A three-port converter energy balance control method based on sectional control

Abstract

The application discloses a three-port converter energy balance control method based on a segmented control. When a load frequency suddenly drops, the three-phase AC source input power is controlled in two stages. The first stage is to control the three-phase AC source input power to linearly decrease to a certain fixed value when the load frequency suddenly drops, and at this time, the three-phase AC source does not provide power to the VH port. The second stage is to control the input source to linearly increase and linearly decrease according to the fastest change rate that the AC / DC converter can provide after the load frequency suddenly drops and one pulse period elapses, so that the energy storage capacitor of the VH port is charged and discharged to recover balance. Compared with the energy balance control method which starts after the load frequency suddenly drops and one pulse period elapses, the VH port voltage does not over-boost in the first stage, and the dynamic time of the energy balance control method in the second stage is shorter. The problems that the VH port voltage over-boosts and the dynamic time is relatively long when the energy balance control method starts after the load frequency suddenly drops and one pulse period elapses are solved.

Description

Technical Field

[0001] This invention relates to the field of pulse load power supply technology, and mainly to a three-port converter energy balance control method based on segmented control for a three-phase AC power supply system with a low peak-to-average power ratio and a low frequency pulse load. Background Technology

[0002] In recent years, new radars have been widely deployed in airborne, shipboard, and ground equipment systems. The radar transceiver components require significantly higher power during transmission than during reception, resulting in strong pulse load characteristics. Peak load power can even reach ten times its average power. The load pulse operating frequency is low and variable, typically ranging from a few Hz to tens of Hz, and the load pulse starts and stops rapidly. These characteristics make it difficult for traditional electromechanical control systems to respond promptly to changes in pulse load power. The strong pulse characteristics also cause a series of problems for the power supply system, such as harmonic current pollution, voltage fluctuations, and flicker.

[0003] When pulse loads such as new radars are operating, their pulse frequency and other operating characteristics may change. Traditional PI control has poor dynamic performance, which will affect the system's performance and may even trigger protection, causing it to lose its ability to operate. After the load frequency decreases and the required data is detected after one pulse cycle, the system switches to energy balance control. This method can shorten the system's dynamic time to some extent when the pulse load frequency suddenly drops. However, during pulse detection and data acquisition, it can cause the three-phase AC source to overcharge the VH port capacitor, which may cause overvoltage damage to system components; and because the VH port capacitor voltage is too high, the system... When performing energy balance control, it is necessary to compensate for the energy difference by adding a decoupling capacitor. Therefore, the optimal dynamic performance of the system cannot be guaranteed during a sudden drop in load pulse frequency.

[0004] When the pulse load frequency suddenly increases, the system can directly switch to the energy balance control method proposed in the literature "Energy Balance Control Method of Three-Port Converter Based on Load Pulse Period Detection and Compensation (Application No. 202211614755.1)" to minimize the dynamic time of the system when the load pulse frequency changes abruptly.

[0005] When the pulse load frequency suddenly drops, directly switching the energy balance method will result in the three-phase AC source power being too low to meet the pulse load power demand under this power distribution mode, causing the voltage at the pulse load terminal to drop and the system dynamic time to increase. Therefore, energy balance control cannot be switched directly; the system power distribution mode must be changed before switching energy balance control. The energy redistribution-based scheme proposed in document "202310300189.5" can reduce voltage drop. However, the schemes in documents "202211614755.1" and "202310300189.5" will cause the three-phase AC source to overcharge the VH port capacitor when acquiring pulse detection data. The technical solution in document "202310300189.5" can only achieve energy balance control after detecting the frequency drop (ta+T2). When the load frequency decreases and energy balance control switches after one pulse cycle, the three-phase AC source will overcharge the capacitor voltage at the VH port after a new pulse cycle. This necessitates compensation for the energy difference at the VH port during the energy balance control process. This allows the system to recover to its steady-state fluctuation value, resulting in a relatively long dynamic recovery time. The fundamental reason for this is that detection precedes compensation, with detection and compensation occurring sequentially. Summary of the Invention

[0006] 1. Purpose of the invention

[0007] This invention provides an energy balance control method for a three-port converter based on segmented control. It adopts the control concept of "compensation and detection in parallel" and starts to operate from time ta+T1. It proposes a segmented control method. In the first stage, the VH port voltage is kept constant to avoid voltage overshoot and there is no need to compensate for the energy difference in the second stage. This solves the problem that starting energy balance control after a sudden drop in load frequency and after one pulse cycle will cause the VH port voltage to rise excessively and the dynamic time to be long.

