CN100588074C - Hybrid energy storage device for elevator and control method thereof - Google Patents

Abstract

A hybrid energy storage device for elevators, comprising a supercapacitor bank [10], a battery pack [20], a supercapacitor charging and discharging circuit [30], a battery charging circuit [40], a battery discharging circuit [50], a supercapacitor charging Discharge control circuit [60], storage battery charging control circuit [70] and storage battery discharge control circuit [80]. The DC busbar [11] is connected with the supercapacitor bank [10] through the supercapacitor charging and discharging circuit [30], and the supercapacitor bank [10] is connected with the battery bank [20] through the battery charging circuit [40], and the energy is transferred from the supercapacitor bank [ 10] flow to the battery pack [20]. The battery pack [20] is connected to the DC bus [11] through the battery discharge circuit [40], and the energy flows from the battery pack [20] to the DC bus [11]. The present invention realizes uninterrupted power supply and power buffering by controlling the supercapacitor charge and discharge control circuit [60], the battery charge control circuit [70] and the battery discharge control circuit [80]; the supercapacitor bank [10] and the battery bank [ 20] to minimize the installed capacity; optimize the charging and discharging working state of the battery pack [20], and prolong the service life.

Description

Hybrid energy storage device for elevator and control method thereof

technical field

The invention relates to a hybrid energy storage device and a control method thereof, in particular to a hybrid energy storage device for elevators and a control method thereof.

Background technique

In the drive system of the elevator, the inverter drive mode is generally used. The power grid is directly rectified and connected to the DC bus to form a DC power supply system, and the frequency converter is controlled to work in a variable voltage and frequency conversion mode to output three-phase AC power to drive the elevator motor. In this power supply system, due to the strong nonlinearity of the motor, large power will be drawn from the DC bus during startup and acceleration, resulting in a decrease in bus voltage; In this state, power is fed to the DC bus, causing the bus voltage to rise. If the DC bus voltage fluctuates too much, it will affect the working performance of the frequency converter and elevator auxiliary equipment. Therefore, it is generally necessary to configure an energy discharge circuit between the DC buses, but this will cause a large energy loss and reduce the economy of the system.

In addition, when the power grid fails, instantaneous voltage drop or interruption occurs, the frequency converter and its auxiliary equipment cannot operate without backup energy support, which will cause inconvenience and even danger to personnel, goods and equipment. Configure energy storage devices, such as rechargeable batteries, supercapacitors, flywheel energy storage devices, etc., to provide energy support for a certain period of time for the DC bus in the event of a power outage or instantaneous voltage drop or interruption to ensure the safety of personnel and goods. s position. In addition, the energy storage device can also act as a power buffer. When the load power demand is large, the energy storage device outputs electric energy and provides the required power together with the grid to reduce the power output demand of the grid; when the motor feeds, the energy storage device absorbs part of the power to avoid excessive bus voltage, which can Save the discharge circuit or reduce its installation capacity.

Rechargeable batteries are a very common energy storage device, such as lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries, etc. It is applied to the power supply system of the elevator, directly connected to the DC bus, or connected to the DC bus through the charging and discharging device, as the emergency power supply or power buffer of the system. US Patent US6457565B2 discloses an emergency power supply for elevators. The power grid is connected to the DC bus after being rectified and filtered. The rechargeable battery is used as the energy storage device, and it is connected to the DC bus through a chargeable/dischargeable bidirectional power converter. When the load is light, the DC bus passes the power converter to the battery. Charge. When the DC bus voltage rises due to the energy feedback of the motor, the DC bus charges the battery through the power converter and releases it when the load is heavy to play the role of power buffer. When the power grid fails, or the grid voltage is interrupted or dropped for a short time, the battery releases energy through the power converter to maintain the DC bus voltage within the normal range to ensure the normal operation of the system.

There are certain deficiencies in using a rechargeable battery as an emergency power source. First of all, during the working process of the battery, the electrode active material will undergo chemical changes, which will cause the expansion and contraction of the electrode structure, resulting in the performance degradation of the battery. In the elevator power supply system, because the battery needs to absorb or release energy continuously, deep charge and discharge must be carried out frequently to ensure uninterrupted power supply in areas with unreliable grid power supply, which shortens the service life of the battery and requires frequent replacement, which increases the system the cost of. Secondly, the recovery time of the capacity of the battery after discharge is relatively long. After the power grid is restored, due to the large discharge depth of the battery, it usually takes a long time to restore the capacity to a certain level, resulting in a long time for the elevator to recover after a power outage. recovery time to operate safely again. Thirdly, the power density of the storage battery is small, while the power of the elevator is generally large. In order to ensure the normal operation of the system when the power grid fails, the storage battery needs to output a large power. Therefore, in the actual design, it is necessary to configure a battery pack with a large capacity to meet the power demand of the load, which increases the cost of the system and reduces the economy. In addition, batteries need frequent maintenance, and the metal materials after use are not easy to handle, which will cause serious environmental pollution.

Supercapacitor is a new type of energy storage device that has emerged in recent years. At present, it is generally believed that supercapacitors include two types: Electric Double Layer Capacitor (Electric Double Layer Capacitor) and Electrochemical Capacitor (Electrochemical Capacitor). Among them, the electric double layer capacitor uses activated carbon with high specific surface area, and works based on the separation of charges on the interface between the carbon electrode and the electrolyte to generate an electric double layer capacitance. Electrochemical capacitors use noble metal oxides such as RuO ₂ as electrodes, and oxidation-reduction reactions occur on the surface and bulk phase of oxide electrodes to generate adsorption capacitance, also known as Faraday quasi-capacitance, which can be divided into metal oxides and conductive capacitors according to different electrode materials. Two types of electrochemical capacitors based on permanent polymers. Since the generation mechanism of Faraday quasi-capacitance is similar to that of batteries, its capacitance is several times that of electric double layer capacitors under the same electrode area; but the power characteristics of instantaneous large current discharge of electric double layer capacitors are better than those of Faraday capacitors.

Supercapacitors have good power characteristics and can be charged and discharged quickly with high current and high efficiency. Since the charging and discharging process is always a physical process, there is no electrochemical reaction and no change in the electrode structure, so its cycle life is long. In addition, supercapacitors also have many advantages such as good high and low temperature performance, simple and accurate energy judgment, no maintenance, and environmental friendliness, and are increasingly becoming an efficient and practical energy storage device.

