DC converter, and place a temperature sensor at each acquisition point.

[0054] Secondly, the i-th isolated DC-DC converter is switched at the corresponding i-th switching frequency f. i Work.

[0055] Then, based on the temperature values ​​collected by the temperature sensors at each collection point, the temperature rise value at each collection point is calculated.

[0056] Finally, the average temperature rise values ​​at all sampling points are calculated, and the resulting average value is taken as the temperature rise T of the i-th isolated DC-DC converter. iAlternatively, as another embodiment, the maximum value among all the temperature rise values ​​collected can be used as the temperature rise T of the i-th isolated DC-DC converter. i .

[0057] The switching frequency affects the EMC over-baseline percentage of isolated DC-DC converters, so the EMC over-baseline percentage should be considered during the selection process.

[0058] like Figure 4 As shown, the method for determining the EMC overshoot ratio of the i-th isolated DC-DC converter is as follows:

[0059] First, the i-th isolated DC-DC converter is switched at the corresponding i-th switching frequency f. i Work.

[0060] Secondly, EMC tests are performed on the i-th isolated DC-DC converter under the preset overall frequency band to obtain the EMC noise-frequency curve of the i-th isolated DC-DC converter.

[0061] Then, based on the EMC noise-frequency curve of the i-th isolated DC-DC converter, the bandwidth Δf corresponding to the EMC exceeding the baseline is analyzed. i The EMC baseline is a horizontal straight line within the preset overall frequency band. The EMC noise-frequency curve is a curve that intersects with or does not intersect with the EMC baseline. If there is no intersection, the bandwidth of the EMC exceeding the baseline is equal to 0. If there is an intersection, the bandwidth of the EMC exceeding the baseline is obtained by subtracting the intersection frequency points.

[0062] Finally, using the formula: The EMC over-baseline ratio pe of the i-th isolated DC-DC converter was calculated. i ;wherein, Δf all This indicates the bandwidth corresponding to the preset overall frequency band.

[0063] The higher the switching frequency of an isolated DC-DC converter, the smaller the parameter values ​​of its inductors, capacitors, and transformers will be, and the smaller the size of the inductors, capacitors, and transformers will be. This results in a smaller overall circuit size for the isolated DC-DC converter. Therefore, the proportion of the total component volume must be considered during component selection.

[0064] like Figure 5 As shown, the method for determining the total volume percentage of components in the i-th isolated DC-DC converter is as follows:

[0065] First, a 3D model of all components of the i-th isolated DC-DC converter is created (the method of creation is existing technology).

[0066] Then, based on the established 3D model, the total volume V of the components was calculated.i (Mainly includes capacitor volume, inductor volume, and transformer volume).

[0067] Finally, using the formula: The total component volume ratio (pv) of the i-th isolated DC-DC converter was calculated. i Among them, V all This indicates the preset total volume of the high-voltage power supply, which is the volume corresponding to the allowable space of the high-voltage power supply on the electric vehicle.

[0068] Step 3: Determine the ripple measurement value X corresponding to the voltage ripple of the i-th isolated DC-DC converter. i Determine the efficiency metric Y corresponding to the efficiency of the i-th isolated DC-DC converter. i Determine the temperature rise measure Z corresponding to the temperature rise of the i-th isolated DC-DC converter. i Determine the EMC measurement value R corresponding to the percentage of EMC exceeding the baseline for the i-th isolated DC-DC converter. i Determine the volume measurement value S corresponding to the total volume ratio of the components in the i-th isolated DC-DC converter. i Then proceed to step four.

[0069] Determine the ripple measure X corresponding to the voltage ripple of the i-th isolated DC-DC converter. i The method is as follows: based on the voltage ripple ΔU of the i-th isolated DC-DC converter i Query the preset ripple measurement value table to obtain the corresponding ripple measurement value X. i The preset ripple measurement table is a table showing the correspondence between voltage ripple and ripple measurement values. The smaller the voltage ripple, the larger the ripple measurement value.

[0070] Determine the efficiency metric Y corresponding to the efficiency of the i-th isolated DC-DC converter. i The method is as follows: based on the efficiency η of the i-th isolated DC-DC converter i Query the preset efficiency measurement value table to obtain the corresponding efficiency measurement value Y. i Among them, the preset efficiency measurement value table is a correspondence table between efficiency and efficiency measurement value. The higher the efficiency, the larger the efficiency measurement value.

