Output end capacitance type selection method of conversion circuit, electronic equipment and program product

Abstract

The invention provides an output end capacitor type selection method of a conversion circuit, electronic equipment and a program product, and aims at a high-low voltage conversion circuit of a hybrid vehicle to realize accurate type selection of an output end capacitor in the conversion circuit by establishing a dynamic parameter calculation model.

Description

Technical Field

[0001] The present application relates to the technical field of hybrid power systems, and in particular to a method for selecting an output capacitor of a conversion circuit, an electronic device, and a program product. Background Art

[0002] Hybrid electric vehicles (HEVs) have become a key development direction for the automotive industry due to their fuel economy and low emissions. Compared to traditional fuel vehicles, hybrid systems achieve multi-mode coordinated energy management by incorporating high-voltage components such as motors and power batteries. Hybrid systems also contain internal conversion circuits. Existing technologies often rely on experience to select components (such as inductors and capacitors) within these circuits, leading to issues such as irrational selection and poor matching. Summary of the Invention

[0003] The purpose of the embodiments of the present application is to provide a method, electronic device and program product for selecting the output capacitor of a conversion circuit, so as to solve the problems that the existing technology is mostly based on experience to select various components (inductors, capacitors, etc.) in the conversion circuit, resulting in unreasonable selection and poor matching.

[0004] An embodiment of the present application provides a method for selecting a conversion circuit, wherein the conversion circuit includes an input capacitor, a switching device, an inductor, and an output capacitor; The method comprises: Determining a designed average current of the inductor according to a target load current; Calculating a design inductance value of the inductor according to a target output voltage, a target input voltage, a target on-time, and a target current ripple factor; Determine the voltage, equivalent resistance, and capacitance of the output capacitor based on the target load current, target output voltage, target input voltage, target frequency, and designed inductance value; Select the output capacitor based on the voltage, equivalent resistance and capacitance value of the output capacitor.

[0005] The above technical solution proposes a conversion circuit selection method. This method addresses the device parameter calculation and selection issues in the high- and low-voltage conversion circuits of hybrid vehicles. By establishing a dynamic parameter calculation model, it enables accurate selection of output capacitors (core components). The specific process is as follows: In some optional embodiments, the positive end of the power battery is connected to the first end of the input capacitor and the first end of the switching device, the second end of the switching device is connected to the first end of the inductor and the first end of the diode, and the second end of the inductor is connected to the first end of the output capacitor, the first end of the low-voltage battery, and the first end of the load electrical appliance; the second end of the input capacitor, the second end of the diode, the second end of the output capacitor, the second end of the low-voltage battery, and the second end of the load electrical appliance are all connected to the negative end of the power battery; the power battery is also connected to the motor.

[0006] In the above technical solution, the conversion circuit realizes the bidirectional transmission and dynamic management of energy between high voltage (such as power battery) and low voltage (such as low-voltage battery and load electrical appliances).

[0007] In some optional embodiments, when the following conditions are met: the output voltage of the conversion circuit is greater than the low-voltage battery voltage; the power battery SOC value is greater than a first threshold; the low-voltage battery SOC value is less than a second threshold; and the motor has no driving torque request, the torque control value is 0.

[0008] Then, the conversion circuit is in a high-voltage to low-voltage conversion mode, and the power battery outputs energy to the conversion circuit. The energy output by the conversion circuit is used to charge the low-voltage battery on the one hand, and to power the load electrical appliances on the other hand.

[0009] In some optional embodiments, when the following conditions are met: the output voltage of the conversion circuit is greater than the low-voltage battery voltage; the power battery SOC value is greater than a first threshold; the low-voltage battery SOC value is greater than a second threshold; the motor has no drive torque request and the torque control value is 0; and the load electrical appliance current demand value is greater than the current threshold.

[0010] Then, the conversion circuit is in a working mode where the current at the output end continues to increase. In order to maintain stable power output, the output voltage of the conversion circuit decreases as the output current increases. When the output voltage of the conversion circuit drops to the voltage threshold, undervoltage protection is performed. At this time, the output voltage no longer decreases and the output current can no longer increase; the power battery energy is output to the conversion circuit, and the conversion circuit supplies power to the load electrical appliances.

