Ship wharf shore power supply system for realizing single-point high-capacity power supply

Abstract

The invention provides a ship wharf shore power supply system for realizing single-point high-capacity power supply. The ship wharf shore power supply system comprises a high-voltage electric box, a high-voltage switch cabinet, a high-voltage transformer TR1, a distribution box, a frequency converter I, a frequency converter II, a controller, an isolation transformer TR2 and an isolation transformer TR3 which are connected in sequence. The high-voltage transformer TR1 outputs a group of 400V three-phase alternating-current power supply and a group of 480V three-phase alternating-current power supply, the frequency converter I and the frequency converter II are connected to the 480V three-phase alternating-current power supply in parallel, and optical fiber communication plates of the slave inverter I, the slave inverter II and the slave inverter III are all connected with an optical fiber communication plate of the master inverter through optical fibers. And the controller is connected with the controller communication boards of the master inverter and the slave inverter II through optical fibers. On one hand, the two sets of inverters are connected to the same set of power supply in parallel, and phase synchronization is achieved by connecting the two sets of inverters through optical fibers. And on the other hand, the corresponding output voltage and frequency are controlled through the high-voltage transformer and the controller, so that the shore power system has very high compatibility.

Description

Technical Field

[0001] This invention relates to the field of power equipment technology, specifically to a shore power supply system for ship docks that enables large-capacity power supply at a single point. Background Technology

[0002] Shore power technology for ship terminals is an important component of modern port electrification and environmental protection measures. With increasing global awareness of environmental protection, reducing pollution emissions from ships while berthed in port has become a key focus for governments and international organizations. Traditionally, ships use their onboard auxiliary generators to provide the electricity they need after docking, which not only consumes a large amount of fuel but also generates noise, air pollutants, and greenhouse gas emissions. To address these issues, many countries and regions have begun to implement Alternative Maritime Power (AMP) systems, which connect ships to the land-based power grid via cables while they are docked, replacing the onboard diesel generators.

[0003] However, in practical applications, traditional shore power systems typically use 380V, 630A / 1250A junction boxes, resulting in low voltage and high current. The need to lay numerous temporary cables increases the complexity and cost of installation and maintenance, while also limiting the maximum power output to approximately 500KW, which is far from sufficient for large cruise ships or container ships. Furthermore, the two frequency converters in traditional shore power systems are powered independently by two separate power sources, each with a smaller current draw, thus limiting the overall power capacity. This design struggles to meet the high-power demands of modern large ships, especially in situations requiring large-capacity power at a single point, such as the power needs of large cruise ships or container ships during berthing. Summary of the Invention

[0004] To address the problem of limited power supply capacity in existing shore power systems at ship terminals, this invention provides a shore power supply system for ship terminals to achieve large-capacity power supply at a single point. On the one hand, it uses a three-phase AC power supply of 9.5~11.5KV, 50~60Hz to replace the traditional 380V junction box. On the other hand, it connects two sets of frequency converters in parallel to the circuit, with the same power supply voltage and the current added together, thus meeting the demand for large-capacity power supply at a single point.

