FIELD OF THE INVENTION
The present invention relates to the Control System for DC Converter used in wind turbine electronic for an isolated renewable energy system, this system help energy produced by a small wind turbine is used to extract hydrogen from water. The components, their power losses, and their measured behavior were covered. Losses in energy reduced which help to improve the low lifetime of some converter components.
BACKGROUND ART
US8311679 teaches about an efficient matrix converter for wind energy conversion systems (WECS) using permanent magnet DC generators, incorporating control algorithms integrated with rotor aerodynamics, generator dynamics and the wind environment. Using a complete model of the system enables the design of an integrated control scheme for the WECS that improves the overall system efficiency. Estimates of wind velocity and rotor speed measurements are fed forward to the matrix converter subsystem for efficient switching. US5594636 explains An AC-to-AC converter for connection between an input power source and an output load, said converter comprising a plurality of switch groups; each of said plurality of switch groups having a plurality of switch means for selective unidirectional control of current flow in either of two directions; each of said plurality of switch groups being associated with a corresponding common output phase line; each of said plurality of switch means being associated with a respective input line phase; each of said plurality of switch groups having a gating control means for delaying the turn-OFF of each of said plurality of switch means within respective ones of said plurality of switch groups by an overlap period without delaying the turn-ON of each of said plurality of switch means within respective ones of said plurality of switch groups so that two of said plurality of switch means within said switch group selected for conduction in sequence are simultaneously enabled for conduction during at least a portion of said overlap time period; and said gating control means being connectable with respective ones of said plurality of switch means within one switching group and interposed between said respective ones of said plurality of switch means and a matrix converter controller. CN108318707 discloses a wind resource monitoring device. The device comprises a box body which is taken as equipment main body. The right end surface of the box body is fixedly provided with a vertical rod which is extended downwardly. The right end surface of the vertical rod is fixedly provided with a display screen. The lower end surface of the vertical rod is fixedly provided with a handle.A transmission chamber A is arranged in the box body. A transmission

chamber D which is located below the transmission chamber A is arranged in the box body. The right portion of the transmission chamber D is provided with a transmission chamber E located in the box body. The right portion of the transmission chamber E is provided with a transmission chamber B which is located in the box body andis located below the transmission chamber A. A transmission chamber C located in the box body is arranged below the transmission chamber D and the transmission chamber E. In the invention, the structure of the device is simple, usage is convenient, a sensor is adopted to detect wind energy intensity in the device, and the device has a self power generation function and power can be provided for anelectric appliance component so that detection efficiency is effectively increased. US9425726 discloses rotor-side converter having A system, comprising a doubly fed induction generator (DFIG) comprising a rotor and a stator coupled to an electrical grid, the DFIG configured to generate power for the electrical grid; rotor-side converter (RSC) circuitry coupled to at least the rotor, the RSC circuitry to control the power generation on the rotor side of the DFIG; and nine-switch converter circuitry coupled to at least the stator and the electrical grid, the nine-switch converter circuitry to at least maintain a pre-fault voltage across windings in the stator during a grid fault; wherein the nine-switch converter circuitry provides a first independent three-phase output and a second independent three-phase output, the first independent three-phase output comprising six of the nine switches in the nine-switch converter circuitry, the six switches corresponding to grid-side converter (GSC) circuitry in the DFIG, and the second independent three-phase output comprising six of the nine switches in the nine-switch converter circuitry, the six switches corresponding to neutral-side control (NSC) circuitry coupled to a neutral side of windings in the stator to provide series voltage compensation to the DFIG when a fault occurs in the grid.
US8457800 discloses system for encouraging the use of renewable energy sources and suitable for the conservation of energy resources through the efficient management of energy storage and delivery includes connections to a power source, an energy storage subsystem, and a power grid. The system includes a power routing subsystem coupled to the source and grid, and adapted to operate in a bypass mode, in which energy is transferred from the source to the grid. The system includes a conversion subsystem coupled to the routing and storage subsystems, and switchable in substantially real-time between a storage mode, in which energy is transferred from the routing to the storage subsystem, and a generation mode, in which energy is transferred from the storage to the routing subsystem for delivery to the grid. The system also includes a controller for directing the modes based at least in part on a market factor.

