Power supply system and control method

Abstract

The invention discloses a power supply system and a control method. The system comprises a battery pack, an AC-DC / AC unit and an AC / DC unit, the AC-DC / AC unit is provided with a first input end, a second input end, a first output end and a second output end; the first input end is used for being connected with a battery pack, the second input end is used for being connected with alternating current, the first output end is used for being connected with an AC / DC unit, the second output end is used for being connected with a first load, and the output end of the AC / DC unit is used for being connected with a second load; and the control unit is connected with the AC-DC / AC unit.

Description

TECHNICAL FIELD

[0001] The embodiment of the present application relates to the technical field of power supply, in particular to a power supply system and a control method. BACKGROUND

[0002] The secondary power supply in the energy storage system has the characteristics of diversity, and the commonly used power supply in a set of system includes AC power (AC 120V-AC 277V) and DC power (DC 24V). The AC power is generally derived from the mains, and the DC power is derived from the mains rectification.

[0003] The existing system is usually equipped with UPS (Uninterruptible Power System) as an emergency power supply, and the standby time of the UPS is generally 2h. In the case of no one on-site operation and maintenance or holiday, the standby time is far more than 2h, and the UPS cannot achieve long standby. In addition, the cost of the UPS is too high, and the volume is too large, which generally needs to be installed separately with a cabinet, further increasing the material cost and transportation cost.

[0004] In summary, a power supply system and a control method are needed to solve the problems of short standby time, large volume of backup battery, separate cabinet installation and high use cost when using UPS as an emergency power supply in the prior art. SUMMARY

[0005] The present application provides a power supply system and a control method to solve at least one defect in the prior art.

[0006] The embodiment of the present application provides a power supply system, which comprises a battery pack, an AC-DC / AC unit, an AC / DC unit.

[0007] The AC-DC / AC unit is configured with a first input end, a second input end, a first output end and a second output end;

[0008] The first input end is used for connecting with the battery pack, the second input end is used for connecting with AC power, the first output end is used for connecting with the AC / DC unit, and the second output end is used for connecting with a first load. The output end of the AC / DC unit is used for connecting with a second load.

[0009] Further comprising a control unit connected with the AC-DC / AC unit, the control unit is configured to control the output voltage of the first output end and the second output end to be converted by the AC power when the AC power is normal, and to control the output voltage of the first output end and the second output end to be converted by the DC power of the battery pack when the AC power is abnormal.

[0010] Optionally, the AC-DC / AC unit comprises: a first AC output unit, a second AC output unit, a switching control circuit;

[0011] The output terminals of the first AC output unit and the second AC output unit are respectively connected with the input terminals of the switching control circuit;

[0012] The input terminal of the first AC output unit is used for connecting the battery pack, and the first AC output unit is used for AC conversion of DC of the battery pack;

[0013] The input terminal of the second AC output unit is used for connecting the AC power, and the second AC output unit is used for AC conversion of the AC power;

[0014] The control unit is connected with the switching control circuit, and the switching control circuit is used for connecting the first AC output unit or the second AC output unit according to the control signal of the control unit.

[0015] Optionally, the first AC output unit comprises: a DC-DC step-down circuit, a first DC-AC inversion circuit;

[0016] The first input terminal is connected with the first DC-AC inversion circuit through the DC-DC step-down circuit, and the first DC-AC inversion circuit is connected with the switching control circuit.

[0017] Optionally, the first AC output unit further comprises: a pre-charge circuit;

[0018] The first input terminal is connected with the DC-DC step-down circuit through the pre-charge circuit.

[0019] Optionally, the first AC output unit further comprises: a control circuit;

[0020] The control circuit is connected with the pre-charge circuit, the DC-DC step-down circuit and the first DC-AC inversion circuit respectively;

[0021] The control circuit is configured to output a driving control signal required for the DC-DC step-down circuit and the first DC-AC inversion circuit to work, and the control circuit is further configured to control the pre-charge circuit to pre-charge the DC-DC step-down circuit.

[0022] Optionally, the first AC output unit further comprises: a protection circuit;

[0023] The protection circuit is connected with the control circuit, the pre-charge circuit, the DC-DC step-down circuit and the first DC-AC inversion circuit;

[0024] The protection circuit is configured to disconnect the faulty circuit among the pre-charging circuit, the DCDC step-down circuit or the first DCAC inversion circuit according to the control signal of the control circuit when the pre-charging circuit, the DCDC step-down circuit or the first DCAC inversion circuit fails.

[0025] Optionally, the second AC output unit comprises an ACDC rectifier circuit and a second DCAC inversion circuit.

[0026] The second input end is connected with the second DCAC inversion circuit through the ACDC rectifier circuit, and the second DCAC inversion circuit is connected with the switching control circuit.

[0027] Optionally, the second AC output unit further comprises a filter circuit.

[0028] The second input end is connected with the ACDC rectifier circuit through the filter circuit.

[0029] Optionally, the second AC output unit further comprises a PFC correction circuit.

[0030] The ACDC rectifier circuit is connected with the second DCAC inversion circuit through the PFC correction circuit.

[0031] Optionally, the AC-DC / AC unit further comprises a transformer circuit, a rectifier filter circuit and a voltage stabilizing circuit.

[0032] The switching control circuit is connected with the first output end and the second output end through the transformer circuit, the rectifier filter circuit and the voltage stabilizing circuit.

[0033] Optionally, the AC-DC / AC unit further comprises a first circuit breaker.

[0034] The AC power is connected with the second input end through the first circuit breaker, and the first circuit breaker is configured to be tripped when the AC power is disconnected.

[0035] Optionally, the first circuit breaker comprises an under-voltage coil and an auxiliary contact.

[0036] The under-voltage coil is configured to be tripped when the voltage between the two ends of the under-voltage coil is lost.

[0037] The auxiliary contact is configured to be connected with a battery management system, and the battery management system is configured to determine the tripping state of the first circuit breaker according to the on-off state of the auxiliary contact.

[0038] Optionally, the AC-DC / AC unit further comprises a second circuit breaker.

[0039] The battery pack is connected to the first input terminal through the second circuit breaker, and the second circuit breaker is configured to trip when the voltage of the battery pack is lower than a threshold voltage.

[0040] The application also provides a power supply system control method, comprising:

[0041] determining whether the AC power connected to the second input terminal of the AC-DC / AC unit is normal, and if the AC power is normal, controlling the output voltages of the first output terminal and the second output terminal of the AC-DC / AC unit to be converted from the AC power;

[0042] if the AC power is abnormal, controlling the output voltages of the first output terminal and the second output terminal to be converted from the DC power of the battery pack connected to the first input terminal of the AC-DC / AC unit;

[0043] The first output terminal is configured to supply power to a second load through the AC / DC unit, and the second output terminal is configured to supply power to a first load.

