An auxiliary power system for a power conversion system (PCS) and a control method thereof

Abstract

The application discloses an auxiliary power supply system for an energy storage converter PCS and a control method thereof, wherein the whole system is divided into four different zones according to a reference ground by arranging a first partition unit, a second partition unit, a third partition unit, a switching power supply unit and a fourth partition unit, the electric energy of the whole system is derived from a PCS DC bus of the energy storage converter, the first partition unit is a partition with a negative electrode Vbus- of the PCS DC bus voltage as the reference ground, the second partition unit is a working area of a step-down control module IC1, the third partition unit is a partition with a power device Q1 in the step-down control module as the reference ground, and the fourth partition unit is a working area of an output voltage of the whole system; the first partition unit receives an input voltage of the PCS DC bus, the step-down control module performs step-down processing on the input voltage to obtain a target voltage, and the switching power supply unit supplies power to an IO circuit in the fourth partition unit according to the target voltage, so that the gradually realized low-cost and high-reliability auxiliary power supply system can be achieved, and the whole auxiliary power supply system can stably work.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage and current conversion, and in particular relates to an auxiliary power supply system for an energy storage current converter (PCS) and a control method thereof. Background Art

[0002] As a new driving force for the development of the new energy sector, energy storage systems are widely used both on the grid and user sides. Large-scale storage is the main focus on the grid side, while industrial and commercial energy storage is the main focus on the user side. In particular, industrial and commercial energy storage has emerged in the past two years, combining with distributed photovoltaics, new energy vehicle charging stations, and large-scale, uninterrupted production workshops, among other power generation or electricity-consuming entities. Thanks to local electricity price policies and flexible charging and discharging operation strategies, investors can achieve rapid profitability. With the gradual release of domestic battery production capacity, industrial and commercial energy storage will inevitably maintain rapid growth and become an important driver of economic growth. Within the energy storage industry, refined management and control, intelligent strategies, and automated operations and maintenance have all been applied on-site. New software technologies such as virtual power plant algorithms and grid-connected converters are also contributing to the realization of electricity spot market transactions. Based on these development trends in the energy storage market, large-scale grid-side storage and industrial and commercial energy storage on the user side will inevitably penetrate each other, and the boundary between the two will become further blurred. As the power density of battery cells gradually and steadily increases, the single-unit capacity of industrial and commercial energy storage will continue to increase, and the DC side battery voltage will continue to increase. For example, in a 400V grid system, a 100kW, 215kWh, 1000V DC system will be upgraded to a 150kW, 320kWh, 1500V DC system; for another example, in a 690V grid system, a 200kW, 400kWh, 1500V DC system will be upgraded to a 250kW, 500kWh, 2000V DC system. This requires that the energy storage converter (hereinafter referred to as PCS) be able to adapt to at least 2000V DC side voltage. In addition to the withstand voltage insulation of components in the main circuit, which must withstand a voltage level of 2000V, the auxiliary power system, as a key component of the PCS, must also be able to withstand a voltage of 2000V.

[0003] All power electronics converters include an auxiliary power system, whose primary function is to provide power to the main control system CPU, power device driver circuits, communication circuits, I / O digital input / output interfaces, and fan cooling systems. The reliability of the auxiliary power system directly impacts the stable operation of the entire PCS, making it even more crucial than the main circuit. However, the auxiliary power supply for a PCS requires power from the DC side, requiring it to withstand high DC voltages. Currently, most commercial and industrial energy storage systems, which account for the largest share of the market, have DC side voltages below 1000V. At this voltage level, commonly used switching power supply topologies (flyback, half-bridge, full-bridge, etc.) offer easy selection of cost-effective power semiconductors. However, above 1000V, due to the presence of magnetic components in the circuit, the power semiconductors in these commonly used switching power supply topologies must withstand voltages approximately twice the input voltage, making it difficult to select standard components and achieve a low-cost auxiliary power supply. Summary of the Invention

[0004] The present invention provides an auxiliary power supply system for an energy storage converter PCS and a control method thereof. This system can realize a low-cost, high-reliability auxiliary power supply system in an energy storage system with gradually increasing DC voltage, thereby enabling the entire auxiliary power supply system to operate stably. This system is specifically implemented using the following technical solutions.

[0005] In a first aspect, the present invention provides an auxiliary power supply system for an energy storage converter PCS, the auxiliary power supply system comprising a first partition unit, a second partition unit, a third partition unit, a switching power supply unit, and a fourth partition unit, wherein the second partition unit and the third partition unit are both connected to the first partition unit, the first partition unit is connected to the positive input and negative output terminals of the PCS DC bus, the output terminal of the first partition unit is connected to the input terminal of the switching power supply unit, and the output terminal of the switching power supply unit is connected to the fourth partition unit;

[0006] The second partition unit includes a step-down control module, a first DC conversion module, a second DC conversion module, and a third DC conversion module. The input end of the first DC conversion module is located in the first partition unit, the output end of the first DC conversion module is located in the second partition unit and connected to the step-down control module, the input end of the second DC conversion module is located in the second partition unit and connected to the step-down control module, the output end of the second DC conversion module is located in the third partition unit, the output end of the third DC conversion module is located in the second voltage dividing unit and connected to the step-down control module, and the input end of the third DC conversion module is located in the first partition unit;

[0007] Among them, the first partition unit receives the input voltage of the PCS DC bus, the buck control module bucks the input voltage to obtain a target voltage, and the switching power supply unit supplies power to the IO circuit in the fourth partition unit according to the target voltage.

