A low-ripple multifunctional portable energy storage power supply

Abstract

This invention relates to a low-ripple, multi-functional portable energy storage power supply, wherein terminals A and B on the AC side of the power supply... N C N The circuit is connected to a three-phase bridge arm via a three-phase LC filter. The DC side of the three-phase bridge arm has a supporting capacitor C3. The DC side is connected to the subsequent energy storage battery via a first DC / DC converter circuit. At least two switches k2 have one end connected to the negative bus of the three-phase bridge arm through capacitor C4. The other end of one switch k2 is connected to inductor L2, and the other end of the other switch k2 is connected to inductor L3. This invention enables rapid charging of the energy storage battery, with no 2H current ripple during charging or discharging. The power supply can power single-phase or three-phase loads, achieving the practicality and convenience of a portable energy storage power supply while meeting the demand for higher power.

Description

Technical Field

[0001] This invention relates to a low-ripple multifunctional portable energy storage power supply and its control method. Background Technology

[0002] Portable power storage devices are currently used outdoors to charge mobile phones, laptops, car refrigerators, drones, and small kitchen appliances, solving power problems for outdoor entertainment, office work, and emergency vehicle starting. Typically, portable power storage devices only output single-phase AC power, with relatively small capacities, ranging from a few hundred watts to five kilowatts. However, traditional portable power storage devices are unsuitable for special applications requiring three-phase AC power or demanding higher power outputs. Furthermore, with increasing power consumption, traditional portable power supplies, operating under load with a single-phase output, generate larger second-harmonic currents during battery discharge, severely impacting battery life. Summary of the Invention

[0003] To fully leverage the practicality and convenience of portable energy storage power supplies and meet the demands for higher power (e.g., 5 or 10 kilowatts or more, carried by a vehicle during outdoor travel or work), this paper proposes a fully functional, low-ripple, high-power portable energy storage power supply main circuit electrical topology and its corresponding main control methods.

[0004] To address this, a low-ripple, multi-functional portable energy storage power supply is provided, comprising four terminals A, B on the AC side. N C N And N, three inductors L1, L2 and L3, three filter capacitors C0, C1 and C2, a three-phase bridge arm composed of six semiconductor power switches, a support capacitor C3, a first DC / DC converter circuit for bidirectional energy flow, an energy storage battery, and at least two switches k2 and a capacitor C4.

[0005] Terminals A and B N C N The three-phase bridge arm is connected via inductors L1, L2, and L3 respectively. The supporting capacitor C3 is connected across the positive and negative DC buses of the three-phase bridge arm to form a DC side. The positive terminal DP and the negative terminal DN of the DC side are connected to the first DC / DC conversion circuit. The first DC / DC conversion circuit is a DC voltage adapter circuit and is connected to the energy storage battery. Capacitor C0 is connected across the end of inductors L1 and L3 that is closer to the AC side, capacitor C1 is connected across the end of inductors L1 and L2 that is closer to the AC side, and capacitor C2 is connected across the end of inductors L2 and L3 that is closer to the AC side.

[0006] At least two of the switches k2 are connected together at one end and then connected to the negative busbar of the three-phase bridge arm via the capacitor C4. The other end of one of the switches k2 is connected to the end of the inductor L2 near the AC side, and the other end of the switch k2 is connected to the end of the inductor L3 near the AC side.

[0007] Furthermore, it also includes a photovoltaic DC power supply and a second DC / DC conversion circuit, wherein the photovoltaic DC power supply charges the energy storage battery via the second DC / DC conversion circuit.

[0008] Furthermore, a pre-charging branch is provided on the AC side.

[0009] The system also provides a control method for the aforementioned low-ripple multifunctional portable energy storage power supply, including:

[0010] In the three-phase bridge arm, power switches G1 and G2 form the left bridge arm, power switches G3 and G4 form the middle bridge arm, and power switches G5 and G6 form the right bridge arm. Among them, power switches G1, G3, and G5 are the upper power switches of the bridge arm, and power switches G2, G4, and G6 are the lower power switches of the bridge arm.