[0011] Among them, the conversion circuit output voltage V dcout >V 低压蓄电池, ensuring that energy flows from the high-voltage side to the low-voltage side, meeting the basic operating conditions of the buck-boost circuit. The power battery SOC> the first threshold (such as 40%), to avoid over-discharge of the high-voltage battery and retain sufficient power to meet sudden driving needs. The low-voltage battery SOC> the second threshold (such as 37%), the low-voltage battery has sufficient power and does not need to be charged, and priority is given to powering the load electrical appliances. There is no drive request for the motor (torque = 0), and the motor is not turned on. The load current demand> the current threshold (such as 5A), and the EBS detects a sudden increase in load current (such as starting the car air conditioner), triggering the mode switch.

[0012] According to the formula P=V dcout I dcout , when the load current I dcout When it increases, in order to maintain power stability, the output voltage V dcout Automatically reduce. When V dcout When the voltage is ≤10.5V (calibration threshold), undervoltage protection is triggered.

[0013] In some optional embodiments, when the following conditions are met: the output voltage of the conversion circuit is greater than the voltage of the low-voltage battery; the power battery SOC value is less than a first threshold; the low-voltage battery SOC value is less than a second threshold; and the motor is in a power generation state, the conversion circuit operates in a high-voltage to low-voltage conversion mode, and the motor generates power for the power battery and the conversion circuit. The conversion circuit charges the low-voltage battery and supplies power to the load electrical appliances.

[0014] Among them, the conversion circuit output voltage V dcout >V 低压蓄电池 The motor's generated energy is transferred to the low-voltage side through a conversion circuit. If the power battery SOC is less than the first threshold (e.g., 36%), the power battery is low and requires recharging first. If the low-voltage battery SOC is less than the second threshold (e.g., 33%), the low-voltage battery is charged simultaneously to improve energy utilization. The motor is generating electricity, either through braking energy recovery or by the engine driving the motor.

[0015] In some optional embodiments, when the following conditions are met: the output voltage of the conversion circuit is greater than the voltage of the low-voltage battery; the state of charge (SOC) value of the power battery is greater than a first threshold; the state of charge (SOC) value of the low-voltage battery is less than a second threshold; and the motor is in a driving state, the conversion circuit operates in a high-voltage to low-voltage conversion mode. The power battery outputs energy to the motor and the conversion circuit, which in turn charges the low-voltage battery and supplies power to the load electrical appliances.

[0016] Among them, the conversion circuit output voltage V dcout >V 低压蓄电池The power battery supplies power for the motor drive and the low-voltage system. When the SOC of the power battery is greater than a first threshold (for example, 40%), the double-path energy output (drive + low-voltage power supply) is supported. When the SOC of the low-voltage battery is less than a second threshold (for example, 33%), the low-voltage battery needs to be charged to ensure system redundancy. The motor is in a driving state, and the motor drive is a high-power load, and the energy distribution needs to be dynamically balanced.

[0017] In some optional embodiments, the design average current of the inductor : ; The design inductance value of the inductor : ; Wherein, is a target load current, is a target output voltage, is a target input voltage, is a target on-time, is a target current ripple coefficient.

[0018] The derivation process of the design average current and the design inductance value of the inductor is as follows: Let the voltage on the left side of the conversion circuit be , the voltage on the right side of the conversion circuit be , the inductance value be H, and the current value be I. According to the characteristics of the conversion circuit, the control switch device is turned on, and the diode is not turned on, so the voltage across the inductor is .

[0019] According to the theoretical formula , the following can be calculated and derived: ; Further calculation and derivation give: ; In the above formula, can be detected by the BMS of the power battery, can be detected by the EBS of the low-voltage battery.

[0020] For the switch device, in one cycle T, the switch on period and the switch off period are divided, and here, the switch on period is T1 and the switch off period is T2, so we get: ; During the switch on period in one cycle, let the inductor current increase amount be , and according to the above formula, further calculation and derivation give: ； According to the characteristics of the conversion circuit, the control switch device is disconnected, the diode is turned on, and the diode conduction voltage is set to V1. Then the voltage on the left side of the inductor is -V1, which can be calculated and derived: ; Further calculation and derivation yield: ; Because the diode conduction voltage is very small, V1 can be ignored, and further calculation and derivation can be obtained: ; During the switch off period in one cycle, the inductor current decreases by , then further calculation is derived as (taking the absolute value): ; According to the volt-second law, in one cycle, the increase in inductor current is equal to the decrease in inductor current, that is: ； The further calculation is deduced as: ; And because: ; The further calculation is deduced as: ; Further calculations lead to the following derivation: ; Let the frequency be f, since the period is T, we can calculate and derive the frequency as: ; Assuming the on-time of the switch device is T3, the calculation is derived to obtain: ; Assuming the disconnection time of the switch device is T4, the calculation is derived to obtain: ; Through the low-voltage battery EBS detection, the output voltage when high voltage is converted to low voltage during normal operation can be obtained. Basically in a steady state, that is, the voltage across the output capacitor does not change, then the average current flowing into and out of the capacitor is 0A. Furthermore, the average current of the inductor is equal to the average current of the load electrical appliance, which can be set to .