US Patent US6938733B2 discloses an elevator emergency power supply device, in which a supercapacitor bank is connected to a DC bus through a power regulating device. When the power grid fails, the voltage drops or is interrupted, the supercapacitor bank supplies power to the DC bus through the power conditioning equipment to maintain the normal operation of the motor and elevator auxiliary equipment until reaching the next floor. The supercapacitor bank can also continuously absorb or release energy through the power regulation equipment, and act as a power buffer to ensure that the DC bus voltage is stable and within the normal range.

Although supercapacitors have many advantages, their disadvantages are also obvious. Its energy density is lower than that of rechargeable batteries. At present, the energy density of electric double layer supercapacitors is about 20% of that of valve-regulated lead-acid batteries, and it is not suitable for large-capacity electric energy storage. Due to the high power and long duration of the elevator, if a supercapacitor is used as the emergency power supply, a large capacity needs to be configured, which will make the equipment too bulky and cumbersome. Moreover, the price of supercapacitors is currently relatively high, and the configuration of such a large capacity has greatly increased the cost of the system and reduced the economy.

If supercapacitors are used in combination with rechargeable batteries, combining the high energy density of batteries with the characteristics of high power density and long cycle life of supercapacitors will undoubtedly bring great performance improvements to electric energy storage. The hyperhybrid energy storage device has better energy storage capacity and power capacity, which can reduce the volume of the energy storage device and improve reliability. The battery works in parallel with the supercapacitor in a certain way, which can optimize the charging and discharging process of the battery, reduce the number of charging and discharging cycles, reduce internal loss, increase the discharge time, and prolong the service life. The use of supercapacitor battery energy storage devices can greatly improve the technical performance and economic performance of the system, and it is a good choice to solve the current power energy storage problems. In the elevator emergency power supply device disclosed in U.S. Patent US6938733B2, in order to prolong the discharge time of the emergency power supply, the patent proposes a design method using a combination of a rechargeable battery and a supercapacitor, but does not provide a specific combination of the two energy storage devices and energy management methods.

Contents of the invention

The purpose of the present invention is to provide a hybrid energy storage device and control method for elevators, which can provide emergency power supply for power failure, voltage drop or interruption; and can provide power buffer for bus voltage fluctuations caused by changes in motor working conditions, To maintain the stability of the bus voltage, to save the discharge circuit or reduce its installation capacity.

The hybrid energy storage device of the present invention is composed of a supercapacitor bank, a battery pack, a supercapacitor charging and discharging circuit, a battery charging circuit, a battery discharging circuit, a supercapacitor charging and discharging control circuit, a battery charging control circuit, and a battery discharging control circuit. The supercapacitor bank is connected to the DC bus through the supercapacitor charging and discharging circuit, and connected to the battery pack through the battery charging circuit. The battery pack is connected to the DC bus through the battery discharging circuit. The supercapacitor charging and discharging control circuit controls the operation of the supercapacitor charging and discharging circuit. The storage battery charging control circuit controls the operation of the storage battery charging circuit, and the storage battery discharge control circuit controls the operation of the storage battery discharging circuit.

Supercapacitors can be electric double layer capacitors or electrochemical capacitors. Single supercapacitors are first connected in series to form a series branch, and then two or more series branches are connected in parallel to form a supercapacitor bank. The specific series-parallel combination scheme depends on the actual situation of the system. In order to improve the capacity utilization rate of the supercapacitor bank and limit the single voltage below the maximum working voltage, the supercapacitor bank can use a series voltage equalizer or a series-parallel conversion circuit. The battery pack also consists of a number of single cells connected in series to form a series branch, and then two or more series branches are connected in parallel to form a battery pack. The specific series-parallel combination scheme depends on the actual situation of the system.

Supercapacitor charging and discharging circuits are generally composed of non-isolated DC/DC power converters. Since energy needs to flow in both directions during actual work, it is designed as a bidirectional DC/DC. The bidirectional DC/DC used in the present invention is actually composed of a step-down BUCK circuit and a step-up BOOST circuit, including two power switch tubes, two power diodes, an inductor, and two filter capacitors . The two circuits share an inductor, and each circuit has a pair of power switches and power diodes. When one circuit is working, the pair of power switches and power diodes of the other circuit is always inactive, and vice versa. The two circuits work alternately in different time periods, forming a bidirectional DC/DC.

The energy of the battery charging circuit can only flow from the supercapacitor bank to the battery bank, which can be a step-up type, a step-down type, or a buck-boost type. Capacity and combined structure. Considering that the terminal voltage fluctuation range of the supercapacitor bank is very large during the working process, and the terminal voltage fluctuation range of the storage battery pack is small, therefore, the present invention adopts a buck-boost DC/DC (BUCK-BOOST), which consists of a power switch tube , a power diode, an inductor, and a filter capacitor. The power converter has a negative polarity output. When the power switch tube is turned on, the inductor stores energy. When the power switch tube is turned off, the inductor stores energy in the filter capacitor through the power diode, and the filter capacitor supplies power to the load.

The energy of the battery discharge circuit can only flow from the battery pack to the DC bus, which can be a boost type, a step-down type, or a buck-boost type. Because the voltage of the DC bus is relatively high, the present invention adopts a step-up DC/DC (BOOST), which is composed of a power switch tube, a power diode, an inductor, and a filter capacitor. When the power switch tube is turned on, the inductor stores energy. When the power switch tube is turned off, the power supply and the inductor are connected in series to provide energy to the load, and the output voltage is greater than the power supply voltage.

Supercapacitor charge and discharge control circuit, battery charge control circuit, battery discharge control circuit mainly include signal sampling unit, A/D conversion unit, user instruction unit, calculation control unit (CPU), isolation drive unit, etc. The specific control and management process is Realized by software programming.

The signal sampling unit detects the state parameters of the system, including the terminal voltage, temperature, electrolyte density, charge and discharge current of the battery pack; the terminal voltage and charge and discharge current of the supercapacitor pack; the terminal voltage and its rate of change of the DC bus; the position of the elevator , load capacity, speed, acceleration, etc.; and grid voltage, power outage time, voltage interruption time and voltage drop degree, etc. The system detects these parameters through the signal sampling unit, generates a corresponding voltage signal, and sends it to the A/D conversion unit, and the A/D conversion unit sends the converted digital signal to the calculation control unit as the entry parameter of the system control.

The user instruction unit accepts user instructions, including elevator lift, destination floor, etc., and sends these instructions to the calculation control unit as entry parameters for system control.