[0005] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0006] A shore power supply system for ship docks to achieve single-point large-capacity power supply includes a high-voltage electrical box, a high-voltage switch cabinet, a high-voltage transformer TR1, a distribution box, a frequency converter I, a frequency converter II, a controller, an isolation transformer TR2, and an isolation transformer TR3. The high-voltage electrical box is used to provide a three-phase AC power supply of 9.5~11.5KV, 50~60Hz, and its output terminal is connected to the input terminal of the high-voltage switchgear. The input terminal of the high-voltage transformer TR1 is connected to the output terminal of the high-voltage switchgear, and the output terminal of the high-voltage transformer TR1 is connected to the input terminal of the distribution box. The high-voltage transformer TR1 outputs a set of 400V three-phase AC power and a set of 480V three-phase AC power. The inverter I includes a main inverter I, a slave inverter I, and a filter circuit I. The three-phase power input terminal of the main inverter I, the detection board of the main inverter I, and the three-phase power input terminal of the slave inverter I are connected in parallel and connected to a 480V three-phase AC power supply in the distribution box. The fiber optic communication board of the slave inverter I is connected to the fiber optic communication board of the main inverter I via fiber optic cable. The first filter circuit includes a three-phase inductor L1 connected to the three-phase power output terminal of the main inverter I, a three-phase filter capacitor C1 connected to the output terminal of the three-phase inductor L1, a three-phase inductor L2 connected to the three-phase power output terminal of the slave inverter I, and a three-phase filter capacitor C2 connected to the output terminal of the three-phase inductor L2. The output terminals of the three-phase filter capacitor C1 and the three-phase filter capacitor C2 are respectively connected to the three-phase power input terminal of the isolation transformer TR2. The inverter II includes a main inverter II, a slave inverter II, and a filter circuit II. The three-phase power input terminals of the main inverter II, its detection board, and the three-phase power input terminals of the slave inverter II are connected in parallel and connected to a 480V three-phase AC power supply in the distribution box. The fiber optic communication boards of the main inverter II and the slave inverter II are connected to the fiber optic communication board of the main inverter I via optical fibers. The positive terminals of the main inverter I, slave inverter I, main inverter II, and slave inverter II are connected in series. The negative terminals of inverter I, main inverter II, and slave inverter II are connected together. The filter circuit II includes a three-phase inductor L3 connected to the three-phase power output terminal of the main inverter II, a three-phase filter capacitor C3 connected to the output terminal of the three-phase inductor L3, a three-phase inductor L4 connected to the three-phase power output terminal of the slave inverter II, and a three-phase filter capacitor C4 connected to the output terminal of the three-phase inductor L4. The output terminals of the three-phase filter capacitor C3 and the three-phase filter capacitor C4 are respectively connected to the three-phase power input terminal of the isolation transformer TR3. The controller is connected to the controller communication boards of main inverter I and main inverter II via optical fiber, and is used to control the corresponding output voltage and frequency by synchronously controlling the conduction angle and trigger frequency of main inverter I, main inverter II, slave inverter I, and slave inverter II respectively. The rated input voltage of the isolation transformer TR2 is adapted to the output voltage of the main inverter I and the slave inverter I. The rated input voltage of the isolation transformer TR3 is adapted to the output voltage of the main inverter II and the slave inverter II. The isolation transformers TR2 and TR3 respectively output a set of 400~720V three-phase AC power supply with the same frequency and voltage.

[0007] Furthermore, the high-voltage transformer TR1 is equipped with several tap switches for changing the turns ratio between the high-voltage winding and the low-voltage winding.

[0008] Furthermore, it also includes a UPS power supply, which supplies power to the high-voltage switchgear and the distribution box respectively.

[0009] Furthermore, the high-voltage switchgear is also equipped with a high-voltage outdoor emergency stop button SBG1 and a low-voltage indoor emergency stop button SBG2 for cutting off the high-voltage power supply.

[0010] Furthermore, it also includes multiple fans, temperature sensors, and a temperature controller; the temperature sensors are used to detect the temperature of the high-voltage transformer in real time and send it to the temperature controller; the temperature controller is installed on the connection circuit between the fans and the distribution box, and is used to control the start and stop of the fans according to the temperature of the high-voltage transformer; the connection circuit between the temperature controller and the distribution box is also equipped with a fuse FU20.

[0011] Furthermore, the controller is powered by a 24V DC voltage and is connected to a touch screen.

[0012] Furthermore, it also includes a power supply transformer TR4, whose three-phase power input terminal is connected to a 400V three-phase AC power supply in the distribution box, and the power supply transformer TR4 outputs a set of 440V three-phase AC power.

[0013] Furthermore, fuse QF1 is installed at the three-phase power input terminal of main inverter I, the detection board of main inverter I, the connection point of the three-phase power input terminal of slave inverter I, and the connection line to the 480V three-phase AC power supply; fuse QF2 is installed on the output circuit of isolation transformer TR2; fuse QF3 is installed at the three-phase power input terminal of main inverter II, the detection board of main inverter II, the connection point of the three-phase power input terminal of slave inverter II, and the connection line to the 480V three-phase AC power supply; and fuse QF4 is installed on the output circuit of isolation transformer TR3.

[0014] Furthermore, the three-phase power output terminal and zero point of the isolation transformer TR3 are respectively connected to the three-phase power output terminal and zero point of the isolation transformer TR2, and the two sets of connection points are respectively located between the three-phase power output terminal of the isolation transformer TR2 and the fuse QF2, and between the three-phase power output terminal of the isolation transformer TR3 and the fuse QF3.

