Bus balance control method and device of inverter and storage medium
By collecting the bus voltage in a three-level inverter to calculate the energy imbalance value, determining the periodic energy transfer, and calculating the duty cycle of the switching transistors, the problem of bus voltage imbalance is solved, achieving fast and stable bus voltage balance control, and ensuring system safety and power quality.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-19
- Publication Date
- 2026-03-13
AI Technical Summary
In a three-level inverter, it is difficult to maintain a balance between the positive and negative bus voltages on the DC side, especially under light load or low half-wave load conditions, which affects the safe and stable operation of the system. Existing software control schemes are complex and ineffective, while hardware improvement schemes have the risk of voltage or current overshoot.
By collecting positive and negative bus voltages, calculating energy imbalance values, determining periodic energy transfer, and calculating the duty cycle of the switching transistor based on the inductance value, the switching transistor is driven to achieve bus voltage balance, thus avoiding overshoot and harmonic injection in closed-loop feedback regulation.
It achieves fast, overshoot-free bus voltage balance control, ensuring system stability and power quality, and avoiding the negative impact of harmonics on the power grid.
Smart Images
Figure CN121664012A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of inverter technology, and particularly relates to a bus balance control method, device and storage medium for an inverter. Background Technology
[0002] Inverters are core power conversion devices in new energy fields such as photovoltaic power generation and energy storage systems, and their performance and reliability are of paramount importance. Among them, the three-level inverter topology has been widely used due to its advantages such as high output waveform quality and low switching losses. However, this topology has an inherent technical challenge: it is difficult to maintain the voltage balance between the positive and negative bus capacitors on the DC side. Especially under light load and low half-wave load conditions, the voltage imbalance between the positive and negative buses is particularly significant, threatening the safe and stable operation of the entire system.
[0003] Currently, there are two main technical solutions for achieving voltage balance between the positive and negative busbars of an inverter: I. Software Control Scheme: This scheme achieves voltage balance by detecting the voltage difference between the positive and negative buses and adjusting the duty cycle of the drive signals of the power switching devices. However, this scheme has significant drawbacks. Its control algorithm is complex, and when the inverter operates under light load conditions, the system output power is low, resulting in limited adjustment margin and often poor bus balance control, failing to meet actual operational requirements. Another software control scheme involves injecting harmonics. By injecting specific frequency harmonic components into the inverter output current, the system's power flow characteristics are altered, thereby adjusting the energy distribution between the positive and negative buses to achieve voltage balance. While this scheme improves bus balance control to some extent, the injected harmonics negatively impact the power quality on the grid side, leading to excessive harmonic content.
[0004] II. Hardware Auxiliary Solution: An additional two-level circuit module is added to the existing three-level circuit. By independently controlling the power switching devices of the newly added two-level circuit, the positive and negative bus voltages are actively adjusted to compensate for the shortcomings of the original three-level circuit in bus balance control. However, this hardware improvement solution also has technical risks: the newly added two-level circuit is prone to voltage or current overshoot during control, leading to decreased system stability; simultaneously, the inductors in the two-level circuit may saturate due to excessive current, affecting the safe and reliable operation of the entire inverter system. Summary of the Invention
[0005] This invention provides a bus balance control method for inverters, which aims to solve the problem of voltage imbalance between the positive and negative busbars of a DC bus.
