Energy recovery system with bidirectional charge and discharge, control method and power utilization system

Abstract

The application discloses a bidirectional charge-discharge energy recovery system, a control method and a power utilization system, and relates to the technical field of electric energy recovery. The application comprises an energy storage assembly, a detection circuit, a bidirectional switch circuit and a control circuit. The application replaces the traditional bidirectional DC / DC converter with the bidirectional switch circuit composed of simple switch devices, realizes the bidirectional independent controllability of charging and discharging, simplifies the system complexity and reduces the system cost. Specifically, the low-loss characteristics of the switch device in the conduction state are utilized to construct an efficient energy path, so as to eliminate the inherent energy loss caused by the DC / DC conversion link on the hardware, and improve the system efficiency. Meanwhile, the topology structure greatly reduces the number of inductors, capacitors and other power elements, reduces the system cost and volume, and replaces the complex PWM modulation and closed-loop algorithm through the logical on-off control of the switch device, so as to realize the independent management of the charge-discharge path and the simplification of the system control.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric energy recovery, and in particular to a bidirectional charging and discharging energy recovery system, a control method and a power utilization system. BACKGROUND

[0002] In the industrial and construction fields, when the load is lowered or braked during the operation of equipment such as elevators, gantry cranes and the like, the motor will be converted into a generator state to generate regenerative energy. If this part of energy cannot be effectively utilized, it can only be dissipated in the form of heat energy through a braking resistor, causing energy waste. For this reason, an energy recovery system has emerged, and the core idea of which is to store regenerative energy in an energy storage component and release it back to the system when needed to achieve the purpose of energy saving.

[0003] In the prior art, in order to realize the charging and discharging management of the energy storage component, a solution based on a bidirectional DC / DC converter is generally adopted. Although this solution can improve the flexibility and intelligent degree of energy utilization, the energy transfer path thereof must pass through the bidirectional DC / DC converter for voltage conversion. The bidirectional DC / DC converter itself has energy loss, which reduces the overall energy recovery efficiency of the system. At the same time, this topology introduces multiple power devices such as inductors and capacitors, which not only increases the volume and cost of the system, but also requires a complex pulse width modulation control algorithm to stabilize operation, thereby increasing the system complexity and control difficulty. SUMMARY

[0004] The main purpose of the present application is to provide a bidirectional charging and discharging energy recovery system, a control method and a power utilization system, which aims to solve the technical problems of low system energy conversion efficiency, high hardware cost and complex control strategy caused by the use of a bidirectional DC-DC converter for energy recovery in the prior art.

[0005] To achieve the above-mentioned purpose, the present application provides a bidirectional charging and discharging energy recovery system, comprising:

[0006] an energy storage component;

[0007] at least one bidirectional switch circuit, each of the bidirectional switch circuits having a first port and a second port, the first port being electrically connected to the energy storage component, and the second port being electrically connected to an external DC bus;

[0008] a control circuit, which is electrically connected to the controlled end of the bidirectional switch circuit and the energy storage component, is used to acquire a state parameter of the energy storage component, and outputs a control signal to the bidirectional switch circuit according to the state parameter, so as to realize independent control of charging and discharging of the energy storage component.

[0009] In an embodiment, the bidirectional switch circuit comprises a first switch device and a second switch device connected in series, the first switch device and the second switch device being connected in series between the energy storage assembly and the DC bus.

[0010] In an embodiment, the control circuit is electrically connected to the controlled ends of the first switch device and the second switch device, for controlling the first switch device to be closed and the second switch device to be opened, to form a charging loop from the DC bus to the energy storage assembly;

[0011] and for controlling the first switch device to be opened and the second switch device to be closed, to form a discharging loop from the energy storage assembly to the DC bus;

[0012] and further for controlling the first switch device and the second switch device to be both closed, to form a bidirectional conduction loop between the energy storage assembly and the DC bus.

[0013] In an embodiment, the first switch device comprises a first switch tube, and the second switch device comprises a second switch tube, the first switch tube and the second switch tube being arranged in a back-to-back manner, for realizing unidirectional conduction of current through the body diode of the first switch tube or an external separate diode.

[0014] In an embodiment, the first switch device comprises a first contact switch and a first diode connected in anti-parallel with the first contact switch, and the second switch device comprises a second contact switch and a second diode connected in anti-parallel with the second contact switch;

[0015] One end of the first contact switch is electrically connected to the energy storage assembly and the anode of the first diode, and the other end is electrically connected to one end of the second contact switch and the cathode of the first diode;

[0016] One end of the second contact switch is electrically connected to the anode of the second diode, and the other end is electrically connected to the cathode of the second diode and the external DC bus.

[0017] In an embodiment, the control circuit comprises:

[0018] a detection circuit, an input end of which is electrically connected to the energy storage assembly, for monitoring a state parameter of the energy storage assembly and outputting a detection signal;

[0019] a main control circuit, an output end of which is electrically connected to the detection circuit, for outputting a control signal to the bidirectional switch circuit according to the detection signal output by the detection circuit, to realize independent control of charging and discharging of the energy storage assembly.

[0020] In an embodiment, the energy storage assembly is a super capacitor, a power battery pack or an energy battery pack.

[0021] In addition, to achieve the above object, the application further provides a control method, which is realized based on the energy recovery system with bidirectional charge and discharge as described above, and comprises the following steps of:

[0022] obtaining a state parameter of the energy storage assembly and a voltage of the DC bus;

[0023] controlling a combination of on and off of the first switch device and the second switch device in the bidirectional switch circuit based on the state parameter and the voltage of the DC bus, so as to realize independent control of charging and discharging of the energy storage assembly.