[0071] Determine the temperature rise measurement value Z corresponding to the temperature rise of the i-th isolated DC-DC converter. i The method is as follows: based on the temperature rise T of the i-th isolated DC-DC converter i Query the preset temperature rise measurement table to obtain the corresponding temperature rise measurement value Z. i The preset temperature rise measurement table is a table showing the correspondence between temperature rise and temperature rise measurement value. The smaller the temperature rise, the larger the temperature rise measurement value.

[0072] Determine the EMC measurement value R corresponding to the percentage of EMC exceeding the baseline for the i-th isolated DC-DC converter. i The method is as follows: based on the EMC over-baseline ratio pe of the i-th isolated DC-DC converter. i Query the preset EMC measurement value table to obtain the corresponding EMC measurement value R. i The preset EMC measurement value table is a table showing the correspondence between the percentage of EMC exceeding the baseline and the EMC measurement value. The smaller the percentage of EMC exceeding the baseline, the larger the EMC measurement value.

[0073] Determine the volume measurement value S corresponding to the total volume ratio of the components in the i-th isolated DC-DC converter. i The method is as follows: based on the total volume ratio (pv) of the components in the i-th isolated DC-DC converter. i Query the preset volume measurement value table to obtain the corresponding volume measurement value S. i The preset volume measurement value table is a table showing the correspondence between the total volume ratio of components and the volume measurement value. The smaller the total volume ratio of components, the larger the volume measurement value.

[0074] Step 4: Using the weighted function: f(i) = a*X i +b*Y i +c*Z i +d*R i +e*S i Calculate the evaluation value f(i) of the i-th isolated DC-DC converter to obtain n evaluation values ​​(i.e., f(1), f(2), ..., f(n)) for n isolated DC-DC converters; then execute step five. Where a represents the preset ripple measurement weight, b represents the preset efficiency measurement weight, c represents the preset temperature rise measurement weight, d represents the preset EMC measurement weight, and e represents the preset volume measurement weight, a+b+c+d+e=1. The specific values ​​of a, b, c, d, and e are preset according to the application scenario and focus. As an example, in this embodiment, a=0.2, b=0.25, c=0.15, d=0.1, and e=0.3.

[0075] Step 5: Determine if there is only one maximum value among the n evaluation values. If so, proceed to step 6; otherwise (i.e., when there are j equal values ​​among the n evaluation values ​​and j≥2), proceed to step 7.

[0076] Step 6: Select the isolated DC-DC converter corresponding to the maximum value among the n evaluation values ​​as the isolated DC-DC converter for the high-voltage power supply of the electric vehicle, and then end.

[0077] Step 7: Next, prioritize the largest volume measurement value (first priority), largest efficiency measurement value (second priority), largest ripple measurement value (third priority), largest temperature rise measurement value (fourth priority), and largest EMC measurement value (fifth priority). From the j isolated DC-DC converters corresponding to the j largest values ​​out of n evaluation values, select one isolated DC-DC converter as the isolated DC-DC converter for the electric vehicle's high-voltage power supply. For example: if there are four largest values ​​out of n evaluation values, the largest volume measurement value is used as the basis for selection; if there is only one largest volume measurement value, the isolated DC-DC converter corresponding to that largest volume measurement value is selected as the isolated DC-DC converter for the electric vehicle's high-voltage power supply; if there are two equal largest volume measurement values, the largest efficiency measurement value is used as the basis for selection; if there is only one largest efficiency measurement value, the isolated DC-DC converter corresponding to that largest efficiency measurement value is selected as the isolated DC-DC converter for the electric vehicle's high-voltage power supply; and so on, until the final isolated DC-DC converter for the electric vehicle's high-voltage power supply is selected.