[0044] Optionally, if the AC power is normal, controlling the output voltages of the first output terminal and the second output terminal of the AC-DC / AC unit to be converted from the AC power comprises:

[0045] generating a first control signal for controlling the switching circuit to act, and connecting the AC power to the first output terminal and the second output terminal through the switching circuit;

[0046] The switching circuit is arranged in the AC-DC / AC unit.

[0047] Optionally, if the AC power is abnormal, controlling the output voltages of the first output terminal and the second output terminal to be converted from the DC power of the battery pack connected to the first input terminal of the AC-DC / AC unit comprises:

[0048] generating a second control signal for controlling the switching circuit to act, and connecting the battery pack to the first output terminal and the second output terminal through the switching circuit;

[0049] The switching circuit is arranged in the AC-DC / AC unit.

[0050] Optionally, the method further comprises:

[0051] if the single-cell voltage of the battery pack is lower than a set threshold value, generating a trip instruction for controlling the second circuit breaker to trip;

[0052] The second circuit breaker is arranged between the battery pack and the first input terminal.

[0053] Compared with the prior art, the power supply system provided by the application has the advantages that the power supply system comprises an AC-DC / AC unit, the integrated power supply conversion (integration of AC-DC, DC-DC and DC-AC functions) is realized by using the AC-DC / AC unit, the cost and installation space of the power supply system can be reduced, the battery pack is used as a backup power supply, and through the design and use of the battery pack, a single battery pack can realize backup power supply for more than 2 hours for a conventional load, thereby meeting the emergency demand for long-time power failure. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 is a structural block diagram of the power supply system in the embodiment;

[0055] Figure 2 is a structural schematic diagram of the AC-DC / AC unit in the embodiment;

[0056] Figure 3 is another structural schematic diagram of the power supply system in the embodiment;

[0057] Figure 4 is another structural schematic diagram of the AC-DC / AC unit in the embodiment;

[0058] Figure 5 is another structural schematic diagram of the power supply system in the embodiment;

[0059] Figure 6 is another structural schematic diagram of the power supply system in the embodiment;

[0060] Figure 7 is a working flowchart of the power supply system in the embodiment;

[0061] Figure 8 is a control method flowchart of the power supply system in the embodiment. DETAILED DESCRIPTION

[0062] The application will be further described below in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the application, but not to limit the application. In addition, it should be noted that, for the convenience of description, only the parts related to the application are shown in the drawings, but not all the structures.

[0063] Embodiment one

[0064] Figure 1 is a structural block diagram of the power supply system in the embodiment, referring to Figure 1 , the power supply system comprises a battery pack 100, an AC-DC / AC unit 200 and an AC / DC unit 300.

[0065] The AC-DC / AC unit 200 is configured with a first input end, a second input end, a first output end and a second output end.

[0066] The first input end is configured to be connected with the battery pack 100, the second input end is configured to be connected with AC power, the first output end is configured to be connected with the AC / DC unit 300, and the second output end is configured to be connected with the first load 11. The output end of the AC / DC unit 300 is configured to be connected with the second load 12.

[0067] The control unit 400 is further included, which is connected with the AC-DC / AC unit 200. The control unit 400 is configured to control the output voltage of the first output end and the second output end to be converted from AC power when the AC power is normal, and to control the output voltage of the first output end and the second output end to be converted from DC power of the battery pack 100 when the AC power is abnormal.

[0068] In the present scheme, the battery pack 100 can be an energy storage battery pack, which is mainly used as a backup power source for the first load 11 and the second load 12 when the AC power is abnormal (e.g. power failure or unstable voltage). The battery pack 100 can be a high-voltage battery pack with a voltage of 1000-1500V.

[0069] For example, in the present scheme, the AC power can be commercial power (the voltage range of the commercial power can be 120-277V), and accordingly, the second input end of the AC-DC / AC unit 200 can be connected with the power grid.

[0070] For example, in the present scheme, the AC-DC / AC unit 200 can support AC-DC conversion and DC-AC conversion. When AC power is used as the power source, the AC-DC / AC unit 200 can convert AC-DC-AC to output AC power from the second output end. When the battery pack 100 is used as the power source, the battery pack 100 can convert DC-AC to output AC power from the first output end.

[0071] For example, in the present scheme, the AC-DC / AC unit 200 can realize independent operation of the above two paths through a mode selection circuit, thereby avoiding bidirectional energy flow.

[0072] For example, in the present scheme, the first input end is set as the DC side, and the second input end is set as the AC side. The AC side can be provided with a contactor or a relay, and the DC side can be provided with a MOS switch. When DC is needed as the input, the contactor of the AC side can be disconnected, and the MOS switch of the DC side can be closed to activate the DC-AC path. When AC is needed as the input, the MOS switch of the DC side can be disconnected, and the contactor of the AC side can be closed to activate the AC-DC-AC path.

[0073] Exemplarily, in the present scheme, the conversion of AC-DC can be realized by a rectifier module, which can be implemented by a diode rectifier bridge or a MOS tube rectifier bridge. Among them, the diode rectifier bridge converts AC to DC through the one-way conduction characteristic, and outputs stable DC voltage after being smoothed by the filter capacitor. The MOS tube rectifier bridge works through the PWM control signal, and the PWM control signal controls the periodic conduction and turn-off of the MOS tube, thereby realizing the conversion of AC to DC.

[0074] Exemplarily, in the present scheme, the conversion of DC-AC can be realized by an inverter module, which can include a three-phase inverter circuit and a drive circuit. Among them, the drive circuit is used to output the PWM drive signal (for example, generate 6-way complementary PWM signals through SVPWM algorithm), and the PWM drive signal controls the switch tube in each bridge arm of the three-phase inverter circuit to turn on and off according to the specified rule, thereby realizing the conversion of DC to AC.

[0075] Exemplarily, in the present scheme, one path can be configured with an inverter module, and the AC-DC / AC unit 200 can also be configured with a switching control circuit, which can set a relay or a static switch. The switching control circuit is used to switch the output of the inverter module of the corresponding path to the corresponding load (the first output end and the second output end) in different working modes (AC or DC as the power supply).

[0076] In the present scheme, the structural design of the AC / DC unit 300 can be the same as the design method of the aforementioned rectifier module. The output voltage level of the AC / DC unit 300 is different from the output voltage level of the aforementioned rectifier module, and the output voltage level of the AC / DC unit 300 matches the power consumption voltage level of the second load 12.