[0024] In an embodiment of the control method, the specific step of controlling the combination of on and off of the first switch device and the second switch device in the bidirectional switch circuit based on the state parameter and the voltage of the DC bus, so as to realize independent control of charging and discharging of the energy storage assembly comprises the following steps of:

[0025] if the current capacity of the energy storage assembly is greater than or equal to the upper limit of the charging capacity, or any single cell voltage is greater than or equal to the upper limit of the charging voltage, entering a limited charging mode, and controlling the first switch device to be off and the second switch device to be on;

[0026] if the current capacity of the energy storage assembly is less than or equal to the lower limit of the discharging capacity, or any single cell voltage is less than or equal to the lower limit of the discharging voltage, entering a limited discharging mode, and controlling the first switch device to be on and the second switch device to be off;

[0027] if the current capacity of the energy storage assembly and the single cell voltage are both within the normal working range, entering a mode of allowing charging and discharging, and controlling the first switch device and the second switch device to be on.

[0028] In addition, to achieve the above object, the application further provides a power utilization system, which comprises:

[0029] a power grid power supply unit;

[0030] a load;

[0031] the energy recovery system with bidirectional charge and discharge as described above, which is connected to a DC bus between the power grid power supply unit and the load.

[0032] The one or more technical solutions provided by the application have at least the following technical effects:

[0033] The application replaces the traditional bidirectional DC / DC converter with a bidirectional switch circuit composed of simple switch devices, realizes bidirectional independent controllable charging and discharging, simplifies the system complexity and reduces the system cost. Specifically, the low-loss characteristics of the switch device in the on state are used to construct a high-efficiency energy path, thereby eliminating the inherent energy loss caused by the DC / DC conversion link in hardware, improving the system efficiency; at the same time, the topology structure greatly reduces the number of inductors, capacitors and other power elements, reduces the system cost and volume, and replaces the complex PWM modulation and closed-loop algorithm through the logical on-off control of the switch device, realizes the independent management of the charging and discharging paths and the simplification of the system control. BRIEF DESCRIPTION OF DRAWINGS

[0034] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiment or prior art description will be briefly introduced as follows, and obviously, other drawings can also be obtained by those skilled in the art without creative labor.

[0036] Figure 1 A block diagram of a bidirectional charging and discharging energy recovery system according to the present application;

[0037] Figure 2 A circuit diagram of the use state of a bidirectional switch circuit according to the present application;

[0038] Figure 3 A three-circuit diagram of the use state of a bidirectional switch circuit according to the present application;

[0039] Figure 4 A flowchart of a control method embodiment one according to the present application is provided;

[0040] Figure 5 A flowchart of step S200 of a control method embodiment two according to the present application is provided;

[0041] Figure 6 A flowchart of a control method embodiment three according to the present application is provided.

[0042] Explanation of reference numerals: energy storage component 01, detection circuit 02, bidirectional switch circuit 03, main control circuit 04.

[0043] The purpose implementation, functional characteristics and advantages of the present application will be further explained with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0044] It should be understood that the specific embodiments described herein are merely for the purpose of illustrating the technical solutions of the present application and are not intended to limit the present application.

[0045] In order to better understand the technical solutions of the present application, the following will be described in detail in combination with the drawings of the specification and specific embodiments.

[0046] The present application provides a bidirectional charge-discharge energy recovery system, as shown in Figure 1 The present application provides a bidirectional charge-discharge energy recovery system, as shown in

[0047] The energy storage assembly 01; at least one bidirectional switch circuit 03, each bidirectional switch circuit 03 has a first port and a second port, the first port is electrically connected with the energy storage assembly 01, and the second port is electrically connected with the external DC bus; a control circuit, which is electrically connected with the controlled end of the bidirectional switch circuit 03 and the energy storage assembly 01, is used to output a control signal to the bidirectional switch circuit 03 according to the detection signal output by the detection circuit 02, so as to realize independent control of charging and discharging of the energy storage assembly 01.

[0048] More specifically, in the field of industry and construction, heavy equipment such as elevators, gantry cranes, etc. often enter the generating state during operation due to frequent start-stop, lifting or braking of the load, generating a large amount of regenerative energy. If this part of the electric energy cannot be absorbed and reused in time, it usually needs to be dissipated in the form of heat through a braking resistor, not only causing direct waste of energy, but also possibly causing temperature rise of the equipment and increasing the heat dissipation burden. Therefore, an energy recovery system is introduced into such application scenarios, and the core goal is to effectively store the regenerative energy in the energy storage assembly 01 such as battery or super capacitor, and release it again when the system power demand is high, so as to realize the reduction of overall energy consumption and the improvement of energy efficiency.

[0049] Currently, in order to realize flexible management of the charging and discharging process of the energy storage unit, the industry generally adopts a system architecture based on bidirectional DC / DC converter. This kind of scheme realizes the regulation of voltage and current direction by adding a bidirectional working DC / DC conversion link between the energy storage unit and the DC bus, so as to support energy storage and feedback. Although this way has certain flexibility and controllability in function, the energy must be converted by the DC / DC converter, and this conversion process itself is accompanied by multiple energy losses such as switching loss, conduction loss and magnetic core loss, which restricts the further improvement of the overall energy efficiency of the system. In addition, in order to realize efficient and stable conversion of energy, the bidirectional DC / DC topology usually needs to introduce power inductors, high-frequency capacitors and multiple fully controlled switching devices, which not only increases the hardware complexity and manufacturing cost of the system, but also puts higher requirements on its control strategy, and needs to be equipped with corresponding pulse width modulation mechanism and closed-loop control algorithm, further increasing the difficulty of system design and debugging.

[0050] The bidirectional charge-discharge energy recovery system proposed in this application abandons the traditional bidirectional DC / DC converter and instead adopts an energy path management architecture coordinated by a bidirectional switching circuit 03 and a control circuit. The system includes an energy storage component 01, a detection circuit 02, a bidirectional switching circuit 03, and a control circuit. By controlling the physical path through which energy flows, it achieves independent and efficient management of the charging and discharging process of the energy storage component 01.