The hybrid energy storage device and its control method of the present invention, on the premise of realizing the above functions, strive for high efficiency and energy saving, and can reduce the installation capacity of the supercapacitor bank and the battery bank, prolong the service life of the battery, and improve the economy. The basic principles of its control thoughts include the following points.

First, give full play to the variable current control functions of the supercapacitor charging and discharging circuit, battery charging circuit, and battery discharging circuit, and rationally configure the capacity of the battery pack and the supercapacitor pack to meet larger power and energy demands with a smaller capacity , to reduce the installation cost of energy storage devices.

Second, control the charging and discharging circuit of the supercapacitor so that the energy exchange between the DC bus and the hybrid energy storage device occurs as much as possible on the supercapacitor and as little as possible on the battery, so as to fully utilize the power of the supercapacitor The advantages of high density, long cycle life, high charge and discharge efficiency and fast speed.

Third, control the battery charging circuit and the battery discharging circuit, so that the charging and discharging process of the battery is in an optimized state as much as possible, and reduce the number of charging and discharging cycles or small cycles of the battery, or reduce the depth of discharge, so as to prolong the service life of the battery.

Fourth, according to the system information such as the state of the power grid, the state of charge of the energy storage device, the state of the elevator, and user instructions, the power and energy to be output by the hybrid energy storage device can be judged in advance, and the power and energy of the supercapacitor bank and the battery pack can be controlled in a timely and accurate manner. The working process improves the rapid response capability of the energy storage device.

The working process of the present invention is to charge the supercapacitor bank and the storage battery bank in a certain way before the elevator starts to run, so that they are in a certain state of charge. Use a larger current to charge the supercapacitor bank, and charge the battery pack in an optimized way, such as constant current charging or pulse charging.

When the elevator starts and accelerates, it absorbs a large amount of power from the DC bus through the frequency converter, causing the voltage of the bus to drop. When the grid voltage is interrupted or dropped for a short time, the voltage of the bus will also drop. When the bus voltage is lower than a certain set value, the supercapacitor bank supplies power to the DC bus through the charging and discharging circuit, and the output power depends on the power change rate of the bus. In general, the peak power demand of the system can be met only through the supercapacitor bank, but when the terminal voltage of the supercapacitor bank is lower than a certain set value due to discharge, or it is judged according to the system status and user instructions that the battery pack needs to be released When the power and energy are certain, the battery pack is discharged at a constant current through the battery discharge circuit, and together with the supercapacitor bank, provides the required power and energy to the DC bus.

When the motor regenerates energy, the voltage of the DC bus will increase. When it is higher than a certain set value, the DC bus charges the supercapacitor bank through the supercapacitor charging and discharging circuit, and the charging power depends on the power change rate of the DC bus. Under normal circumstances, only charging the supercapacitor bank can achieve the purpose of absorbing the peak power, but when the terminal voltage of the supercapacitor bank is higher than a certain set value, or it is judged according to the system status and user instructions that the battery bank needs to absorb a certain amount of power. When the power and energy are used, the supercapacitor bank charges the battery pack through the battery charging circuit, and the charging method can be optimized constant current charging or pulse charging.

When the power grid fails, the hybrid energy storage device needs to provide a certain amount of power and energy to the DC bus to ensure the reliable start-up of the backup power generation device and output electric energy, or to ensure that the electrical equipment can be shut down safely, or to continue to run until the power supply of the grid is restored. Control the battery discharge circuit so that the battery pack is discharged in an optimized constant current mode, and the output power is equal to the average power of the elevator load; control the supercapacitor charge and discharge circuit so that the supercapacitor bank provides the peak power of the elevator during work.

For elevators and mine hoists in high-rise sightseeing towers, because there are few stops, they need to travel a long distance after a power outage before the elevator can reach the stops, and the auxiliary power needs to be supported for a long time. There are also some special applications that require the elevator to run continuously for several hours after a power outage. The hybrid energy storage device can give full play to the advantages of high energy density of the battery, control the battery discharge circuit, and make the battery pack discharge in an optimized constant current output mode. The length of support time mainly depends on the capacity of the battery pack.

When the power grid returns to normal, in order to ensure safe work (there may be a short interval between two power outages), the elevator cannot work immediately, but the hybrid energy storage device needs to be charged in a certain way. Use higher current to charge the supercapacitor bank and charge the battery pack in an optimized way. When the state of charge of the storage battery pack and the supercapacitor pack reaches the set value, the elevator can work again.

The invention adopts supercapacitor-battery hybrid energy storage, and is equipped with an effective control method, which has the following advantages:

(1) The hybrid energy storage of super capacitor and battery can give full play to the advantages of high energy density of battery and high power density of super capacitor, long cycle life, fast charge and discharge speed and high energy storage efficiency, so that the energy storage device has good technical performance.

(2) Due to the function of the battery charging circuit, battery discharging circuit, and its control circuit, the charging and discharging process of the battery can be optimized, the number of small charging and discharging cycles of the battery can be reduced, or the discharge depth when a small charging and discharging cycle occurs, and the service life can be extended life.

(3) Due to the supercapacitor charging and discharging circuit and its control ability, the terminal voltage of the supercapacitor bank can be very different from the DC bus voltage. Under the premise of meeting the same power demand, the energy utilization rate of the supercapacitor is greatly improved. The installation capacity of the supercapacitor bank is reduced, and the system cost is reduced.

(4) Due to the variable flow of the battery charging circuit, battery discharging circuit, and supercapacitor charging and discharging circuit, the terminal voltage of the battery pack, the terminal voltage of the supercapacitor bank, and the terminal voltage of the DC bus can be very different , so that the structural configuration of the supercapacitor bank and battery pack is more flexible.

(5) When the motor generates energy feedback, through the control of the supercapacitor charging and discharging circuit, the instantaneous high power on the DC bus can be effectively absorbed, and there is no need to use a discharge circuit, or the discharge circuit can be greatly reduced. The installed capacity reduces energy consumption and improves economy.

(6) The battery only supplies power to the DC bus through the first-stage DC/DC, which reduces energy loss and improves the discharge efficiency of the battery.