[0008] As a preferred embodiment of the above technical solution, the first voltage divider unit includes a relay RKY1, a resistor R1, a resistor R2, a Zener diode Z1, a resistor R3 and a Zener diode Z2, one end of the relay RKY1 is connected to the second partition unit, the other end of the relay RKY1 is connected to the resistor R3, the resistor R3 is connected to the cathode of the Zener diode Z2 and the input end of the first DC conversion module, the anode of the Zener diode Z2 is connected to the negative input end of the PCS DC bus, the resistor R1 and the resistor R2 are connected in parallel to the positive input end and the negative input end of the PCS DC bus, and the resistor R2 is connected in parallel to the Zener diode Z1.

[0009] As a preferred embodiment of the above technical solution, the first partition unit also includes a diode D1, a Zener diode Z3, a resistor R4, a resistor R5 and an inductor L1, the anode of the diode D1 is connected to the negative input terminal of the PCS DC bus, the cathode of the diode D1 is connected to the third partition unit, one end of the inductor L1 is connected to the positive input terminal of the PCS DC bus, and the other end of the inductor L1 is connected to the resistor R4 and the resistor R5 in sequence, and the resistor R5 and the Zener diode Z3 are connected in parallel to the negative input terminal of the PCS DC bus.

[0010] As a preferred embodiment of the above technical solution, the second partition unit includes a chip IC1, a linear optocoupler OP1, a linear optocoupler OP2, a diode D2 and a diode D3. The secondary side of the linear optocoupler OP1 and the secondary side of the linear optocoupler OP2 are connected to the chip IC1, the primary side of the linear optocoupler OP1 is connected in parallel with the Zener diode Z1, and the primary side of the linear optocoupler OP2 is connected in parallel with the Zener diode Z3. The anode of the diode D2 is connected to the output end of the first DC conversion module, the cathode of the diode D2 is connected to the input end of the second DC conversion module, the cathode of the diode D3, and the chip IC1, the cathode of the diode D3 is connected to the input end of the second DC conversion module, and the anode of the diode D3 is connected to the output end of the third DC conversion module.

[0011] As a preferred embodiment of the above technical solution, the third partition unit includes a power device Q1 and a driving optocoupler DOP1, the gate of the power device Q1 is connected to the secondary side of the driving optocoupler DOP1, the source of the power device Q1 is connected to the inductor L1 and the cathode of the diode D1, the drain of the power device Q1 is connected to the positive input end of the PCS DC bus, the primary diode of the driving optocoupler DOP1 is driven by the output pulse of the chip IC1, and the secondary side of the driving optocoupler DOP1 is connected to the output end of the second DC conversion module.

[0012] As a preferred embodiment of the above technical solution, the switching power supply unit includes a chip IC2, a power device Q2, a resistor R8, a transformer T1, a linear optocoupler OP3 and a Zener diode Z5. The resistor R8 and the Zener diode Z5 are connected in parallel to the chip IC2, the gate of the power device Q2 is connected to the chip IC2, the source of the power device Q2 is connected to the negative input end of the PCS DC bus, the drain of the power device Q2 and the resistor R8 are connected to the primary side of the transformer T1, the secondary side of the linear optocoupler OP3 is connected to the chip IC2 and the Zener diode Z5, and the secondary side of the transformer and the primary side of the linear optocoupler OP3 are located in the fourth partition unit.

[0013] As a preferred embodiment of the above technical solution, the fourth partition unit includes a resistor R6, a resistor R7, a Zener diode Z4, an inductor L2, a diode D4, a capacitor C3 and an IO circuit, the secondary side of the transformer T1 is connected to the anode of the diode D4, the cathode of the diode is connected to one end of the inductor L2, the other end of the inductor L2 is connected to the IO circuit, the capacitor C3, and the resistor R6, the resistor R7, the Zener diode Z4, and the primary side of the linear optocoupler OP3 are connected in parallel to the other end of the resistor R6, and the IO circuit includes multiple LDO modules.

[0014] As a preferred embodiment of the above technical solution, the auxiliary power supply system also includes a capacitor C1 and a capacitor C2, and the capacitor C1 and the capacitor C2 are connected in parallel at both ends of the first partition unit. The capacitor C1 is used to filter the PCS DC bus voltage Vbus, and the capacitor C2 is used to filter the target voltage.

