RU2721013C2 - Preliminary charging of capacitor bank - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: disclosed are systems and methods for preliminary charging of capacitor bank. Power switch and the current limiting device are connected in series between the power supply and the capacitor bank. Force key is controlled to limit peak charging current applied to capacitor bank during pre-charging process. Disturbance of the pulse signal can be modified based on the measured current flowing into the current-limiting device. At that, control over voltage on capacitor bank may also be performed, and the preliminary charging procedure can be terminated when the controlled voltage reaches a threshold value.

EFFECT: preliminary charging of capacitor bank is proposed.

20 cl, 7 dwg

Description

Technical field

[0001] The present invention relates generally to wind turbines, in particular to systems and methods for precharging a capacitor bank in a wind turbine.

BACKGROUND OF THE INVENTION

[0002] Wind energy is considered one of the cleanest and most environmentally friendly energy sources available today, and accordingly, for this reason, wind turbines are attracting more and more attention.

A modern wind turbine typically comprises a tower, a generator, a transmission, a nacelle and one or more rotor blades. The rotor blades intercept the kinetic energy of the wind using the well-known principle of the wing and transfer this kinetic energy through rotational energy, which rotates the shaft connected to the rotor blades, to the transmission, or, if the transmission is not used, directly to the generator. Then the generator converts mechanical energy into electrical energy, which can be supplied to the mains.

[0003] During the operation of a wind turbine, its various components are subjected to variable loads resulting from aerodynamic loads on the blades under the influence of wind. The load on the blades depends on the wind speed, the peripheral speed of the blades and / or the angle of inclination of the blades. The peripheral speed is equal to the ratio of the speed of rotation of the blade to the speed of the wind. It may be necessary to control the wind turbine based on signals reflecting peripheral speed (for example, different speed readings), in order to adjust the load on the rotor blades of the wind turbine and / or to increase the power generation of the wind turbine.

[0004] To reduce the load on the rotor blades, various methods and devices have been developed that allow using them to remove part of the load from the rotor blades. Such methods and devices include, for example, changing the angle of inclination of the rotor blades and / or reducing the torque of the generator during its operation. Accordingly, many wind turbines include a turbine controller that allows you to control the wind turbine in various ways depending on the relative speed of the end of the blade and the wind load on the turbine. For example, under variable operating conditions, the wind turbine can adjust the generator torque and / or the angle of inclination of the rotor blades in order to adjust the relative speed of the end of the blade so that it coincides with the relative speed of the end of the blade in order to increase the amount of energy captured wind turbine.

[0005] The control of the angle of inclination of the rotor blades can be performed, for example, using an engine to adjust the angle of inclination of the blades relative to the wind. The motor for adjusting the angle of inclination of the blades relative to the wind can be a direct current (DC) motor powered from a direct current to direct current converter. As a rule, the engine for adjusting the angle of inclination of the blades relative to the wind includes a direct current source, a control circuit, an inverter bridge and / or a capacitor bank containing one or more capacitor devices. Due to the high capacity of the capacitor bank, a pre-charge circuit in combination with a shunt contactor can be used to limit the amplitude of the inrush currents when switched on.

[0006] Conventional pre-charging circuits may include high-power resistors, positive temperature coefficient thermistors (PTCs), transformers, switching current sources, line current sources, or other circuit configurations to limit the current supplied to the capacitor bank. However, such precharge methods may be inefficient, time consuming and / or difficult to implement.

[0007] Accordingly, systems and methods for precharging a capacitor bank are needed in a simple, efficient, and adjustable manner.

SUMMARY OF THE INVENTION

[0008] Some of the aspects and advantages of embodiments of the present invention will be discussed in the description below, may be found based on this description, or may be found in the practical application of embodiments of the present invention.

[0009] One aspect of the present invention relates to a precharge system for a capacitor bank. The system comprises a power switch connected in series to an input DC source and a current limiting device connected in series between the power switch and a capacitor bank containing one or more capacitor devices. The system also includes a first control device configured to control the operation of the power switch by receiving one or more signals indicative of the charging current associated with the capacitor bank, and to control the operation of the power switch at least partially based on the charging current. The system also includes a second control device configured to measure the voltage on the capacitor bank, and also to control the operation of the first control device at least partially based on the measured voltage on the capacitor bank.