[0051] Among them, the energy storage component 01 is used to absorb and store the regenerative energy generated by external equipment during braking or lowering heavy objects, and release the energy to the load equipment when needed, playing a role in peak shaving and valley filling, energy saving and efficiency improvement. It is usually composed of batteries or supercapacitor banks. Its selection depends on the specific requirements of the application scenario for energy density, power density and cycle life.

[0052] The bidirectional switching circuit 03 directly connects or disconnects specific energy flow paths according to control commands, thereby achieving independent control of charging and discharging. Each bidirectional switching circuit 03 is connected to the DC bus of an external frequency converter, and a bridge or combination circuit composed of power switching devices ensures that the current can flow bidirectionally and controllably. Switching devices include, but are not limited to: contactors, a type of electromagnetic mechanical switch suitable for carrying large currents and with extremely low conduction losses. When the system determines that a high-power energy path needs to be established or disconnected, it performs the connection and disconnection of the main circuit and undertakes the main power transmission task. However, its operating speed is relatively slow and its lifespan is limited, making it unsuitable for high-frequency switching. IGBTs (Insulated Gate Bipolar Transistors) and MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) have fast operating speeds and can achieve precise on / off control at high frequencies. IGBTs are suitable for medium-to-high voltage and high-current applications, while MOSFETs have the advantage of low on-resistance in low-voltage and high-current applications. In this system, they can be used in parallel or in combination with contactors, with IGBT / MOSFETs providing fast, arc-free, and precise control, while the contactors take on the steady-state conduction task to reduce losses; they can also independently perform switching functions in low-power applications.

[0053] Among them, there can be multiple bidirectional switching circuits 03, with n bidirectional switching circuits 03 corresponding to n frequency converters, and each frequency converter corresponding to each device that can generate regenerative energy, such as elevators, lifting machinery, oil pumps, and robotic arms. The power consumption of the frequency converter can be obtained from the mains power or from the bidirectional controllable energy recovery system for charging and discharging, and the electrical energy generated by the motor feedback is charged into the energy storage component 01.

[0054] The control circuit analyzes the detected parameters such as the voltage of the energy storage component 01 and the voltage of the DC bus to determine whether to perform charging, discharging or disconnecting operation. Then, the control circuit sends a driving signal to the corresponding switch device in the bidirectional switch circuit 03. For example, when the voltage of the DC bus is higher than the voltage of the energy storage component 01 and charging is needed, the control circuit turns on the switch combination that allows current to flow from the bus to the energy storage component 01; on the contrary, when discharging is needed, the control circuit turns on the switch combination that allows current to flow in the opposite direction. Through this discrete control of the switch state, the energy flow is directly guided, avoiding the loss caused by the forced voltage conversion of the energy through the DC / DC circuit in the traditional scheme.

[0055] The control circuit is usually built with a microcontroller (MCU) or a digital signal processor (DSP) as the core. Its hardware includes CPU, memory, analog-to-digital conversion interface, digital IO port and PWM output module, etc. It is worth noting that the control circuit is configured to obtain the state parameters (such as voltage, current, temperature, etc.) of the energy storage component 01 and generate corresponding control signals according to the state parameters, which are output to the bidirectional switch circuit 03 to achieve independent and precise control of the charging and discharging processes of the energy storage component 01. As for the acquisition of the state parameters, the control circuit can include a detection circuit 02 and a main control circuit 04, which are two independent integrated circuits. The input end of the detection circuit 02 is electrically connected to the energy storage component 01 for real-time monitoring of the state parameters of the energy storage component 01 and outputting detection signals; the main control circuit 04 is electrically connected to the output end of the detection circuit 02 for outputting control signals to the bidirectional switch circuit 03 according to the detection signals output by the detection circuit 02 to achieve independent control of the charging and discharging of the energy storage component. The detection circuit 02 sends the monitored state parameter data to the control circuit through a communication connection (such as I2C, SPI, CAN or UART bus, etc.).

[0056] In addition, the detection function and the control function can also be integrated in the same integrated circuit. That is, the control circuit itself integrates a functional module (such as a built-in analog-to-digital converter ADC and related sampling circuit) for monitoring the state parameters of the energy storage component 01. Under this integrated architecture, the state parameters are processed and transmitted through the signal path inside the integrated circuit.

[0057] After obtaining the state parameters of the energy storage component 01 through any of the above methods, the control logic in the control circuit can calculate according to the preset control algorithm such as constant voltage charging, constant current discharging, temperature protection and other strategies, and generate corresponding pulse width modulation (PWM) signals or switch instructions to drive the bidirectional switch circuit 03 to act and complete the expected energy bidirectional flow management.

[0058] Taking an elevator as an example, when a traction machine of an elevator regenerates power, the DC bus voltage of the frequency converter thereof is raised. The detection unit in the bidirectional switch circuit 03 corresponding to the path transmits the signal to the control circuit. After the control circuit determines that the charging condition is met, the switch device in the path pointing to the energy storage component 01 is turned on immediately, and the regenerated energy directly flows to the energy storage component 01 for storage. When another device needs power, the control circuit can independently turn on the discharge path of the energy storage component 01 to the DC bus of the frequency converter of the device, so as to realize energy feedback. The whole process does not need complex DC / DC voltage conversion, the path is clear, and the loss is reduced.

[0059] The bidirectional switch circuit 03 composed of simple switch devices is adopted to replace the traditional bidirectional DC / DC converter, so that the system complexity is simplified and the system cost is reduced while realizing the bidirectional independent controllability of charging and discharging. Specifically, the low-loss characteristic of the switch device in the on state is used to construct an efficient energy path, so that the inherent energy loss caused by the DC / DC conversion link is eliminated in hardware, and the system efficiency is improved. At the same time, the number of inductors, capacitors and other power elements is greatly reduced, the system cost and volume are reduced, and the complex PWM modulation and closed-loop algorithm are replaced by the logical on-off control of the switch device, so that the independent management of the charging and discharging paths and the simplification of the system control are realized.