[0006] This invention is implemented as follows: a bus balance control method for an inverter, the inverter including a DC bus and a balancing circuit, the balancing circuit including a balancing inductor, a series-connected positive bus-side switch and a series-connected negative bus-side switch, one end of the balancing inductor being connected to the midpoint of the series-connected positive bus-side switch and negative bus-side switch, and the other end of the balancing inductor being connected to the midpoint of the DC bus, the bus balance control method for the inverter including the following steps: Collect the positive bus voltage and negative bus voltage of the DC bus; Calculate the energy imbalance value between the positive and negative busbars of the DC busbar based on the positive busbar voltage and the negative busbar voltage; Based on the energy imbalance value, determine the periodic energy that needs to be transferred in each switching cycle; The peak inductor current is calculated based on the periodic energy and the inductance value of the balanced inductor. The first duty cycle of the positive bus-side switch is calculated based on the peak inductor current and the positive bus voltage, and the second duty cycle of the negative bus-side switch is calculated based on the peak inductor current and the negative bus voltage. The positive bus-side switch is driven to operate according to the first duty cycle, and the negative bus-side switch is driven to operate according to the second duty cycle, so that the positive bus voltage and the negative bus voltage tend to be balanced.
[0007] Furthermore, the step of calculating the energy imbalance value between the positive and negative buses of the DC bus based on the positive bus voltage and the negative bus voltage includes: The collected positive bus voltage and negative bus voltage are filtered. Based on the filtered positive bus voltage and the negative bus voltage, using the formula... Calculate the energy imbalance value between the positive bus and the negative bus of the DC bus; E is the energy imbalance value, C is the capacitance value of the DC bus, and Vbus+ and Vbus- are the positive bus voltage and the negative bus voltage, respectively.
[0008] Furthermore, the step of determining the periodic energy to be transferred in each switching cycle based on the energy imbalance value includes: The energy imbalance value is processed by a moving average. Obtain the switching frequency and control frequency of the inverter control system, and calculate the frequency ratio of the switching frequency to the control frequency; Substitute the energy imbalance value after moving average processing and the frequency ratio into the formula. To determine the periodic energy that needs to be transferred in each switching cycle; The periodic energy is N, and the frequency ratio is N.
[0009] Furthermore, the step of calculating the peak inductor current based on the periodic energy and the inductance value of the balancing inductor includes: Substituting the periodic energy and the inductance value of the balancing inductor into the formula To calculate the peak inductor current; where L is the inductance value of the balancing inductor, and I... speak This represents the peak current of the inductor.
[0010] Furthermore, the step of calculating the first duty cycle of the positive bus-side switch based on the inductor peak current and the positive bus voltage, and calculating the second duty cycle of the negative bus-side switch based on the inductor peak current and the negative bus voltage, includes: Based on the inductor peak current and the positive bus voltage, using the formula Calculate the first duty cycle of the positive busbar-side switch transistor; the D pos For the first duty cycle, T s For switching cycles; Based on the inductor peak current and the negative bus voltage, using the formula Calculate the second duty cycle of the switch transistor on the negative bus side; the D neg This is the second duty cycle.
[0011] Furthermore, before the step of driving the positive bus-side switch according to the first duty cycle and driving the negative bus-side switch according to the second duty cycle to balance the positive bus voltage and the negative bus voltage, the method further includes: Obtain the maximum current allowed to flow through the balanced inductor; Based on the maximum current, calculate the maximum duty cycle using the volt-second balance principle; The first duty cycle and the second duty cycle are limited within the maximum duty cycle.
[0012] The present invention also provides a bus balance control device for an inverter, including a memory, a processor, and an inverter bus balance control program stored in the memory and executable on the processor. When the processor executes the inverter bus balance control program, it implements the steps of the inverter bus balance control method as described in any of the preceding claims.
[0013] The present invention also provides a storage medium storing a bus balance control program for an inverter, wherein when the inverter bus balance control program is executed by a processor, the inverter bus balance control program implements the steps of the inverter bus balance control method as described in any of the preceding claims.