The invention mixes the supercapacitor and the rechargeable storage battery, combines the characteristics of high energy density of the storage battery with the high power density and long cycle life of the supercapacitor, and improves the performance of the electric energy storage device. The supercapacitor-battery hybrid energy storage device has good energy storage capacity and power input and output capacity, can reduce the volume of the energy storage device, and improve reliability. The battery works in parallel with the supercapacitor in a certain way, which can optimize the charging and discharging process of the battery, reduce the number of charging and discharging cycles, reduce internal loss, increase the discharge time, and prolong the service life. The use of supercapacitor battery energy storage devices can greatly improve the technical performance and economic performance of the system. It is a good choice to solve the current power energy storage problem. Using it in elevators has obvious advantages.

Description of drawings

Fig. 1 is a block diagram of the working principle of the hybrid energy storage device of the present invention applied to the elevator power supply system;

Fig. 2 is the schematic diagram of the bidirectional DC/DC converter of the supercapacitor charging and discharging circuit of the present invention;

Fig. 3 is the schematic diagram of the unidirectional DC/DC converter of the storage battery charging circuit of the present invention;

Fig. 4 is the schematic diagram of the unidirectional DC/DC converter of the storage battery discharge circuit of the present invention;

Fig. 5 is the functional block diagram of supercapacitor charging and discharging control circuit of the present invention;

Fig. 6 is a functional block diagram of the storage battery charging control circuit of the present invention;

Fig. 7 is a functional block diagram of the storage battery discharge control circuit of the present invention;

Fig. 8 is a flow chart of the pre-charging control of the hybrid energy storage device of the present invention before the elevator runs;

Fig. 9 is a control flow chart of the hybrid energy storage device of the present invention when the bus voltage drops;

Fig. 10 is a control flow chart of the hybrid energy storage device of the present invention when the load generates energy feedback;

Fig. 11 is a control flow chart of the hybrid energy storage device of the present invention when the power grid fails;

Fig. 12 is a working principle block diagram of the hybrid energy storage device of the present invention applied to a multi-elevator power supply system.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

As shown in FIG. 1 , the elevator device of the present invention includes a rectifier 200 , a DC bus 11 , a bus filter capacitor 300 , a discharge circuit 100 , a frequency converter 901 , a motor and its load 902 . Wherein, the bleed circuit 100 is connected in parallel with the DC bus 11 , and includes a bleed resistor 101 and a bleed control switch 102 . The three-phase AC power of the grid is rectified by the rectifier 200, the output terminal is connected to the DC bus 11, the bus filter capacitor 300 filters the DC bus 11, the input terminal of the frequency converter 901 is connected to the DC bus 11, and the output three-phase AC drives the motor and its load 902.

The hybrid energy storage device for elevators of the present invention includes a supercapacitor bank 10, a battery pack 20, a supercapacitor charging and discharging circuit 30, a battery charging circuit 40, a battery discharging circuit 50, a supercapacitor charging and discharging control circuit 60, and a battery charging control circuit 70 , and the battery discharge control circuit 80. The supercapacitor bank 10 is connected to the DC bus 11 through the supercapacitor charging and discharging circuit 30 , the supercapacitor bank 10 is connected to the battery pack 20 through the battery charging circuit 40 , and the battery pack 20 is connected to the DC bus 11 through the battery discharging circuit 50 . The supercapacitor charge and discharge control circuit 60 controls the supercapacitor charge and discharge circuit 30 to determine the energy exchange process between the supercapacitor bank 10 and the DC bus 11 . Before the elevator starts to work, the DC bus 11 charges the supercapacitor bank 10 with relatively large power through the supercapacitor charging circuit 30 until its state of charge reaches the set value. The battery charging control circuit 70 controls the battery charging circuit 40 to determine the charging process of the battery pack 20 by the supercapacitor pack 10 . Before the elevator starts to work, the supercapacitor bank 10 charges the battery pack 20 in an optimized constant current or pulse mode through the battery charging circuit 40 until its state of charge reaches the set value. The battery discharge control circuit 80 controls the battery discharge circuit 50 to determine the discharge process of the battery pack 20 to the DC bus 11 . During the working process, the battery charging control circuit 70 and the battery discharging control circuit 80 control the battery charging circuit 40 and the battery discharging circuit 50, and judge the output or input power and energy of the battery pack 20 according to the system status and user instructions. When the battery pack 20 needs to provide a certain amount of energy within a specific time, the battery discharge circuit 50 is controlled to discharge the battery pack 20 in an optimized constant current manner. When the battery pack 20 needs to absorb a certain amount of energy within a specific time, the battery charging circuit 40 is controlled to charge the battery pack 20 in an optimized constant current or pulse mode.

FIG. 2 shows the bidirectional DC/DC converter of the supercapacitor charging and discharging circuit 30 of the present invention. It is composed of controllable power switch tubes 32, 34, power diodes 33, 35, inductor 31, filter capacitors 36, 37, and ports 38, 39. One end 31a of the inductance 31 is connected to the positive end 38a of the port 38; the other end 31b of the inductance 31 is connected to the collector 32a of the power switch tube 32, and is connected to the cathode 33a of the power diode 33, and the emitter 32b of the power switch tube 32 is connected to the The anode 33b of the diode 33 is connected to the negative terminal 38b of the port 38 and the negative terminal 39b of the port 39; the other end 31b of the inductor 31 is connected to the emitter 34a of the power switch tube 34 and connected to the anode 35a of the power diode 35 , the collector 34b of the power switching tube 34 is connected to the cathode 35b of the diode 35, and is connected to the positive terminal 39a of the port 39; the filter capacitor 36 is connected in parallel to the port 38, and the filter capacitor 37 is connected in parallel to the port 39. Among them, the controllable power switch tubes 32 and 34 include but are not limited to MOSFET, IGBT, IGCT, etc. This embodiment adopts an IPM module that integrates the IGBT power switch device and its driving circuit. Protective function. When the port 38 is used as the input terminal and the port 39 is used as the output terminal, the circuit is a step-up DC/DC, the power switch tubes 34 and 33 are cut off, and the power switch tube 32 is used as a controllable switch to control the working process of the circuit together with the power diode 35 . When the port 39 is used as the input terminal and the port 38 is used as the output terminal, the circuit is a step-down DC/DC, the power switch tubes 32 and 35 are cut off, and the power switch tube 34 is used as a controllable switch to control the operation of the circuit together with the power diode 33 . Since the voltage of the DC bus 11 is relatively high, the port 38 is connected to the supercapacitor bank 10 , and the port 39 is connected to the DC bus 11 . When the energy flows from the supercapacitor bank 10 to the DC bus 11 , it is a step-up DC/DC, and when the energy flows from the DC bus 11 to the supercapacitor bank 10 , it is a step-down DC/DC.