[0011] When switch K2 is closed, power switches G3 and G5 use the same drive signal, and power switches G4 and G6 use the same drive signal.

[0012] Furthermore, in the charging rectification condition under single-phase input, based on terminals A and B N Single-phase input voltage Obtain a sinusoidal signal synchronized with the power grid, sin( ), control the DC bus voltage on capacitor C3 With the target given value The difference is low-pass filtered, and then adjusted by a proportional-integral regulator to obtain the command current of inductor L1. , will command current The modulated wave obtained by adjusting and limiting the difference between the sampling feedback current of inductor L1 and the modulated wave obtained by the proportional resonant controller is based on the sinusoidal signal sin( The obtained triangular carrier waves are compared to obtain two PWM pulses that are opposite to each other, which are then sent to power switches G1 and G2 for PWM control.

[0013] Control DC bus voltage With the target given value The difference is obtained after adjustment by a proportional resonant controller. It is related to the command current. Add them together to get an intermediate variable. The setpoint for controlling the DC bus voltage The preset multiple and the sampling feedback voltage on capacitor C4 The difference is adjusted by proportional-integral scaling and then limited to obtain a current compensation amount. Obtain intermediate variables With current compensation amount The difference, plus the current in inductors L2 and L3, The difference is processed by a proportional resonant regulator and then limited to obtain a modulated wave signal. This signal is compared with a triangular carrier wave to obtain two PWM pulse control signals that are opposite to each other. One of these signals is used to control power switches G3 and G5 simultaneously, while the other signal is used to control power switches G4 and G6 simultaneously.

[0014] Furthermore, in single-phase inverter control mode, the target command for the peak AC voltage of the control output is... A sinusoidal signal with a frequency of power frequency sin( Multiply by , and you get the target value of the AC output voltage. It is connected to terminals A and B. N Output AC voltage After the error is adjusted by the proportional resonant regulator, the command current of inductor L1 is obtained. Control command current The difference between the sampled feedback current of inductor L1 and the modulated wave obtained after being controlled, adjusted, and limited by a proportional resonant controller is compared with the sinusoidal signal sin( The triangular carrier wave is compared to obtain two PWM pulses that are opposite to each other, which are then sent to power switches G1 and G2 for PWM control.

[0015] Detect output voltage The instantaneous power P is obtained by multiplying the sampled feedback current of inductor L1 with the sampled feedback current. This product is then used to obtain a 2nd harmonic bandpass filter. The error between this filter and the zero-value setpoint is adjusted by a proportional resonant regulator to output the current command. Control current command With command current Add them together to get an intermediate variable. The setpoint of the DC bus voltage on the control capacitor C3 The preset multiple and the sampling feedback voltage on capacitor C4 The difference is adjusted by proportional-integral scaling and then limited to obtain a current compensation amount. Take intermediate variables With current compensation amount The difference, plus the current in inductors L2 and L3, The difference is processed by a proportional resonant regulator and then limited to obtain a modulated wave signal. This signal is compared with a triangular carrier wave to obtain two PWM pulse control signals that are opposite to each other. One signal is used to control power switches G3 and G5 simultaneously, and the other signal is used to control power switches G4 and G6 simultaneously.

[0016] Furthermore, the preset multiple is 0.5.

[0017] Furthermore, in the charging condition under three-phase AC input, a DC voltage closed-loop control method is adopted to stabilize the DC side voltage, and the first DC / DC converter is controlled to charge the energy storage battery using a constant current control method.

[0018] Furthermore, when the energy storage battery is charged by a photovoltaic DC power source and the three-phase inverter is connected to the grid for power generation, a DC voltage closed-loop control method is adopted to stabilize the DC side voltage, and the first DC / DC conversion circuit is controlled to transmit energy to the DC side using current closed-loop control.

[0019] Furthermore, when the energy storage battery is charged by a photovoltaic DC power source and is in a single-phase inverter grid-connected power generation mode, the switching control mode of the three bridge arms is the same as that of the bridge arm switching control mode under the charging and rectification mode under single-phase input. The first DC / DC conversion circuit is controlled to transmit energy to the DC side using current closed-loop control.