[0077] In the present scheme, the control unit 400 is configured to automatically switch the power input path according to the state of the grid AC power, and to ensure the continuous power supply of the first load 11 and the second load 12. Specifically, it is configured to monitor the stability of the AC power at the input side of the AC-DC / AC unit 200 in real time, and to control the working mode of the AC-DC / AC unit 200 according to whether the AC power is abnormal, thereby realizing the switching between the battery pack 100 and the grid power supply.

[0078] Exemplarily, in the present scheme, the control unit 400 can be configured to monitor the AC power connected to the second input end (such as voltage amplitude, frequency, waveform distortion rate and other parameters) in real time through voltage sensors, frequency sensors and other elements.

[0079] When the AC power parameters are within the set threshold range (such as voltage fluctuation ±10%, frequency 50Hz±0.5Hz), it is determined that the AC power is normal; when the AC power is interrupted, the voltage drops suddenly, the frequency is abnormal or there is serious harmonic pollution, it is determined that the AC power is abnormal.

[0080] For example, when the AC power is normal, the control unit 400 sends a command to the switching control circuit of the AC-DC / AC unit 200 to activate the AC-DC-AC mode.

[0081] In this mode, the AC power enters the AC-DC / AC unit 200 through the second input terminal, is first converted into DC power through AC-DC rectification, and is then converted into stable AC power through DC-AC inversion, and is synchronously output from the first output terminal and the second output terminal to supply power to the AC / DC unit 300 and the first load 11.

[0082] When the AC power is abnormal, the control unit 400 switches the input path of the AC power by controlling the specified relays and switching tubes, and sends a command to the switching control circuit to activate the DC-AC mode.

[0083] In this mode, the DC power of the battery pack 100 enters the AC-DC / AC unit 200 through the first input terminal, is converted into AC power through DC-AC inversion, and is synchronously output from the first output terminal and the second output terminal to maintain load power supply.

[0084] In the present scheme, the first load 11 directly obtains the output of the AC-DC / AC unit. The first load 11 only uses AC power.

[0085] In the present scheme, the power supply of the second load 12 is the power supply converted through the AC / DC unit 300, and the second load 12 can adapt to DC power through the AC / DC unit 300.

[0086] The embodiment proposes a power supply system including an AC-DC / AC unit. The present scheme realizes integrated power conversion (integrates AC-DC, DC-DC, and DC-AC functions) by using the AC-DC / AC unit, can reduce the cost and installation space of the power supply system, uses a battery pack as a backup power supply, and through the design and use of the battery pack, a single battery can realize backup power supply for a conventional load for more than 2 hours, and meets the long-time power failure emergency demand.

[0087] Figure 2 FIG. 1 is a structural schematic diagram of the AC-DC / AC unit in the embodiment, and FIG. 2 is a structural schematic diagram of the AC-DC / AC unit in the embodiment. Figure 2 On the basis of any of the foregoing schemes, in an implementable scheme, the AC-DC / AC unit includes: a first AC output unit 201, a second AC output unit 202, and a switching control circuit 203.

[0088] The output terminals of the first AC output unit 201 and the second AC output unit 202 are respectively connected to the switching control circuit 203, and the output terminal of the switching control circuit 203 is connected to a voltage stabilizing unit 204.

[0089] The input end of the first AC output unit 201 is connected to the battery pack 100, and the first AC output unit 201 is used for AC conversion of the DC power of the battery pack 100.

[0090] The input end of the second AC output unit 202 is connected to AC power, and the second AC output unit 202 is used for AC conversion of the AC power.

[0091] The control unit is connected to the switching control circuit 203, and the switching control circuit 203 is used for connecting the first AC output unit 201 or the second AC output unit 202 according to the control signal of the control unit.

[0092] In the present scheme, the switching of the DC power input path and the AC power input path is realized through the dual-path parallel inverter and the switching control architecture, the first AC output unit 201 is provided to convert the DC power of the battery pack 100 into AC power (DC-AC inversion).

[0093] In the present scheme, the switching control circuit 203 is configured to select the first AC output unit 201 or the second AC output unit 202 according to the instruction of the control unit.

[0094] For example, in an implementation scheme, the AC-DC / AC unit can further include a voltage stabilizing unit 204, the switching control circuit 203 is connected to the voltage stabilizing unit 204, and the voltage stabilizing unit 204 is configured with a first output end and a second output end.

[0095] For example, in the present scheme, the voltage stabilizing unit 204 outputs one AC power, which can be configured to be divided into two paths through parallel connection of two conductors, and the two paths of AC power are respectively output through the first output end and the second output end, so as to realize the same value of the AC power output by the first output end and the second output end.

[0096] In the present scheme, the way of dividing one AC power into two paths is not limited, and other ways can also be used to divide one AC power into two paths, such as a two-way distributor.

[0097] In the present scheme, the voltage stabilizing unit 204 is configured to stabilize the output voltage and ensure no voltage fluctuation when switching between the two power sources, and the dual output ends are configured to supply power to different loads.

[0098] For example, in the present solution, when the AC power is normal, the switching control circuit 203 connects the second AC output unit 202 to be powered by the external AC power; when the AC power is abnormal, the switching control circuit switches to the first AC output unit 201 to be powered by the battery pack 100.

[0099] For example, in the present solution, the first AC output unit 201 can adopt a three-phase full-bridge IGBT inverter circuit to convert the DC power of the battery pack 100 into three-phase AC power of a specified voltage level.

[0100] In the present solution, the three-phase full-bridge IGBT inverter circuit can include a three-phase bridge arm composed of six IGBT modules, a DC bus capacitor group, an output filter inductor, and a filter capacitor to form an LCL filter.

[0101] For example, in the present solution, the second AC output unit 202 can include a rectifier circuit and an inverter circuit, the rectifier circuit is used to rectify the input AC power into DC power of a certain voltage, and the inverter circuit converts the DC power into AC power of a certain voltage level.

[0102] For example, in the present solution, the switching control circuit 203 can be designed to include a static switch and a mechanical switch, the static switch can be composed of anti-parallel IGBTs, and the mechanical switch can adopt a magnetic latching relay.

[0103] The control unit can be configured to control the mechanical switch to be closed and the static switch to be in an off state when the AC power is normal, at which time the second AC output unit 202 is powered. When the control unit detects that the AC power is abnormal, the static switch is first controlled to be turned on, and after a certain time delay (for example, 5ms), the mechanical switch is controlled to be turned off, at which time the first AC output unit 201 is powered.

[0104] For example, in the present solution, the voltage stabilizing unit 204 can include an LC filter circuit and a Buck-Boost chopper circuit, the LC filter circuit can be a second-order low-pass filter composed of a filter inductor and a filter capacitor. The Buck-Boost chopper circuit can be composed of IGBTs and fast recovery diodes.