FIG. 3 shows the unidirectional DC/DC converter of the battery charging circuit 40 of the present invention. It consists of a controllable power switch tube 42, a power diode 45, an inductor 41, a filter capacitor 47, and ports 48 and 49. The collector 42a of the power switch tube 42 is connected with the positive end 48a of the port 48; the emitter 42b of the power switch tube 42 is connected with one end 41a of the inductance 41, and is connected with the cathode 45a of the power diode 45, and the other end 41b of the inductance 41 is connected with The negative terminal 48b of the port 48 is connected to the positive terminal 49a of the port 49, the anode 55b of the power diode 45 is connected to the negative terminal 49b of the port 49; the filter capacitor 47 is connected to the port 49 in parallel. Among them, the controllable power switch tube 42 includes but not limited to MOSFET, IGBT, IGCT, etc. This embodiment adopts an IPM module that integrates the IGBT power switch device and its driving circuit, and the module has over-current and over-heat protection functions inside. . The port 48 is connected to the supercapacitor bank 10, and the port 49 is connected to the battery pack 20. Energy can only flow from the supercapacitor bank 10 to the battery pack 20, which is a buck-boost structure.

FIG. 4 shows the unidirectional DC/DC converter of the storage battery discharge circuit 50 of the present invention. It consists of a controllable power switch tube 52, a power diode 55, an inductor 51, a filter capacitor 57, and ports 58 and 59. One end 51a of the inductance 51 is connected to the positive end 58a of the port 58; the other end 51b of the inductance 51 is connected to the collector 52a of the power switch tube 52, and is connected to the anode 55a end of the power diode 55, and the 52b end of the power switch tube 52 is connected to the The negative terminal 58b of the port 58 is connected to the negative terminal 59b of the port 59, the cathode 55b of the power diode 55 is connected to the positive terminal 59a of the port 59; the filter capacitor 57 is connected to the port 59 in parallel. Among them, the controllable power switch tube 52 includes but is not limited to MOSFET, IGBT, IGCT, etc. This embodiment adopts an IPM module that integrates the IGBT power switch device and its driving circuit, and the module has over-current and over-heat protection functions inside. . Since the voltage of the DC bus 11 is relatively high, the port 58 is connected to the battery pack 20, and the port 59 is connected to the DC bus 11. Energy can only flow from the battery pack 20 to the DC bus 11, which is a boost structure.

As shown in FIG. 5 , the supercapacitor charge and discharge control circuit 60 of the present invention includes a signal sampling unit 61 , an A/D conversion unit 62 , a user instruction unit 63 , a calculation control unit 64 , and an isolation drive unit 65 . Wherein, the computing control unit 64 includes but is not limited to a digital signal processor DSP, a single-chip microcomputer, an embedded system, and the like. The signal sampling unit 61 uses voltage sensors, current sensors, temperature sensors, speed sensors, acceleration sensors, position sensors, concentration sensors, and load cells to sample the state parameters of the system, including grid voltage, bus voltage, elevator position, Load capacity, speed and acceleration, voltage and charge and discharge current of the supercapacitor bank 10, voltage, temperature, electrolyte density and charge and discharge current of the battery pack 20, etc. The output voltage signal is sent to the A/D conversion unit 62 , and the A/D conversion unit 62 sends the converted digital signal to the calculation control unit 64 . The user instruction unit 63 sends user instructions to the computing control unit 64, including elevator lift, destination floor and so on. The calculation control unit 64 outputs control signals according to the set control process, and sends them to the isolation drive unit 65 to drive the power switch tubes 32 and 34 in the supercapacitor charging and discharging circuit 30 to realize the control process. The set control process includes: before the elevator runs, control the power switch tube 32 to cut off, drive the power switch tube 34, and the DC bus 11 supplies power to the supercapacitor bank 10 and the battery charging circuit 40; The power switch tube 34 is turned off, the power switch tube 32 is driven, and the supercapacitor bank 10 provides energy to the DC bus 11; during the energy feedback process of the elevator, the power switch tube 32 is controlled to be turned off, the power switch tube 34 is driven, and the DC bus bar 11 is supplied to the supercapacitor The group 10 and the battery charging circuit 40 supply power; during the grid power failure process, the control power switch tube 34 is turned off, and the power switch tube 32 is driven to provide energy to the DC bus 11 .

As shown in FIG. 6 , the battery charging control circuit 70 of the present invention includes a signal sampling unit 71 , an A/D conversion unit 72 , a user command unit 73 , a calculation control unit 74 , and an isolation drive unit 75 . Wherein, the computing control unit 74 includes but is not limited to a digital signal processor DSP, a single-chip microcomputer, an embedded system, and the like. The signal sampling unit 71 uses voltage sensors, current sensors, temperature sensors, speed sensors, acceleration sensors, position sensors, concentration sensors, and load cells to sample the state parameters of the system, including grid voltage, bus voltage, elevator position, Load capacity, speed and acceleration, voltage and charge and discharge current of the supercapacitor bank 10, voltage, temperature, electrolyte density and charge and discharge current of the battery pack 20, etc. The output voltage signal is sent to the A/D conversion unit 72 , and the A/D conversion unit 72 sends the converted digital signal to the calculation control unit 74 . The user instruction unit 73 sends user instructions to the computing control unit 74, including elevator lift, destination floor and so on. The calculation control unit 74 outputs a control signal according to the set control process, and sends it to the isolation drive unit 75 to drive the power switch tube 42 in the supercapacitor charging circuit 40 to realize the control process. The set control process includes: before the elevator runs, drive the power switch tube 42, and the supercapacitor bank 10 charges the battery pack 20; during the energy feedback process of the elevator, if the voltage of the supercapacitor bank 10 is higher than the set value, The power switch tube 42 and the supercapacitor bank 10 charge the battery pack 20 .