[0015] Furthermore, it also includes a voltage regulation and protection board connected to the controller signal. The voltage regulation and protection board is used to sample the voltage output of isolation transformer TR2 / isolation transformer TR3, and adjust the conduction angle of main inverter I, slave inverter I, main inverter II, and slave inverter II through the controller to adjust the voltage output of isolation transformer TR2 / isolation transformer TR3 to the target voltage value.

[0016] The beneficial effects of this invention are as follows: On the one hand, this invention uses a 9.5~11.5kV, 50~60Hz three-phase AC power supply, replacing the traditional 380V junction box, thus increasing the power supply voltage and effectively solving the problems of complex cable laying and limited power transmission caused by low voltage and high current in traditional systems. On the other hand, by connecting two sets of frequency converters in parallel to the circuit and ensuring that the power supply voltage is the same while the current is added, the power supply capacity is significantly increased. These two improvements achieve the goal of providing a large-capacity power supply at a single point.

[0017] This invention equips each parallel inverter with a fiber optic communication board, enabling high-speed, low-latency communication between the inverters via fiber optic connections. This design not only ensures synchronized AC signals output by each inverter, solving the problem of phase synchronization difficulties among multiple inverters, but also significantly reduces circulating current. Reduced circulating current not only lowers energy loss but also improves system stability and reliability, extending equipment lifespan. Simultaneously, the controller adjusts the conduction angle and trigger frequency of each inverter in real time, ensuring stable synchronous operation of the system under load changes or grid fluctuations. This further enhances the system's anti-interference capability and adaptability.

[0018] The shore power supply system for ships and docks of this invention possesses extremely high compatibility, capable of handling different levels of power input. Whether it's 9.5~10.5kV, 50Hz three-phase AC power output from a high-voltage substation or 10.5~11.5kV, 60Hz three-phase AC power output from a temporary ship power supply, the system can, through precise adjustments of the high-voltage transformer and inverter, ultimately output 400~720V, 50~60Hz three-phase AC power. This allows the power supply system of this invention to quickly switch to backup power when the main power supply fails. By adjusting the number of turns of the high-voltage transformer, as well as the conduction angle and trigger frequency of the inverter, it adapts to the backup power supply, outputting three-phase AC power with the same voltage and frequency as before, ensuring the safe operation of the ship.

[0019] The two sets of frequency converters in this invention are connected in parallel to form a redundant structure. When one of the frequency converters fails, the remaining frequency converters can continue to work, ensuring the continuity and reliability of power supply.

[0020] The high-voltage transformer in this invention can adjust the turns ratio by controlling the opening and closing of multiple switches. Thus, when switching the main power supply, it can change the turns ratio and still output a three-phase AC power supply with the same voltage as before, even if the input power supply changes. This reduces voltage fluctuations caused by power supply switching and protects the safe operation of the ship's equipment.

[0021] The shore power supply system for ship terminals in this invention can replace traditional diesel generators, significantly reducing fuel consumption, lowering operating costs, and reducing noise, air pollutant, and greenhouse gas emissions. It aligns with the global trend of green shipping and helps improve the environmental quality around ports. Attached Figure Description

[0022] Figure 1 This is a circuit diagram of the shore power supply system for ship docks described in Example 1.

[0023] Figure 2 This is a circuit diagram of the shore power supply system for ship docks described in Example 2. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0025] Example 1 The shore power supply system for ship docks used to achieve single-point large-capacity power supply described in this embodiment includes a high-voltage electrical box, a high-voltage switchgear, a high-voltage transformer TR1, a distribution box, frequency converter I, frequency converter II, a controller, isolation transformers TR2 and TR3, and a voltage stabilization and protection board. Figure 1This is a circuit diagram of the shore power supply system for ship docks described in this embodiment.

[0026] The high-voltage electrical box is used to provide three-phase AC power, and its output terminal is connected to the input terminal of the high-voltage switchgear. The high-voltage electrical box provides three-phase AC power of 9.5~11.5KV and 50~60Hz.