[0015] In a second aspect, the present invention further provides a control method for an auxiliary power supply system for an energy storage converter PCS, which is applied to the auxiliary power supply system for the energy storage converter PCS, and includes the following steps:

[0016] After the energy storage converter starts working, the auxiliary power system is initialized and the PCS DC bus is energized;

[0017] According to the normally closed contact of the relay RLY1 being in the closed state, the Zener diode Z2 is controlled to start voltage stabilization, so that the first DC conversion module provides the first control power supply to the auxiliary power supply system;

[0018] The chip IC1 receives the first control power supply to control the operation of the second DC conversion module and provide driving power to the circuit of the third partition unit where the power device Q1 is located;

[0019] According to the chip IC1 outputting normal pulses to the power device Q1 to enable the step-down circuit of the PCS DC bus Vbus to the target voltage Vmid to work, the output voltage of the third DC conversion module provides the second control power supply to the auxiliary power supply system;

[0020] The normally closed contact of the relay RLY1 is controlled to be disconnected according to the second control power supply to de-energize the Zener diode Z2, and the first DC conversion module stops working.

[0021] As a preferred embodiment of the above technical solution, after the first DC conversion module is powered on and replaced by the third DC conversion module, the chip IC1 obtains input voltage feedforward from the linear optocoupler OP1 and obtains output voltage feedback from the linear optocoupler OP2 to obtain a stable operating voltage value;

[0022] When the target voltage Vmid is stable, the chip IC2 and the fourth partition unit are powered and enter normal operation, and the Vout output is sent to multiple LDO modules through the PCS DC bus. Among them, the chip IC2 obtains the feedback signal from the linear optocoupler OP3 to control the voltage of Vout to be constant.

[0023] The present invention provides an auxiliary power supply system for an energy storage converter (PCS) and a control method thereof. By providing a first partition unit, a second partition unit, a third partition unit, a switching power supply unit, and a fourth partition unit, the entire system is divided into four different zones according to a reference ground. The electric energy of the entire system is derived from the DC bus of the energy storage converter (PCS), with Vbus+ being the positive pole and Vbus- being the negative pole. The first partition unit uses the negative pole Vbus- of the PCS DC bus voltage as the reference ground for the partition. The second partition unit is the working area of ​​a step-down control module IC1. The third partition unit uses the power device Q1 in the step-down control module as the reference ground for the partition. The fourth voltage divider unit is the working area of ​​the output voltage of the entire system. The first partition unit receives the input voltage of the PCS DC bus. The step-down control module steps down the input voltage to obtain a target voltage. The switching power supply unit supplies power to the IO circuit in the fourth partition unit according to the target voltage. This can realize a low-cost, high-reliability auxiliary power supply system in an energy storage system with gradually increasing DC voltage, so that the entire auxiliary power supply system operates stably. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 A structural block diagram of the auxiliary power supply system for the energy storage converter PCS provided by the present invention;

[0026] Figure 2 A schematic diagram of the auxiliary power supply system provided by the present invention;

[0027] Figure 3 A circuit diagram of the BUCK circuit provided by the present invention;

[0028] Figure 4 A flow chart of a control method for an auxiliary power supply system of an energy storage converter PCS provided by the present invention;

[0029] Figure 5 This is a diagram of the implementation process of the auxiliary power supply system provided by the present invention.

[0030] The main component symbols are described as follows:

[0031] 100 - first partition unit; 110 - second partition unit; 120 - third partition unit; 130 - switching power supply unit; 140 - fourth partition unit; 150 - step-down control module; 160 - first DC conversion module; 170 - second DC conversion module; 180 - third DC conversion module. DETAILED DESCRIPTION

[0032] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0033] Reference Figure 1 and Figure 2The present invention provides an auxiliary power supply system for an energy storage converter PCS, the auxiliary power supply system comprising a first partition unit 100, a second partition unit 110, a third partition unit 120, a switching power supply unit 130, and a fourth partition unit 140. The second partition unit 110 and the third partition unit 120 are both connected to the first partition unit 100. The first partition unit 100 is connected to the positive input and negative output terminals of a PCS DC bus. The output terminal of the first partition unit 100 is connected to the input terminal of the switching power supply unit 130, and the output terminal of the switching power supply unit 130 is connected to the fourth partition unit 140.

[0034] The second partition unit 110 includes a step-down control module 150, a first DC conversion module 160, a second DC conversion module 170, and a third DC conversion module 180. The input end of the first DC conversion module 160 is located in the first partition unit 100, the output end of the first DC conversion module 160 is located in the second partition unit 110 and connected to the step-down control module 150, the input end of the second DC conversion module 170 is located in the second partition unit 110 and connected to the step-down control module 150, the output end of the second DC conversion module 170 is located in the third partition unit 120, the output end of the third DC conversion module 180 is located in the second voltage dividing unit 110 and connected to the step-down control module 150, and the input end of the third DC conversion module 180 is located in the first partition unit 100;

[0035] The first partition unit 100 receives the input voltage of the PCS DC bus, the step-down control module 150 steps down the input voltage to obtain a target voltage, and the switching power supply unit 130 supplies power to the IO circuit in the fourth partition unit 140 according to the target voltage.