[0105] For example, in the present solution, a PID control can be used to generate a control signal for adjusting the duty cycle of the Buck-Boost circuit, thereby realizing voltage stabilizing control of the output voltage.

[0106] On the basis of any of the preceding solutions, in an implementable solution, the first AC output unit includes: a DCDC step-down circuit, a first DCAC inverter circuit.

[0107] The first input end is connected to the first DCAC inverter circuit through the DCDC step-down circuit, and the first DCAC inverter circuit is connected to the switching control circuit.

[0108] For example, in this scheme, the high-voltage DC of the battery pack is processed through a two-stage conversion architecture, a DCDC step-down circuit is provided for reducing the high-voltage of the battery pack to an intermediate voltage suitable for inversion. A first DCAC inversion circuit is provided for converting the stepped-down DC into AC.

[0109] In this scheme, the input voltage is first stepped down by the DCDC step-down circuit, and then converted into AC, which can optimize the inversion efficiency, avoid the switching loss and EMI problem caused by direct high-voltage inversion, and improve the system reliability.

[0110] On the basis of any of the foregoing schemes, in an implementable scheme, the first AC output unit further comprises: a pre-charge circuit; the first input end is connected to the DCDC step-down circuit through the pre-charge circuit.

[0111] In this scheme, the (high-voltage) battery pack is connected to the DCDC step-down circuit through the pre-charge circuit, which can include a main contactor K1, a pre-charge contactor K2, and a pre-charge resistor R. The first input end is connected to the DCDC step-down circuit through the main contactor K1, and the pre-charge contactor K2 is connected in series with the pre-charge resistor R and is connected in parallel across the main contactor K1.

[0112] In this scheme, the pre-charge circuit is provided for charging the bus capacitor in the DCDC step-down circuit. When pre-charging, K1 is open, K2 is closed, and the pre-charge resistor R is connected to the circuit. The battery pack voltage charges the bus capacitor through the pre-charge resistor R. When the voltage of the bus capacitor reaches a threshold value, the pre-charging is completed. At this time, K1 is closed first, the pre-charge resistor R is short-circuited, and then K2 is opened, and the pre-charge circuit exits the work.

[0113] In this scheme, the pre-charge circuit functions to avoid the damage to capacitors, IGBTs and other elements in the subsequent circuit caused by the inrush current when the battery pack is connected.

[0114] On the basis of any of the foregoing schemes, in an implementable scheme, the second AC output unit comprises: an ACDC rectifier circuit, a second DCAC inversion circuit; the second input end is connected to the second DCAC inversion circuit through the ACDC rectifier circuit, and the second DCAC inversion circuit is connected to the switching control circuit.

[0115] In this scheme, the second AC output unit adopts an AC-DC-AC two-stage conversion architecture to convert external AC power into stable standard AC power. The input AC power is rectified into DC power by the ACDC rectifier circuit, and then the rectified DC power is inverted into AC power by the DCAC inversion circuit, and then output to the switching control circuit.

[0116] In the scheme, through the two-stage structure of rectification and inversion, the second AC output unit can realize input and output electrical isolation, and the output voltage can be flexibly adjusted and has harmonic suppression capability.

[0117] On the basis of any of the foregoing schemes, in an implementable scheme, the second AC output unit further comprises: a filter circuit; and the second input end is connected with the ACDC rectifier circuit through the filter circuit.

[0118] In the scheme, the filter circuit is arranged to suppress grid-side harmonics, which can filter out high-frequency harmonics (such as 5th, 7th, and 11th harmonics) in the input AC power, so as to avoid the high-frequency harmonics from entering the ACDC rectifier circuit. The filter circuit can also reduce EMI interference, buffer grid voltage fluctuations and surges, and prolong the service life of power devices such as IGBT in the subsequent circuit.

[0119] For example, in the scheme, the filter circuit can be designed as an LCL three-order filter circuit, which can include a common-mode inductor Lc, a differential-mode inductor L1, a filter capacitor C, X capacitors (Cx1 and Cx2), and a Y capacitor Cy.

[0120] Among them, the common-mode inductor Lc is used to suppress common-mode interference, the differential-mode inductor L1 is used to suppress differential-mode harmonics, the X capacitors Cx1 and Cx2 are used to suppress differential-mode high-frequency noise, and the Y capacitor Cy is used to suppress common-mode high-frequency noise.

[0121] On the basis of any of the foregoing schemes, in an implementable scheme, the second AC output unit further comprises: a PFC correction circuit; and the ACDC rectifier circuit is connected with the second DCAC inversion circuit through the PFC correction circuit.

[0122] In the scheme, the PFC correction circuit is arranged between the ACDC rectifier circuit and the second DCAC inversion circuit. The ACDC rectifier circuit first converts the input AC power into DC power. The PFC correction circuit intervenes to optimize the rectified DC voltage, improve the power factor, and reduce current harmonics. Finally, the second DCAC inversion circuit inverts the optimized DC power into standard AC power output.

[0123] Through the addition of the PFC correction circuit, the problems of low power factor and large harmonics of the traditional rectifier circuit are effectively solved, so that the power supply system is more efficient and stable.

[0124] For example, in the scheme, the PFC correction circuit usually adopts a Boost step-up topology structure, which can include a power switching device, a step-up inductor, an output filter capacitor, a control chip, and a sampling circuit.

[0125] The power switch device is used for high-frequency switch control. The boost inductor is used for storing and releasing energy to achieve voltage boosting. The output filter capacitor is used for smoothing the output voltage. The control chip is used for executing the PFC control algorithm to control the turn-on and turn-off of the power switch device. The sampling circuit is used for monitoring the input voltage, current and output voltage to provide feedback signals for the control chip.

[0126] For example, in this scheme, the PFC control includes voltage outer loop control, current inner loop control and switch control.

[0127] The voltage outer loop control compares the error signal obtained by sampling the output DC voltage and the reference voltage, and the error signal is adjusted by the PID regulator to serve as the reference amplitude of the current inner loop.

[0128] The current inner loop control compares the input current and the reference current amplitude output by the voltage outer loop, and generates a PWM signal through a current regulator.

[0129] The PWM signal serves as the control signal in the switch control, drives the power switch device, and makes the input current waveform track the input voltage waveform, so as to improve the power factor to close to 1 and reduce the current harmonic content.

[0130] In this scheme, by setting the PFC correction circuit, the power factor can be improved, the reactive power loss can be reduced, the power grid transmission efficiency can be improved, the line loss and equipment capacity demand can be reduced. The input current harmonic content can be reduced to avoid harmonic interference on the power grid and other equipment. The PFC correction circuit can provide stable DC voltage for the second DCAC inverter circuit, thereby improving the power quality of the output of the second DCAC inverter circuit.