[0020] Based on this electrical topology, energy storage batteries can be charged quickly, and there is no 2 times frequency current ripple when the battery is charged or discharged. The power supply can carry single-phase or three-phase loads. When the power supply equipment is not taken out for application, it can be placed indoors for a long time as a converter for photovoltaic grid-connected power generation, giving full play to its use value. Attached Figure Description

[0021] Figure 1 This is a topology diagram of the main circuit of the system of the present invention.

[0022] Figure 2 This is the electrical topology for connecting a three-phase AC / DC converter to a subsequent DC / DC converter.

[0023] Figure 3 This is an electrical topology for connecting a single-phase AC / DC converter to a subsequent DC / DC converter.

[0024] Figure 4 This is a schematic flowchart of the system control process of the present invention.

[0025] Figure 5 This is a schematic diagram of the sampling and detection of electrical and physical variables controlled by the system of the present invention.

[0026] Figure 6 This is the AC-side electrical topology for a conventional portable energy storage power supply.

[0027] Figure 7 It is a single-phase PWM rectifier with an external decoupling capacitor.

[0028] Figure 8 This is a schematic diagram of the single-phase AC charging rectification control principle of the present invention.

[0029] Figure 9 This is a schematic diagram of the single-phase AC output control principle of the present invention. Detailed Implementation

[0030] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0031] Figure 1 This is a topology diagram of the main circuit of the proposed power supply system. The left side is the AC side, with A and B... N C N The four terminals N and switch k3 together with resistors R1 and R2 form a pre-charge branch.

[0032] L1, L2, and L3 are three independent inductors with identical parameters. They are used as filter capacitors C0, C1, and C2 with the same parameters but smaller capacitance values ​​to form a filter circuit. They can also function as boost inductors in charging mode. L1, L2, and L3 are connected to a three-phase bridge arm composed of six semiconductor power switching devices (such as IGBTs with freewheeling diodes). The DC-side support capacitor C3 is located between the positive and negative DC buses of the three-phase bridge arm. The positive terminal DP and the negative terminal DN of the DC side are connected to the first DC / DC converter circuit. This first DC / DC converter circuit is a DC voltage adapter circuit connected to the subsequent energy storage battery, which is charged through DC / DC converter circuit 1. Additionally, to facilitate charging the energy storage battery using photovoltaic power generation, the main circuit is expanded to include a subsequent charging circuit that allows the photovoltaic DC power supply to charge the energy storage battery via a second DC / DC converter circuit.

[0033] One end of switch k2 is connected to the negative busbar of the three-phase bridge arm through capacitor C4, and the other end is connected to the left side of inductors L2 and L3 on the AC side.

[0034] The DC / DC converter circuit can be any type of DC-to-DC circuit that enables bidirectional energy flow. Its internal structure, principle and control method can be found in existing papers and literature. It is not an innovation of this invention. Therefore, the main circuit is only simplified with a box in the system diagram and is not described in detail.

[0035] based on Figure 1 The system's main circuit topology diagram shows how various application requirements can be met through switch switching control.

[0036] 1) Fast charging function

[0037] Traditional portable power storage systems have a high AC output power from the inverter, meaning the battery discharge power is also high. However, the battery is charged by a separate low-power charging circuit, resulting in slow charging speed. To achieve fast charging, the main circuit of this system uses three bridge arms capable of high current operation as AC-to-DC conversion circuits. The battery is then charged via a subsequent DC / DC converter, thus achieving a charging rated power that reaches the rated discharge power level of the inverter output AC when carrying a load.

[0038] (a) Fast charging scenario when the external environment is three-phase AC.

[0039] See Figure 1 When the external power supply is a three-phase AC power source (e.g., 380Vac three-phase power), switch K2 remains open, and the three-phase AC power supply is connected to three terminals A and B. N C N , Figure 1 Reduced to Figure 2 The diagram shows a classic circuit structure for a three-phase AC / DC converter connected to a DC / DC converter.