[0036] In this embodiment, the first voltage divider unit 100 includes a relay RKY1, a resistor R1, a resistor R2, a Zener diode Z1, a resistor R3, and a Zener diode Z2. One end of the relay RKY1 is connected to the second partition unit 110, and the other end of the relay RKY1 is connected to the resistor R3. The resistor R3 is connected to the cathode of the Zener diode Z2 and the input end of the first DC conversion module 160. The anode of the Zener diode Z2 is connected to the negative input end of the PCS DC bus. The resistors R1 and R2 are connected in parallel to the positive input end and the negative input end of the PCS DC bus. The resistor R2 is connected in parallel to the Zener diode Z1. The first partition unit 100 also includes a diode D1, a Zener diode Z3, a resistor R4, a resistor R5 and an inductor L1. The anode of the diode D1 is connected to the negative input terminal of the PCS DC bus, the cathode of the diode D1 is connected to the third partition unit 120, one end of the inductor L1 is connected to the positive input terminal of the PCS DC bus, and the other end of the inductor L1 is connected to the resistor R4 and the resistor R5 in sequence. The resistor R5 and the Zener diode Z3 are connected in parallel to the negative input terminal of the PCS DC bus. The second partition unit 110 includes a chip IC1, a linear optocoupler OP1, a linear optocoupler OP2, a diode D2, and a diode D3. The secondary side of the linear optocoupler OP1 and the secondary side of the linear optocoupler OP2 are connected to the chip IC1, the primary side of the linear optocoupler OP1 is connected in parallel with the Zener diode Z1, and the primary side of the linear optocoupler OP2 is connected in parallel with the Zener diode Z3. The anode of the diode D2 is connected to the output end of the first DC conversion module 160, and the cathode of the diode D2 is connected to the input end of the second DC conversion module 170, the cathode of the diode D3, and the chip IC1. The cathode of the diode D3 is connected to the second DC conversion module 170. The input end of the DC conversion module 170 is connected, the anode of the diode D3 is connected to the output end of the third DC conversion module 180, the third partition unit 180 includes a power device Q1 and a driving optocoupler DOP1, the gate of the power device Q1 is connected to the secondary side of the driving optocoupler DOP1, the source of the power device Q1 is connected to the inductor L1 and the cathode of the diode D1, the drain of the power device Q1 is connected to the positive input end of the PCS DC bus, the primary side diode of the driving optocoupler DOP1 is driven by the output pulse of the chip IC1, and the secondary side of the driving optocoupler DOP1 is connected to the output end of the second DC conversion module 170.

[0037] It should be noted that the switching power supply unit includes a chip IC2, a power device Q2, a resistor R8, a transformer T1, a linear optocoupler OP3 and a Zener diode Z5. The resistor R8 and the Zener diode Z5 are connected in parallel to the chip IC2, the gate of the power device Q2 is connected to the chip IC2, the source of the power device Q2 is connected to the negative input end of the PCS DC bus, the drain of the power device Q2 and the resistor R8 are connected to the primary side of the transformer T1, the secondary side of the linear optocoupler OP3 is connected to the chip IC2 and the Zener diode Z5, and the secondary side of the transformer and the primary side of the linear optocoupler OP3 are located in the fourth partition unit. The fourth partition unit includes a resistor R6, a resistor R7, a Zener diode Z4, an inductor L2, a diode D4, a capacitor C3, and an IO circuit. The secondary side of the transformer T1 is connected to the anode of the diode D4, the cathode of the diode is connected to one end of the inductor L2, and the other end of the inductor L2 is connected to the IO circuit, the capacitor C3, and the resistor R6. The resistor R7, the Zener diode Z4, and the primary side of the linear optocoupler OP3 are connected in parallel to the other end of the resistor R6. The IO circuit includes multiple LDO modules. The auxiliary power supply system also includes a capacitor C1 and a capacitor C2. The capacitors C1 and C2 are connected in parallel at both ends of the first partition unit. The capacitor C1 is used to filter the PCS DC bus voltage Vbus, and the capacitor C2 is used to filter the target voltage.