[0060] In an embodiment, as shown in FIG. 1, the bidirectional switch circuit 03 includes a first switch device and a second switch device connected in series, and the first switch device and the second switch device are connected in series between the energy storage component 01 and the DC bus. Figure 2 The control circuit is electrically connected to the controlled ends of the first switch device and the second switch device, and is used to control the first switch device to be closed and the second switch device to be opened, so as to form a charging path from the DC bus to the energy storage component 01; and is used to control the first switch device to be opened and the second switch device to be closed, so as to form a discharging path from the energy storage component 01 to the DC bus.

[0061] In the embodiment, the bidirectional switch circuit 03 includes a first switch device and a second switch device connected in series. The two switch devices thus physically form a bidirectional current path connecting the energy storage component 01 and the DC bus. The first switch device is mainly responsible for controlling the path of the discharging current, and when the first switch device is turned on, it provides a current path for the energy storage component 01 to release energy to the DC bus. The second switch device is mainly responsible for controlling the path of the charging current, and when the second switch device is turned on, it provides a current path for the regenerated energy on the DC bus to flow into the energy storage component 01 for charging. This symmetrical series structure is the physical basis for realizing bidirectional controllability and safety.

[0062] When the system is initializing, on standby or in failure, the control circuit sends off signals to both the first and second switching devices simultaneously. At this moment, no matter whether the DC bus voltage is higher or lower than the energy storage component 01 voltage, current cannot flow between them. This state effectively isolates the energy storage component 01 from the DC bus, ensuring the safety of the system and preventing unnecessary energy loss.

[0063] When the detection circuit 02 monitors that there is regenerative energy on the DC bus and the control logic judges that the charging condition is met, the system enters the charging state. As shown in Figure 2 (a), the control circuit accurately sends on signals to the second switching device while keeping the first switching device in the off state. Since the DC bus voltage is higher than the energy storage component 01 voltage, current will flow from the positive pole of the DC bus, through the second switching device which has been turned on, into the positive pole of the energy storage component 01 to charge it, and finally return to the negative pole of the DC bus. At this moment, the first switching device is cut off due to the polarity of its internal body diode (for MOSFET) or reverse-parallel diode (for IGBT) being in reverse bias, ensuring that current does not flow in the opposite direction. This process realizes the unidirectional injection of energy, i.e., charging the energy storage component 01, forming a charging loop.

[0064] When the detection circuit 02 monitors that the DC bus voltage is lowered and the control logic judges that discharge support is needed, the system enters the discharge state. As shown in Figure 2 (b), the control circuit sends on signals to the first switching device while keeping the second switching device in the off state. At this moment, the energy storage component 01 voltage is higher than the DC bus voltage, and current flows out of the positive pole of the energy storage component 01, through the first switching device which has been turned on, into the positive pole of the DC bus to boost its voltage, and finally returns to the negative pole of the energy storage component 01. At this moment, the diode inside the second switching device is cut off due to reverse bias, preventing current from flowing in the opposite direction into the DC bus. This process realizes the unidirectional release of energy, i.e., the energy storage component 01 discharges the DC bus, forming a discharge loop.

[0065] In an embodiment, as shown in Figure 3 , the control circuit is also used to control both the first and second switching devices to be closed, forming a bidirectional conduction loop between the energy storage component 01 and the DC bus.

[0066] In one embodiment of the application, the first switch device and the second switch device are simultaneously kept in a closed state by a control command, thereby establishing a bidirectional conduction loop between the energy storage assembly 01 and the external DC bus. The topology of the bidirectional switch circuit 03 can be intuitively understood as a common-source back-to-back or common-emission back-to-back connection mode. When the control circuit determines that the system needs to enter the free energy exchange mode, it will simultaneously send a continuous conduction signal to the first switch device and the second switch device. At this time, both switch devices exhibit a low resistance state, which is equivalent to connecting a low-loss wire directly between the energy storage assembly 01 and the DC bus. Energy can automatically and instantaneously determine the flow direction based on the real-time voltage difference between the DC bus and the energy storage assembly 01, greatly improving the system response speed and smoothness. Since the path through which the energy flows is two switch devices in a saturated conduction state, the on-state voltage drop or on-state resistance is very small, so the conduction loss is much lower than that of a DC / DC converter that must operate at high frequency. In situations where dynamic response is extremely high, such as frequent start-stop of elevators or precise braking of mechanical arms, the power exchange direction between the bus and the energy storage assembly 01 changes rapidly. This bidirectional conduction mode can perfectly adapt to such rapid and small-scale energy oscillations, achieving real-time energy balance and efficient utilization.

[0067] In one embodiment, the first switch device includes a first switch tube, and the second switch device includes a second switch tube, the first switch tube and the second switch tube are arranged in a top-to-top manner to realize unidirectional conduction of current through the body diode of the first switch tube or the external discrete diode.

[0068] It can be understood that the top-to-top arrangement means that a certain specific power terminal of the first switch tube and the second switch tube is connected in series to form a common midpoint. Specifically, if MOSFET is used, the source terminals of the two MOSFETs are usually connected together, and if IGBT is used, the emitter terminals of the two IGBTs are usually connected together. The other end of the two switch tubes (the drain of the MOSFET or the collector of the IGBT) is respectively connected to the positive and negative terminals of the DC bus or connected to the energy storage assembly 01 through a specific path to form a loop. In addition, there is a body diode (for MOSFET) or a fast recovery diode (for IGBT) formed by the semiconductor structure inside each switch tube.