[0027] The input terminal of the high-voltage transformer TR1 is connected to the output terminal of the high-voltage switchgear, and the output terminal of the high-voltage transformer TR1 is connected to the input terminal of the distribution box. The high-voltage transformer TR1 outputs one 400V three-phase AC power supply and one 480V three-phase AC power supply. The high-voltage transformer TR1 is equipped with several tap changers for altering the turns ratio between the high-voltage and low-voltage windings. By controlling the opening and closing of these tap changers, it can still output one 400V three-phase AC power supply and one 480V three-phase AC power supply even when the voltage of the three-phase AC power supply changes. The high-voltage switchgear is equipped with a high-voltage outdoor emergency stop button SBG1 and a low-voltage indoor emergency stop button SBG2 for cutting off the high-voltage power supply. The high-voltage switchgear and distribution box are powered by a UPS. The high-voltage transformer is equipped with a cooling system, which includes multiple fans, temperature sensors, and a temperature controller. The temperature sensors are used to detect the temperature of the high-voltage transformer in real time and send the data to the temperature controller. The temperature controller is located on the connection circuit between the fans and the distribution box and is used to control the operation of the fans based on the temperature of the high-voltage transformer. The circuit connecting the thermostat and the distribution box is also equipped with a fuse FU20.

[0028] The inverter I includes a main inverter I, a slave inverter I, and a filter circuit I. The three-phase power input terminals of the main inverter I, its detection board, and the three-phase power input terminals of the slave inverter I are connected in parallel and connected to a 480V three-phase AC power supply in the distribution box. The fiber optic communication board of the slave inverter I is connected to the fiber optic communication board of the main inverter I via optical fiber. The first filter circuit includes a three-phase inductor L1 connected to the three-phase power output terminal of the main inverter I, a three-phase filter capacitor C1 connected to the output terminal of the three-phase inductor L1, a three-phase inductor L2 connected to the three-phase power output terminal of the slave inverter I, and a three-phase filter capacitor C2 connected to the output terminal of the three-phase inductor L2. The output terminals of the three-phase filter capacitors C1 and C2 are respectively connected to the three-phase power input terminals of the isolation transformer TR2, for outputting 430V three-phase AC power to the isolation transformer TR2.

[0029] The inverter II includes a main inverter II, a slave inverter II, and a filter circuit II. The three-phase power input terminals of the main inverter II, its detection board, and the three-phase power input terminals of the slave inverter II are connected in parallel and connected to a 480V three-phase AC power supply in the distribution box. The fiber optic communication boards of the main inverter II and slave inverter II are connected to the fiber optic communication board of the main inverter I via optical fibers. The positive terminals of the main inverter I, slave inverter I, main inverter II, and slave inverter II are connected together, and their negative terminals are connected together. In this embodiment, inverters I and II have built-in rectifiers. During operation, they first rectify the input 480V three-phase AC power supply into DC power, and then convert it into 430V, 50Hz three-phase AC power through the inverters. The filter circuit II includes a three-phase inductor L3 connected to the three-phase power output terminal of the main inverter II, a three-phase filter capacitor C3 connected to the output terminal of the three-phase inductor L3, a three-phase inductor L4 connected to the three-phase power output terminal of the slave inverter II, and a three-phase filter capacitor C4 connected to the output terminal of the three-phase inductor L4. The output terminals of the three-phase filter capacitor C3 and the three-phase filter capacitor C4 are respectively connected to the three-phase power input terminal of the isolation transformer TR3, and are used to output 430V three-phase AC power to the isolation transformer TR3.

[0030] A fuse QF1 is installed at the three-phase power input terminal of the main inverter I, on the detection board of the main inverter I, on the connection point of the three-phase power input terminal of the slave inverter I, and on the connection line to the 480V three-phase AC power supply. A fuse QF2 is installed on the output circuit of the isolation transformer TR2. A fuse QF3 is installed at the three-phase power input terminal of the main inverter II, on the detection board of the main inverter II, on the connection point of the three-phase power input terminal of the slave inverter II, and on the connection line to the 480V three-phase AC power supply. A fuse QF4 is installed on the output circuit of the isolation transformer TR3. Furthermore, the three-phase power output terminal and neutral point of the isolation transformer TR3 are connected to the three-phase power output terminal and neutral point of the isolation transformer TR2, respectively. The two sets of connection points are located between the three-phase power output terminal of the isolation transformer TR2 and fuse QF2, and between the three-phase power output terminal of the isolation transformer TR3 and fuse QF3, respectively. By connecting the output terminals of the isolation transformers TR2 and TR3, phase synchronization can be further achieved.