[0131] On the basis of any of the foregoing schemes, in an implementable scheme, the AC-DC / AC unit further comprises a transformer circuit, a rectification filtering circuit and a voltage stabilizing circuit; the switching control circuit is connected with the first output end and the second output end through the transformer circuit, the rectification filtering circuit and the voltage stabilizing circuit.

[0132] For example, in this scheme, the transformer circuit, the rectification filtering circuit and the voltage stabilizing circuit constitute a voltage stabilizing unit.

[0133] For example, in this scheme, the transformer circuit is used for converting the input voltage into the required voltage according to the turns ratio. The isolation transformer in the transformer circuit can also be used for electrical isolation between the primary side and the secondary side to improve safety.

[0134] For example, in this scheme, the rectification filtering circuit can include a bidirectional thyristor rectifier bridge and an LC filtering network. The bidirectional thyristor rectifier bridge can be composed of four bidirectional thyristors to realize AC full-wave rectification control. The conduction angle of the thyristor can be driven by an optocoupler isolation driving chip.

[0135] The LC filter network can include a filter inductor, a filter capacitor and a sampling circuit, and the LC filter network is used to process the input alternating current into low-harmonic and stable-amplitude alternating current.

[0136] In the scheme, the amplitude of the output voltage can be controlled by adjusting the conduction angle of the thyristor, and the high-frequency harmonics such as 5th and 7th harmonics can be filtered out by using the LC series resonance characteristics, so that the output voltage is low-harmonic alternating current.

[0137] For example, in the scheme, the voltage stabilizing circuit can be designed in a closed-loop feedback architecture, and the voltage stabilizing circuit can include a voltage sampling module, a DSP master chip, a reference voltage source, a solid-state relay and a compensation transformer.

[0138] When the voltage stabilizing circuit is working, the voltage sampling module sends the sampling voltage to the ADC channel of the DSP master chip. The DSP master chip compares the sampling voltage with the reference voltage to obtain a voltage deviation. A control signal is obtained by using PID control according to the voltage deviation, and the control signal controls the solid-state relay to switch the tap of the compensation transformer, thereby realizing the adjustment of the voltage.

[0139] For example, in the scheme, one output of the voltage stabilizing circuit is divided into two paths, and the two paths output alternating currents with the same value through the first output end and the second output end, respectively.

[0140] On the basis of any of the foregoing schemes, in an implementable scheme, the system further includes a first circuit breaker; the alternating current is connected to the second input end through the first circuit breaker, and the first circuit breaker is used to trip when the alternating current is disconnected.

[0141] In the scheme, the alternating current (such as mains) is connected to the second input end through the first circuit breaker. When an abnormality of the alternating current is detected, the first circuit breaker automatically trips to cut off the connection with the rear-end circuit.

[0142] For example, in the scheme, the first circuit breaker can be an electromagnetic circuit breaker, and a control unit is configured to monitor the voltage of the alternating current. If the control unit detects an abnormality (such as voltage loss) of the alternating current, a tripping signal is sent out to drive the tripping coil of the first circuit breaker to act, and a mechanical structure triggers tripping.

[0143] On the basis of any of the foregoing schemes, in an implementable scheme, the system further includes a second circuit breaker; the battery pack is connected to the first input end through the second circuit breaker, and the second circuit breaker is configured to trip when the voltage of the battery pack is lower than a threshold voltage.

[0144] In the scheme, the second circuit breaker is connected in series between the battery pack and the first input end, and serves as a key protection device for the discharge circuit of the battery pack.

[0145] The control unit monitors the battery pack voltage in real time. When the battery pack voltage drops to a preset threshold voltage, the second circuit breaker trips quickly to disconnect the battery pack from the system. The second circuit breaker prevents low voltage conditions of the battery pack from damaging the AC-DC / AC unit and other circuits in the back-end, ensuring the stability and reliability of the entire power supply system.

[0146] In this scheme, the threshold voltage can be set in the control unit, and the control unit periodically reads the voltage sampling value. When the sampling value is detected to be lower than the threshold voltage, a trip signal is triggered. The trip signal drives the split excitation release coil of the circuit breaker. After the release coil is powered on, the circuit breaker contacts are separated by a mechanical mechanism to achieve the trip action.

[0147] Figure 3 is another power supply system structure schematic diagram in the embodiment; Figure 4 is another AC-DC / AC unit structure schematic diagram in the embodiment, Figure 5 is another power supply system structure schematic diagram in the embodiment, Figure 6 is another power supply system structure schematic diagram in the embodiment, for reference Figures 3 to 6 , on the basis of any of the foregoing schemes, in an implementable scheme, the system comprises:

[0148] The battery pack 100, the AC-DC / AC unit 200, the AC / DC unit 300, the control unit 400, the first circuit breaker 501, and the second circuit breaker 502.

[0149] The AC-DC / AC unit 200 is configured with a first input end (DC+, DC-), a second input end (L, N), a first output end (L1, N1), and a second output end (L2, N2).

[0150] The battery pack 100 is connected to the first input end through the second circuit breaker 502, the AC power is connected to the second input end through the first circuit breaker 501, the first output end is used to connect to the AC / DC unit 300, the second output end is used to connect to the first load 11, and the output end of the AC / DC unit 300 is used to connect to the second load 12.

[0151] The AC power can come from the mains, the first load 11 can include a dehumidifier, a water immersion, a liquid cooling unit, a PCS (Power Conversion System, energy storage converter), and the second load 12 can include a BMS, a switch, an EMS (Energy Management System, energy storage management system), and a fire fighting equipment.

[0152] The AC-DC / AC unit 200 includes a first AC output unit, a second AC output unit, a switching control circuit 203, and a voltage stabilizing unit.

[0153] The first AC output unit comprises a pre-charge circuit 2011, a DCDC step-down circuit 2012, a first DCAC inversion circuit 2013, a control circuit 2014, and a protection circuit 2015. The battery pack 100 is connected to the switching control circuit 203 through the pre-charge circuit 2011, the DCDC step-down circuit 2012, and the first DCAC inversion circuit 2013.

[0154] The control circuit 2014 is connected to the pre-charge circuit 2011, the DCDC step-down circuit 2012, and the first DCAC inversion circuit 2013, respectively, and the protection circuit 2015 is connected to the control circuit 2014.