[0069] The first and second switching transistors act as controllable electronic valves. When a valid drive signal is applied to their control electrodes, the transistors conduct, allowing current to flow bidirectionally; when the control electrode signal is removed, the transistors turn off, theoretically blocking the current. The body diode / external discrete diodes act as one-way check valves. They are the physical basis for selective current conduction. Each diode only allows current to flow from its anode to its cathode, and cuts off the flow in the opposite direction. This is key to establishing independent control paths for charging and discharging. The working principle of this structure can be understood by analyzing combinations of different switching states. Its ingenuity lies in selectively allowing or prohibiting current paths in specific directions by controlling the on / off states of the two switching transistors.

[0070] When the system needs to allow charging of energy storage component 01, the control circuit precisely turns on the second switch while keeping the first switch off. At this time, if the DC bus voltage is higher than the battery voltage, current attempts to flow from the bus to the battery. Since the first switch is off, the main path is blocked. However, the diode connected in parallel with the first switch is forward biased. Therefore, current can flow smoothly into the battery through the path formed by this diode and the turned-on second switch to complete charging. In this state, current cannot flow in the reverse direction because any current attempting to flow in this direction would reverse-bias the diode connected in parallel with the second switch, causing it to cut off. This achieves unidirectional control that allows charging but prohibits discharging. Conversely, when the system needs to allow energy storage component 01 to discharge to the DC bus, the control circuit operates in the opposite way: turning on the first switch while keeping the second switch off.

[0071] At this point, if the battery voltage is higher than the DC bus voltage, the discharge current attempts to flow out. The switched-off second switch blocks the direct path, but the diode connected in parallel with the second switch is now forward biased. The current flows to the DC bus through the path formed by the switched-on first switch and this diode, thus discharging. Similarly, this path is unidirectional and cannot form a loop from the bus to the battery for charging, thereby achieving independent control that only allows discharging and prohibits charging.

[0072] The top-mounted structure selectively controls the on / off state of two switching transistors, utilizing the inherent unidirectional conductivity of diodes to physically construct two independent and directionally controllable energy channels. It eliminates the need for complex magnetic energy conversion components, achieving completely independent management of the charging and discharging process of the energy storage component 01 solely through the combination of semiconductor devices and logic control. This avoids various losses common in traditional bidirectional DC / DC converters, optimizing the system in terms of efficiency, cost, and complexity.

[0073] In an embodiment, the first switching device comprises a first contact switch, a first diode connected in anti-parallel with the first contact switch, and the second switching device comprises a second contact switch, a second diode connected in anti-parallel with the second contact switch;

[0074] One end of the first contact switch is electrically connected with the energy storage component 01 and the anode of the first diode, and the other end is electrically connected with one end of the second contact switch and the cathode of the first diode; one end of the second contact switch is electrically connected with the anode of the second diode, and the other end is electrically connected with the cathode of the second diode and the external DC bus.

[0075] The embodiment discloses a particularly classic and reliable bidirectional switch circuit 03. The scheme combines the characteristics of electromagnetic mechanical switches and semiconductor diodes to build an energy path controller with low conduction loss. The bidirectional switch circuit 03 is composed of two structurally symmetrical units connected in series, and each unit contains a contact switch and a diode connected in anti-parallel with the contact switch.

[0076] The first switching device is composed of a first contact switch, such as the contact of a contactor or a relay, and a first diode. The specific connection relationship is that one end of the first contact switch is connected with the energy storage component 01, and at the same time, this end is also connected to the anode of the first diode. The other end of the first contact switch is connected with the second switching device, and at the same time, this end is also connected to the cathode of the first diode. The second switching device is composed of a second contact switch and a second diode. The connection mode is that one end of the second contact switch is connected with the common end of the first switching device, and at the same time, this end is also connected to the anode of the second diode. The other end of the second contact switch is connected with the external DC bus, and at the same time, this end is also connected to the cathode of the second diode.

[0077] The contact switch serves as the main power path controller. When its coil is powered and the contact is closed, it provides a channel with extremely low resistance, similar to a wire, for carrying large steady-state currents. The diode serves as a unidirectional conduction path builder and freewheeling protection element. By using its unidirectional conduction property, it passively defines the direction in which current can flow. Its role is to provide directional conduction function and provide necessary current freewheeling path during switch operation.

[0078] The circuit realizes the management of the charging and discharging path by controlling the opening and closing combination of the two contact switches and cooperating with the directionality of the diode. In the charging mode, the control circuit makes the second contact switch closed and keeps the first contact switch open. When the DC bus voltage is higher than the voltage of the energy storage component 01, the charging current needs to flow. Since the first contact switch is open, the current cannot directly pass through. However, the current can naturally pass through the second contact switch and then reach the cathode of the first diode. At this time, as long as the bus voltage is high enough, the first diode is in a forward bias state, and the current then flows into the energy storage component 01 through the first diode to complete the charging. This path is composed of the "second contact switch + first diode". The existence of the diode ensures that the current can only flow from the bus to the battery in one direction, realizing the single-direction control of charging. If the battery voltage exceeds the bus voltage at this time, the first diode is automatically cut off due to reverse bias, effectively preventing reverse discharge.

[0079] In the discharging mode, the control circuit makes the first contact switch closed and keeps the second contact switch open.

[0080] Energy path: when the voltage of the energy storage component 01 is higher than the DC bus voltage, the discharging demand is generated. The disconnection of the second contact switch prevents the direct path. The current flows out of the energy storage component 01, first passes through the first contact switch, and reaches the anode of the second diode. At this time, the second diode is turned on due to forward bias, and the current is then discharged to the DC bus through the second diode to realize discharging. This path is composed of "first contact switch + second diode". Similarly, the unidirectionality of the diode ensures that the current can only flow from the battery to the bus, realizing the single-direction control of discharging and preventing reverse charging.