[0040] (b) Fast charging scenario when the external current is single-phase AC

[0041] See Figure 1 When the external power source is single-phase AC (e.g., 220Vac single-phase power), switch K2 remains closed. Figure 1 Reduced to Figure 3 The diagram shows a classic circuit structure for a single-phase AC / DC converter connected to a subsequent DC / DC step-down converter. Terminal B... N and C N The two are connected and merged into one through the closing of K2, that is, the external single-phase power supply is connected to A and B. N Or connect A and C N They are exactly the same. The original three filter capacitors C0, C1 and C2 are actually equivalent to capacitor Cf, the size of which is the sum of C0 and C1.

[0042] 2) Situation when the inverter is used as a power supply to drive a three-phase load

[0043] The energy storage battery discharges, undergoes DC / DC conversion, and then is converted to AC by a three-phase inverter to provide a stable three-phase symmetrical AC voltage for the three-phase load. The circuit is as follows: Figure 2 Consistency, that is Figure 1 The main circuit of the system shown is in the state where switch k2 remains open.

[0044] 3) The case of inverter acting as power supply to drive single-phase load

[0045] The energy storage battery discharges, which is then converted by a DC / DC converter and then by a single-phase AC inverter to provide a stable single-phase AC voltage to the load. The circuit is as follows: Figure 3 Consistency, that is Figure 1 The main circuit of the system shown is in the state where switch k2 remains closed.

[0046] 4) Three-phase grid-connected power generation

[0047] If, under special circumstances, it is used as a three-phase low-voltage AC grid-connected converter for photovoltaic power generation, then... Figure 2 The system topology shown is, in other words, for Figure 1 The main circuit topology shown keeps switch k2 in the open state.

[0048] 5) Single-phase grid-connected power generation

[0049] If the power supply is used as a single-phase grid-connected converter for residential photovoltaic power generation, then... Figure 3 The system topology shown is, in other words, for Figure 1 The main circuit topology shown keeps switch k2 closed.

[0050] based on Figure 1 The system's topology is such that its operation mainly consists of charging mode, inverter mode, and grid-connected power generation mode. The main system control processes are as follows: Figure 4 As shown.

[0051] The control principles of several key control processes are as follows:

[0052] like Figure 5 As shown, in order to achieve real-time control of the relevant voltage or current, sensors need to be configured to sample and detect some electrical variables of the system in real time. The electrical variables that need to be sampled and detected are mainly terminals A and B. N voltage between B N With C N voltage between Voltage across decoupling capacitor C4 DC bus voltage (i.e., the voltage across capacitor C3), and the currents of the three inductors. and and Their physical reference positive direction is as follows Figure 5 As indicated by the label.

[0053] Charging rectification control under single-phase input

[0054] Typical portable energy storage power supplies adopt methods such as Figure 6 The topology diagram shows that the AC-to-DC or DC-to-AC conversion uses an H-bridge and an LC filter. (See attached diagram.) Figure 6 External AC charging, assuming the AC power source is... The input current is Then the instantaneous input power is It is evident that the instantaneous input power contains a second harmonic power fluctuation. The input voltage of the energy storage battery can be considered constant over a short period. Assuming the average output current of the energy storage battery is constant over this short period, i.e., the charging power of the energy storage battery is constant, a large voltage fluctuation will occur on the DC side of the H-bridge. This voltage fluctuation, in turn, will affect the control of the DC / DC converter circuit, causing the energy storage battery current to also contain a large second harmonic current. To minimize the voltage fluctuation on the DC side of the H-bridge, the most direct method is to increase the capacitance of the supporting capacitor on this DC side. Figure 6 The C1 in the diagram is used as a supporting capacitor to absorb the second harmonic power fluctuation. However, to achieve a small DC voltage fluctuation, the capacitance of this supporting capacitor needs to be very large. Therefore, a four-switch inverter topology is proposed, which adds a decoupling filter capacitor (such as C1) between the AC side and the negative terminal of the DC side. Figure 7 This method stores twice the power frequency pulsating power energy in a filter capacitor without adding any switching devices. The principle is briefly described below. Figure 7 Because when G3 is activated and G4 is deactivated, The current in inductor L2 will decrease, while when G3 is off and G4 is on, The current in inductor L2 will increase, therefore, the current in inductor L2 can be independently controlled through the bridge arm composed of G3 and G4. Similarly, when G1 is on and G2 is off, The current in inductor L1 will decrease, and when G1 is turned off and G2 is turned on, The current in inductor L1 will increase, therefore the current of inductor L1 can be independently controlled through the bridge arm composed of G1 and G2. When the command current of inductor L1 is set to be in phase with the input AC voltage, the system can operate at unity power factor. Furthermore, by controlling the current of inductor L2, the current of capacitor C can be controlled. dec The voltage on the capacitor C allows the pulsating energy from the DC side to be transferred to the capacitor. dec Storage, while maintaining DC side voltage The constancy of.