[0021] Assume the average current of the inductor is Since the current is equal to the average current of the load appliance, the following equation is obtained: ; Further, let the ripple current of the inductor be , then according to the formula: ; Further calculation and derivation are obtained: ; According to the previously calculated value, that is: ; Further calculation is obtained: ; Let the peak current of the inductor be , then further calculation and derivation of the peak current of the inductor are obtained: ; In the above formula, The current value can be detected by the low-voltage battery EBS. The voltage value can be detected by the low-voltage battery EBS.

[0022] When selecting the inductor parameters, the ripple current of the inductor is normally λ times the average current, that is: ; In the above formula, λ is preferably between 0.25 and 0.35, and here a value can be calibrated, such as 0.3, 0.31, or 0.32, etc.

[0023] Further, according to the above parameters , , , , etc., that is, the following four equations: ; ; ; ; The inductor value can be further calculated and derived as follows: ; Further calculation and derivation are obtained: ; Further calculation and derivation are obtained: ; Then further calculation and deduction can be obtained: ; In the above formula, It can be obtained from the current value detected by the low-voltage battery EBS. It can be obtained from the voltage value detected by the low-voltage battery EBS. It can be obtained from the voltage value detected by the power battery BMS. is the switch on time, which can be detected by a timer. Substituting these parameters into the formula, we can get the inductor selection parameters in the conversion circuit .

[0024] In some optional implementations, determining the voltage, equivalent resistance, and capacitance of the output capacitor according to the target load current, the target output voltage, the target input voltage, the target frequency, and the designed inductance value includes: If the voltage, equivalent resistance, and capacitance of the output capacitor meet the first condition, the output capacitor is selected based on the voltage, equivalent resistance, and capacitance of the output capacitor at this time; The first condition includes: ; in, is the target load current, is the target output voltage, is the target input voltage, is the target frequency, To design the inductance value, is the equivalent resistance of the output capacitor, is the voltage of the output capacitor, is the capacitance value of the output capacitor.

[0025] In some optional implementations, if the voltage, equivalent resistance, and capacitance of the output capacitor satisfy the first condition, selecting the output capacitor according to the voltage, equivalent resistance, and capacitance of the output capacitor at this time includes: If the equivalent resistance of the output capacitor is less than the equivalent resistance threshold, then when the voltage and capacitance of the output capacitor meet the second condition, the output capacitor is selected based on the voltage, equivalent resistance and capacitance of the output capacitor at this time; The second condition includes: ； in, is the target on-time, is the target current ripple factor.

[0026] In some optional embodiments, if the voltage, the equivalent resistance and the capacitance value of the output capacitor satisfy the first condition, the output capacitor is selected according to the voltage, the equivalent resistance and the capacitance value of the output capacitor at this time, including: If the equivalent resistance of the output capacitor is greater than or equal to the equivalent resistance threshold value, in the case that the voltage and the capacitance value of the output capacitor satisfy the third condition, the output capacitor is selected according to the voltage, the equivalent resistance and the capacitance value of the output capacitor at this time. The third condition includes: is a target current ripple coefficient.

[0027] An electronic device provided by an embodiment of the present application includes a processor and a memory, the memory stores machine readable instructions executable by the processor, and the machine readable instructions are executed by the processor to perform the method according to any one of the above.

[0028] A computer program product provided by an embodiment of the present application includes a computer program / instruction, and the computer program / instruction is executed by a processor to implement the steps of the method according to any one of the above. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0030] Figure 1 A conversion circuit structure diagram is provided for the embodiment; Figure 2 A selection method step flow chart of the conversion circuit is provided for the embodiment; Figure 3 A power supply control schematic diagram of the conversion circuit in a first scenario is provided for the embodiment; Figure 4 A power supply control schematic diagram of the conversion circuit in a second scenario is provided for the embodiment; Figure 5 A power supply control schematic diagram of the conversion circuit in a third scenario is provided for the embodiment; Figure 6 A power supply control schematic diagram of the conversion circuit in a fourth scenario is provided for the embodiment; Figure 7 A possible structure of an electronic device provided by an embodiment of the present application is shown.​​ DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.