Summary
Control System for DC Convertor used in wind turbine control system in order to power electrolyzers located at the load centers for producing hydrogen at the generation site and installing a hydrogen pipeline having wind power attached with rotor and stator which generate the voltage show in the control circuit having voltage lookup table connected with voltage signal controller attached with Generator attached with batteries in parallel or in series which store the DC current in batteries after conversion from DC converters; MOSFETS switch; input capacitor comprised of multiple capacitors to create a capacitor bank.; output capacitor; Inductor; diode to provide a return current path for the inductor current; MOSFET controls the output voltage and power flow; ultra capacitor provides extra current with high frequency component; characterized in that Electrolyzer controlled by control system supported by batteries and DC convertor; current loopup table for showing the current voltage flow in loop.
Brief Description of the Drawings
FIG. 1 is a simplified block diagram of a control system.
FIG. 2 is a simplified system electrical diagram.
FIG. 3 shows a line diagram of Control System for DC Convertor used in wind turbine.
FIG. 4 shows operational diagram of control system of wind turbine.
Detailed Description
Hydrogen fuel stations are critical to the deployment of a fuel cell car and, as it stands now, stations accessible to the public are still quite limited". A hurdle to the nation-wide future automotive fuel cell market is the source and distribution of hydrogen. Current hydrogen production is mostly from reformed natural gas. This process is cheap, but also emits pollutants into the environment. The environmental benefit of fuel cells is lost using hydrogen produced from this process. If the demand of hydrogen increases due to a future fuel cell market, natural gas supplies may become depleted. This could cause the price of hydrogen to become unstable, much like current gasoline prices. A simple way to produce hydrogen is by the electrolysis of water. When a DC current flows through pure water, the water molecules are broken down into hydrogen and oxygen. These gases boil off and can be collected. There is much interest and research being conducted into these electrolyzer cells. The Proton Exchange Membrane (PEM) electrolyzers use a thin polymer as the electrolyte. One downside of this technology is that no models are mass produced. Capacity selection and economies of scale factors are limited. Given

this current state of the electrolyzer industry, the feedstock electricity needs to be at the lowest cost possible in order for this method to be economical.
There are few power sources that are both environmentally friendly and cheap. Coal, natural gas, and nuclear power plants all are cheap on large scales, but also produce harmful by-products. Solar and hydro power plants don't produce byproducts, but they are expensive and geographically limited. However, wind power plants don't have any harmful emissions and can be cost-competitive with fossil-fuel power plants. Wind energy is most available in rural areas of the country. The major load centers are located in the highly-populated urban areas of the country. There arises a dilemma: how does one transport wind energy in rural areas to hydrogen in urban areas.
The transmission systems included an electrical nature by upgrading grid infrastructure in order to power electrolyzers located at the load centers or by producing hydrogen at the generation site and installing a hydrogen pipeline.
Fig 1 shows the layout of control system having wind power attached with rotor and stator which generate the voltage show in the voltage lookup table connected with voltage signal controller attached with Generator which store the DC current in batteries after conversion from DC converters; ultra capacitor provides extra current with high frequency component, ultracapacitor energy is low and needs recharging from battery, the battery is designed to provide a minimum power for a request power and any remaining required power is supplied by ultracapacitor. Electrolyzer is controlled by control system supported by batteries and DC converter.
Fig. 2 shows simplified system electrical diagram consisting of rectifier; capacitor; MOSFET; diodode and analogue converters.
Fig 3 shows the invention is on the control system DC/DC converter for the wind turbine and the electrolyzer. The converter will also be responsible for controlling the power extracted from the wind turbine; too much power will cause the turbine to stall, too little power will cause higher cost in hydrogen. The converter will have to handle an input voltage of up to 280 VDC and step it down to about 20 VDC. In doing so, the input current of 10 ADC will step up to 140 ADC. A low cost is desired in order to keep the cost of hydrogen low. The topology of the converter is shown in figure 10 and is called a buck converter. This topology contains a single inductor. Other converter topologies, called inter-leaving designs, contain multiple inductors. While this reduces losses, it complicates the control system and adds cost. The circuit operates by switching the incoming power on and off, then filtering the output. Ideally, the output voltage is related to the input voltage by