[0055] Capacitor C dec For storing fluctuating power energy, the required capacity is smaller than that needed to directly add a capacitor on the DC side to absorb power fluctuations. However, in practice, the circuit will require a larger rated operating current for the right arm of the H-bridge connected to L2, because the current component in L2 includes not only the current flowing through L1 but also the current flowing through the decoupling capacitor C. dec The current. In view of this situation, see... Figure 5This patent proposes a topology for parallel operation of bridge arms. After switch K2 is closed, power switches G3 and G5 use the same drive signal, and G4 and G6 use the same drive signal. In this case, L2 and L3 are equivalent to being connected in parallel. Based on this topology, the three bridge arms are fully utilized, and the rated operating current can be designed to be the same.

[0056] In the case of an external single-phase AC voltage input, to prevent the charging current of the energy storage battery from exhibiting second-harmonic current, it is necessary to control the DC side voltage of the bridge arm to remain constant. The charging rectification control method under single-phase input proposed in this patent proposal is as follows:

[0057] based on Figure 5 The system topology and physical quantity sampling diagram, after switch K2 is closed, press Figure 8 The control flowchart shown is used for control. This is to stabilize the DC bus voltage. To ensure a rectified input power factor of 1 and harmonic-free input current, the control methods for left bridge arms G1 and G2, middle bridge arms G3 and G4, and right bridge arms G5 and G6 are as follows:

[0058] (a) Switching control method for bridge arms G1 and G2

[0059] For single-phase input voltage A single-phase lock-in algorithm (a conventional algorithm; see relevant papers for details) is used to obtain a sinusoidal signal sin( ) synchronized with the power grid. DC bus voltage With the target given value The difference is low-pass filtered, and then adjusted by a proportional-integral (PI) regulator to obtain the command current for inductor L1. The difference between the current and the sampled feedback current of inductor L1 is adjusted and limited by a proportional resonant (PR) controller to obtain a modulated wave based on a sinusoidal signal sin( The obtained triangular carrier waves are compared to obtain two PWM pulses that are opposite to each other. These pulses are then sent to the power switches G1 and G2 on the left bridge arm for PWM control.

[0060] (b) Control methods for intermediate bridge arms G3 and G4, and right bridge arms G5 and G6

[0061] Bus voltage DC side bus voltage With the target given value The difference is obtained after adjustment by a proportional resonance (PR) controller. Its current is the same as the command current obtained in 1) above. Add them together to get an intermediate variable. The given value of the DC bus voltage. 0.5 times the sampling feedback voltage on capacitor C4 The difference is adjusted by proportional-integral (PI) and limited to obtain a current compensation amount. intermediate variables With current compensation amount The difference, plus the current in inductors L2 and L3, The difference is processed by a proportional resonant (PR) regulator and then the modulated wave signal obtained after final amplitude limiting is compared with the triangular carrier wave to obtain two PWM pulse control signals that are opposite to each other. One signal is used to control the upper power switch G3 of the middle bridge arm and the upper power switch G5 of the right bridge arm at the same time, and the other signal is used to control the lower power switch G4 of the middle bridge arm and the lower power switch G6 of the right bridge arm at the same time.