[0032] The selection method of the conversion circuit provided in the embodiments of the present application aims to solve the problems of device parameter calculation and selection in the high-low voltage conversion circuit of a hybrid vehicle, and realizes accurate selection of an inductor (a core component) by establishing a dynamic parameter calculation model.

[0033] Please refer to Figure 1 , Figure 1 The conversion circuit structure diagram provided in the embodiments includes an input capacitor, a switching device, an inductor and an output capacitor.

[0034] Please refer to Figure 2 , Figure 2 The selection method of the conversion circuit provided in the embodiments includes the following steps: Step S1, determining a design average current of the inductor according to a target load current; Step S2, calculating a design inductance value of the inductor according to a target output voltage, a target input voltage, a target on-time and a target current ripple coefficient; Step S3, determining a voltage, an equivalent resistance and a capacitance value of the output capacitor according to the target load current, the target output voltage, the target input voltage, a target frequency and the design inductance value; Step S4, selecting the output capacitor according to the voltage, the equivalent resistance and the capacitance value of the output capacitor.

[0035] In the embodiments of the present application, a selection method of a conversion circuit is provided, which aims to solve the problems of device parameter calculation and selection in the high-low voltage conversion circuit of a hybrid vehicle, and realizes accurate selection of an output capacitor (a core component) by establishing a dynamic parameter calculation model. The specific process is as follows: In some optional embodiments, the positive terminal of the power battery is connected to the first terminal of the input capacitor and the first terminal of the switching device, the second terminal of the switching device is connected to the first terminal of the inductor and the first terminal of the diode, the second terminal of the inductor is connected to the first terminal of the output capacitor, the first terminal of the low-voltage storage battery and the first terminal of the load electrical appliance; the second terminal of the input capacitor, the second terminal of the diode, the second terminal of the output capacitor, the second terminal of the low-voltage storage battery and the second terminal of the load electrical appliance are all connected to the negative terminal of the power battery; and the power battery is also connected to the motor.

[0036] In the embodiments of the present application, the conversion circuit realizes bidirectional energy transmission and dynamic management between high voltage (such as a power battery) and low voltage (such as a low-voltage storage battery and a load electrical appliance).

[0037] Among them, the input capacitor is connected in parallel with the positive and negative terminals of the power battery to absorb the voltage ripple on the high-voltage side, suppress the instantaneous voltage fluctuation caused by the switching action, and ensure the output stability of the power battery.

[0038] Switching devices (such as MOSFET / IGBT): As the control core of energy transmission, they regulate the on and off time through PWM signals to achieve bidirectional energy flow (boost or buck mode). For example, they step down the voltage to supply power when driving the motor and step up the voltage to recharge when braking.

[0039] Inductor: As an energy storage element, it stores energy during the on-time of the switch and releases energy to the output during the off-time. Its value needs to be dynamically calculated based on the load current and ripple factor to avoid magnetic saturation.

[0040] Diode: forms a freewheeling circuit to prevent voltage spikes caused by sudden changes in inductor current when the switch is turned off, while ensuring unidirectional energy flow.

[0041] Output capacitor: stabilizes the low-voltage side output voltage, reduces the impact of ripple on low-voltage batteries and electrical appliances, and extends device life.

[0042] The energy transmission path of the power system based on the conversion circuit can be divided into the following modes: High-voltage → low-voltage power supply mode: The power supply path is power battery → input capacitor → switching device → inductor → output capacitor → low-voltage battery / load electrical appliances. When the power battery has sufficient SOC, it powers or charges the low-voltage system. This is suitable for operating conditions where the motor is not driven and the low-voltage battery is low.

[0043] Low-voltage → High-voltage recharge mode: The path is low-voltage battery / load regenerative energy → output capacitor → inductor → diode → input capacitor → power battery. This improves energy utilization when recovering braking energy or generating power through the motor.

[0044] High- and low-voltage collaborative power supply mode: The path is that the power battery and the low-voltage system simultaneously power the motor, and dynamically distribute energy through the switching device.

[0045] Please refer to Figure 3 , when the following conditions are met: the output voltage of the conversion circuit is greater than the low-voltage battery voltage; the power battery SOC value is greater than the first threshold; the low-voltage battery SOC value is less than the second threshold; and the motor has no driving torque request, the torque control value is 0.