Vol. out = D Vol.in D = t on It period
D is the duty cycle of the MOSFET switch. The frequency of this switching is an important
design parameter. Higher frequencies reduce filter sizes and filter losses, but increases switching
losses. Based upon preliminary test data shown in figure 11, a frequency of 100 kHz is chosen.
The tests were conducted with 20VDC input, 14% duty cycle, and a load resistor of 125 mS.
The maximum power flow point for the converter is at 2.8kW. At this point, the input voltage is
at maximum at 286.0 VDC and the output voltage is at maximum at 20.0VDC, requiring a duty
cycle D of 7.00%. The input current at this operating point is 9.8 A, and the output current is
140 A.
FIG. 4 shows operational diagram of control system of wind turbine and electolyzer with the
help of control system.
System for operation of elctrolyzer consisting of components
Input Capacitor
The input capacitor is an important component in the converter. It must ensure that the switching of the converter does not affect the performance of the source, i.e. the source provides the same power when the switch is on as when it is off. It also must provide the pulse current must also able to move charge in and out fast enough, according to the frequency. Finally, it must have low Equivalent Series Resistance (ESR) in order to ensure low power loss. Due to these demands, the input capacitor is comprised of multiple capacitors to create a capacitor bank. The capacitor shown in graphs shown in figure 13. The expression for the charging current can be reduced to
Icharge = C AV^
To keep the turbine unaffected by the switching, the charging current is set to the input current level. The pulse current is the converter output current minus the input current. Therefore, there is a constant current from the source. Plugging in num equation for Icharge, C=i/i0972 needed. Therefore, for a voltage ripple of 1% the maximum input, the capacitor needed is 31.87TF. To keep the turbine unaffected by the switching, the charging current is set to the input current level. The pulse current is the converter output current minus the input current. Therefore, there is a constant current from the source.

Output Capacitor
The output capacitor is not as significant as the input capacitor. It is only used as a filter to level the voltage to the load. One electrolytic capacitors rated at 4.7mF is used. Inductor
The inductor is an important component of the converter. The inductor stores energy during the 'on' time and delivers energy to the load during the 'off time. The energy is stored by creating a magnetic field. However, care needs to be taken to ensure that while the inductor is absorbing energy, it does not saturate. Saturation is when the inductor can longer increase the magnetic field energy. Proper design considerations are required to ensure that saturation does not occur. Unlike capacitors, which have a nominal capacitance value, inductors are handmade. They are made by winding coil around a magnetic core. The type of coil and core and number of turns of the coil determine the inductance. The expression for the inductance is
L = uN2A/l
where N is the number of turns of the coil A and 1 are the core area and length, respectively, and u is the permeability of the material.
To negate skin effect, stranded wire can be used. Stranded wire is made of many smaller wires stranded together. With more surface area available, the resistance stays low. However, the overall diameter of the stranded cable becomes larger, meaning less room in the core for multiple turns.
Diodes
The diode is a passive switch in the circuit. It turns on and off without a control signal. When
the MOSFET is on and the inductor is charging, the diode is off. However, when the MOSFET is off, the diode turns on in order to provide a return current path for the inductor current. When the converter is operating at maximum power flow, the low duty cycle causes the diodes to be on for most of the time. The high output current rating and the operation frequency limit the selection of diodes. Schottky diodes are a diode technology best suited for this application. These diodes recover quickly; however, they have a lower blocking voltage rating and require hybrid designs for higher voltage ratings. The power losses can be quantified into switching losses, conducting losses, and blocking losses. However, these losses are highly dependent on temperature and are difficult to calculate exact losses. The diode selected is model number MBR40250T. This diode is rated for 250V and 40A. To obtain the desired current rating of 140A, 4 diodes are placed in parallel. Schottky diodes tend to be difficult to place in parallel. In these diodes, as the device heats up, the voltage across it lowers. With the lower voltage, more current wants to flow in the hot diode compared to the others. The higher current causes more

heat. This cycle continues until the diode gets hot enough to break. In order to prevent this and keep the diodes cool, they are attached to a large heat sink. A fan positioned to blow on the MOSFETs also slightly blows across the diode heat sink. The heat sink used is a modified sink. The original heat sink has a thermal resistance of 0.6°C/W. The modified heat sink has half the fins cut off, so the new thermal resistance is close to 1.2 °C/W. Each diode has a thermal resistance of 2.0 °C/W between the diode and the case, so the total diode to atmosphere thermal resistance is about 3.2°C/W. However, the true thermal resistance is slightly different because the 4 diodes are on the same heat sink, but that the fan forces airflow slightly over the fins. According to the data in Appendix D, for an average current of 3 5 A, each diode will have a loss of about 35 W. With the above thermal resistance, the diodes should have a temperature around 112°C above ambient. Using an ambient temperature of 20°C, the temperature at the diode junction will be around 132°C. This is close, but not at, the maximum operating temperature of 150°C.
MOSFET Driver
The MOSFET in a buck converter is not connected to the local ground point. In order to switch the MOSFET, a voltage higher than the negative terminal of the MOSFET has to be applied to the gate terminal. A driver circuit is required to make sure the gate voltage is high enough to switch the device. This driver circuit receives the logic signal from the control system and amplifies it to the appropriate level for the MOSFET. The driver circuit selected is from International Rectifier and the model is IRS2186. This chip has a maximum switch current rating of ±4A, and can supply a maximum turn-on voltage of 15 V.
MOSFET
The MOSFET is the device that controls the system. By controlling the time it is on and off, the
MOSFET controls the output voltage and power flow. The MOSFET receives the switching signal from the driver chip. At the maximum power flow, the low duty cycle means the MOSFETS are not on most of the time. MOSFETS are fast switches and are the only switch technology available to achieve the 100kHz switching frequency. However, they generally cannot handle as much power flow as other switch technologies.
MOSFETS also have a built-in diode, called a Body diode, that would allow current to flow even when off. The direction of this current flow through this diode is from the inductor to the source. The occurrence of this condition is rare, and if it occurs, it would only be when the electrolyzer has lingering charge in it and the turbine source is low. At this condition, the lingering charge is small and won't cause component damage or safety concerns. Unlike the Schottky diodes, MOSFETS are easy to place in parallel. As a MOSFET heats up, carrier mobility decreases. The on-resistance increases due to the decreased carrier mobility. So, if one

