Power allocation based energy balance control method for three-port converter with pulse frequency modulation

Abstract

The application discloses a kind of three-port converter energy balance control method based on power distribution of pulse frequency sudden drop, in the case where load frequency suddenly drops, the power distribution mode of AC / DC converter is switched, and the fastest change rate that AC / DC converter can provide is controlled to control input source power linearly decreases and linearly increases, after a short adjustment time, energy storage capacitor charging and discharging can be balanced, then the system enters new steady state.Compared with load frequency sudden increase, when three-phase alternating current source input power is too small, pulse load frequency sudden drop is limited by the power distribution mode of AC / DC converter, and it can make pulse load voltage fluctuate, so that the dynamic recovery time of decoupling capacitor voltage is too long, and the original power distribution mode cannot meet the demand of pulse load, so the power distribution mode of AC / DC converter needs to be switched.The problem that the dynamic performance of existing pulse power compensation control method is not optimal after load pulse frequency suddenly drops is solved.

Description

Technical Field

[0001] This invention relates to the field of pulse load power supply technology, and mainly to an energy balance control method for a three-port converter based on power distribution and pulse frequency abrupt reduction in 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, exhibiting strong pulse load characteristics; peak load power can even reach 10 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 to respond promptly to changes in pulse load power. The strong pulse characteristics cause a series of problems for the power supply system, such as harmonic current pollution, voltage fluctuations, and flicker. Under constant frequency pulse load conditions, the power allocation method generally adopted is: the VL port transmits the valley power P... n The VH port transmits the remaining dynamic power, and the system efficiency is highest under this power allocation method.

[0003] 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.

[0004] 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 end to drop and the system dynamic time to increase. Therefore, energy balance control cannot be switched directly, and the system power distribution mode must be changed before switching energy balance control. Summary of the Invention

[0005] 1. Purpose of the invention

[0006] This invention provides an energy balance control method for a three-port converter based on a sudden decrease in pulse frequency during power distribution. This method solves the problem that the dynamic performance of the system is not optimal due to pulse load voltage fluctuations when the energy balance control is directly switched under the highest efficiency power distribution mode.

[0007] 2. Technical Solution

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A power-sharing-based pulse frequency reduction pulse balance control method for a three-port converter, wherein the power-sharing-based three-port converter system 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 v sa v sb and v sc After passing through the filter circuit L a C a L b C b and L c C c The rear is connected to the midpoint of the T-shaped bridge arm; each T-shaped bridge arm consists of four switching transistors, namely S... a1 S a2 S a3 S a4 S b1 S b2 S b3 S b4 and S c1 S c2 S c3 S c4 The three ports of the T-arm are connected to ground, VL port, and VH port respectively, with an output capacitor C connected in parallel to VL port. o It is then connected to the pulse load, and a decoupling capacitor C is connected in parallel at the VH port. s 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 method for energy balance control of the three-port converter based on a sudden decrease in pulse frequency due to power distribution comprises the following steps:

[0010] Step S1.1: Obtain the periods T1 and T2 before and after the pulse load frequency change and the average load power P from the pulse detection circuit. o1 P o2 Assuming the pulse load is at t=t a If the time frequency decreases, then the pulse detection stage will be at t=t a At time +T2, a decrease in the load pulse frequency is detected. This time is recorded as time 0, and the d-axis current value i of the three-phase AC source at this time is also recorded. d1 t is obtained from the peak voltage detection module at the VH port. a ~t a The peak voltage v at port VH during the +T2 time period Hm ;

[0011] Step S1.2: The d-axis current value i of the three-phase AC source after the power balance calculation system re-enters steady state. d2 ;

[0012]

[0013] Where P 耗 For system power loss, u d The d-axis voltage of the three-phase AC source, v s P represents the effective value of the phase voltage of the three-phase AC source. o1 P o2 This represents the average load power before and after the sudden change in the pulse load frequency.

[0014] Step S2.1: In the steady state of the system, i.e., when the pulse load frequency is fixed, the valley power P is generally transmitted through the VL port. n The VH port transmits the remaining dynamic power, and this power allocation method has the highest system efficiency under constant frequency pulse load conditions. If the power allocation method in steady state is that the VL port does not transmit power and all pulse load power is transmitted by the VH port, then the dynamic process system can directly switch to energy balance control and jump to step S3.