[0046] Then, the conversion circuit is in a high-voltage to low-voltage conversion mode, and the power battery outputs energy to the conversion circuit. The energy output by the conversion circuit is used to charge the low-voltage battery on the one hand, and to power the load electrical appliances on the other hand.

[0047] Please refer to Figure 4, when the following conditions are met: the output voltage of the conversion circuit is greater than the low-voltage battery voltage; the power battery SOC value is greater than the first threshold; the low-voltage battery SOC value is greater than the second threshold; the motor has no driving torque request and the torque control value is 0; and the load electrical current demand value is greater than the current threshold.

[0048] Then, the conversion circuit is in a working mode where the current at the output end continues to increase. In order to maintain stable power output, the output voltage of the conversion circuit decreases as the output current increases. When the output voltage of the conversion circuit drops to the voltage threshold, undervoltage protection is performed. At this time, the output voltage no longer decreases and the output current can no longer increase; the power battery energy is output to the conversion circuit, and the conversion circuit supplies power to the load electrical appliances.

[0049] Among them, the conversion circuit output voltage V dcout >V 低压蓄电池 , ensuring that energy flows from the high-voltage side to the low-voltage side, meeting the basic operating conditions of the buck-boost circuit. The power battery SOC> the first threshold (such as 40%), to avoid over-discharge of the high-voltage battery and retain sufficient power to meet sudden driving needs. The low-voltage battery SOC> the second threshold (such as 37%), the low-voltage battery has sufficient power and does not need to be charged, and priority is given to powering the load electrical appliances. There is no drive request for the motor (torque = 0), and the motor is not turned on. The load current demand> the current threshold (such as 5A), and the EBS detects a sudden increase in load current (such as starting the car air conditioner), triggering the mode switch.

[0050] According to the formula P=V dcout I dcout , when the load current I dcout When it increases, in order to maintain power stability, the output voltage V dcout Automatically reduce. When V dcout When the voltage is ≤10.5V (calibration threshold), undervoltage protection is triggered.

[0051] Please refer to Figure 5 When the following conditions are met: the output voltage of the conversion circuit is greater than the low-voltage battery voltage; the power battery SOC value is less than a first threshold; the low-voltage battery SOC value is less than a second threshold; and the motor is in a power generation state, the conversion circuit is in a high-voltage to low-voltage conversion mode. The motor generates energy for the power battery and the conversion circuit, which in turn charges the low-voltage battery and supplies power to the load electrical appliances.

[0052] Among them, the conversion circuit output voltage V dcout >V 低压蓄电池The motor's generated energy is transferred to the low-voltage side through a conversion circuit. If the power battery SOC is less than the first threshold (e.g., 36%), the power battery is low and requires recharging first. If the low-voltage battery SOC is less than the second threshold (e.g., 33%), the low-voltage battery is charged simultaneously to improve energy utilization. The motor is generating electricity, either through braking energy recovery or by the engine driving the motor.

[0053] Please refer to Figure 6 When the following conditions are met: the output voltage of the conversion circuit is greater than the low-voltage battery voltage; the power battery SOC value is higher than a first threshold; the low-voltage battery SOC value is less than a second threshold; and the motor is in the driving state, the conversion circuit is in high-voltage to low-voltage conversion mode. The power battery outputs energy to the motor and the conversion circuit, which in turn charges the low-voltage battery and supplies power to the load electrical appliances.

[0054] Among them, the conversion circuit output voltage V dcout >V 低压蓄电池 The power battery simultaneously powers the motor drive and low-voltage system. When the power battery SOC exceeds the first threshold (e.g., 40%), dual energy output (drive + low-voltage power) is supported. When the low-voltage battery SOC is less than the second threshold (e.g., 33%), the low-voltage battery must be charged to ensure system redundancy. When the motor is in drive mode, the motor drive is a high-power load, requiring dynamic energy balance.

[0055] In some optional embodiments, the designed average current of the inductor is : ; Design inductance value of the inductor : ; in, is the target load current, is the target output voltage, is the target input voltage, is the target on-time, is the target current ripple factor.

[0056] The derivation process of the design average current and design inductance value of the above inductor is as follows: Assume the voltage on the left side of the conversion circuit is , the voltage on the right side of the conversion circuit is , the inductance is H, and the current is I. According to the characteristics of the conversion circuit, the control switch device is turned on and the diode is not turned on, then the voltage across the inductor is .