[0062] Single-phase inverter control

[0063] When providing a single-phase AC voltage to an external single-phase load, to prevent the discharge current of the energy storage battery from exhibiting second-harmonic currents, the DC-side voltage of the bridge arm needs to be kept essentially constant. Based on Figure 5 The system topology and physical quantity sampling diagram, after switch K2 is closed, press Figure 9 The control flowchart shown is used for control. This is to stabilize the DC bus voltage. The control methods for left bridge arms G1 and G2, middle bridge arms G3 and G4, and right bridge arms G5 and G6 are as follows:

[0064] (a) Switching control method for left bridge arms G1 and G2

[0065] Output AC voltage peak target command A sinusoidal signal with a frequency of power frequency sin( Multiply by , and you get the target value of the AC output voltage. Its output AC voltage obtained from sampling feedback After the error is adjusted by the proportional resonance (PR) regulator, the command current of inductor L1 is obtained. The difference between the current and the sampling feedback current of inductor L1 is controlled, adjusted and limited by the proportional resonant (PR) controller to obtain a modulated wave, which is compared with the triangular carrier wave to obtain two mutually opposite PWM pulses, which are sent to the power switches G1 and G2 of the left bridge arm for PWM control.

[0066] (b) Control methods for intermediate bridge arms G3 and G4, and right bridge arms G5 and G6

[0067] Detect output voltage With inductor current The product is calculated to obtain the instantaneous power P. A second-harmonic bandpass filter is applied to obtain the second-harmonic oscillating power signal. The error between this signal and the given zero value is then adjusted by a proportional resonant (PR) regulator to output the current command. Its current is the same as the command current obtained earlier. Add them together to get an intermediate variable. The given value of the DC bus voltage. 0.5 times the sampling feedback voltage on capacitor C4 The difference is adjusted by proportional-integral (PI) and limited to obtain a current compensation amount. intermediate variables With current compensation amount The difference, plus the current in inductors L2 and L3, The difference is processed by a proportional resonant (PR) regulator and then the modulated wave signal obtained after final amplitude limiting is compared with the triangular carrier wave to obtain two PWM pulse control signals that are opposite to each other. One signal is used to control the upper power switch G3 of the middle bridge arm and the upper power switch G5 of the right bridge arm at the same time, and the other signal is used to control the lower power switch G4 of the middle bridge arm and the lower power switch G6 of the right bridge arm at the same time.

[0068] 3) Control of other application scenarios

[0069] For charging control under three-phase AC input, unlike single-phase rectification, three-phase rectification does not easily achieve zero power fluctuation under three-phase symmetrical input conditions. Therefore, Figure 1 Disconnecting K2, the actual system topology becomes Figure 2 The electrical topology shown allows for PWM rectification control of the three bridge arms. The specific control strategy involves using closed-loop DC voltage control to stabilize the DC-side voltage (i.e., the DC voltage between the DP and DN terminals), creating a stable DC input voltage for the subsequent DC / DC converter. The first DC / DC converter can then use constant current control to charge the energy storage battery. The charging control method for DC / DC converter 1 has been described in numerous papers and will not be elaborated upon here.

[0070] For inverter control with a three-phase load, in this operating condition, the energy storage battery stabilizes the DC-side voltage (the voltage between DP and DN) via the first DC / DC converter circuit. Figure 1 With K2 disconnected from the electrical topology shown, the actual system topology becomes... Figure 2 The electrical topology shown is Figure 2 The inverter section shown is a traditional three-phase inverter that converts DC to three-phase AC. Under normal conditions of symmetrical load and symmetrical output voltage, the output power will not experience secondary power fluctuations, thus preventing the battery discharge current from exhibiting a second-harmonic ripple current. A traditional three-phase inverter control method can be used here, which has been described in numerous papers and will not be elaborated upon here.

[0071] For applications involving external photovoltaic DC power supply and three-phase inverter grid-connected power generation, please refer to [link to relevant documentation]. Figure 2The switching of the three bridge arms adopts the PWM rectification control method. Specifically, the DC voltage closed-loop control means to stabilize the DC side voltage (i.e., the DC voltage of DP to DN terminal, creating a stable DC output voltage condition for the subsequent DC / DC converter. The subsequent first DC / DC converter circuit uses current closed-loop control to transfer energy to the DC side.