Claims

1. A method for screening isolated DC-DC converters for high-voltage power supplies in electric vehicles, characterized in that, include: The first step is to select n different isolated DC-DC converters and n different corresponding switching frequencies; The second step is to determine the voltage ripple, efficiency, temperature rise, EMC over-baseline percentage, and total component volume percentage of the i-th isolated DC-DC converter. Where i takes all integers from 1 to n; Step 3: Determine the ripple measurement value X corresponding to the voltage ripple of the i-th isolated DC-DC converter. i ; Determine the efficiency metric Y corresponding to the efficiency of the i-th isolated DC-DC converter. i Determine the temperature rise measure Z corresponding to the temperature rise of the i-th isolated DC-DC converter. i Determine the EMC measurement value R corresponding to the percentage of EMC exceeding the baseline for the i-th isolated DC-DC converter. i Determine the volume measurement value S corresponding to the total volume ratio of the components in the i-th isolated DC-DC converter. i ; Step 4: Using a weighted function: Calculate the evaluation value of the i-th isolated DC-DC converter. We obtain n evaluation values ​​for n isolated DC-DC converters; where a represents the preset ripple measurement weight, b represents the preset efficiency measurement weight, c represents the preset temperature rise measurement weight, d represents the preset EMC measurement weight, e represents the preset volume measurement weight, and a+b+c+d+e=1. Step 5: If there is only one maximum value among the n evaluation values, then the isolated DC-DC converter corresponding to the maximum value among the n evaluation values ​​is used as the isolated DC-DC converter for the high-voltage power supply of the electric vehicle; if there are j maximum values ​​among the n evaluation values ​​and Then, based on the requirements of the high-voltage power supply of the electric vehicle, one isolated DC-DC converter is selected from the j isolated DC-DC converters corresponding to the j maximum values ​​of the n evaluation values ​​as the isolated DC-DC converter for the high-voltage power supply of the electric vehicle. The method for determining the EMC overshoot ratio of the i-th isolated DC-DC converter is as follows: First, the i-th isolated DC-DC converter is made to operate at the corresponding i-th switching frequency; Secondly, EMC tests are performed on the i-th isolated DC-DC converter under the preset overall frequency band to obtain the EMC noise-frequency curve of the i-th isolated DC-DC converter; Then, based on the EMC noise-frequency curve of the i-th isolated DC-DC converter, the bandwidth corresponding to the EMC exceeding the baseline is analyzed. ; Finally, using the formula: The EMC over-baseline ratio of the i-th isolated DC-DC converter was calculated. ;in, This indicates the bandwidth corresponding to the preset overall frequency band.

2. The screening method for isolated DC-DC converters for high-voltage power supplies in electric vehicles according to claim 1, characterized in that, Based on the high-voltage power supply requirements of electric vehicles, the method for selecting one isolated DC-DC converter from the j isolated DC-DC converters corresponding to the j maximum values ​​among n evaluation values ​​as the isolated DC-DC converter for the high-voltage power supply of electric vehicles is as follows: The selection criteria are as follows: highest volume measurement value is the first priority, highest efficiency measurement value is the second priority, highest ripple measurement value is the third priority, highest temperature rise measurement value is the fourth priority, and highest EMC measurement value is the fifth priority.

3. The screening method for isolated DC-DC converters for high-voltage power supplies in electric vehicles according to claim 1, characterized in that, The method for determining the voltage ripple of the i-th isolated DC-DC converter is as follows: Operate the i-th isolated DC-DC converter at the corresponding i-th switching frequency, and measure the input voltage of the i-th isolated DC-DC converter. Output voltage ; Using the formula: The voltage ripple of the i-th isolated DC-DC converter is calculated. ;in, This represents the i-th switching frequency corresponding to the i-th isolated DC-DC converter. Let i represent the resonant inductance of the i-th isolated DC-DC converter. This represents the resonant capacitance of the i-th isolated DC-DC converter. , All parameters are known.

4. The screening method for isolated DC-DC converters for high-voltage power supplies in electric vehicles according to claim 1, characterized in that, The voltage ripple of the i-th isolated DC-DC converter is determined as follows: The i-th isolated DC-DC converter is operated at its corresponding i-th switching frequency. An oscilloscope is connected to the output of the i-th isolated DC-DC converter, and the voltage ripple of the i-th isolated DC-DC converter is measured using the oscilloscope. .