[0057] According to the theoretical formula , we can calculate and deduce: ; Further calculation and derivation yield: ; In the above formula, It can be obtained through the BMS detection of the power battery. It can be obtained through EBS detection of low-voltage battery.

[0058] For the switching device, within one cycle T, there are two periods: a switch-on period and a switch-off period. Here, the switch-on period can be set as T1 and the switch-off period as T2, and then: ; During the switch conduction period in one cycle, the inductor current increases by , further calculation and derivation based on the above formula yields: ； According to the characteristics of the conversion circuit, the control switch device is disconnected, the diode is turned on, and the diode conduction voltage is set to V1. Then the voltage on the left side of the inductor is -V1, which can be calculated and derived: ; Further calculation and derivation yield: ; Because the diode conduction voltage is very small, V1 can be ignored, and further calculation and derivation can be obtained: ; During the switch off period in one cycle, the inductor current decreases by , then further calculation is derived as (taking the absolute value): ; According to the volt-second law, in one cycle, the increase in inductor current is equal to the decrease in inductor current, that is: ； The further calculation is deduced as: ; And because: ; The further calculation is deduced as: ; Further calculations lead to the following derivation: ; Let the frequency be f, since the period is T, we can calculate and derive the frequency as: ; Assuming the on-time of the switch device is T3, the calculation is derived to obtain: ; Assuming the disconnection time of the switch device is T4, the calculation is derived to obtain: ; Through the low-voltage battery EBS detection, the output voltage when high voltage is converted to low voltage during normal operation can be obtained. Basically in a steady state, that is, the voltage across the output capacitor does not change, then the average current flowing into and out of the capacitor is 0A. Furthermore, the average current of the inductor is equal to the average current of the load electrical appliance, which can be set to .

[0059] Assume the average current of the inductor is , since this current is equal to the average current of the load electrical appliances, the following formula is obtained: ; Furthermore, let the ripple current of the inductor be , then according to the formula: ; Then further calculation and deduction can be obtained: ; According to the above calculated Value, that is: ; Further calculation yields: ; Assume the peak inductor current is , we can further deduce the peak inductor current as: ; In the above formula, The current value can be detected by the low-voltage battery EBS. The voltage value can be detected by the low-voltage battery EBS.

[0060] When selecting inductor parameters, the ripple current of the inductor is normally λ times the average current, that is: ; In the above formula, the appropriate value of λ is between 0.25 and 0.35. Here, a value such as 0.3, 0.31 or 0.32 can be calibrated.

[0061] Furthermore, according to the parameters obtained above 、 、 、 Etc., that is, the following four formulas: ; ; ; ; The inductance value can be further calculated and derived ,as follows: ; Then further calculation and deduction can be obtained: ; Then further calculation and deduction can be obtained: ; Then further calculation and deduction can be obtained: ; In the above formula, It can be obtained from the current value detected by the low-voltage battery EBS. It can be obtained from the voltage value detected by the low-voltage battery EBS. It can be obtained from the voltage value detected by the power battery BMS. is the switch on time, which can be detected by a timer. Substituting these parameters into the formula, we can get the inductor selection parameters in the conversion circuit .

[0062] In some optional implementations, determining the voltage, equivalent resistance, and capacitance of the output capacitor according to the target load current, the target output voltage, the target input voltage, the target frequency, and the designed inductance value includes: If the voltage, equivalent resistance, and capacitance of the output capacitor meet the first condition, the output capacitor is selected based on the voltage, equivalent resistance, and capacitance of the output capacitor at this time; The first condition includes: ; in, is the target load current, is the target output voltage, is the target input voltage, is the target frequency, To design the inductance value, is the equivalent resistance of the output capacitor, is the voltage of the output capacitor, is the capacitance value of the output capacitor.

[0063] The derivation process of the first condition above includes: According to the conversion circuit design, when the output capacitor current is greater than 0, the output capacitor is charging, and when the output capacitor current is less than 0, the output capacitor is discharging. The output capacitor charging and discharging time are equal, both are half of the period T, which is .

[0064] According to the above calculation, the inductor ripple current , specifically: ; Where H represents the inductance value, Indicates the frequency value.