As shown in FIG. 7 , the battery discharge control circuit 80 of the present invention includes a signal sampling unit 81 , an A/D conversion unit 82 , a user instruction unit 83 , a calculation control unit 84 , and an isolation drive unit 85 . Wherein, the calculation control unit 84 includes but is not limited to a digital signal processor DSP, a single chip microcomputer, an embedded system and the like. The signal sampling unit 81 uses voltage sensors, current sensors, temperature sensors, speed sensors, acceleration sensors, position sensors, concentration sensors, and load cells to sample the state parameters of the system, including grid voltage, bus voltage, elevator position, Load capacity, speed and acceleration, voltage and charge and discharge current of the supercapacitor bank 10, voltage, temperature, electrolyte density and charge and discharge current of the battery pack 20, etc. The output voltage signal is sent to the A/D conversion unit 82 , and the A/D conversion unit 82 sends the converted digital signal to the calculation control unit 84 . The user instruction unit 83 sends user instructions to the calculation control unit 84, including elevator lift, destination floor and so on. The calculation control unit 84 outputs a control signal according to the set control process, and sends it to the isolation drive unit 85 to drive the power switch tube 52 in the supercapacitor discharge circuit 50 to realize the control process. The set control process includes, during the starting and accelerating process of the elevator, if the terminal voltage of the supercapacitor bank 10 drops to a certain set value, the power switch tube 52 is driven, and the battery pack 20 provides energy to the DC bus 11; During a power outage, the power switch tube 52 is driven, and the battery pack 20 supplies energy to the DC bus 11 .

In practical applications, the supercapacitor charge and discharge control circuit 60, the battery charge control circuit 70, and the battery discharge control circuit 80 share a signal acquisition unit, an A/D conversion unit, and a user instruction unit. The calculation control unit can use a CPU, or Multiple CPUs can be used, and there are data communication channels between multiple CPUs.

Before the elevator starts running, the grid supplies power to the DC bus 11 through the rectifier 200 to establish a working voltage for it. The hybrid energy storage device starts precharging, and the charging process is shown in Figure 8. The DC bus 11 charges the supercapacitor bank 10 through the supercapacitor charging and discharging circuit 30, and the charging power is relatively large, so that its state of charge can quickly reach the set requirement. During this working process, the power switch tube 32 is always turned off, and the driving signal output by the supercapacitor charging and discharging control circuit 60 controls the power switch tube 34 to control the power supply process from the DC bus 11 to the supercapacitor bank 10 . At the same time, the supercapacitor bank 10 charges the battery pack 20 through the battery charging circuit 40, and adopts an optimized constant current mode or a pulse mode for charging. During this working process, the battery charging control circuit 70 outputs a control signal to drive the power switch tube 42 to control the power supply process of the supercapacitor bank 10 to the battery pack 20 . When the state of charge of the supercapacitor bank 10 and the storage battery pack 20 reaches the set value, the charging is stopped, and the elevator is ready to run.

When the elevator starts and accelerates, the power demand increases, which will cause the voltage of the DC bus 11 to drop; in addition, when the grid voltage is interrupted or dropped, the voltage of the DC bus 11 will also drop. The hybrid energy storage device supplies power to the DC bus 11 to maintain its voltage within a certain range. The process is shown in FIG. 9 . The supercapacitor charge and discharge control circuit 60 controls the supercapacitor charge and discharge circuit 30 to make the supercapacitor bank 10 supply power to the DC bus 11 . During this working process, the power switch tube 34 is always turned off, and the control signal output by the supercapacitor charging and discharging control circuit 60 drives the power switch tube 32 to control the power supply process of the supercapacitor bank 10 to the DC bus 11 . Under normal circumstances, only the discharge of the supercapacitor bank 10 can meet the system requirements, but when the supercapacitor bank 10 continues to discharge and its terminal voltage drops to a certain set value, or it is judged based on the system status and user instructions that the battery pack 20 When a certain amount of power and energy needs to be released, the battery discharge control circuit 80 controls the battery discharge circuit 50 , and the battery pack 20 and the supercapacitor pack 10 together supply power to the DC bus 11 . During this process, the battery discharge control circuit 80 outputs a control signal to drive the power switch tube 52 to control the power supply process of the battery pack 20 to the DC bus 11 . Detect the state of charge of the supercapacitor bank 10 and the battery pack 20, if it is lower than a certain set value, control the elevator to stop safely, and the hybrid energy storage device stops power supply.

During the process of decelerating and stopping the elevator, the motor is in the power generation state, and feeds power to the DC bus 11 through the frequency converter 901, causing its voltage to rise. When it is higher than the set value, the hybrid energy storage device absorbs this part of power and energy in a certain way, and the process is shown in Figure 10. The DC bus 11 charges the supercapacitor bank 10 through the supercapacitor charging and discharging circuit 30 . During this working process, the power switch tube 32 is always turned off, and the driving signal output by the supercapacitor charging and discharging control circuit 60 controls the power switch tube 34 to control the power supply process from the DC bus 11 to the supercapacitor bank 10 . Under normal circumstances, only charging the supercapacitor bank 10 can achieve the purpose of absorbing peak power, but when the supercapacitor bank 10 is continuously charged and its terminal voltage rises to a certain set value, or it is judged according to system information and user instructions When the battery pack 20 needs to absorb a certain amount of power and energy, the supercapacitor pack 10 charges the battery pack 20 through the battery charging circuit 40 . During this process, the battery charging control circuit 70 outputs a driving signal to control the power switch tube 42 to control the power supply process of the supercapacitor bank 10 to the battery pack 20 . Generally, the battery pack 20 works in an optimized constant current charging or pulse charging mode. When the state of charge of the supercapacitor bank 10 and battery pack 20 reaches the set value and the voltage of the DC bus 11 is still higher than the set value, the control switch 102 in the discharge circuit 100 is closed, and the DC bus 11 is discharged through the discharge resistor 101 , until the voltage drops to the set value, the control switch 102 is turned off.

When the power grid fails, the hybrid energy storage device provides the power and energy required for the normal operation of the elevator to achieve uninterrupted power supply. The process is shown in Figure 11. The battery pack 20 supplies power to the DC bus 11 through the battery discharge circuit 50, and the battery pack 20 outputs a constant current, and its output power is equal to the average power during the running of the elevator. During this process, the battery discharge control circuit 80 outputs a drive signal to control the power switch tube 52 to control the power supply process of the battery pack 20 to the DC bus 11 . The supercapacitor bank 10 supplies power to the DC bus 11 through the supercapacitor charging and discharging circuit 30, and is mainly used to provide the peak power demand of the elevator when starting and accelerating, and to absorb the peak power of the DC bus 11 during the elevator deceleration and stopping. During this process, the driving signal output by the supercapacitor charge and discharge control circuit 60 controls the power switch tube 32 and the power switch tube 34 to work alternately in different time periods, so as to realize the bidirectional flow of energy. The hybrid energy storage device continues to work until the elevator continues to run to the next floor and the elevator door is opened, or other backup power generation equipment starts and outputs electricity, or continues to run until the grid restores power. If the power failure time is too long and the state of charge of the battery pack 20 and the supercapacitor pack 10 is lower than the set lower limit, the system controls the elevator to stop safely at an appropriate floor and stops the power supply of the hybrid energy storage device.