[0014] The technical solution of this invention involves acquiring the positive and negative bus voltages of the DC bus and calculating the energy imbalance between them. This determines the cyclic energy to be transferred in each switching cycle. Based on the cyclic energy and the inductance value of the balancing inductor, the peak inductor current is calculated. Then, the duty cycle of the corresponding switching transistors on the positive and negative bus sides is calculated based on the peak inductor current and the positive and negative bus voltages. Finally, the corresponding switching transistors are driven to operate according to the calculated duty cycle. Because this invention directly calculates the switching transistor duty cycle based on the energy imbalance value, replacing traditional closed-loop feedback regulation, it avoids control overshoot and system oscillation problems caused by loop delay and improper gain adjustment. Furthermore, since energy transfer is achieved through a balancing circuit, there is no need to inject any form of harmonics into the power grid, fundamentally ensuring power quality. Attached Figure Description
[0015] Figure 1 This is a flowchart illustrating the first embodiment of the inverter bus balance control method provided by the present invention; Figure 2 This is a structural diagram of an inverter to which the bus balance control method for inverters provided by this invention is applied; Figure 3 This is a flowchart illustrating the second embodiment of the inverter bus balance control method provided by the present invention. Detailed Implementation
[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0017] Existing technologies mainly rely on closed-loop regulation based on voltage difference feedback or harmonic injection methods to achieve voltage balance between the positive and negative DC bus. This invention, however, converts voltage imbalance values into energy imbalance values and calculates the duty cycle of the switching transistors based on these energy imbalance values. This fundamentally eliminates the overshoot and oscillation problems inherent in traditional closed-loop control, while also avoiding the damage to power grid quality caused by harmonic injection, thus achieving fast, overshoot-free voltage balance control.
[0018] Example 1 Reference Figure 1 This invention provides a bus balance control method for an inverter, applied to an inverter, aiming to achieve balanced control of the positive and negative bus voltages of its DC bus. The specific structure of this inverter can be found in [reference needed]. Figure 2As shown, the inverter includes a DC bus and a balancing circuit. The balancing circuit includes a balancing inductor L, a positive bus-side switch Q1, and a negative bus-side switch Q2 connected in series. One end of the balancing inductor L is connected to the midpoint of the series-connected positive bus-side switch Q1 and negative bus-side switch Q2, and the other end of the balancing inductor L is connected to the midpoint of the DC bus. The positive bus-side switch Q1 and the negative bus-side switch Q2 can be selected as IGBTs or MOSFETs.
[0019] The bus balance control method for this inverter includes the following steps: Step S10: Collect the positive bus voltage and negative bus voltage of the DC bus; The DC bus consists of a positive bus and a negative bus. The positive bus voltage Vbus+ refers to the potential difference between the positive bus and the common reference point. The negative bus voltage Vbus- refers to the potential difference between the negative bus and the common reference point.
[0020] In practice, the positive bus voltage Vbus+ and negative bus voltage Vbus- of the DC bus are obtained through corresponding voltage sampling devices such as resistive voltage divider circuits or Hall voltage sensors. Of course, these voltage sampling devices include, but are not limited to, resistive voltage divider circuits or Hall voltage sensors, and can be reasonably set according to actual needs.
[0021] Step S20: Calculate the energy imbalance value between the positive and negative busbars of the DC bus based on the positive busbar voltage and the negative busbar voltage. The energy imbalance value E refers to the difference in electric field energy stored in the positive and negative bus capacitors due to unequal positive and negative bus voltages. To ensure the accuracy of the calculation, the acquired positive bus voltage Vbus+ and negative bus voltage Vbus- can first be filtered by a notch filter. This notch filter can be a 150Hz notch filter to eliminate interference signals of specific frequencies, such as 150Hz. Subsequently, the inverter's control system, such as a DSP, calculates the energy imbalance value E between the positive and negative DC buses based on the filtered positive bus voltage Vbus+ and negative bus voltage Vbus- according to preset rules.
[0022] In one specific embodiment, step S20 includes: Step S201: Filter the collected positive bus voltage and negative bus voltage. Step S202: Based on the filtered positive bus voltage and the negative bus voltage, use the formula... Calculate the energy imbalance value between the positive bus and the negative bus of the DC bus; E is the energy imbalance value, C is the capacitance value of the DC bus, and Vbus+ and Vbus- are the positive bus voltage and the negative bus voltage, respectively.