[0155] The second AC output unit comprises a filter circuit 2021, an ACDC rectifier circuit 2022, a PFC correction circuit 2023, and a second DCAC inversion circuit 2024. The AC power is connected to the switching control circuit 203 through the filter circuit 2021, the ACDC rectifier circuit 2022, the PFC correction circuit 2023, and the second DCAC inversion circuit 2024.

[0156] The control unit 400 is connected to the switching control circuit 203.

[0157] The voltage stabilizing unit comprises a transformer circuit 2041, a rectifier filter circuit 2042, and a voltage stabilizing circuit 2043. The switching control circuit 203 is connected to the voltage stabilizing circuit 2043 through the transformer circuit 2041 and the rectifier filter circuit 2042. The voltage stabilizing circuit 2043 is provided with a first output end and a second output end.

[0158] For example, in the present scheme, the control circuit 2014 is configured to comprehensively control the working states of the pre-charge circuit 2011, the DCDC step-down circuit 2012, and the first DCAC inversion circuit 2013, so as to realize precise control of the energy of the battery pack.

[0159] The control circuit 2014 can be specifically configured to adjust the duty cycle of the DCDC step-down circuit 2012 and the output frequency / amplitude of the first DCAC inversion circuit 2013 in real time, so as to adapt to the system load demand.

[0160] For example, in the present scheme, the control circuit 2014 can comprise a master control chip, a sampling circuit, and a driving circuit. The master control chip generates a specified driving control signal by driving the DCDC step-down circuit 2012 and the first DCAC inversion circuit 2013 through the driving circuit. The sampling circuit can be configured to collect and feed back the voltage of the battery pack 100 and the current of the DCDC step-down circuit 2012 to the master control chip, so as to generate the specified driving control signal.

[0161] In the scheme, the AC / DC unit 300 can convert AC 120V-AC 277V voltage into DC 24V voltage to supply the energy storage system DC 24V load.

[0162] For example, in the scheme, the protection circuit 2015 can be connected with the control circuit 2014, the precharge circuit 2013, the DC / DC step-down circuit 2012, and the first DC / AC inversion circuit 2013.

[0163] The protection circuit 2015 is configured to disconnect the faulty circuit in the precharge circuit 2013, the DC / DC step-down circuit 2012, or the first DC / AC inversion circuit 2013 according to the control signal of the control circuit 2014 when the precharge circuit, the DC / DC step-down circuit 2012, or the first DC / AC inversion circuit 2013 fails.

[0164] For example, in the scheme, the protection circuit 2015 can be configured to monitor the abnormal working conditions (such as overvoltage, overcurrent, short circuit, overheating, etc.) of the battery pack 100, the DC / DC step-down circuit 2012, and the first DC / AC inversion circuit 2013 in real time, and trigger the corresponding protection action (such as current limiting, power reduction, driving relay tripping, etc.) when the abnormal working conditions occur.

[0165] For example, in the scheme, the protection circuit 2015 can be configured with a voltage comparator (for voltage detection), a current sensor (for current detection), and a temperature sensor (for temperature detection). The protection circuit 2015 can also include a relay for disconnecting the faulty circuit in the precharge circuit 2011, the DC / DC step-down circuit 2012, or the first DC / AC inversion circuit 2013.

[0166] In the scheme, the first input end of the AC-DC / AC unit 200 is connected to a 1500V DC power supply (battery pack), and the second input end is connected to a 120-277V AC power supply (mains). According to the AC priority principle, when the input end is supplied with AC and DC at the same time, AC power supply is preferred.

[0167] In the scheme, when the AC power is detected to be valid, the second AC output unit is valid, and the control unit 400 controls the switching control circuit 203 to input AC power. When the AC power is detected to be invalid, the control unit 400 controls the switching control circuit 203 to switch to DC power input. When the AC power is detected to be valid, the control unit 400 controls the switching control circuit 203 to switch to AC input again, and the cycle continues.

[0168] Figure 7 is the working flowchart of the power supply system in the embodiment, please refer to Figure 7In the scheme, the first input end and the second input end are respectively provided with the second circuit breaker 502 and the first circuit breaker 501, the first circuit breaker 501 is provided with an under-voltage coil MN and an auxiliary contact OF2, and the under-voltage coil MN has the function of being attracted when the voltage at both ends is lost and tripping the miniature circuit breaker.

[0169] When the mains is normally powered, the second input end is powered, and when the mains is powered off (or under-voltage), the first circuit breaker 501 is disconnected. The second circuit breaker 502 is connected to the BMS of the battery pack 100, and when the BMS detects that the cell voltage of the battery pack is too low, the BMS controls the second circuit breaker 502 to be disconnected to avoid over-discharge of the cell. When the mains is powered again, the second input end side is powered.

[0170] For example, in the scheme, when the mains is normally powered, the first circuit breaker 501 and the second circuit breaker 502 are set to be in the closed state, at this time, the mains (AC 120V-AC 277V) is powered, the second AC output unit of the AC-DC / AC unit 200 is turned on, the AC / DC unit 300 is turned on, the first output end and the second output end are turned on, 220V AC is output, and the AC / DC unit 300 outputs 24V DC.

[0171] When the mains power is powered off, the under-voltage coil MN of the first circuit breaker 501 acts, the first circuit breaker 501 is tripped, the AC-DC / AC unit 200 switches to the first AC output unit being turned on, and at this time the battery pack 100 is powered.

[0172] When the BMS detects that the single cell voltage of the battery pack 100 is too low (exceeds the set threshold), the BMS sends a trip command to the auxiliary contact OF1 of the second circuit breaker 502, the second circuit breaker 502 trips, and the battery pack 100 is forced to cut off the power supply to the first load and the second load to prevent over-discharge of the cell and damage the cell. At this time, the first output end and the second output end are powered off.

[0173] When the mains is powered again, the AC-DC / AC unit 200 switches to the second AC output unit being turned on, and the above cycle continues.

[0174] For example, in the scheme, the auxiliary contact OF2 of the first circuit breaker 501 and the auxiliary contact OF1 of the second circuit breaker 502 are connected to the BMS, and the BMS is configured to determine the tripping and closing states of the first circuit breaker 501 and the second circuit breaker 502 according to the on-off state of the auxiliary contact.

[0175] For example, in the scheme, when the power supply is switched from the battery pack to the AC power supply, the BMS can send a closing command to the under-voltage coil MN of the first circuit breaker 501 to control the under-voltage coil MN to be attracted.

[0176] Exemplarily, in the scheme, the BMS can also be configured to determine whether the opening and closing operation of the first circuit breaker 501 or the second circuit breaker 502 is successful according to the opening and closing states of the first circuit breaker 501 and the second circuit breaker 502, and perform a preset operation (such as alarming or sending a control instruction again) when the operation fails.