Fig. 12 is an application example of the hybrid energy storage device of the present invention in a multi-elevator power supply system. On the basis of the system shown in Figure 1, the power grid is rectified by the rectifier circuit 200 and the generated DC power is sent to the DC bus 11, and the DC bus 11 drives multiple sets of loads 90 composed of frequency converters 901 and motors 902. In this embodiment , all elevator devices share a set of discharge circuit 100 (including discharge discharge group 101 and discharge control switch 102 ) through DC bus 11 .

The working process and control method of the hybrid energy storage device are similar to the embodiment shown in FIG. 1 . The advantage of this embodiment is that by driving multiple sets of loads 90 through the DC bus 11, the energy complementarity between the loads due to the asynchronous working process can be fully utilized, so that the installation capacity of the hybrid energy storage device can be further reduced, and the The working time of the hybrid energy storage device improves the energy utilization efficiency of the system.

Claims (8)

1. A hybrid energy storage device for elevators, characterized in that it includes a supercapacitor bank [10], a battery pack [20], a supercapacitor charging and discharging circuit [30], a battery charging circuit [40], and a battery discharging circuit [50], supercapacitor charge and discharge control circuit [60], storage battery charge control circuit [70], and storage battery discharge control circuit [80]; the supercapacitor bank [10] communicates with the elevator power supply system through the supercapacitor charge and discharge circuit [30] The DC busbar [11] in the battery is connected, the supercapacitor bank [10] is connected with the battery pack [20] through the battery charging circuit [40], and the battery pack [20] is connected with the DC busbar [11] through the battery discharge circuit [50]; The supercapacitor charging and discharging circuit [30] is composed of a non-isolated DC/DC converter with bidirectional energy flow, the battery charging circuit [40] is composed of a non-isolated DC/DC converter with unidirectional energy flow, and the battery discharge circuit [50] It is composed of a non-isolated DC/DC converter with one-way energy flow; the supercapacitor charge and discharge control circuit [60] includes a signal sampling unit [61], an A/D conversion unit [62], a user command unit [63], a calculation control unit unit [64], and an isolated drive unit [65]; the storage battery charging control circuit [70] includes a signal sampling unit [71], an A/D conversion unit [72], a user instruction unit [73], and a calculation control unit [74] , and an isolated drive unit [75]; the storage battery discharge control circuit [80] includes a signal sampling unit [81], an A/D conversion unit [82], a user command unit [83], a calculation control unit [84], and an isolated drive unit unit[85]; In the super capacitor charge and discharge control circuit [60], the signal sampling unit [61] collects the state parameters of the power grid, the DC bus [11], the elevator, the super capacitor bank [10] and the battery pack [20], and outputs voltage signals to A/ The D conversion unit [62], the A/D conversion unit [62] sends the converted digital signal to the calculation control unit [64], the user instruction unit [63] sends the user instruction to the calculation control unit [64], and the calculation control unit [64] output the control signal to the isolated drive unit [65]; in the battery charging control circuit [70], the signal sampling unit [71] collects power grid, DC bus [11], elevator, supercapacitor bank [10] and battery pack The state parameters of [20], the output voltage signal is given to the A/D conversion unit [72], the A/D conversion unit [72] sends the converted digital signal to the calculation control unit [74], and the user command unit [73] sends the user Instructions are sent to the calculation control unit [74], and the calculation control unit [74] outputs control signals to the isolation drive unit [75]; in the battery discharge control circuit [80], the signal sampling unit [81] collects the power grid, DC bus 11], elevator, supercapacitor bank [10] and battery pack [20] state parameters, output voltage signal to A/D conversion unit [82], A/D conversion unit [82] sends the converted digital signal to the calculation The control unit [84] and the user instruction unit [83] send user instructions to the calculation control unit [84], and the calculation control unit [84] outputs control signals to the isolation drive unit [85]. 2. The hybrid energy storage device for elevators according to claim 1, characterized in that: the non-isolated DC/DC converter in which the energy of the supercapacitor charging and discharging circuit [30] can flow bidirectionally is composed of the first and second control power switch tubes [32, 34], first and second power diodes [33, 35], first inductance [31], first and second filter capacitors [36, 37], first and second ports [ 38, 39]; one end [31a] of the first inductance [31] is connected to the positive end [38a] of the first port [38]; the other end [31b] of the first inductance [31] is connected to the first controllable power The collector [32a] of the switch tube [32] is connected, and is connected with the cathode [33a] of the first power diode [33], and the emitter [32b] of the first controllable power switch tube [32] is connected with the first power diode The anode [33b] of [33] is connected and connected with the negative end [38b] of the first port [38] and the negative end [39b] of the second port [39]; the other end [31b] of the first inductance [31] ] is connected with the emitter [34a] of the second controllable power switch tube [34], and is connected with the anode [35a] of the second power diode [35], and the collector [34] of the second controllable power switch tube [34] 34b] is connected with the cathode [35b] of the second power diode [35], and connected with the positive end [39a] of the second port [39]; the first filter capacitor [36] is connected in parallel with the first port [38], The second filter capacitor [37] is connected in parallel with the second port [39], the first port [38] is connected with the supercapacitor bank [10], and the second port [39] is connected with the DC bus [11]. 3. The hybrid energy storage device for elevators according to claim 2, characterized in that: the non-isolated DC/DC converter in which the energy of the battery charging circuit [40] flows in one direction is controlled by the third controllable power switch tube [ 42], the third power diode [45], the second inductor [41], the third filter capacitor [47], the first input port [48] and the first output port [49]; the third controllable power switch tube The collector [42a] of [42] is connected with the positive end [48a] of the first input port [48]; the emitter [42b] of the third controllable power switch tube [42] is connected with one end of the second inductor [41] [41a] is connected and connected with the cathode [45a] of the third power diode [45], the other end [41b] of the second inductance [41] is connected with the negative end [48b] of the first input port [48] and the first The positive end [49a] of the output port [49] is connected, the anode [45b] of the third power diode [45] is connected with the negative end [49b] of the first output port [49]; the third filter capacitor [47] is connected with the first output port [49] One output port [49] is connected in parallel, the first input port [48] is connected with the supercapacitor bank [10], and the first output port [49] is connected with the battery pack [20]. 