[0038] Specifically, the first DC conversion module, the second DC conversion module, and the third DC conversion module are all DCDC converters, and are respectively denoted as DC1, DC2, and DC3. In order to realize a low-cost and high-reliability auxiliary power supply system in an energy storage system with gradually increasing DC voltage, the high input voltage must be first reduced to a reasonable economic voltage (which is easiest for selecting components in the subsequent circuit and ensures overall high efficiency). The simplest and most economical circuit is the buck topology, such as Figure 3As shown, in the common BUCK circuit, the BUCK IC (control chip) will obtain the input voltage through the voltage division of resistor R1 and resistor R2, and the output voltage through the voltage division of resistor R4 and resistor R5, and control the opening duty cycle of power device Q1 through pulse; when Q1 is closed, Vin supplies power to the load (Load) through inductor L1, at this time, the gate of Q1 (G1) takes Vs point as the reference ground, and the voltage of Vs point is input voltage Vin, and the working reference ground of IC is GND; when Q1 is opened, the circuit composed of L1-Load-D1 performs freewheeling; in the working process, the maximum voltage drop borne by the BUCK IC is about Vin (the voltage between Vs and GND when Q1 is closed), and the voltage resistance of the common BUCK IC is less than 60V, therefore, the conventional BUCK voltage reduction circuit is often used in low-voltage circuits, and for the direct current voltage level (1000V-2000V level) of the energy storage system, it cannot be directly used, so a special circuit must be designed to solve the high input voltage BUCK.

[0039] In order to solve the problem of the PCS auxiliary power supply system, the application provides a multi-partition isolation type step-down DC / DC power supply system specially used for high direct current input voltage, and belongs to the field of power electronic switching mode step-down power supply. Figure 2 As shown, the whole system is divided into four different areas, i.e., working areas, according to the different levels of the reference ground, and is respectively a first voltage division unit, a second voltage division unit, a third voltage division unit and a fourth voltage division unit, and is respectively marked as "[Sect1]~[Sect4]"; wherein "[Sect1]" is a partition taking the negative pole "Vbus-" of the PCS direct current bus voltage as the reference ground. Figure 2 As shown in the figure, "[Sect2]" is the working area of the step-down BUCK control IC, and takes the chip "ground" of the BUCK IC, i.e., "GND-B", as the reference ground of the area, Figure 2 As shown in the figure, This partition belongs to a low-voltage area and is isolated from the high-voltage area on the circuit. In order to ensure the safe operation of the BUCK IC, i.e., chip IC1, the highest voltage in this area is the working power supply voltage of the BUCK IC; "[Sect3]" is a partition taking the source (or emitter) of the main switch Q1 in the step-down BUCK circuit as the reference ground, i.e., "GND-D", as shown in the figure, This partition is mainly to ensure the normal closing and opening of Q1 driving level, this partition is directly connected with [Sect1] in the circuit, but belongs to low voltage area, because the highest voltage is the opening voltage of Q1 relative to the reference ground of this area; [Sect4] is the partition of the output voltage of the whole system, which belongs to the low voltage partition, and the highest voltage is Vout, usually less than 30V, and the reference ground is the ground of PCS control power supply, that is, GND_L, which is marked as

[0040]

[0041] Among them, the step-down control module is a step-down BUCK circuit, the switching power supply unit is an SMPS circuit, Q1 and Q2 are semiconductor power devices, which can be but are not limited to thyristor, triode, IGBT, MOSFET, PCS Vbus is between 600V and 2000V, but the present embodiment does not limit this voltage; Vmid is between 200V and 300V, but the present embodiment does not limit this voltage. The auxiliary power supply system is to convert the high voltage of the PCS bus voltage level into Vmid (Voltage_middle, middle voltage) of about 200V-300V through the first stage BUCK circuit, to supply the input stage of the switching mode isolated source of the later stage, and the Vmid voltage can facilitate the realization of the switching power supply in the later stage in terms of economy, efficiency and easy availability of devices, wherein Vmid is the target voltage, BUCK IC1 and SMPS IC2 are not limited to chip models, and can be a comprehensive system of power supply chips and peripheral circuits with specific functions, or a comprehensive system including controllers such as MCU DSP and software and peripheral circuits; the circuit shown by SMPS IC2 is only an example, and can be but is not limited to single-tube flyback, half-bridge, full-bridge and other circuits.