[0008] 2. Technical Solution

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A method for energy balance control of a three-port converter based on segmented control, wherein the three-port converter based on segmented control includes a three-phase AC source, a T-type three-level AC / DC converter, an embedded DC / DC converter, and a pulse load; the three-phase AC source , and They pass through filter circuits respectively , and The rear is connected to the midpoint of the T-shaped bridge arm; each T-shaped bridge arm consists of four switching transistors, which are respectively... , and The three ports of the T-arm are connected to ground, VL port, and VH port respectively, with an output capacitor connected in parallel to VL port. It is then connected to the pulse load, and a decoupling capacitor is connected in parallel at the VH port. The three-phase AC source is then connected to a DC / DC converter and subsequently to a pulse load. The three-phase AC source is connected to a three-phase current sensor, the T-type three-level AC / DC converter is connected to a voltage sensor, the DC / DC converter is connected to an inductor current sensor, and the pulse load is connected to a load current sensor. The characteristic feature is that the energy balance control method for the three-port converter based on segmented control comprises the following specific steps:

[0011] Step S1.1: Obtain the period before and after the pulse load frequency change by the pulse detection circuit. , and average power of load , Assuming the pulse load is in As the timing frequency decreases, the pulse detection stage... If no load pulse is detected at a certain moment, the system detects a decrease in the load pulse frequency and records this moment as [a specific time point]. At time 1, record the d-axis current value of the three-phase AC source at that moment. ;

[0012] Step S1.2: Calculate the power balance to show that the three-phase AC source only provides valley power. d-axis current value at time and the d-axis current value of the three-phase AC source after the system re-enters steady state ;

[0013]

[0014] in For system power loss, The d-axis voltage of the three-phase AC source. This represents the effective value of the three-phase AC source phase voltage. , This represents the average load power before and after the sudden change in the pulse load frequency.

[0015] Step S2: The first-stage control objective is for the three-phase AC source to only provide the load's valley power. This keeps the VH port voltage at Controlling the d-axis current of a three-phase AC source exist Within a time period The rate of change decreased linearly to ;exist The d-axis current remains at a certain level during the time period. Unchanged. Among them... It can be represented in segments as follows:

[0016]

[0017] Ideal moment and It can be represented as:

[0018]

[0019] Step S3: The second-stage control objective is to provide the average power of the pulsed load to the three-phase AC source. Furthermore, the dynamic process achieves energy balance. This involves controlling the d-axis current of the three-phase AC source. exist Within a time period The rate of change increases linearly; in Within a time period The rate of change decreased linearly to For ease of calculation, let's call it... If the time is 0, then It can be represented in segments as follows:

[0020]

[0021] Ideal moment and the end time of energy balance control according to The expression, and the d-axis current values ​​before and after the second stage control. and It can be represented as:

[0022]

[0023] Step S4: Based on the concept of energy balance, during the energy balance control period:

[0024]

[0025] in for:

[0026]

[0027] It can be represented as:

[0028]

[0029] The relevant time can be obtained from this. , , .

[0030] Beneficial effects:

[0031] This invention proposes an energy balance control method for a three-port converter based on segmented control. During a sudden drop in load frequency, the system proactively... The system operates at specific times to prevent overcharging of the VH port capacitor, maintaining its voltage level during the first stage of control. The system is in The second-stage control, i.e., energy balance control, does not require compensation for the energy difference of the decoupling capacitor, allowing the system to enter a new steady state more quickly and achieving optimal dynamic performance. This solves the problem of excessive voltage rise at the VH port and prolonged dynamic time caused by initiating energy balance control after a sudden drop in load frequency and a pulse cycle. Attached Figure Description

[0032] Figure 1 The three-port converter circuit topology provided by this invention;

[0033] Figure 2 The control flowchart of the energy balance control method based on segmented control provided by the present invention under the condition of load pulse frequency decrease;

[0034] Figure 3 This is the technical solution flowchart for document "202310300189.5";

[0035] Figure 4 The waveform of the VH port voltage when the load frequency decreases and the energy balance control switches after one pulse cycle.