[0081] Bidirectional conduction mode: the control circuit makes the first contact switch and the second contact switch closed at the same time. At this time, the energy storage component 01 and the DC bus are directly connected through the two closed contact switches, forming a bidirectional, low-impedance straight-through channel. The current can freely flow in both directions according to the voltage difference. The diode is short-circuited by the contact switch in this mode and does not participate in the main energy transmission. This mode is used for occasions that require fast and seamless bidirectional exchange of energy. Since the current flows through mechanical contacts with extremely small resistance, the conduction loss is minimized, and the system efficiency is highest.

[0082] In an embodiment, the energy storage component 01 is a super capacitor, a power battery pack or an energy battery pack.

[0083] In the system of the present application, the selection of the energy storage component 01 directly determines the ability of the system to cope with different energy scenarios. Different types of energy storage media can be flexibly selected according to the specific needs of the application scenario, or a hybrid architecture can be adopted to achieve optimal performance and economic benefits. The main options include super capacitors, power battery packs and energy battery packs.

[0084] Super-capacitors and power-type batteries mainly act as power buffer or peak power processor for the system, focusing on high efficiency, fast absorption and release of huge instantaneous power. Super-capacitors work on the principle of double-layer, and their charging and discharging process is physical ion adsorption and desorption, not chemical reaction. This makes it have extremely high power density and extremely long cycle life. Its internal resistance is very small, allowing current to flow in and out instantaneously, with extremely fast response speed.

[0085] Power-type batteries are usually specially designed lithium-ion batteries, such as power-type variants of LTO lithium titanate batteries or lithium iron phosphate batteries, whose chemical system and organizational structure are optimized to reduce internal resistance and support continuous high-rate charging and discharging. In scenarios such as elevator braking, heavy machinery lowering, or robotic arm emergency stopping, the motor will generate a huge amount of regenerative energy in a very short time. If this part of energy is directly sent back to the power grid, it will cause an impact on the power grid, and may cause the inverter DC bus voltage to be too high and trigger a fault if not handled in time. At this time, if the system is equipped with super-capacitors or power-type batteries, the control circuit will quickly connect them to the DC bus. Because they have the ability to accept large current charging, they can instantly absorb this power flood like a high-efficiency "energy sponge", stabilizing the bus voltage. Conversely, when the device needs to start or accelerate suddenly, they can immediately release the stored energy to make up for the delay and insufficient power supply of the power grid, avoiding a large current impact on the power grid. This peak shaving and valley filling protects the power grid and equipment, and realizes local energy balance.

[0086] Energy-type batteries provide continuous and stable energy storage and supply, ensuring long-term operation of the system or achieving deeper energy scheduling. They include but are not limited to lithium batteries, sodium batteries, and traditional lead-acid batteries. The most notable feature of this type of battery is high energy density, i.e. it can store more energy per unit weight or volume, but its power density and fast charging and discharging capability are generally lower than that of specialized power-type devices.

[0087] Energy-type batteries are responsible for handling energy flows with relatively flat power changes but long duration. For example, in the case of continuous operation of a pumping unit or long-term operation of multiple devices, surplus energy can be continuously absorbed from the power-type energy storage component 01 or directly from the DC bus for "trickle" charging, converting intermittent regenerative energy into long-term usable reserve power. When the system needs continuous power supply, it can also release energy stably to supplement the power of the power-type battery or directly support the continuous power demand of special equipment. In this hybrid system, energy-type batteries and power-type energy storage components 01 can complement each other's advantages.

[0088] When the energy storage assembly 01 is a plurality of battery packs, the detection module is divided into a plurality of sub-battery detection modules to meet the monitoring needs of hundreds or thousands of battery cells. The battery detection module usually adopts a distributed and hierarchical structure.

[0089] Each sub-module is responsible for monitoring the voltage and temperature of a specific number of series-connected battery cells in a battery module. This grouping design simplifies the wiring complexity and improves the scalability and reliability of the system.

[0090] Real-time monitoring of the terminal voltage of each battery cell is a direct basis for determining whether the battery cell is working within a safe voltage window and for passive or active balancing. When an abnormal high or low voltage of a battery cell is detected, the system can take timely intervention measures. By arranging temperature sensors on the surface of the battery cell or at key points inside the module, the temperature change is monitored in real time. Temperature is a key factor affecting battery performance, life and safety, and overheating can cause thermal runaway. Temperature data is used to control the size of the charging and discharging current and trigger protection when the temperature is too high. By integrating voltage, current and time data and applying advanced algorithms, the state of charge of the battery pack, i.e. the remaining capacity, is estimated in real time. This is equivalent to a power meter for the system, allowing the manager to know how much energy is available in the energy storage assembly 01. All sub-battery detection modules upload the collected raw data to the central system management module in real time through a reliable communication bus.

[0091] In addition, the application also proposes a control method, which is realized based on the bidirectional charge-discharge energy recovery system as described above, as shown in Figure 4 , comprising:

[0092] S100: obtaining state parameters of the energy storage assembly and a voltage of a direct current bus;

[0093] S200: based on the state parameters and the voltage of the direct current bus, controlling the on-off combination of the first switching device and the second switching device in the bidirectional switching circuit to realize independent control of charging and discharging of the energy storage assembly.

[0094] It can be understood that the control method proposed in the application is a decision-making and execution process for driving the efficient and safe operation of the aforementioned bidirectional charge-discharge energy recovery system. In step S100, key parameters affecting energy scheduling are collected. First, the state parameters of the energy storage assembly are obtained, including reading detailed data from the battery detection module. Specific parameters include: voltage information of each battery cell, temperature of key points inside the battery pack, state of charge. Second, the voltage of the direct current bus is obtained. The voltage value of the direct current bus is a direct indicator of the energy balance of all devices connected to the bus. When the motor is in the electric mode, it consumes energy, and the bus voltage will decrease. When the motor is in the generating mode, it feeds back energy, and the bus voltage will increase. Therefore, the high and low of the bus voltage directly indicates whether the system is short of electricity or has excess electricity.