[0042] Specifically, for the first-stage BUCK buck circuit, the core is the BUCK controller IC1 in "[Sect2]". The PCS DC bus voltage Vbus is filtered by capacitor C1; the voltage obtained by the voltage divider and voltage stabilization network composed of resistors R1, R2, and Zener diode Z1 represents the Vbus voltage value, driving the primary diode of the linear optocoupler OP1. The secondary side of OP1 is connected to IC1, serving as the feedforward (ff1) of the BUCK circuit. Similarly, the main function of capacitor C2 is to filter the voltage Vmid. The voltage obtained by the voltage divider and voltage stabilization network composed of resistors R4, R5, and Zener diode Z3 provides feedback (fb1) of the output voltage Vmid of the first-stage BUCK buck circuit to the BUCK IC1 through the linear optocoupler OP2. Diode D1 is the freewheeling device of the buck circuit, and L1 is the energy storage and filtering inductor. DOP1 (Driver Optocupler) is the driver optocoupler of the power device Q1. The primary diode is driven by the output pulse of the buck IC1, and the secondary side is connected to the gate of Q1, thereby realizing the buck. IC1 drives the pulse isolation of Q1. For the first-stage BUCK step-down circuit, the control power supply of chip IC1 is provided by three low-voltage isolated DC / DC power converters: DC1, DC2, and DC3. 1 represents the power flow direction of the power converter. When the system is initially powered on, the Vbus voltage supplies power to DC1 through the voltage regulator circuit consisting of the normally closed contact of relay RLY1, resistor R3, and Zener diode Z2. Its output voltage "V_A" is then used to supply power to the various components in "[Sect2]" through the anti-reverse diode D2, namely "V_B" in the figure. After the first-stage buck IC has operated for several cycles, the Vmid voltage rises to the starting voltage of DC3, DC3 begins to operate, and the output voltage "V_C" passes through the anti-reverse diode D3. While supplying power to the various components in "[Sect2]", it also drives relay RLY1, opening its normally closed contact, de-energizing DC1. DC1 is then de-energized, and only DC3 is used to power "[Sect2]". The main power-consuming component in "[Sect3]" is the optocoupler DOP1, which is powered by the isolated DC-DC power supply DC2. The DC2 input voltage is the value "V_B" obtained from DC1 or DC3. The internal pulse generation and overvoltage and overcurrent protection of the buck IC1 are well-known technologies and are not further described in this embodiment. The core part of the second-stage circuit is the switch-mode power supply control chip SMPSIC2, which obtains control power through resistor R8 and Zener diode Z5, and pulse-drives power semiconductor Q2, thereby obtaining pulses on the primary side of the isolated high-frequency transformer T1. The secondary side of T1 obtains the output voltage Vout through diode D4, inductor L2 and capacitor C3. As mentioned above, the output voltage feedback circuit is composed of resistor R6, resistor R7, Zener diode Z4 and OP3. The above-mentioned Vout directly powers the IO circuit of the PCS, such as the coil drive of the relay, the switch return status, the panel LED and other status indication drivers, etc.; the third-level circuit is multiple LDOs, for example, LDO1 is the main power supply of the CPU, and the commonly used voltages are 5V, 3.3V, 1.8V, 1.2V, etc. LDO2 is the driving power supply of the main power device of the PCS, and the conventional voltage is ±15V dual power supply; LDO3 is the power supply of the communication interface, such as CAN, RS485, and the conventional voltage is 5V, 12V, etc.; LDO4 is the fan voltage, and the conventional voltage is 15V; other power supplies that may be included are not described in detail in this design.

[0043] It should be understood that by providing a first partition unit, a second partition unit, a third partition unit, a switching power supply unit, and a fourth partition unit, the entire system is divided into four different zones according to the reference ground. The electric energy of the entire system comes from the energy storage converter PCS DC bus, with Vbus+ as the positive pole and Vbus- as the negative pole. The first partition unit uses the negative pole Vbus- of the PCS DC bus voltage as the reference ground for the partition. The second partition unit is the working area of ​​the buck control module IC1. The third partition unit uses the power device Q1 in the buck control module as the reference ground for the partition. The fourth voltage divider unit is the working area of ​​the output voltage of the entire system. The first partition unit receives the input voltage of the PCS DC bus, the buck control module steps down the input voltage to obtain a target voltage, and the switching power supply unit supplies power to the IO circuit in the fourth partition unit according to the target voltage. This can achieve a low-cost, high-reliability auxiliary power supply system in an energy storage system with gradually increasing DC voltage, so that the entire auxiliary power supply system can operate stably.

[0044] See Figure 4 and Figure 5 The present invention also provides a control method for an auxiliary power supply system for an energy storage converter PCS, which is applied to the auxiliary power supply system for the energy storage converter PCS, and includes the following steps:

[0045] S1: After the energy storage converter starts working, the auxiliary power system is initialized and the PCS DC bus is energized;

[0046] S2: According to the normally closed contact of the relay RLY1 being in the closed state, the Zener diode Z2 is controlled to start voltage stabilization, so that the first DC conversion module provides the first control power supply to the auxiliary power supply system;

[0047] S3: Chip IC1 receives the first control power supply to control the second DC conversion module to operate and provide driving power to the circuit of the third partition unit where the power device Q1 is located;

[0048] S4: The chip IC1 outputs a normal pulse to the power device Q1 to operate the step-down circuit from the PCS DC bus Vbus to the target voltage Vmid, and the output voltage of the third DC conversion module provides a second control power supply to the auxiliary power system;

[0049] S5: According to the second control power supply, the normally closed contact of the relay RLY1 is controlled to be open to de-energize the Zener diode Z2, and the first DC conversion module stops working.

[0050] In this embodiment, after the first DC conversion module is powered on and replaced by the third DC conversion module, the chip IC1 obtains input voltage feedforward from the linear optocoupler OP1 and obtains output voltage feedback from the linear optocoupler OP2 to obtain a stable operating voltage value; when the target voltage Vmid is stable, the chip IC2 and the fourth partition unit are powered on and enter a normal working state, and the Vout output of the PCS DC bus is sent to multiple LDO modules for operation, wherein the chip IC2 obtains a feedback signal from the linear optocoupler OP3 to control the voltage of Vout to be constant.