[0015] Step S2.2: If the power distribution mode in steady state is the highest efficiency power distribution mode, during the energy balance control time period from 0 to t3, the output power of the three-phase AC source is less than the valley power P. n At that time, the power supplied by the VL port to the load is less than P. n The VH port provides power P to the load. m -P n (Load pulse start) or 0W (load pulse stop) The three-port converter does not provide enough power to the pulse load, causing the pulse load voltage to fluctuate and the system dynamic time to increase. Therefore, it is necessary to switch the power distribution mode.

[0016] Step S2.3: Switch signal S W Set the level to high to enable the circuit to operate in VH transmission mode, where all the energy from the three-phase AC source is delivered to the pulse load through the VH port.

[0017] Step S2.3, DC / DC converter inductor current given i in pulse load voltage control Lref byi dc -I dcn Change to i dc That is, the power transferred from the VH port to the pulsed load is P m -P n (Load pulse start) or 0W (load pulse stop) changes to P m (Load pulse start) or P n (Load pulse stops), where i dcI is the instantaneous current of the pulse load. dcn This represents the valley current of the pulse load.

[0018] Step S3, i d It can be represented in segments as follows:

[0019]

[0020] The ideal time t1 and the end time t3 of energy balance control are based on i d The expression, and the d-axis current value i before and after energy balance control. d1 and i d2 It can be represented as:

[0021]

[0022]

[0023] Step S4: Based on the energy balance principle, during the energy balance control period, the energy supplied by the AC source to the decoupling capacitor compensates the peak voltage of the VH port to the given peak voltage V. Href The energy difference ΔE can be expressed as:

[0024]

[0025] Where S A for:

[0026]

[0027] S B +S C It can be represented as:

[0028]

[0029] From this, the relevant times t1, t2, and t3 can be obtained.

[0030] Beneficial effects:

[0031] This invention proposes an energy balance control method for a three-port converter based on power allocation and pulse frequency drop. During a sudden drop in load frequency, the original power allocation method cannot meet the power demand of the pulse load in a dynamic process. By transmitting all the power from the three-phase AC source through the VH port and controlling the input power of the three-phase AC source to complete a linear decrease and linear increase, the charging and discharging of the energy storage capacitor can be restored to balance, and the system enters a new steady state with optimal dynamic performance. This solves the problem that directly switching energy balance control under the highest efficiency power allocation mode of the three-port converter causes pulse load voltage fluctuations, resulting in suboptimal system dynamics. Attached Figure Description

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

[0033] Figure 2 The control flowchart of the power balance control method based on power allocation provided by the present invention under the condition of power allocation with maximum efficiency in the steady state of the system;

[0034] Figure 3 The VH port voltage waveform diagram for directly switching energy balance control when the load frequency decreases and the power distribution mode is always in the highest efficiency power distribution mode;

[0035] Figure 4 The energy balance control method provided for the "Energy Balance Control Method for Three-Port Converter Based on Load Pulse Period Detection and Compensation (Application No. 202211614755.1)" shows the VH port voltage waveform under the condition of reduced load frequency and the highest efficiency power distribution mode in steady state.

[0036] Figure 5 The energy balance control method provided by the present invention shows the VH port voltage waveform under the condition of reduced load frequency and VH transmission mode steady-state power distribution.

[0037] Figure 6 The generalized implementation steps of the power distribution-based energy balance control method provided by the present invention when the load pulse frequency decreases are as follows. Detailed Implementation

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

[0039] A power-sharing-based pulse frequency reduction pulse balance control method for a three-port converter, wherein the power-sharing-based three-port converter system topology 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 v sa v sb and v sc After passing through the filter circuit L a C a L b C b and L c C c The rear is connected to the midpoint of the T-shaped bridge arm; each T-shaped bridge arm consists of four switching transistors, namely S... a1 S a2 S a3 S a4 S b1 S b2 S b3S b4 and S c1 S c2 S c3 S c4 The three ports of the T-arm are connected to ground, VL port, and VH port respectively, with an output capacitor C connected in parallel to VL port. o It is then connected to the pulse load, and a decoupling capacitor C is connected in parallel at the VH port. s 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 a sudden decrease in pulse frequency due to power allocation, taking the power allocation method with the highest efficiency in steady state as an example, includes the following specific steps:

[0041] Step S1.1: Obtain the periods T1 and T2 before and after the pulse load frequency change and the average load power P from the pulse detection circuit. o1 P o2 Assuming the pulse load is at t=t a If the time frequency decreases, then the pulse detection stage will be at t=t a At time +T2, a decrease in the load pulse frequency is detected. This time is recorded as time 0, and the d-axis current value i of the three-phase AC source at this time is also recorded. d1 t is obtained from the peak voltage detection module at the VH port. a ~t a The peak voltage v at port VH during the +T2 time period Hm ;

[0042] Step S1.2: The d-axis current value i of the three-phase AC source after the power balance calculation system re-enters steady state. d2 ;

[0043]

[0044] Where P 耗 For system power loss, u d The d-axis voltage of the three-phase AC source, v s P represents the effective value of the phase voltage of the three-phase AC source. o1 P o2 This represents the average load power before and after the sudden change in the pulse load frequency.

[0045] Step S2.1, using the load pulse power peak power P m =2000W, Peak Power P nTaking 500W as an example, when the load starts with pulse power, the VL port transmits the valley power P. n The VH port transmits the remaining dynamic power; this method achieves the highest system efficiency under constant frequency pulse load conditions. During the energy balance control period from 0 to t3, when the output power of the three-phase AC source is less than the valley power of 500W, the VL port provides less than 500W of power to the load, and the VH port provides 1500W (load pulse start) or 0W (load pulse stop) of power to the load. The pulse load voltage drops suddenly, and the system dynamic time becomes longer, so it is necessary to switch the power distribution mode.

[0046] Step S2.2: Switch signal S W Set the level to high to enable the circuit to operate in VH transmission mode, where all the energy from the three-phase AC source is delivered to the pulse load through the VH port.

[0047] Step S2.3, DC / DC converter inductor current given i in pulse load voltage control Lref byi dc -I dcn Change to i dc That is, the power transmitted from the VH port to the pulsed load changes from 1500W or 0W to 2000W or 500W, where i dc I is the instantaneous current of the pulse load. dcn This represents the valley current of the pulse load.

[0048] Step S3, i d It can be represented in segments as follows:

[0049]

[0050] The ideal time t1 and the end time t3 of energy balance control are based on i d The expression, and the d-axis current value i before and after energy balance control. d1 and i d2 It can be represented as:

[0051]

[0052]

[0053] Step S4: Based on the energy balance principle, during the energy balance control period, the energy supplied by the AC source to the decoupling capacitor compensates the peak voltage of the VH port to the given peak voltage V. Href The energy difference ΔE can be expressed as:

[0054]

[0055] Where S A for:

[0056]

[0057] S B +S C It can be represented as:

[0058]

[0059] From this, the relevant times t1, t2, and t3 can be obtained.

[0060] like Figure 3 The figure shows the VH port voltage waveform when the load frequency decreases and the power distribution mode is always the highest efficiency power distribution mode. When the pulse load frequency decreases, if the power distribution mode is not changed, the converter will not be able to meet the power demand of the pulse load, causing the voltage at its two ends to fluctuate and the system dynamic recovery time is long.

[0061] like Figure 4 The image shows the VH port voltage waveform of the energy balance control method provided in the application "Energy Balance Control Method for Three-Port Converter Based on Load Pulse Period Detection and Compensation (Application No. 202211614755.1)" under the condition of reduced load frequency and the highest efficiency power distribution mode in steady state. Figure 5 The figure shows the VH port voltage waveform of the energy balance control method provided by this invention under the condition of reduced load frequency and VH transmission mode in steady state power distribution. By comparison, it can be found that the first VH drop value after time 0 is... Figure 4 The waveform drops even lower.