[0023] In the actual operating environment of an inverter, the switching action of power switching devices and grid interference introduce high-frequency noise, which may cause glitches and oscillations in the acquired positive bus voltage Vbus+ and negative bus voltage Vbus-. Direct use of these data may affect the accuracy of energy imbalance calculations. Therefore, it is necessary to filter the acquired positive bus voltage Vbus+ and negative bus voltage Vbus-. In practice, a notch filter can be used to filter out interference signals in specific frequency bands while retaining the DC and low-frequency components of the voltage. The center frequency of the notch filter can be set at the main interference frequency, such as 150Hz.
[0024] The energy stored in the DC bus capacitor is proportional to the square of the voltage across it. Therefore, the inverter's control system can determine the energy based on the filtered positive bus voltage Vbus+ and negative bus voltage Vbus-, and by calling the pre-stored DC bus capacitance value C, using the formula... Calculate the energy imbalance value E between the positive and negative DC bus. The sign and magnitude of the energy imbalance value E precisely quantify the total energy that needs to be transferred from one bus to the other to restore voltage balance between the positive and negative buses.
[0025] Step S30: Based on the energy imbalance value, determine the periodic energy that needs to be transferred in each switching cycle; Cyclic energy ΔE refers to the energy value that needs to be transferred between the positive and negative buses within a single switching cycle. This means that the energy imbalance value E in the control cycle is evenly distributed across each switching cycle to avoid current surges and system oscillations caused by excessive energy transfer in a single cycle.
[0026] In one specific embodiment, step S30 includes: Step S301: Perform a moving average processing on the energy imbalance value; Step S302: Obtain the switching frequency and control frequency of the inverter control system, and calculate the frequency ratio of the switching frequency to the control frequency; Step S303: Substitute the energy imbalance value after moving average processing and the frequency ratio into the formula. To determine the periodic energy that needs to be transferred in each switching cycle; The periodic energy is N, and the frequency ratio is N.
[0027] First, obtain the switching frequency f_switch and control frequency f_control of the inverter control system, and calculate their frequency ratio N, i.e., frequency ratio N = f_switch / f_control. The frequency ratio N represents the number of switching cycles contained in a single control cycle. Second, perform a moving average processing on the energy imbalance value E to be transferred to filter out fluctuations caused by disturbances and obtain a smooth energy imbalance value E. Finally, calculate the cycle energy ΔE to be transferred in each switching cycle according to the formula ΔE = E / N.
[0028] In this embodiment, the energy imbalance value E that needs to be transferred within a control cycle, i.e. the energy imbalance value E after moving average processing, is evenly distributed to the N consecutive switching cycles contained therein for execution, so as to achieve smooth and stable energy transfer control, avoid the current stress problem caused by excessive energy transfer in a single cycle, and provide the system with smooth and stable response characteristics.
[0029] Step S40: Calculate the peak inductor current based on the periodic energy and the inductance value of the balancing inductor; A balancing inductor is a component used in a balanced circuit to achieve energy transfer; this balancing inductor is... Figure 2 The inductor L is shown. The peak inductor current I is... speak It refers to the maximum current required in the inductor to balance the transfer of periodic energy ΔE between the positive and negative buses within a switching cycle.
[0030] This step involves determining the maximum current that the balancing inductor L needs to reach, i.e., the peak inductor current I, based on the periodic energy ΔE and the inductance value of the balancing inductor L. speak This provides a direct basis for the final generation of the duty cycle signal of the switching transistor.
[0031] In one specific embodiment, step S40 includes: Step S401: Substitute the periodic energy and the inductance value of the balancing inductor into the formula. To calculate the peak inductor current; where L is the inductance value of the balancing inductor, and I... speak This represents the peak current of the inductor.