[0051] It should be noted that when the energy storage converter PCS begins operation, the power supply initializes and waits for Ubus to be energized. After Ubus is energized, Z2 begins to regulate the voltage because the normally closed contact of relay RLY1 is closed. When the voltage at Z2 stabilizes, DC1 begins to operate, providing control power for the entire auxiliary power system. This voltage, "VA," passes through diode D2 to obtain "VB." Once DC1 is operating, IC1 begins to operate, while DC2 also provides drive power to the circuitry in the main switch area. As IC1 outputs normal pulses to Q1, the buck circuit (from Vbus to Vmid) begins to operate, and Vmid begins to build. When Vmid reaches the operating voltage of switching power supply DC-DC module DC3, DC3 begins to operate, and its output voltage begins to provide control power for the entire auxiliary power system. This voltage, "VC," passes through diode D3 to obtain "VB." Simultaneously, "VC" drives the coil of RLY1, opening the normally closed contact, de-energizing Z2 and shutting down DC1, thus replacing DC3's function of providing control power for the system. In other words, DC1 only works for a short time after Vbus is powered on and will soon be replaced by DC3; next, IC1 obtains input voltage feedforward from OP1 and output voltage feedback from OP2, entering a closed-loop working state and obtaining a stable voltage value; when Vmid is working stably, IC2 and its subsequent main circuit are powered on and enter normal working state, Vout is output, and IC3 obtains feedback signal from OP3, thereby controlling the voltage of Vout to be constant. Vout supplies the last stage of multiple LDOs to work, thereby making the entire auxiliary power supply system work stably.

[0052] In all examples shown and described herein, any specific values ​​should be interpreted as merely exemplary and not limiting, and thus other examples of the exemplary embodiments may have different values.

[0053] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0054] The above-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that variations and modifications are possible without departing from the scope of the present invention, and such variations and modifications are fully within the scope of protection of the present invention.

Claims

1. An auxiliary power supply system for a PCS energy storage converter, characterized in that: The auxiliary power supply system includes a first partition unit, a second partition unit, a third partition unit, a switching power supply unit, and a fourth partition unit. The first partition unit, the second partition unit, the third partition unit, and the fourth partition unit are divided according to a reference ground. The second partition unit and the third partition unit are both connected to the first partition unit. The first partition unit is connected to the positive input terminal and the negative output terminal of the PCS DC bus. The output terminal of the first partition unit is connected to the input terminal of the switching power supply unit. The output terminal of the switching power supply unit is connected to the fourth partition unit. The second partition unit includes a step-down control module, a first DC conversion module, a second DC conversion module, and a third DC conversion module. The input end of the first DC conversion module is located in the first partition unit, the output end of the first DC conversion module is located in the second partition unit and connected to the step-down control module, the input end of the second DC conversion module is located in the second partition unit and connected to the step-down control module, the output end of the second DC conversion module is located in the third partition unit, the output end of the third DC conversion module is located in the second partition unit and connected to the step-down control module, and the input end of the third DC conversion module is located in the first partition unit; Among them, the first partition unit receives the input voltage of the PCS DC bus, the buck control module bucks the input voltage to obtain a target voltage, and the switching power supply unit supplies power to the IO circuit in the fourth partition unit according to the target voltage.

2. The auxiliary power supply system for the energy storage converter PCS according to claim 1, characterized in that: The first partition unit includes a relay RKY1, a resistor R1, a resistor R2, a Zener diode Z1, a resistor R3 and a Zener diode Z2. The coil of the relay RKY1 is connected to the second partition unit, one end of the relay RKY1 is connected to the positive input end of the PCS DC bus, the other end of the relay RKY1 is connected to one end of the resistor R3, the other end of the resistor R3 is connected to the cathode of the Zener diode Z2 and the input end of the first DC conversion module, the anode of the Zener diode Z2 is connected to the negative input end of the PCS DC bus, the resistor R1 and the resistor R2 are connected in parallel to the positive input end and the negative input end of the PCS DC bus, and the resistor R2 is connected in parallel to the Zener diode Z1.

3. The auxiliary power supply system for the energy storage converter PCS according to claim 2, characterized in that: The first partition unit also includes a diode D1, a Zener diode Z3, a resistor R4, a resistor R5 and an inductor L1. The anode of the diode D1 is connected to the negative input terminal of the PCS DC bus, the cathode of the diode D1 is connected to the third partition unit, one end of the inductor L1 is connected to the positive input terminal of the PCS DC bus, and the other end of the inductor L1 is connected to the resistor R4 and the resistor R5 in sequence. The resistor R5 and the Zener diode Z3 are connected in parallel to the negative input terminal of the PCS DC bus.