[0036] Figure 5 The figure shown is a waveform of the VH port voltage under the condition of reduced load frequency in the energy balance control method provided by the present invention.

[0037] Figure 6 The generalized implementation steps of the energy balance control method based on segmented control provided by the present invention when the load pulse frequency decreases. Detailed Implementation

[0038] The invention will now be further described with reference to the accompanying drawings.

[0039] A method for energy balance control of a three-port converter based on piecewise control, wherein the topology of the three-port converter based on piecewise control is as follows: Figure 1 As shown, it includes a three-phase AC source, a T-type three-level AC / DC converter, an embedded DC / DC converter, and a pulse load; the three-phase AC source , and They pass through filter circuits respectively , and The rear is connected to the midpoint of the T-shaped bridge arm; each T-shaped bridge arm consists of four switching transistors, which are respectively... , and The three ports of the T-arm are connected to ground, VL port, and VH port respectively, with an output capacitor connected in parallel to VL port. It is then connected to the pulse load, and a decoupling capacitor is connected in parallel at the VH port. The DC / DC converter is then connected to the pulse load; the three-phase AC source is connected to a three-phase current sensor, the T-type three-level AC / DC converter is connected to a voltage sensor, the DC / DC converter is connected to an inductor current sensor, and the pulse load is connected to a load current sensor.

[0040] like Figure 2 As shown, the energy balance control method for a three-port converter based on segmented control includes the following specific steps:

[0041] Step S1.1: Obtain the period before and after the pulse load frequency change by the pulse detection circuit. , and average power of load , Assuming the pulse load is in As the timing frequency decreases, the pulse detection stage... If no load pulse is detected at a certain moment, the system detects a decrease in the load pulse frequency and records this moment as [a specific time point]. At time 1, record the d-axis current value of the three-phase AC source at that moment. ;

[0042] Step S1.2: Calculate the power balance to show that the three-phase AC source only provides valley power. d-axis current value at time and the d-axis current value of the three-phase AC source after the system re-enters steady state ;

[0043]

[0044] in For system power loss, The d-axis voltage of the three-phase AC source. This represents the effective value of the three-phase AC source phase voltage. , This represents the average load power before and after the sudden change in the pulse load frequency.

[0045] Step S2: The first-stage control objective is for the three-phase AC source to only provide the load's valley power. This keeps the VH port voltage at Controlling the d-axis current of a three-phase AC source exist Within a time period The rate of change decreased linearly to ;exist The d-axis current remains at a certain level during the time period. Unchanged. Among them... It can be represented in segments as follows:

[0046]

[0047] Ideal moment and It can be represented as:

[0048]

[0049] Step S3: The second-stage control objective is to provide the average power of the pulsed load to the three-phase AC source. Furthermore, the dynamic process achieves energy balance. This involves controlling the d-axis current of the three-phase AC source. exist Within a time period The rate of change increases linearly; in Within a time period The rate of change decreased linearly to For ease of calculation, let's call it... If the time is 0, then It can be represented in segments as follows:

[0050]

[0051] Ideal moment and the end time of energy balance control according to The expression, and the d-axis current values ​​before and after the second stage control. and It can be represented as:

[0052]

[0053] Step S4: Based on the concept of energy balance, during the energy balance control period:

[0054]

[0055] in for:

[0056]

[0057] It can be represented as:

[0058]

[0059] The relevant time can be obtained from this. , , .

[0060] Figure 3 The flowchart for the technical solution in document "202310300189.5" shows that energy balance control can only be achieved after the frequency decrease is detected at the moment (ta+T2). Figure 4 The diagram shows the voltage waveform at the VH port when the load frequency decreases and energy balance control switches after one pulse cycle. After a new pulse cycle, the three-phase AC source overcharges the capacitor voltage at the VH port, causing the energy balance control process to need to compensate for the energy difference at the VH port. The system needs to be restored to its steady-state fluctuation value, therefore the dynamic recovery time is relatively long.