5. The screening method for isolated DC-DC converters for high-voltage power supplies in electric vehicles according to claim 1, characterized in that, The efficiency of the i-th isolated DC-DC converter is determined as follows: Operate the i-th isolated DC-DC converter at the corresponding i-th switching frequency, and measure the input voltage of the i-th isolated DC-DC converter. Input current Output voltage Output current ; Using the formula: The efficiency of the i-th isolated DC-DC converter is calculated. .

6. The screening method for isolated DC-DC converters for high-voltage power supplies in electric vehicles according to claim 1, characterized in that, The method for determining the temperature rise of the i-th isolated DC-DC converter is as follows: First, select multiple acquisition points in the i-th isolated DC-DC converter, and place a temperature sensor at each acquisition point; Secondly, the i-th isolated DC-DC converter is made to operate at the corresponding i-th switching frequency; Then, based on the temperature values ​​collected by the temperature sensors at each collection point, the temperature rise value at each collection point is calculated; Finally, the average temperature rise values ​​at all sampling points are calculated, and the average value is taken as the temperature rise T of the i-th isolated DC-DC converter. i ; Alternatively, the maximum value among all temperature rise values ​​collected can be used as the temperature rise T of the i-th isolated DC-DC converter. i .

7. The screening method for isolated DC-DC converters for high-voltage power supplies in electric vehicles according to claim 1, characterized in that, The method for determining the total component volume percentage of the i-th isolated DC-DC converter is as follows: First, establish 3D models of all components of the i-th isolated DC-DC converter; Then, the total volume V of the components is calculated based on the 3D model. i ; Finally, using the formula: The total volume ratio of components in the i-th isolated DC-DC converter is calculated. ; Among them, V all This indicates the preset total volume of the high-voltage power supply, which is the volume corresponding to the allowable space of the high-voltage power supply on the electric vehicle.

8. The screening method for isolated DC-DC converters for high-voltage power supplies in electric vehicles according to claim 1, characterized in that: a, b, c, d, and e also satisfy: .

9. The screening method for isolated DC-DC converters for high-voltage power supplies in electric vehicles according to any one of claims 1 to 8, characterized in that: Determine the ripple measure X corresponding to the voltage ripple of the i-th isolated DC-DC converter. i The method is as follows: Based on the voltage ripple of the i-th isolated DC-DC converter, a preset ripple measurement value X is obtained by querying the table. i The preset ripple measurement table is a table showing the correspondence between voltage ripple and ripple measurement values. The smaller the voltage ripple, the larger the ripple measurement value. Determine the efficiency metric Y corresponding to the efficiency of the i-th isolated DC-DC converter. i The method is as follows: Based on the efficiency of the i-th isolated DC-DC converter, a preset efficiency measurement table is consulted to obtain the corresponding efficiency measurement value Y. i Among them, the preset efficiency measurement value table is a correspondence table between efficiency and efficiency measurement value. The higher the efficiency, the larger the efficiency measurement value. Determine the temperature rise measurement value Z corresponding to the temperature rise of the i-th isolated DC-DC converter. i The method is as follows: Based on the temperature rise of the i-th isolated DC-DC converter, the preset temperature rise measurement value Z is obtained by querying the temperature rise measurement value table. i Among them, the preset temperature rise measurement value table is a correspondence table between temperature rise and temperature rise measurement value. The smaller the temperature rise, the larger the temperature rise measurement value. Determine the EMC measurement value R corresponding to the percentage of EMC exceeding the baseline for the i-th isolated DC-DC converter. i The method is as follows: Based on the percentage of EMC exceeding the baseline for the i-th isolated DC-DC converter, the corresponding EMC measurement value R is obtained by querying the preset EMC measurement value table. i The preset EMC measurement value table is a table showing the correspondence between the percentage of EMC exceeding the baseline and the EMC measurement value. The smaller the percentage of EMC exceeding the baseline, the larger the EMC measurement value. Determine the volume measurement value S corresponding to the total volume ratio of the components in the i-th isolated DC-DC converter. i The method is as follows: Based on the total volume ratio of the components in the i-th isolated DC-DC converter, a preset volume measurement value table is consulted to obtain the corresponding volume measurement value S. i The preset volume measurement value table is a table showing the correspondence between the total volume ratio of components and the volume measurement value. The smaller the total volume ratio of components, the larger the volume measurement value.

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