[0095] In step S200, by controlling different on-off combinations of the switching devices in the bidirectional switch circuit, independent control of the charging and discharging processes of the energy storage assembly is achieved. The system management module performs fusion analysis on all the data obtained in S100. In combination with the change trend of the DC bus voltage and the state of charge of the energy storage assembly, the core requirements of the current system are determined. For example, if the bus voltage continues to rise and the energy storage assembly still has charging space, charging should be started to recover energy; on the contrary, if the bus voltage is pulled down and the energy storage assembly has sufficient power, discharging should be started to support system operation. Under the premise of safety, the strategy also considers optimization goals such as maximizing energy efficiency, prolonging battery life, responding to peak-valley electricity prices, etc. According to the above analysis results, the system management module will generate control instructions for a specific bidirectional switch circuit to determine the on or off state of the first and second switching devices. As in the previous embodiment, different on-off combinations correspond to different energy paths:

[0096] The charging mode instruction controls the second switching device to be on while keeping the first switching device off. This combination uses the unidirectional nature of diodes to build a channel that only allows energy to flow from the DC bus to the energy storage assembly; the discharging mode instruction controls the first switching device to be on while keeping the second switching device off; this combination builds a channel that only allows energy to flow from the energy storage assembly to the DC bus; the bidirectional on mode instruction controls the first and second switching devices to be on simultaneously. This combination establishes a low-loss bidirectional path suitable for scenarios where energy needs to flow quickly and frequently in both directions; the off mode instruction controls the first and second switching devices to be off simultaneously. This combination completely disconnects the energy storage assembly from the bus for system standby, fault or maintenance state.

[0097] In an embodiment of the control method, step S200 controls the on-off combination of the first and second switching devices in the bidirectional switch circuit based on the state parameters and the DC bus voltage to achieve independent control of the charging and discharging of the energy storage assembly, as shown in Figure 5 , including steps S210-S230:

[0098] S210: If the current capacity of the energy storage assembly is greater than or equal to the upper limit of the charging capacity, or any single voltage is greater than or equal to the upper limit of the charging voltage, enter the limited charging mode, control the first switching device to be off and the second switching device to be on;

[0099] S220: If the current capacity of the energy storage assembly is less than or equal to the lower limit of the discharging capacity, or any single voltage is less than or equal to the lower limit of the discharging voltage, enter the limited discharging mode, control the first switching device to be on and the second switching device to be off;

[0100] S230: If the current capacity and individual voltage of the energy storage component are both within the normal operating range, then enter the allowed charging and discharging mode, and control both the first and second switching devices to be turned on.

[0101] This embodiment details the decision-making mechanism of step S200, namely, how the system management module switches between three core operating modes based on the key state parameters of the energy storage components to ensure that the system operates within an absolutely safe range while realizing the basic functions of energy management.

[0102] In step S210, if the current capacity of the energy storage component is less than or equal to the lower limit of the discharge capacity, or if the voltage of any single cell is less than or equal to the lower limit of the discharge voltage, the system automatically prohibits charging, protecting the energy storage component, regardless of the DC bus voltage. The system will only exit this mode when the status parameters fall back to the safe range.

[0103] In step S220, the voltage of any single cell in the battery pack is less than or equal to its lower discharge voltage limit. This is also to prevent any single cell from reaching a depleted state before the whole pack due to individual differences, thus preventing over-discharge damage. The system prohibits the energy storage components from discharging externally. However, it can still accept charging from the DC bus, thereby providing the possibility of restoring power.

[0104] In step S230, when the current capacity of the energy storage component and the voltage of all individual cells are within a preset normal operating range, i.e., above the lower discharge limit and below the upper charge limit, energy can freely flow into or out of the energy storage component according to the instantaneous fluctuations of the DC bus voltage. When the bus voltage rises, the energy storage component automatically absorbs energy; when the bus voltage falls, the energy storage component automatically releases energy.

[0105] like Figure 6 As shown, the specific operating scenarios and protection mechanisms are detailed below:

[0106] This system uses a voltage balance pre-charge method and does not require a pre-charge resistor. The current collected by the system management module is now defined as follows: The total voltage is The maximum value of the battery voltage collected by the battery monitoring module is The minimum value is The DC bus voltage collected by the meter is The switch's load-bearing current-breaking capacity is The equivalent capacitance of the DC bus is C, the equivalent internal resistance of the system is R, and the instantaneous withstand power of the switch is P. To ensure that the switch does not stick together, the power generated at the moment of maximum closure must be less than the instantaneous withstand power of the switch, i.e. ,when This ensures that the total voltage of the battery pack and the DC bus voltage are in a relatively balanced state, thus guaranteeing the lifespan of the switch.

[0107] The upper limit of the battery capacity is defined as When the current capacity ≥ , or the current single battery voltage ≥ , it indicates that the battery pack has reached the upper limit of charging, when the loop current ≤ is detected, the charging switch is turned off, and under the action of the diode unidirectional conduction, the system can only discharge.

[0108] The upper limit of the battery capacity is defined as When the current capacity ≤ , or the current single battery voltage ≤ , it indicates that the battery pack has reached the lower limit of discharging, when the loop current ≤ is detected, the discharging switch is turned off, and under the action of the diode unidirectional conduction, the system can only charge.

[0109] When the current capacity > , and < , > , and < , the battery pack can be charged and discharged, at this time the charging switch and the discharging switch are closed at the same time, and the system can be charged and discharged.

[0110] The AC voltage collected by the electric meter is defined as When <10, the AC power loss protection is turned on, and at the same time the system management module monitors and protects the battery pack through the collected voltage, temperature and current, including overvoltage, undervoltage, overtemperature, overcurrent and other faults.

[0111] In addition, the application also provides a power utilization system, comprising: a power grid power supply unit; a load; and the bidirectional charging and discharging energy recovery system as described above, which is connected to a DC bus between the power grid power supply unit and the load.