[0065] Assume that the output capacitor current change value is ,but: ; Further calculation and derivation show that the charging current and discharging current of the capacitor are ; Because in one cycle T, the output capacitor charging and discharging time are equal to ; In summary, the charging time of the output capacitor is , the maximum current during charging is ; For the output capacitor, since the charge and discharge amounts are equal, let the output capacitor charge be , the voltage of the output capacitor is , the capacitance of the output capacitor is , is the frequency. Then: ; Furthermore, based on the fact that the charge capacity is equal to the product of the charge time and the charge current, the charge of the output capacitor can be calculated as follows: ; Further calculations are derived as follows: ; because: ; so: ; Further derivation and calculation are: ; Assuming the charging current direction of the output capacitor is positive, the discharge current direction is negative. Because the current directions are different, the voltage drop caused is also opposite. According to the above calculation, the maximum charging current of the capacitor is , the maximum discharge current is .

[0066] The current passes through the equivalent resistance inside the output capacitor The voltage change caused by , then the equivalent resistance The total voltage change caused is: ; Further derivation and calculation are: ; because: ; so: ; Considering the equivalent resistance The total voltage of the output capacitor is set to ,but: ; Further calculations are derived as follows: ; Further calculations are derived as follows: .

[0067] In some optional implementations, if the voltage, equivalent resistance, and capacitance of the output capacitor satisfy the first condition, selecting the output capacitor according to the voltage, equivalent resistance, and capacitance of the output capacitor at this time includes: If the equivalent resistance of the output capacitor is less than the equivalent resistance threshold, then when the voltage and capacitance of the output capacitor meet the second condition, the output capacitor is selected based on the voltage, equivalent resistance and capacitance of the output capacitor at this time; The second condition includes: ； in, is the target on-time, is the target current ripple factor.

[0068] The derivation process of the above second condition includes: when When it is smaller, for example, less than 35mΩ, The value of Decide.

[0069] According to the parameters and The selected value is a positive value, according to ,get: ; Further calculation and derivation: ; According to the above calculated for: ; Further calculation and derivation: ; According to the above calculation, H is: ; Further calculation and derivation: ; Further calculation and derivation: ; Further calculation and derivation: ; Further calculations are performed to derive the final result: ; In the above formula, 、 、 、 、 is a known value, so we need to judge and Whether the above formula is satisfied or not is used for selection. That is, in this case, when selecting the output capacitor, it can only be selected if the above calculation formula is satisfied.

[0070] In some optional implementations, if the voltage, equivalent resistance, and capacitance of the output capacitor satisfy the first condition, selecting the output capacitor according to the voltage, equivalent resistance, and capacitance of the output capacitor at this time includes: If the equivalent resistance of the output capacitor is greater than or equal to the equivalent resistance threshold, then when the voltage and capacitance of the output capacitor meet the third condition, the output capacitor is selected based on the voltage, equivalent resistance, and capacitance of the output capacitor at this time; The third condition includes: ; in, is the target current ripple factor.

[0071] The derivation process of the third condition mentioned above includes: when When it is larger, for example, greater than 35mΩ, The value of the main determined.

[0072] is a positive value, according to , we get: ; According to the foregoing has been calculated: ; ; Further calculation derivation: ; Further calculation derivation: ; Further calculation derivation: ; Further calculation derivation: ; Further calculation derivation of the final result: ; In the above formula, , is a known value, so it is necessary to determine whether and satisfy the above formula for selection.

[0073] In this case, when selecting the output end capacitor, only the calculation formula can be satisfied.

[0074] Figure 7 Fig. 1 shows a possible structure of an electronic device provided by an embodiment of the present application. Referring to Figure 7 , the electronic device includes a processor, a memory and a communication interface, and these components are interconnected and communicate with each other through a communication bus and / or other forms of connection mechanism (not shown).

[0075] The memory includes one or more (only one is shown in the figure), which may be, but is not limited to, random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), and electrically erasable programmable read-only memory (EEPROM). The processor and other possible components can access the memory and read and / or write data therein.

[0076] The processor includes one or more (only one is shown in the figure), which can be an integrated circuit chip with signal processing capabilities. The above-mentioned processor can be a general-purpose processor, including a central processing unit (CPU), a microcontroller unit (MCU), a network processor (NP), or other conventional processors; it can also be a special-purpose processor, including a neural network processing unit (NPU), a graphics processing unit (GPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. Moreover, when there are multiple processors, some of them can be general-purpose processors and others can be special-purpose processors.

[0077] The communication interface includes one or more (only one is shown in the figure) and can be used to communicate directly or indirectly with other devices to exchange data. The communication interface can include an interface for wired and / or wireless communication.