[0032] formula This reflects the relationship between inductor current and magnetic field energy. Substituting the periodic energy ΔE and the inductance L of the balancing inductor into the formula... The peak inductor current I is obtained by mathematical transformation. speak .
[0033] This step distributes the energy imbalance value E of the control cycle evenly to the cycle energy ΔE of each switching cycle, and then quantifies the cycle energy ΔE of each switching cycle into the peak inductor current I of the balancing inductor within each switching cycle.speak By determining the target current value through energy calculations, overshoot is avoided in principle, thus improving the system response speed.
[0034] Step S50: Calculate the first duty cycle of the positive bus-side switch based on the peak inductor current and the positive bus voltage, and calculate the second duty cycle of the negative bus-side switch based on the peak inductor current and the negative bus voltage. First duty cycle D pos This represents the ratio of the on-time of the positive busside switch to the switching period T_s within one switching cycle. Second duty cycle D neg This represents the ratio of the on-time of the switch transistor on the negative bus side to the switching period T_s within one switching cycle.
[0035] This step is used to measure the peak inductor current I. speak This is converted into a duty cycle signal that drives the switching transistors. Specifically, the duty cycle of the switching transistors on the positive and negative bus sides can be calculated based on the corresponding inductance equations.
[0036] In one specific embodiment, step S50 includes: Step S501: Based on the inductor peak current and the positive bus voltage, using the formula...
[0037] Calculate the first duty cycle of the positive busbar-side switch transistor; the D pos For the first duty cycle, T s For switching cycles; Step S502, based on the inductor peak current and the negative bus voltage, using the formula
[0038] Calculate the second duty cycle of the switch transistor on the negative bus side; the D neg This is the second duty cycle.
[0039] Based on the inductance equation Calculate the first duty cycle of the positive busside switch Q1. This calculation establishes the relationship between the positive bus voltage Vbus+ and the conduction time of the positive busside switch Q1, using the first duty cycle D. pos By adjusting the on-time of the positive bus-side switch Q1, energy transfer from the positive bus to the balance inductor is achieved. This is based on the same inductance equation. Calculate the second duty cycle of the negative bus-side switch Q2. This calculation establishes the relationship between the negative bus voltage Vbus and the on-time of the negative bus-side switch Q2, using the second duty cycle D. neg Adjusting the on-time of the switch Q2 on the negative bus side enables energy transfer from the balance inductor to the negative bus.
[0040] By precisely controlling the on-time of the switching transistors on the positive and negative bus sides, the current of the balancing inductor can be accurately tracked by the peak current of the inductor, thereby achieving precise bidirectional energy transfer control.
[0041] Step S60: Drive the positive bus-side switch to operate according to the first duty cycle, and drive the negative bus-side switch to operate according to the second duty cycle, so that the positive bus voltage and the negative bus voltage tend to be balanced.
[0042] During the execution phase, the calculated first and second duty cycles are converted into drive commands for the corresponding switching transistors to complete the final energy transfer, thereby achieving balanced control of the positive and negative bus voltages of the DC bus.
[0043] Specifically, the inverter's control system calculates the first duty cycle D. pos With the second duty cycle D neg The signals are output to the corresponding pulse width modulation (PWM) modules. The PWM modules generate corresponding PWM signals based on the received duty cycle. These PWM signals are amplified by the drive circuit for voltage and current, and then applied to the control terminals (such as the gate of an IGBT or the gate of a MOSFET) of the positive bus-side switch Q1 and the negative bus-side switch Q2, respectively. This precisely controls the on / off timing of the two switches in each switching cycle, ultimately bringing the positive and negative bus voltages closer together, achieving positive and negative bus voltage balance. For example, when the positive bus voltage is too high, the control system uses the first duty cycle D... pos The drive transistor Q1 on the positive bus side transfers excess energy from the positive bus to the balancing inductor L for storage; when the negative bus voltage is low, the system uses the second duty cycle D neg The negative bus-side switch Q2 releases the energy stored in the balancing inductor L to the negative bus, thereby achieving balanced control of the positive and negative bus voltages. It is important to note that to ensure safe and reliable system operation, the positive bus-side switch Q1 and the negative bus-side switch Q2 cannot be turned on simultaneously to prevent a direct short circuit in the DC bus.