[0112] The power utilization system proposed in the present application integrates traditional power grid power supply, load equipment and the above-mentioned bidirectional charge-discharge energy recovery system. The power grid power supply unit converts alternating current into stable direct current through a rectifier unit and supplies the direct current to a direct current bus. In the special equipment scenario of the present application, the load mainly refers to a motor driven by a frequency converter and a mechanical equipment dragged by the motor, such as an elevator, a crane, a port mechanical equipment, etc. These loads will generate severe power fluctuations when running. The bidirectional charge-discharge energy recovery system is directly connected in parallel to the direct current bus between the power grid power supply unit and the load. The internal energy storage component 01 and the multiple bidirectional switch circuits 03 precisely controlled by the system management module make it an active energy buffer and regulation node.

[0113] When the energy recovery system is connected to the direct current bus, the instantaneous current will sharply pull down the direct current bus voltage when the load suddenly starts or accelerates and requires huge power. At this time, the energy recovery system will immediately switch to the discharge mode and quickly release the stored energy to the direct current bus to support the load demand together with the power grid power supply unit. This effectively avoids drawing instantaneous large current from the power grid side, reduces the impact on the upper power grid and improves the power quality of the power grid. When the load is in the regenerative braking state, the motor becomes a generator, converts mechanical energy into electrical energy and feeds back to the direct current bus, resulting in an increase in the bus voltage. At this time, the energy recovery system quickly switches to the charging mode and efficiently stores the regenerative energy that would otherwise be consumed by the braking resistor. This not only saves energy, but also avoids the heat and energy consumption caused by using the braking resistor, realizing energy recycling.

[0114] In the extreme case of temporary fluctuations or interruptions of the power grid power supply, the energy recovery system can act as a temporary backup power source to continue to provide short-time power support for critical loads, improving the robustness of the system. At the same time, its intelligent management system can perform more complex energy scheduling optimization according to the battery state, electricity price signal, etc., to realize economic operation.

[0115] The above only describes some embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation made by using the content of the present application specification and drawings, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. A bidirectional charge-discharge energy recovery system, characterized in that, include: Energy storage components; At least one bidirectional switching circuit, each of the bidirectional switching circuits having a first port and a second port, the first port being electrically connected to the energy storage component and the second port being electrically connected to an external DC bus; The control circuit is electrically connected to the controlled terminal of the bidirectional switching circuit and the energy storage component. It is used to acquire the state parameters of the energy storage component and output a control signal to the bidirectional switching circuit according to the state parameters, so as to realize independent control of charging and discharging of the energy storage component. The bidirectional switching circuit includes a first switching device and a second switching device connected in series, which are connected in series between the energy storage component and the DC bus; the first switching device includes a first contact switch and a first diode connected in reverse parallel with the first contact switch; the second switching device includes a second contact switch and a second diode connected in reverse parallel with the second contact switch. One end of the first contact switch is electrically connected to the energy storage component and the anode of the first diode, and the other end is electrically connected to one end of the second contact switch and the cathode of the first diode; One end of the second contact switch is electrically connected to the anode of the second diode, and the other end is electrically connected to the cathode of the second diode and the external DC bus.

2. The bidirectional charge-discharge energy recovery system as described in claim 1, characterized in that, The control circuit is electrically connected to the controlled terminals of the first switching device and the second switching device, and is used to control the first switching device to close and the second switching device to open, so as to form a charging circuit from the DC bus to the energy storage component; And, for controlling the first switching device to open and the second switching device to close, so as to form a discharge circuit from the energy storage component to the DC bus; Furthermore, it is also used to control both the first switching device and the second switching device to be closed, forming a bidirectional conduction loop between the energy storage component and the DC bus.

3. The bidirectional charge-discharge energy recovery system as described in claim 1, characterized in that, The control circuit includes: The detection circuit, with its input terminal electrically connected to the energy storage component, is used to monitor the state parameters of the energy storage component and output a detection signal. The main control circuit and the output circuit of the detection circuit are used to output control signals to the bidirectional switching circuit according to the detection signal output by the detection circuit, so as to realize independent control of the charging and discharging of the energy storage component.

4. The bidirectional charge-discharge energy recovery system as described in any one of claims 1-3, characterized in that, The energy storage component is a supercapacitor, a power battery pack, or an energy battery pack.

5. A control method, implemented based on the bidirectional charge-discharge energy recovery system as described in any one of claims 1 to 4, characterized in that, include: Obtain the state parameters of the energy storage component and the voltage of the DC bus; Based on the state parameters and DC bus voltage, the on / off combination of the first and second switching devices in the bidirectional switching circuit is controlled to achieve independent control of the charging and discharging of the energy storage component.

6. The control method as described in claim 5, characterized in that, The specific steps for controlling the on / off combination of the first and second switching devices in the bidirectional switching circuit based on the state parameters and DC bus voltage to achieve independent control of the charging and discharging of the energy storage component include: If the current capacity of the energy storage component is greater than or equal to the upper limit of the charging capacity, or the voltage of any single cell is greater than or equal to the upper limit of the charging voltage, then the limited charging mode is entered, and the first switching device is turned off and the second switching device is turned on. If the current capacity of the energy storage component is less than or equal to the lower limit of the discharge capacity, or the voltage of any single cell is less than or equal to the lower limit of the discharge voltage, then the limited discharge mode is entered, and the first switching device is turned on and the second switching device is turned off. If the current capacity and individual voltage of the energy storage component are both within the normal operating range, the system enters the allowed charging and discharging mode, controlling both the first and second switching devices to be turned on.

7. An electrical system, characterized in that, include: Power grid supply unit; load; The bidirectional charging and discharging energy recovery system as described in any one of claims 1 to 4, wherein the bidirectional charging and discharging energy recovery system is connected to the DC bus between the power grid supply unit and the load.

Images