[0177] In the scheme, the battery pack is used as a backup power supply to replace the traditional UPS power supply, and a backup power time of more than 2 hours can be realized; both 220V AC loads and 24V DC loads are included in the backup power category, which improves the power supply reliability of the entire system compared with the traditional scheme of only taking 24V DC load as backup power. The AC input supports 120-227V wide voltage input, which can adapt to most single-phase voltages in most countries in the world. The AC-DC / AC power conversion module is used to replace the UPS and backup battery, saving installation space.

[0178] In the scheme, the AC-DC / AC unit, the AC / DC unit, the first circuit breaker, the second circuit breaker, and the battery pack constitute a complete auxiliary power supply control system. The system can realize ultra-long backup power, improve system reliability, and has smaller module size, smaller installation space, and lower cost.

[0179] Embodiment Two

[0180] Figure 8 is a flowchart of the power supply system control method in the embodiment, and reference is made to Figure 8 The embodiment provides a power supply system control method, which comprises the following steps:

[0181] S101. Determine whether the AC power connected to the second input end of the AC-DC / AC unit is normal. If the AC power is normal, the output voltages of the first output end and the second output end of the AC-DC / AC unit are converted from the AC power.

[0182] S102. When the AC power is abnormal, the output voltages of the first output end and the second output end are converted from the DC power of the battery pack connected to the first input end of the AC-DC / AC unit.

[0183] In the scheme, the first output end is used to supply power to the second load through the AC / DC unit, and the second output end is used to supply power to the first load.

[0184] In the scheme, the control method is applied to the control of the power supply system of the embodiment one, and the structure and working principle of the power supply system are the same as the corresponding contents described in the embodiment one.

[0185] Exemplarily, in the present solution, when the detection signal loop detects that the AC power supply is normal, the AC loop is effective, the AC loop input is controlled, and the load loop output; when the detection signal loop detects that the AC is invalid, the control is switched to the DC loop input, and the load loop output; when the AC power supply is detected to be effective, the control is switched to the AC loop input again, and the cycle is repeated.

[0186] In the present solution, the first load is an AC load, and the second load is a DC load. The control method includes the AC load and the DC load in the standby power supply category, which improves the power supply reliability of the entire system compared with the traditional solution that only considers the DC load as the standby power supply. The control method uses the battery pack as the standby power supply to replace the traditional UPS power supply, which can achieve a standby power supply time of more than 2 hours.

[0187] On the basis of any of the preceding solutions, in an implementable solution, if the AC power is normal, the output voltages of the first output end and the second output end of the AC-DC / AC unit are converted from the AC power, including:

[0188] A first control signal is generated, which is used to control the switching circuit to act, and the AC power is connected to the first output end and the second output end through the switching circuit.

[0189] Exemplarily, in the present solution, the switching circuit is arranged in the AC-DC / AC unit, and the switching circuit can adopt any of the switching circuits described in Embodiment 1.

[0190] Exemplarily, in the present solution, when the AC power is detected to be normal, the system needs to switch the output of the AC-DC / AC unit to be directly converted by the AC power supply. The specific implementation is to generate a first control signal to drive the switching circuit, connect the AC power path to the first output end and the second output end, and thus realize the power supply to the two loads.

[0191] Exemplarily, in the present solution, the first control signal can be an electrical signal generated by a control unit (such as a microcontroller, etc.), which is used to instruct the switching circuit to act.

[0192] On the basis of any of the preceding solutions, in an implementable solution, when the AC power is abnormal, the output voltages of the first output end and the second output end are converted from the DC power of the battery pack connected to the first input end of the AC-DC / AC unit, including:

[0193] A second control signal is generated, which is used to control the switching circuit to act, and the battery pack is connected to the first output end and the second output end through the switching circuit.

[0194] Exemplarily, in the present solution, the switching circuit is arranged in the AC-DC / AC unit, and the switching circuit can adopt any of the switching circuits described in Embodiment 1.

[0195] In an example, when the AC power is abnormal, the system switches the power source from AC power to the battery pack to ensure the load continues to work. The process is achieved by generating a second control signal to drive the switching circuit to connect the battery pack to the output terminal, and convert the DC power to AC power.

[0196] In an example, the second control signal can be a trigger signal generated by the control unit, which is used to instruct the switching circuit to disconnect the AC power path and connect the battery pack path.

[0197] In an example, the method of determining whether the AC power is abnormal can be that the voltage comparator determines whether the AC voltage is lower than a threshold value. The method of determining whether the AC power is in a power-off state (the voltage is 0V for more than a set time).

[0198] In any of the foregoing aspects, in an example implementation, the control method further includes:

[0199] When the single cell voltage of the battery pack is lower than a set threshold value, a trip instruction is generated, which is used to control the second circuit breaker to trip.

[0200] In an example, the second circuit breaker can be any of the second circuit breakers described in Embodiment 1, and the second circuit breaker is arranged between the battery pack and the first input terminal.

[0201] In an example, the single cell voltage of the battery pack is monitored, and when the voltage is lower than a safety threshold value, the connection between the battery pack and the system is automatically cut off to prevent over-discharge of the battery.

[0202] In an example, the BMS can be configured to monitor the voltage of each single cell in the battery pack, and when any single cell voltage is lower than a set threshold value, a trip instruction is generated to control the second circuit breaker to disconnect, thereby cutting off the connection between the battery pack and the AC-DC / AC unit.

[0203] In an example, the BMS or the control unit can generate the trip instruction.

[0204] In an example, when the single cell voltage of the battery pack is lower than a set threshold value, the battery pack is controlled to stop supplying power, which can prevent irreversible damage and shorten the service life of the battery due to over-discharge.

[0205] Reference Figure 6 and Figure 7 In any of the foregoing aspects, in an example implementation, the control method can include:

[0206] When the mains power is normal, the first circuit breaker 501 and the second circuit breaker 502 are set to be controlled by the MCU to be in the closed state, at this time, the AC-DC / AC unit 200 is powered by the mains (AC 120V~AC 277V), the second AC output unit of the AC-DC / AC unit 200 is turned on, the AC / DC unit 300 is turned on, the first output and the second output are turned on, 220V AC power is output, and the AC / DC unit 300 outputs 24V DC power.

[0207] When the mains power is off, the under-voltage coil MN of the first circuit breaker 501 is actuated, the first circuit breaker 501 is opened, the second circuit breaker 502 is in the closed state, and the AC-DC / AC unit 200 is switched to the first AC output unit being turned on, at this time, the battery pack 100 is powered.