[0044] The technical solution of this invention involves acquiring the positive and negative bus voltages of the DC bus and calculating the energy imbalance between them. Based on this, the required periodic energy to be transferred in each switching cycle is determined. The peak inductor current is calculated based on the periodic energy and the inductance value of the balancing inductor. Then, the duty cycle of the switching transistors on the positive and negative bus sides is calculated based on the peak inductor current and the positive and negative bus voltages, respectively. Finally, the corresponding switching transistors are driven according to the determined duty cycle to balance the positive and negative bus voltages. Because this invention directly calculates the switching transistor duty cycle based on the energy imbalance value, replacing traditional closed-loop feedback regulation, it avoids control overshoot and system oscillation problems caused by loop delay and improper gain adjustment. Since energy transfer is achieved through a balancing circuit, there is no need to inject any form of harmonics into the grid, fundamentally ensuring the power quality of the grid-connected current.
[0045] Example 2 Reference Figure 3 In one embodiment, before step S60, the method further includes: Step S601: Obtain the maximum current allowed to flow through the balanced inductor; Step S602: Calculate the maximum duty cycle based on the volt-second balance principle according to the maximum current; Step S603: Limit the first duty cycle and the second duty cycle within the maximum duty cycle.
[0046] In this embodiment, a duty cycle safety limit is added before the positive and negative bus-side switching transistors are driven to prevent magnetic saturation of the balance inductor L, thereby further ensuring the safe and reliable operation of the system.
[0047] The inverter control system first reads the pre-stored maximum current value allowed to flow through the balancing inductor L; then, based on the volt-second balance principle, it calculates the maximum duty cycle using a formula. Specifically, the maximum duty cycle can be calculated based on parameters such as the maximum current allowed to flow through the balancing inductor L, the inductance value of the balancing inductor L, the positive bus voltage Vbus+, and the switching cycle; finally, it limits the first and second duty cycles to not exceed this maximum duty cycle, ensuring that the current of the balancing inductor L can be completely reset in each switching cycle, thereby fundamentally preventing the occurrence of inductor magnetic saturation.
[0048] That is, before outputting the drive signal, the control system will calculate the first duty cycle D. pos Second duty cycle D neg Each duty cycle is compared to the maximum duty cycle. If any duty cycle exceeds the maximum duty cycle, it is forcibly limited to within the maximum duty cycle as a key protection measure to ensure the safety of the power circuit.
[0049] This embodiment first obtains the maximum current value that the balancing inductor is allowed to flow through, then calculates the maximum duty cycle based on the volt-second balance principle, and finally limits the first duty cycle and the second duty cycle within the maximum duty cycle to effectively prevent the balancing inductor from becoming magnetically saturated. By limiting the first duty cycle and the second duty cycle within a safe range, it ensures that the switching transistors on the positive and negative bus sides always operate within a safe range, thereby significantly improving the reliability of the system.
[0050] The present invention also provides an inverter bus balance control device, including a memory, a processor, and an inverter bus balance control program stored in the memory and executable on the processor. When the processor executes the inverter bus balance control program, it implements the steps of the inverter bus balance control method as described above.
[0051] The present invention also provides a storage medium storing an inverter bus balance control program, which, when executed by a processor, implements the steps of the inverter bus balance control method as described above.