[0072] For applications involving external photovoltaic DC power supply and single-phase inverter grid-connected power generation, see [link to relevant documentation]. Figure 3 Reference for switching control of the three bridge arms Figure 8 The control method shown aims to stabilize the DC-side voltage (i.e., the DC voltage between the DP and DN terminals) to create a stable DC output voltage condition for the subsequent DC / DC1. The subsequent first DC / DC converter circuit uses current closed-loop control to transfer energy to the DC side.

[0073] Compared with existing technologies, this patent proposal has the following advantages:

[0074] 1. The power supply using this patented solution has the function of fast charging under both single-phase and three-phase AC input, overcoming the defect of traditional portable energy storage power supplies that can only adapt to single-phase power input to charge energy storage batteries. Correspondingly, the power supply using this patented solution can drive both single-phase and three-phase loads when outputting AC power, overcoming the limitation of traditional portable energy storage power supplies that can only drive single-phase loads when outputting AC power.

[0075] 2. Based on the power supply using this patented solution, when it is not needed for outdoor use, it can be mainly used at home as a household photovoltaic power generation converter, thus fully utilizing the value of the power supply.

[0076] 3. Based on the power supply using this patented solution, whether it is single-phase AC charging, single-phase load, or single-phase grid-connected power generation, the secondary current harmonics of the discharge or charging current of the energy storage battery are eliminated, thereby reducing the heat generation of the energy storage battery and improving its service life.

[0077] 4. The system electrical topology proposed in this patent, which is compatible with both single-phase and three-phase systems and eliminates low-order ripple in energy storage batteries, can achieve a good cost-performance ratio in product development.

[0078] The above specific embodiments are merely several preferred embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A low-ripple, multi-functional portable energy storage power supply, characterized in that: Including the four terminals A and B on the AC side N C N And N, three inductors L1, L2 and L3, three filter capacitors C0, C1 and C2, a three-phase bridge arm composed of six semiconductor power switches, a support capacitor C3, a first DC / DC converter circuit for bidirectional energy flow, an energy storage battery, and at least two switches k2 and a capacitor C4. Terminals A and B N C N The three-phase bridge arm is connected via inductors L1, L2, and L3 respectively. The supporting capacitor C3 is connected across the positive and negative DC buses of the three-phase bridge arm to form a DC side. The positive terminal DP and the negative terminal DN of the DC side are connected to the first DC / DC conversion circuit. The first DC / DC conversion circuit is a DC voltage adapter circuit and is connected to the energy storage battery. Capacitor C0 is connected across the end of inductors L1 and L3 that is closer to the AC side, capacitor C1 is connected across the end of inductors L1 and L2 that is closer to the AC side, and capacitor C2 is connected across the end of inductors L2 and L3 that is closer to the AC side. At least two of the switches k2 are connected together at one end and then connected to the negative busbar of the three-phase bridge arm via the capacitor C4. The other end of one of the switches k2 is connected to the end of the inductor L2 near the AC side, and the other end of the switch k2 is connected to the end of the inductor L3 near the AC side. In the three-phase bridge arm, power switches G1 and G2 form the left bridge arm, power switches G3 and G4 form the middle bridge arm, and power switches G5 and G6 form the right bridge arm. Among them, power switches G1, G3, and G5 are the upper power switches of the bridge arm, and power switches G2, G4, and G6 are the lower power switches of the bridge arm. When switch K2 is closed, power switches G3 and G5 use the same drive signal, and power switches G4 and G6 use the same drive signal. In the charging rectification operation under single-phase input, based on terminals A and B N Single-phase input voltage A sinusoidal signal sin(ωt) synchronized with the power grid is obtained, controlling the DC bus voltage on capacitor C3. With the target given value The difference is low-pass filtered, and then adjusted by a proportional-integral regulator to obtain the command current of inductor L1. The difference between the command current and the sampled feedback current of inductor L1 is adjusted and limited by a proportional resonant controller to obtain a modulated wave, which is compared with a triangular carrier wave obtained based on a sine wave signal sin(ωt) to obtain two mutually opposite PWM pulses, which are then sent to power switches G1 and G2 for PWM control. The difference between the control DC bus voltage and the target setpoint is obtained after adjustment by a proportional resonant controller. This difference is added to the command current to obtain an intermediate variable. The difference between the preset multiple of the control DC bus voltage setpoint and the sampled feedback voltage on capacitor C4 is adjusted by proportional-integral control and limited to obtain a current compensation amount. The difference between the intermediate variable and the current compensation amount is obtained and then compared with the difference between the sum of the currents of inductors L2 and L3 by a proportional resonant regulator and limited to obtain a modulation wave signal. This signal is compared with a triangular carrier wave to obtain two mutually opposite PWM pulse control signals. One signal is used to simultaneously control power switches G3 and G5, and the other signal is used to simultaneously control power switches G4 and G6.