out of the four MOSFETS begins to heat more than the others, the current start to divert to the other MOSFETS, which allows the heated MOSFET to cool. Therefore, smaller heat sinks can be used since there isn't the threat of a run-away condition. The fan used on the diode heat sink is positioned to also blow on the MOSFET heat sinks.
Control System
A simple control system is designed to control the circuit. Both the wind turbine and the
electrolyzer have nonlinear behavior. To deal with this in the control circuit, two look-up tables composed of RAM chips are used. The available power from the wind turbine can be characterized by the input voltage to the converter. The power consumed by the electrolyzer can be characterized by the current through it. The control diagram is shown in figure 17. The input voltage is the input signal to the system. This signal is fed into two look-up tables: one to calculate the expected load current and the other to calculate the duty cycle. The expected load current is compared with the actual load current to generate a current error signal. The current error signal is used to minimally adjust the duty cycle signal. The duty cycle signal is then fed into the pulse width modulator generator chip to generate the actual duty cycle waveform. This waveform is fed into the MOSFET in the DC/DC controller. The controller allows the appropriate power to flow into the electrolyzer. The electrolyzer sets the load current based upon the power flowing into it. The load current is the feedback element to finalize the closed circuit signal path. The load current signal is also used to prevent power overflow. The current level is fed into the PWM Generator circuit through a resistor divider. If the current level is too high, the PWM Generator will not generate a pulse. This will cause the MOSFET in the DC/DC converter to stay off. The load current will decrease until the point where it is safe to resume operation. The circuit diagram for the entire system is shown in figure 18. Note that the area outlined in green is part of the MOSFET switching circuit. Each component is duplicated four times and in parallel. Not shown is the circuitry to extract power for the control system components. Components costs are listed in Appendix F.

I Claim:
1. Control System for DC Converter used in wind turbine control system in order to power electrolyzers located at the load centers for producing hydrogen at the generation site and installing a hydrogen pipeline having wind power attached with rotor and stator which generate the voltage show in the control circuit having voltage lookup table connected with voltage signal controller attached with Generator attached with batteries in parallel or in series which store the DC current in batteries after conversion from DC converters; MOSFETS switch; input capacitor comprised of multiple capacitors to create a capacitor bank.; output capacitor; Inductor; diode to provide a return current path for the inductor current; MOSFET controls the output voltage and power flow; ultra capacitor provides extra current with high frequency component; characterized in that Electrolyzer controlled by control system supported by batteries and DC converter; current loopup table for showing the current voltage flow in loop.
2. Control System as claim in claim 1 wherein control circuit, two look-up tables composed of RAM chips.
3. Control System as claim in claim 1 wherein signal is fed into two look-up tables: one to calculate the expected load current and the other to calculate the duty cycle.
4. Control System as claim in claim 1 wherein MOSFETS are fast switches and available to achieve the 100kHz switching frequency.
5. Control System as claim in claim 1 wherein diode is rated for 250V and 40A and placed 4 diodes are placed in parallel.
6. Control System as claim in claim 1 wherein electrolytic capacitors rated is at 4.7mF
7. Control System as claim in claim 1 wherein electrolyzers use a thin polymer as the electrolyte
8. Control System as claim in claim 1 wherein electrolyzers located at the load centers or by producing hydrogen at the generation site and installing a hydrogen pipeline