[0078] One or more computer program instructions may be stored in the memory, and the processor may read and execute these computer program instructions to implement the method provided in the embodiment of the present application.

[0079] Understandably, Figure 7 The structure shown is only for illustration, and the electronic device may also include Figure 7 More or fewer components than shown, or with Figure 7 Different structures are shown. Figure 7 The components shown in the figure can be implemented using hardware, software, or a combination thereof. The electronic device can be a physical device, such as a PC, laptop, tablet, mobile phone, server, embedded device, etc., or a virtual device, such as a virtual machine or virtualized container. Furthermore, the electronic device is not limited to a single device and can also be a combination of multiple devices or a cluster consisting of a large number of devices.

[0080] A computer program product provided in an embodiment of the present application includes a computer program / instruction, which implements the steps of any of the above methods when executed by a processor.

[0081] In the embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interface, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0082] In addition, the units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0083] Furthermore, the functional modules in each embodiment of the present application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0084] In this document, relational terms such as first and second, etc. are used merely to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any actual relationship or order between these entities or operations.

[0085] The above merely provides an example of the present application, and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for selecting an output capacitor of a conversion circuit, characterized in that: The conversion circuit includes an input terminal capacitor, a switching device, an inductor and an output terminal capacitor; The method comprises: Determining a designed average current of the inductor according to a target load current; Calculating a design inductance value of the inductor according to a target output voltage, a target input voltage, a target on-time, and a target current ripple factor; Determine the voltage, equivalent resistance, and capacitance of the output capacitor based on the target load current, target output voltage, target input voltage, target frequency, and designed inductance value; Select the output capacitor based on the voltage, equivalent resistance and capacitance value of the output capacitor.

2. The method according to claim 1, wherein Design average current of the inductor : ； Design inductance value of the inductor : ； in, is the target load current, is the target output voltage, is the target input voltage, is the target on-time, is the target current ripple factor.

3. The method according to claim 2, wherein The step of determining the voltage, equivalent resistance, and capacitance of the output capacitor according to the target load current, the target output voltage, the target input voltage, the target frequency, and the designed inductance value includes: If the voltage, equivalent resistance, and capacitance of the output capacitor meet the first condition, the output capacitor is selected based on the voltage, equivalent resistance, and capacitance of the output capacitor at this time; The first condition includes: ； in, is the target load current, is the target output voltage, is the target input voltage, is the target frequency, To design the inductance value, is the equivalent resistance of the output capacitor, is the voltage of the output capacitor, is the capacitance value of the output capacitor.

4. The method according to claim 3, wherein If the voltage, equivalent resistance, and capacitance of the output capacitor satisfy the first condition, selecting the output capacitor according to the voltage, equivalent resistance, and capacitance of the output capacitor at this time includes: If the equivalent resistance of the output capacitor is less than the equivalent resistance threshold, then when the voltage and capacitance of the output capacitor meet the second condition, the output capacitor is selected based on the voltage, equivalent resistance and capacitance of the output capacitor at this time; The second condition includes: ； in, is the target on-time, is the target current ripple factor.

5. The method according to claim 3, wherein If the voltage, equivalent resistance, and capacitance of the output capacitor satisfy the first condition, selecting the output capacitor according to the voltage, equivalent resistance, and capacitance of the output capacitor at this time includes: If the equivalent resistance of the output capacitor is greater than or equal to the equivalent resistance threshold, then when the voltage and capacitance of the output capacitor meet the third condition, the output capacitor is selected based on the voltage, equivalent resistance, and capacitance of the output capacitor at this time; The third condition includes: ； in, is the target current ripple factor.

6. The method according to claim 1, wherein The positive end of the power battery is connected to the first end of the input capacitor and the first end of the switching device, the second end of the switching device is connected to the first end of the inductor and the first end of the diode, and the second end of the inductor is connected to the first end of the output capacitor, the first end of the low-voltage battery, and the first end of the load electrical appliance; the second end of the input capacitor, the second end of the diode, the second end of the output capacitor, the second end of the low-voltage battery, and the second end of the load electrical appliance are all connected to the negative end of the power battery; the power battery is also connected to the motor.

7. An electronic device, characterized in that: include: A processor and a memory, wherein the memory stores machine-readable instructions executable by the processor, and when the machine-readable instructions are executed by the processor, the method according to any one of claims 1 to 6 is performed.

8. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instruction is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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