[0031] The controller is connected to the controller communication boards of main inverter I and main inverter II via optical fiber. The controller is powered by 24V DC voltage and is connected to a touch screen. The controller is used to control the corresponding output voltage and frequency by synchronously controlling the conduction angle and trigger frequency of main inverter I, main inverter II, slave inverter I, and slave inverter II.

[0032] The rated input voltage of isolation transformer TR2 is adapted to the output voltage of main inverter I and slave inverter I, and the rated input voltage of isolation transformer TR3 is adapted to the output voltage of main inverter II and slave inverter II. Isolation transformers TR2 and TR3 each output a set of 400~720V three-phase AC power with the same frequency and voltage. In this embodiment, the rated input voltage of isolation transformers TR2 and TR3 is 430V, and the rated output voltage has two levels: 450V and 700V. The rated output voltage is selected according to actual needs.

[0033] The voltage stabilization and protection board is used to sample the voltage output of isolation transformer TR2 / isolation transformer TR3, and adjust the conduction angle of the main inverter, slave inverter I, slave inverter II, and slave inverter III through the controller to adjust the voltage output of isolation transformer TR2 / isolation transformer TR3 to the target voltage value.

[0034] Example 2 The difference between this embodiment and Embodiment 1 is that it also includes a power supply transformer TR4, while the rest of the structure is the same as in Embodiment 1. Figure 2 This is a circuit diagram of the shore power supply system for ship docks described in this embodiment. The three-phase power input terminal of the power supply transformer TR4 is connected to the 400V three-phase AC power supply in the distribution box. The power supply transformer TR4 outputs a set of 440V three-phase AC power to supply power to electrical appliances with a rated voltage of 440V.

[0035] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A shore power supply system for ship docks to achieve single-point high-capacity power supply, characterized in that, This includes a high-voltage electrical box, a high-voltage switchgear, a high-voltage transformer TR1, a distribution box, a frequency converter I, a frequency converter II, a controller, an isolation transformer TR2, and an isolation transformer TR3; The high-voltage electrical box is used to provide a three-phase AC power supply of 9.5~11.5KV and 50~60Hz. Its output terminal is connected to the high-voltage transformer TR1 through a high-voltage switch cabinet. The power output from the high-voltage transformer TR1 is distributed through the distribution box to output a set of 400V three-phase AC power and a set of 480V three-phase AC power. The 400V three-phase AC power and the 480V three-phase AC power are rectified and frequency-regulated by frequency converter I and frequency converter II respectively. The frequency converter I includes a main inverter I, a slave inverter I, and a filter circuit I; The three-phase power input terminal of the main inverter I, the detection board of the main inverter I, and the three-phase power input terminal of the slave inverter I are connected in parallel and connected to the 480V three-phase AC power supply in the distribution box; the fiber optic communication board of the slave inverter I is connected to the fiber optic communication board of the main inverter I through fiber optic cable; the filter circuit I includes a three-phase inductor L1 connected to the three-phase power output terminal of the main inverter I, a three-phase filter capacitor C1 connected to the output terminal of the three-phase inductor L1, a three-phase inductor L2 connected to the three-phase power output terminal of the slave inverter I, and a three-phase filter capacitor C2 connected to the output terminal of the three-phase inductor L2; the output terminals of the three-phase filter capacitor C1 and the three-phase filter capacitor C2 are respectively connected to the three-phase power input terminal of the isolation transformer TR2. The inverter II includes a main inverter II, a slave inverter II, and a filter circuit II; the three-phase power input terminal of the main inverter II, the detection board of the main inverter II, and the three-phase power input terminal of the slave inverter II are connected in parallel and connected to the 480V three-phase AC power supply in the distribution box; the fiber optic communication boards of the main inverter II and the slave inverter II are respectively connected to the fiber optic communication board of the main inverter I through optical fibers. The positive terminals of the main inverter I, slave inverter I, main inverter II, and slave inverter II are connected together, and the negative terminals of the main inverter I, slave inverter I, main inverter II, and slave inverter II are connected together. The filter circuit II includes a three-phase inductor L3 connected to the three-phase power output terminal of the main inverter II, a three-phase filter capacitor C3 connected to the output terminal of the three-phase inductor L3, a three-phase inductor L4 connected to the three-phase power output terminal of the slave inverter II, and a three-phase filter capacitor C4 connected to the output terminal of the three-phase inductor L4. The output terminals of the three-phase filter capacitor C3 and the three-phase filter capacitor C4 are respectively connected to the three-phase power input terminal of the isolation transformer TR3. The controller is connected to the controller communication boards of main inverter I and main inverter II via optical fiber, and is used to control the corresponding output voltage and frequency by synchronously controlling the conduction angle and trigger frequency of main inverter I, main inverter II, slave inverter I, and slave inverter II respectively. The rated input voltage of the isolation transformer TR2 is adapted to the output voltage of the main inverter I and the slave inverter I. The rated input voltage of the isolation transformer TR3 is adapted to the output voltage of the main inverter II and the slave inverter II. The isolation transformers TR2 and TR3 respectively output a set of 400~720V three-phase AC power supply with the same frequency and voltage.