4. The auxiliary power supply system for the energy storage converter PCS according to claim 3, characterized in that: The second partition unit includes a chip IC1, a linear optocoupler OP1, a linear optocoupler OP2, a diode D2 and a diode D3. The secondary side of the linear optocoupler OP1 and the secondary side of the linear optocoupler OP2 are connected to the chip IC1, the primary side of the linear optocoupler OP1 is connected in parallel with the Zener diode Z1, and the primary side of the linear optocoupler OP2 is connected in parallel with the Zener diode Z3. The anode of the diode D2 is connected to the output end of the first DC conversion module, the cathode of the diode D2 is connected to the input end of the second DC conversion module, the cathode of the diode D3 and the chip IC1, and the anode of the diode D3 is connected to the output end of the third DC conversion module.

5. The auxiliary power supply system for the energy storage converter PCS according to claim 4, characterized in that: The third partition unit includes a power device Q1 and a driving optocoupler DOP1. The gate of the power device Q1 is connected to the secondary side of the driving optocoupler DOP1, the source of the power device Q1 is connected to one end of the inductor L1 and the cathode of the diode D1, the drain of the power device Q1 is connected to the positive input end of the PCS DC bus, the primary diode of the driving optocoupler DOP1 is driven by the output pulse of the chip IC1, and the secondary side of the driving optocoupler DOP1 is connected to the output end of the second DC conversion module.

6. The auxiliary power supply system for the energy storage converter PCS according to claim 5, characterized in that: The switching power supply unit includes a chip IC2, a power device Q2, a resistor R8, a transformer T1, a linear optocoupler OP3 and a Zener diode Z5. One end of the resistor R8 is connected to the cathode of the Zener diode Z5 and to the chip IC2. The gate of the power device Q2 is connected to the chip IC2. The source of the power device Q2 is connected to the negative input end of the PCS DC bus. The drain of the power device Q2 and the other end of the resistor R8 are connected to the primary side of the transformer T1. The secondary side of the linear optocoupler OP3 is connected to the chip IC2 and the anode of the Zener diode Z5. The secondary side of the transformer T1 and the primary side of the linear optocoupler OP3 are located in the fourth partition unit.

7. The auxiliary power supply system for the energy storage converter PCS according to claim 6, characterized in that: The fourth partition unit includes a resistor R6, a resistor R7, a Zener diode Z4, an inductor L2, a diode D4, a capacitor C3 and an IO circuit. The secondary side of the transformer T1 is connected to the anode of the diode D4, the cathode of the diode D4 is connected to one end of the inductor L2, the other end of the inductor L2 is connected to the IO circuit, one end of the capacitor C3, and one end of the resistor R6. The resistor R7, the Zener diode Z4, and the primary side of the linear optocoupler OP3 are connected in parallel between the other end of the resistor R6 and ground. The other end of the capacitor C3 is grounded. The IO circuit includes multiple LDO modules.

8. The auxiliary power supply system for the energy storage converter PCS according to claim 7, characterized in that: The auxiliary power supply system further includes a capacitor C1 and a capacitor C2, which are connected in parallel at both ends of the first partition unit. The capacitor C1 is used to filter the PCS DC bus voltage Vbus, and the capacitor C2 is used to filter the target voltage.

9. A control method for an auxiliary power supply system for an energy storage converter PCS, applied to the auxiliary power supply system for an energy storage converter PCS according to claim 8, characterized in that: The following steps are involved: After the energy storage converter starts working, the auxiliary power system is initialized and the PCS DC bus is energized; According to the normally closed contact of the relay RLY1 being in the closed state, the Zener diode Z2 is controlled to start voltage stabilization, so that the first DC conversion module provides the first control power supply to the auxiliary power supply system; The chip IC1 receives the first control power supply to control the operation of the second DC conversion module and provide driving power to the circuit of the third partition unit where the power device Q1 is located; According to the chip IC1 outputting normal pulses to the power device Q1 to enable the step-down circuit of the PCS DC bus Vbus to the target voltage Vmid to work, the output voltage of the third DC conversion module provides the second control power supply to the auxiliary power supply system; The normally closed contact of the relay RLY1 is controlled to be disconnected according to the second control power supply to de-energize the Zener diode Z2, and the first DC conversion module stops working.

10. The control method for the auxiliary power supply system of the energy storage converter PCS according to claim 9, characterized in that: After the first DC conversion module is powered and replaced by the third DC conversion module, the chip IC1 obtains input voltage feedforward from the linear optocoupler OP1 and output voltage feedback from the linear optocoupler OP2 to obtain a stable operating voltage value; When the target voltage Vmid is stable, the chip IC2 and the fourth partition unit are powered and enter normal operation, and the Vout output is sent to multiple LDO modules through the PCS DC bus. Among them, the chip IC2 obtains the feedback signal from the linear optocoupler OP3 to control the voltage of Vout to be constant.

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