[0062] When the load pulse decreases, the AC / DC converter power distribution mode is changed and switched to energy balance control. The pulse load power is provided by the VH port to ensure that the voltage at both ends of the pulse load is basically stable. The input power of the three-phase AC source changes in two stages, i.e. rises and falls, so that the decoupling capacitor voltage is compensated at the fastest speed, the system dynamic performance is optimal, and the recovery time is the fastest.

Claims

1. A method for energy balance control of a three-port converter based on a sudden decrease in pulse frequency due to power distribution, characterized in that, The specific steps are as follows: Step S1: Record the moment when the load pulse frequency decreases as t. a Record the moment when the load pulse frequency decreases as time 0, and obtain the d-axis current value i of the three-phase AC source at time 0. d1 Pulse detection period t a Peak voltage v at the VH port within ~0 Hm The d-axis current value i of the three-phase AC source at time t3 after the abrupt change and re-entering steady state. d2 ; Step S2: When the load pulse frequency decreases, change the power distribution mode to transmit all power through the VH port. If the power distribution mode is transmitted all power through the VH port in steady state, then ignore step S2. Step S3: Control the d-axis current i of the three-phase AC source d It decreases linearly with a rate of change of -k1 during the time interval 0 to t2, and increases linearly with a rate of change of k2 during the time interval t2 to t3 until it reaches i. d2 ; Step S4: Calculate the energy error value of the pulse detection cycle, and then obtain t1, t2, and t3.

2. The energy balance control method for a three-port converter based on a sudden decrease in pulse frequency according to claim 1, characterized in that, The specific process of step S1 is as follows: Step S1.1: Obtain the periods T1 and T2 before and after the pulse load frequency change and the average load power P from the pulse detection circuit. o1 P o2 Assuming the pulse load is at t=t a If the time frequency decreases, then the pulse detection stage will be at t=t a At time +T2, a decrease in the load pulse frequency is detected. This time is recorded as time 0, and the d-axis current value i of the three-phase AC source at this time is also recorded. d1 t is obtained from the peak voltage detection module at the VH port. a ~t a The peak voltage v at port VH during the +T2 time period Hm ; Step S1.2: The d-axis current value i of the three-phase AC source after the power balance calculation system re-enters steady state. d2 ; Where P 耗 For system power loss, u d The d-axis voltage of the three-phase AC source, v s P represents the effective value of the phase voltage of the three-phase AC source. o1 P o2 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 a sudden decrease in pulse frequency according to claim 1, characterized in that, In step S2, if the power distribution mode in steady state is the highest efficiency power distribution mode, the output power of the three-phase AC source is less than the valley power P during the energy balance control time period from 0 to t3. n At that time, the power supplied by the VL port to the load is less than P. n The VH port provides power P to the load. m -P n If the power supplied by the three-port converter to the pulse load is insufficient (e.g., 0W), the voltage of the pulse load will fluctuate, and the dynamic time of the system will increase. Switching the power distribution mode involves the following steps: Step S2.1: Switch signal S W Set the level to high to make the circuit work in VH transmission mode, and all the energy from the three-phase AC source is delivered to the pulse load through the VH port; Step S2.2, DC / DC converter inductor current given i in pulse load voltage control Lref by i dc -I dcn Change to i dc That is, the power transferred from the VH port to the pulsed load is P m -P n Or 0W becomes P m or P n , where i dc I is the instantaneous current of the pulse load. dcn This represents the valley current of the pulse load.

4. The energy balance control method for a three-port converter based on a sudden decrease in pulse frequency according to claim 1, characterized in that, The specific steps of step S3 include: setting i d The segmented representation is as follows: The ideal time t1 and the end time t3 of energy balance control are based on i d The expression, and the d-axis current value i before and after energy balance control. d1 and i d2 Represented as:

5. The energy balance control method for a three-port converter based on a sudden decrease in pulse frequency according to claim 1, characterized in that, Step S4 specifically includes the following steps: Based on the energy balance concept, during the energy balance control period, the energy provided by the AC source to the decoupling capacitor compensates the peak voltage of the VH port to the given peak voltage V. Href The energy difference ΔE is expressed as: Where S A for: S B +S C Represented as: From this, the relevant times t1, t2, and t3 can be obtained.

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