2. The low-ripple multifunctional portable energy storage power supply according to claim 1, characterized in that: It also includes a photovoltaic DC power supply and a second DC / DC conversion circuit, wherein the photovoltaic DC power supply charges the energy storage battery via the second DC / DC conversion circuit.

3. The low-ripple multifunctional portable energy storage power supply according to claim 1, characterized in that: The AC side is equipped with a pre-charging branch.

4. The low-ripple multifunctional portable energy storage power supply according to claim 1, characterized in that: In single-phase inverter control mode, the target value of the AC output voltage peak is multiplied by a sinusoidal signal sin(ωt) with the power frequency to obtain the target value of the AC output voltage, which is then multiplied by terminals A and B. N The error of the output AC voltage between the two is adjusted by the proportional resonant regulator to obtain the command current of inductor L1. The difference between the control command current and the sampled feedback current of inductor L1 is controlled, adjusted and limited by the proportional resonant controller to obtain the modulation wave. It is compared with the triangular carrier wave based on the sinusoidal signal sin(ωt) to obtain two mutually opposite PWM pulses, which are sent to power switches G1 and G2 respectively for PWM control. The output voltage and the sampled feedback current of inductor L1 are detected, and their product is calculated to obtain the instantaneous power P. This product is then subjected to a 2-fold bandpass filter. The error between this filter and the zero-value setpoint is adjusted by a proportional-integral regulator to generate a current command. The control current command is added to the command current to obtain an intermediate variable. The difference between the preset multiple of the setpoint value of the DC bus voltage on control capacitor C3 and the sampled feedback voltage on capacitor C4 is adjusted by proportional-integral regulation and limited to obtain a current compensation amount. The difference between the intermediate variable and the current compensation amount is then taken, and compared with the difference between the sum of the currents of inductors L2 and L3. This difference is then adjusted by a proportional-integral regulator and limited to obtain a modulated wave signal, which is then compared with a triangular carrier wave to obtain two mutually inverse PWM pulse control signals. One signal is used to simultaneously control power switches G3 and G5, and the other signal is used to simultaneously control power switches G4 and G6.

5. A low-ripple multifunctional portable energy storage power supply according to claim 1 or 4, characterized in that: The preset multiple is 0.

5.

6. The low-ripple multifunctional portable energy storage power supply according to claim 1, characterized in that: In the charging condition under three-phase AC input, DC voltage closed-loop control is adopted to stabilize the DC side voltage, and the first DC / DC converter is controlled to charge the energy storage battery using constant current control.

7. The low-ripple multifunctional portable energy storage power supply according to claim 1, characterized in that: When the energy storage battery is charged by a photovoltaic DC power source and the three-phase inverter is connected to the grid for power generation, a DC voltage closed-loop control method is adopted to stabilize the DC side voltage, and the first DC / DC conversion circuit is controlled to transmit energy to the DC side using current closed-loop control.

8. The low-ripple multifunctional portable energy storage power supply according to claim 1, characterized in that: When the energy storage battery is charged by a photovoltaic DC power source and is in a single-phase inverter grid-connected power generation condition, the switching control method of the three bridge arms is the same as that of the bridge arm switching control method under the charging and rectification condition under single-phase input. The first DC / DC conversion circuit is controlled to transmit energy to the DC side using current closed-loop control.

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