[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A bus balance control method for an inverter, characterized in that, The inverter includes a DC bus and a balancing circuit. The balancing circuit includes a balancing inductor, a series-connected positive bus-side switch, and a series-connected negative bus-side switch. One end of the balancing inductor is connected to the midpoint of the series-connected positive bus-side switch and negative bus-side switch, and the other end of the balancing inductor is connected to the midpoint of the DC bus. The inverter's bus balancing control method includes the following steps: Collect the positive bus voltage and negative bus voltage of the DC bus; Calculate the energy imbalance value between the positive and negative busbars of the DC busbar based on the positive busbar voltage and the negative busbar voltage; Based on the energy imbalance value, determine the periodic energy that needs to be transferred in each switching cycle; The peak inductor current is calculated based on the periodic energy and the inductance value of the balanced inductor. The first duty cycle of the positive bus-side switch is calculated based on the peak inductor current and the positive bus voltage, and the second duty cycle of the negative bus-side switch is calculated based on the peak inductor current and the negative bus voltage. The positive bus-side switch is driven to operate according to the first duty cycle, and the negative bus-side switch is driven to operate according to the second duty cycle, so that the positive bus voltage and the negative bus voltage tend to be balanced.
2. The inverter bus balance control method as described in claim 1, characterized in that, The step of calculating the energy imbalance value between the positive and negative DC bus based on the positive bus voltage and the negative bus voltage includes: The collected positive bus voltage and negative bus voltage are filtered. Based on the filtered positive bus voltage and the negative bus voltage, using the formula... Calculate the energy imbalance value between the positive bus and the negative bus of the DC bus; E is the energy imbalance value, C is the capacitance value of the DC bus, and Vbus+ and Vbus- are the positive bus voltage and the negative bus voltage, respectively.
3. The inverter bus balance control method as described in claim 2, characterized in that, The step of determining the periodic energy to be transferred in each switching cycle based on the energy imbalance value includes: The energy imbalance value is processed by a moving average. Obtain the switching frequency and control frequency of the inverter control system, and calculate the frequency ratio of the switching frequency to the control frequency; Substitute the energy imbalance value after moving average processing and the frequency ratio into the formula. To determine the periodic energy that needs to be transferred in each switching cycle; The periodic energy is N, and the frequency ratio is N.
4. The inverter bus balance control method as described in claim 3, characterized in that, The step of calculating the peak inductor current based on the periodic energy and the inductance value of the balanced inductor includes: Substituting the periodic energy and the inductance value of the balancing inductor into the formula To calculate the peak inductor current; where L is the inductance value of the balancing inductor, and I... speak This represents the peak current of the inductor.
5. The inverter bus balance control method as described in claim 4, characterized in that, The steps of calculating the first duty cycle of the positive bus-side switch based on the inductor peak current and the positive bus voltage, and calculating the second duty cycle of the negative bus-side switch based on the inductor peak current and the negative bus voltage, include: Based on the inductor peak current and the positive bus voltage, using the formula Calculate the first duty cycle of the positive busbar-side switch transistor; the D pos For the first duty cycle, T s For switching cycles; Based on the inductor peak current and the negative bus voltage, using the formula Calculate the second duty cycle of the switch transistor on the negative bus side; the D neg This is the second duty cycle.
6. The bus balance control method for an inverter as described in any one of claims 1-5, characterized in that, Before the step of driving the positive bus-side switch according to the first duty cycle and driving the negative bus-side switch according to the second duty cycle to balance the positive bus voltage and the negative bus voltage, the method further includes: Obtain the maximum current allowed to flow through the balanced inductor; Based on the maximum current, calculate the maximum duty cycle using the volt-second balance principle; The first duty cycle and the second duty cycle are limited within the maximum duty cycle.
7. A bus balance control device for an inverter, characterized in that, The inverter includes a memory, a processor, and a bus balance control program for the inverter stored in the memory and executable on the processor. When the processor executes the bus balance control program for the inverter, it implements the steps of the bus balance control method for the inverter as described in any one of claims 1-6.
8. A storage medium, characterized in that, The storage medium stores a bus balance control program for the inverter, which, when executed by a processor, implements the steps of the bus balance control method for the inverter as described in any one of claims 1-6.