2. The shore power supply system for ship docks according to claim 1, characterized in that, The high-voltage transformer TR1 is equipped with several tap switches for changing the turns ratio between the high-voltage winding and the low-voltage winding.

3. The shore power supply system for ship docks according to claim 1, characterized in that, It also includes UPS power supplies, which provide power to the high-voltage switchgear and the distribution box respectively.

4. The shore power supply system for ship docks according to claim 1, characterized in that, The high-voltage switchgear is also equipped with a high-voltage outdoor emergency stop button SBG1 and a low-voltage indoor emergency stop button SBG2 for cutting off the high-voltage power supply.

5. The shore power supply system for ship docks according to claim 1, characterized in that, It also includes multiple fans, temperature sensors, and a temperature controller; the temperature sensors are used to detect the temperature of the high-voltage transformer in real time and send it to the temperature controller; the temperature controller is installed on the connection circuit between the fans and the distribution box, and is used to control the start and stop of the fans according to the temperature of the high-voltage transformer; the connection circuit between the temperature controller and the distribution box is also equipped with a fuse FU20.

6. The shore power supply system for ship docks according to claim 1, characterized in that, The controller is powered by 24V DC voltage and is connected to a touch screen.

7. The shore power supply system for ship docks according to claim 1, characterized in that, It also includes a power supply transformer TR4, whose three-phase power input terminal is connected to a 400V three-phase AC power supply in the distribution box, and the power supply transformer TR4 outputs a set of 440V three-phase AC power.

8. The shore power supply system for ship docks according to claim 1, characterized in that, A fuse QF1 is installed at the three-phase power input terminal of the main inverter I, on the detection board of the main inverter I, on the connection point of the three-phase power input terminal of the slave inverter I, and on the connection line to the 480V three-phase AC power supply; a fuse QF2 is installed on the output circuit of the isolation transformer TR2; a fuse QF3 is installed at the three-phase power input terminal of the main inverter II, on the detection board of the main inverter II, on the connection point of the three-phase power input terminal of the slave inverter II, and on the connection line to the 480V three-phase AC power supply; and a fuse QF4 is installed on the output circuit of the isolation transformer TR3.

9. The shore power supply system for ship docks according to claim 8, characterized in that, The three-phase power output terminal and zero point of the isolation transformer TR3 are respectively connected to the three-phase power output terminal and zero point of the isolation transformer TR2, and the two sets of connection points are respectively located between the three-phase power output terminal of the isolation transformer TR2 and the fuse QF2, and between the three-phase power output terminal of the isolation transformer TR3 and the fuse QF3.

10. The shore power supply system for ship docks according to claim 1, characterized in that, It also includes a voltage regulator protection board connected to the controller signal. The voltage regulator protection board is used to sample the voltage output of isolation transformer TR2 / isolation transformer TR3 and adjust the conduction angle of main inverter I, slave inverter I, main inverter II, and slave inverter II through the controller to adjust the voltage output of isolation transformer TR2 / isolation transformer TR3 to the target voltage value.

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