[0208] When the BMS detects that the single-cell voltage of the battery pack 100 is too low (exceeding the set threshold), the BMS sends a trip command to the trip coil MX1 of the second circuit breaker 502, the second circuit breaker 502 is tripped, and the battery pack 100 is forced to cut off the power supply to the first load and the second load, preventing the damage of the battery cell due to over-discharge, at this time, the first output and the second output are powered off.

[0209] When the mains power is restored, the AC-DC / AC unit 200 is switched to the second AC output unit being turned on, and the above cycle continues.

[0210] Note that the above is only the preferred embodiment of the present application and the technical principle applied. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and those skilled in the art can make various obvious changes, re-adjustments and substitutions without departing from the scope of the present application. Therefore, although the present application has been described in more detail through the above embodiments, the present application is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the appended claims.

Claims

1. A power supply system characterized by comprising: The application relates to a battery pack, an AC-DC / AC unit and an AC / DC unit. The AC-DC / AC unit is provided with a first input end, a second input end, a first output end and a second output end. The first input end is used for connecting with the battery pack, the second input end is used for connecting with AC power, the first output end is used for connecting with the AC / DC unit, the second output end is used for connecting with a first load, and the output end of the AC / DC unit is used for connecting with a second load. The application further comprises a control unit connected with the AC-DC / AC unit. The control unit is configured to control the output voltage of the first output end and the second output end to be converted from AC power when the AC power is normal, and to control the output voltage of the first output end and the second output end to be converted from DC power of the battery pack when the AC power is abnormal.

2. The power supply system of claim 1, wherein, The AC-DC / AC unit comprises a first AC output unit, a second AC output unit and a switching control circuit. The output ends of the first AC output unit and the second AC output unit are respectively connected with the switching control circuit. The input end of the first AC output unit is used for connecting with the battery pack, and the first AC output unit is used for AC conversion of DC power of the battery pack. The input end of the second AC output unit is used for connecting with the AC power, and the second AC output unit is used for AC conversion of the AC power. The control unit is connected with the switching control circuit, and the switching control circuit is used for connecting the first AC output unit or the second AC output unit according to the control signal of the control unit.

3. The power supply system of claim 2, wherein The first AC output unit comprises a DCDC voltage reduction circuit and a first DCAC inversion circuit. The first input end is connected with the first DCAC inversion circuit through the DCDC voltage reduction circuit, and the first DCAC inversion circuit is connected with the switching control circuit.

4. The power supply system of claim 3, wherein The first AC output unit further comprises a pre-charge circuit. The first input end is connected with the DCDC voltage reduction circuit through the pre-charge circuit.

5. The power conversion device of claim 4, wherein, The first AC output unit further comprises a control circuit. The control circuit is connected with the pre-charge circuit, the DCDC voltage reduction circuit and the first DCAC inversion circuit respectively. The control circuit is configured to output a driving control signal required for the operation of the DCDC voltage reduction circuit and the first DCAC inversion circuit, and the control circuit is further configured to control the pre-charge circuit to pre-charge the DCDC voltage reduction circuit.

6. The power conversion device of claim 5, wherein, The first AC output unit further comprises a protection circuit. The protection circuit is connected with the control circuit, the pre-charge circuit, the DCDC voltage reduction circuit and the first DCAC inversion circuit. The protection circuit is configured to disconnect the circuit with a fault in the pre-charge circuit, the DCDC voltage reduction circuit or the first DCAC inversion circuit according to the control signal of the control circuit.

7. The power supply system according to any one of claims 2 to 6, wherein The second AC output unit comprises an AC-DC rectifier circuit and a second DC-AC inverter circuit. The second input end is connected to the second DC-AC inverter circuit through the AC-DC rectifier circuit, and the second DC-AC inverter circuit is connected to the switching control circuit.

8. The power supply system of claim 7, wherein, The second AC output unit further comprises a filter circuit. The second input end is connected to the AC-DC rectifier circuit through the filter circuit.

9. The power supply system of claim 7, wherein, The second AC output unit further comprises a PFC correction circuit. The AC-DC rectifier circuit is connected to the second DC-AC inverter circuit through the PFC correction circuit.

10. The power supply system according to any one of claims 2 to 6, wherein The AC-DC / AC unit further comprises a transformer circuit, a rectifier filter circuit, and a voltage stabilizing circuit. The switching control circuit is connected to the first output end and the second output end through the transformer circuit, the rectifier filter circuit, and the voltage stabilizing circuit.

11. The power supply system according to any one of claims 1 to 6, wherein Further comprising a first circuit breaker. The AC power is connected to the second input end through the first circuit breaker, and the first circuit breaker is used to trip when the AC power is disconnected.

12. The power supply system of claim 11, wherein, The first circuit breaker comprises an under-voltage coil and an auxiliary contact. The under-voltage coil is configured to trip when the voltage at both ends is lost. The auxiliary contact is configured to be connected to a battery management system, and the battery management system is configured to determine the tripping state of the first circuit breaker according to the on-off state of the auxiliary contact.

13. The power supply system of claim 7, wherein, Further comprising a second circuit breaker. The battery pack is connected to the first input end through the second circuit breaker, and the second circuit breaker is configured to trip when the voltage of the battery pack is lower than a threshold voltage.

14. A power supply system control method characterized by comprising: Comprising: determining whether the AC power connected to the second input end of the AC-DC / AC unit is normal, and if the AC power is normal, controlling the output voltage of the first output end and the second output end of the AC-DC / AC unit to be converted from the AC power; and when the AC power is abnormal, controlling the output voltage of the first output end and the second output end to be converted from the DC power of the battery pack connected to the first input end of the AC-DC / AC unit; The first output end is used to supply power to a second load through the AC-DC / AC unit, and the second output end is used to supply power to a first load.

15. The power system control method of claim 14, wherein If the AC power is normal, controlling the output voltage of the first output end and the second output end of the AC-DC / AC unit to be converted from the AC power comprises: generating a first control signal for controlling the switching circuit to operate, and connecting the AC power to the first output end and the second output end through the switching circuit; The switching circuit is arranged in the AC-DC / AC unit.

16. The power system control method of claim 14, wherein When the AC power is abnormal, controlling the output voltage of the first output end and the second output end to be converted from the DC power of the battery pack connected to the first input end of the AC-DC / AC unit comprises: generating a second control signal for controlling the switching circuit to operate, and connecting the battery pack to the first output end and the second output end through the switching circuit; The switching circuit is arranged in the AC-DC / AC unit.

17. The power system control method according to any one of claims 14 to 16, characterized by, Further comprising: A trip instruction is generated when a cell voltage of the battery pack is lower than a set threshold, the trip instruction being used to control the second circuit breaker to trip; The second circuit breaker is arranged between the battery pack and the first input.

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