4. The hybrid energy storage device for elevators according to claim 3, characterized in that: the non-isolated DC/DC converter in which the energy of the battery discharge circuit [50] flows in one direction is controlled by the fourth controllable power switch tube [ 52], the fourth power diode [55], the third inductor [51], the fourth filter capacitor [57], the second input port [58] and the second output port [59]; the third inductor [51] One end [51a] is connected to the positive end [58a] of the second input port [58]; the other end [51b] of the third inductor [51] is connected to the collector [52a] of the fourth controllable power switch tube [52] , and connected with the anode [55a] of the fourth power diode [55], the emitter [52b] of the fourth controllable power switch tube [52] and the negative terminal [58b] of the second input port [58] and the second The negative end [59b] of the output port [59] is connected, the cathode [55b] of the fourth power diode [55] is connected with the positive end [59a] of the second output port [59]; the fourth filter capacitor [57] is connected with the first The two output ports [59] are connected in parallel, the second input port [58] is connected to the battery pack [20], and the second output port [59] is connected to the DC bus [11]. 5. The hybrid energy storage device for elevators according to claim 1, characterized in that: the hybrid energy storage device is applied to the power supply system of multiple elevators, and each elevator motor [902] is connected to the DC The bus bars [11] are connected and share a discharge circuit [100]. 6. A control method for the hybrid energy storage device for elevators according to claim 4, characterized in that the signal sampling unit [61] of the supercapacitor charge and discharge control circuit [60] samples the grid voltage, the bus voltage, The position, load capacity, speed and acceleration of the elevator, the voltage and charge and discharge current of the supercapacitor bank [10], the voltage, temperature, electrolyte density and charge and discharge current of the battery pack [20], the output voltage signal is sent to the A/D The conversion unit [62], the A/D conversion unit [62] sends the converted digital signal to the calculation control unit [64]; the user instruction unit [63] sends the user instruction to the calculation control unit [64], and the calculation control unit [64] 64] Output the control signal according to the set control process, and control the first and second controllable power switch tubes [32, 34] in the supercapacitor charging and discharging circuit [30] through the isolated drive unit [65] to realize the control process The set control process includes: before the elevator runs, control the first controllable power switch tube [32] to cut off, drive the second controllable power switch tube [34], and the DC bus [11] to the supercapacitor bank [10] and battery charging circuit [40] to supply power; in the start-up and acceleration process of the elevator, the second controllable power switch tube [34] is controlled to cut off, the first controllable power switch tube [32] is driven, and the supercapacitor bank [10] The DC busbar [11] provides energy; during the energy feedback process of the elevator, the first controllable power switch tube [32] is controlled to cut off, the second controllable power switch tube [34] is driven, and the DC busbar [11] is supplied to the supercapacitor bank [10] and battery charging circuit [40] supply power; in the process of grid power failure, control the second controllable power switch tube [34] to cut off, drive the first controllable power switch tube [32], and the supercapacitor bank [10] DC bus bar [11] provides energy; The signal sampling unit [71] of the battery charging control circuit [70] samples the grid voltage, the bus voltage, the position, load, speed and acceleration of the elevator, the voltage and the charging and discharging current of the supercapacitor bank [10], and the battery bank [20] The voltage, temperature, electrolyte density and charge and discharge current, the output voltage signal is sent to the A/D conversion unit [72], and the A/D conversion unit [72] sends the converted digital signal to the calculation control unit [74]. The instruction unit [73] transmits user instructions to the calculation control unit [74], and the calculation control unit [74] outputs control signals according to the set control process, and drives the battery charging circuit [40] through the isolation drive unit [75]. The third controllable power switch tube [42] realizes the control process; the set control process includes, before the elevator runs, drives the third controllable power switch tube [42], and the supercapacitor bank [10] supplies the storage battery pack [20] ] charging; in the process of energy feedback generated by the elevator, if the terminal voltage of the supercapacitor bank [10] is higher than the set value, the third controllable power switch tube [42] is driven, and the supercapacitor bank [10] supplies the battery pack [ 20] charging; The signal sampling unit [81] of the battery discharge control circuit [80] samples the grid voltage, the bus voltage, the position, load, speed and acceleration of the elevator, the voltage and the charging and discharging current of the supercapacitor bank [10], and the battery bank [20] The voltage, temperature, electrolyte density and charge and discharge current, the output voltage signal is sent to the A/D conversion unit [82], and the A/D conversion unit [82] sends the converted digital signal to the calculation control unit [84]. The instruction unit [83] transmits user instructions to the calculation control unit [84], and the calculation control unit [84] outputs control signals according to the set control process, and drives the battery discharge circuit [50] through the isolation drive unit [85]. The fourth controllable power switch tube [52] realizes the control process; the set control process includes: during the start-up and acceleration process of the elevator, if the terminal voltage of the supercapacitor bank [10] drops to a certain set value, the drive The fourth controllable power switch tube [52], the storage battery pack [20] supplies energy to the DC bus [11]; during the grid power outage, the fourth controllable power switch tube [52] is driven, and the storage battery pack [20] supplies energy to the DC bus [11]. The bus bar [11] provides energy. 7. The control method for a hybrid energy storage device for an elevator according to claim 6, characterized in that: before the elevator starts to work, the supercapacitor charge and discharge control circuit [60] controls the supercapacitor charge and discharge circuit [30], the DC The bus bar [11] charges the supercapacitor bank [10] through the supercapacitor charging and discharging circuit [30]; at the same time, the battery charging control circuit [70] controls the battery charging circuit [40], and the supercapacitor bank [10] passes the battery charging circuit [ 40] Charge the battery pack [20] in a constant current mode or pulse mode until the state of charge of the supercapacitor bank [10] and the battery pack [20] reaches the set value. 8. The control method for the hybrid energy storage device for elevators according to claim 6, characterized in that: the battery charging control circuit [70] and the battery discharging control circuit [80] respectively control the battery charging circuit [40] and the battery The discharge circuit [50] judges the output or input power and energy of the battery pack [20] according to the system status and user instructions; when the battery pack [20] needs to provide energy, it controls the battery discharge circuit [50] to make the battery pack [20] 20] discharge in a constant current mode; when the storage battery pack [20] needs to absorb energy, control the storage battery charging circuit [40] so that the storage battery pack [20] is charged in a constant current mode or a pulse mode.

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