[0061] like Figure 5 The figure shown is the VH port voltage waveform of the energy balance control method provided by the present invention under the condition of reduced load frequency. If no load pulse is detected, it is determined that the system load pulse frequency has decreased, and the input power of the three-phase AC source is controlled to maintain the voltage of the capacitor at the VH port. ,exist By constantly controlling the input power of the three-phase AC source to change in two stages (rise and fall), the decoupling capacitor voltage is compensated at the fastest speed, resulting in optimal system dynamic performance and the fastest recovery time.

[0062] The generalized implementation steps of the above control method are as follows: Figure 6 As shown.

Claims

1. A method for energy balance control of a three-port converter based on segmented control, characterized in that, In the event of a sudden drop in load frequency, the input power of the three-phase AC source is controlled in two stages. The first stage involves linearly reducing the input power of the three-phase AC source to a fixed value when a sudden drop in load frequency is detected. At this time, the three-phase AC source does not provide power to the VH port, and the voltage of the VH port remains unchanged. The second stage involves linearly increasing and decreasing the input power according to the fastest rate of change that the AC / DC converter can provide, after the sudden drop in load frequency and one pulse cycle, so that the charging and discharging of the energy storage capacitor at the VH port can be restored to balance. The specific steps are as follows: Step S1: Record the moment when the load pulse frequency decreases. The moment when the load pulse frequency is detected to decrease is recorded as _____. At any time, get d-axis current value of a three-phase AC source at any given time Three-phase AC power source only provides off-peak power. d-axis current value at time After mutation, it re-enters a steady state d-axis current value of the three-phase AC source at time t ; Step S2: Control the d-axis current of the three-phase AC source exist Within a time period The rate of change decreased linearly to ,exist It remains unchanged over the time period; Step S3: Control the d-axis current of the three-phase AC source exist Within a time period The rate of change increases linearly, in Within a time period The rate of change decreased linearly to ; Step S4: Obtain the relevant time points from the energy balance. , , .

2. The energy balance control method for a three-port converter based on segmented control according to claim 1, characterized in that, The specific process of step S1 is as follows: Step S1.1: Obtain the period before and after the pulse load frequency change by the pulse detection circuit. , and average power of load , Assuming the pulse load is in As the timing frequency decreases, the pulse detection stage... If no load pulse is detected at a certain moment, the system detects a decrease in the load pulse frequency and records this moment as [a specific time point]. At time 1, record the d-axis current value of the three-phase AC source at that moment. ; Step S1.2: Calculate the power balance to show that the three-phase AC source only provides valley power. d-axis current value at time and the d-axis current value of the three-phase AC source after the system re-enters steady state ; ； in For system power loss, The d-axis voltage of the three-phase AC source. This represents the effective value of the phase voltage of the three-phase AC source. , This represents the average load power before and after the sudden change in the pulse load frequency.

3. The energy balance control method for a three-port converter based on segmented control according to claim 2, characterized in that, The specific process of step S2 is as follows: The first-stage control objective is to ensure that the three-phase AC source only provides peak load power. This keeps the VH port voltage at Controlling the d-axis current of the three-phase AC source exist Within a time period The rate of change decreased linearly to ;exist The d-axis current remains at a certain level during the time period. Unchanged; among them The segmented representation is as follows: ； Ideal moment and Represented as: 。 4. The energy balance control method for a three-port converter based on segmented control according to claim 3, characterized in that, The specific process of step S3 is as follows: The second-stage control objective is to provide the average power of the pulsed load to the three-phase AC source. And the dynamic process energy balance; control the d-axis current of the three-phase AC source. exist Within a time period The rate of change increases linearly; in Within a time period The rate of change decreased linearly to ;remember If the time is 0, then The segmented representation is as follows: ； Ideal moment and the end time of energy balance control according to The expression, and the d-axis current values ​​before and after the second stage control. and Represented as: 。 5. The energy balance control method for a three-port converter based on segmented control according to claim 4, characterized in that, The specific process of step S4 is as follows: Based on the concept of energy balance, during the period of energy balance control: ； in for: ； Represented as: ； From this, the relevant time can be obtained. , , .

Images