[0010] Another aspect of the present invention relates to a method for controlling the pre-charging of a capacitor bank comprising one or more capacitor devices. The capacitor bank is connected in series with the power switch and the current limiting device between the power source and the capacitor bank. The method includes supplying, by a power source, a DC input for use when charging a capacitor bank. The method also includes monitoring the magnitude of the direct current flowing into the current limiting device. The method also includes controlling, with a choice, the operation of the power switch so that when the DC current reaches the threshold current value, the power switch is opened. The method also includes monitoring the voltage on the capacitor bank. The method also includes, when the voltage across the capacitor bank reaches a voltage threshold value, stopping pre-charging the capacitor bank so that a current limiting device is bypassed.

[0011] Another example of aspects of the present invention relates to a wind turbine system. The wind turbine system comprises a rotor, a stator, and a tilt motor of one or more rotor blades associated with this system. The wind turbine system also includes one or more control devices configured to precharge the capacitor bank associated with the tilt adjustment motor by starting the precharging process of the capacitor bank to control the direct current flowing into the current limiting device that is connected in series between the capacitor bank and the power supply, for selectively controlling the operation of the power switch so that when the DC current reaches the threshold current value, the power switch is opened, which reduces the amount of current supplied to the current-limiting device, monitoring the voltage on the capacitor bank, and when the voltage on the capacitor bank reaches the threshold voltage values, termination of the pre-charge process.

[0012] In the considered embodiments of the present invention, various changes and modifications may be made.

[0013] For a more detailed understanding of these and other distinguishing features, aspects and advantages of various embodiments of the present invention, reference should be made to the description below and the attached claims. The accompanying drawings, which are part of the present description and are an integral part thereof, illustrate embodiments of the present invention. The accompanying drawings, together with a description, serve to clarify the intent of the present invention.

Brief Description of the Drawings

[0014] A detailed description of embodiments of the present invention, intended for specialists in this field of technology, is given below in the examples of the attached drawings, among which:

[0015] in FIG. 1 is a perspective view of an example of a wind turbine in accordance with embodiments of the present invention;

[0016] in FIG. 2 shows an internal view of a typical wind turbine nacelle in accordance with embodiments of the present invention;

[0017] in FIG. 3 is a perspective view illustrating an example of a tilt adjustment engine control system in accordance with embodiments of the present invention;

[0018] in FIG. 4 is a block diagram of a typical controller in accordance with embodiments of the present invention;

[0019] in FIG. 5 is a perspective view showing an example of a precharge control system for a capacitor bank in accordance with embodiments of the present invention;

[0020] in FIG. 6 shows an example of a graph of a charging current supplied to a capacitor bank in accordance with embodiments of the present invention; and

[0021] in FIG. 7 is a flow chart of a method for precharging a capacitor bank in accordance with embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention will now be described in more detail using specific embodiments thereof, one or more of which are illustrated in the accompanying drawings. Each example is provided for the purpose of explaining the present invention, and not limiting it. Indeed, it will be apparent to those skilled in the art that many different changes and modifications can be made within the spirit and scope of the present invention. For example, features illustrated or described as part of one embodiment of the present invention can be used in combination with another embodiment, whereby another embodiment of the present invention can be obtained. Thus, it is intended that the present invention covers all such modifications and changes that fall within the scope of the appended claims and their equivalents.

[0023] Examples of aspects of the present invention relate to systems and methods for precharging a capacitor bank. For example, a power switch and a current limiting device, such as an inductive device, may be included between a DC power source and a capacitor bank containing one or more capacitor devices. The operation of the power switch can be controlled to limit the peak value of the charging current flowing through the current limiting device to the capacitor bank. When the voltage on the capacitor bank reaches the threshold voltage value, the pre-charging procedure may be terminated. For this purpose, a bypass contactor can be installed so that when the bypass contactor is closed, current does not flow through the pre-charging circuit (for example, a power switch and a current limiting device).

[0024] In particular, the power switch may be a power switch controlled by pulse width modulation (PWM), for example, a metal-oxide-semiconductor field-effect transistor (MOSFET) field-effect transistor, bipolar an insulated gate transistor (IGBT), one or more contactors, a power relay, or another power switch. The current limiting device may be an inductive device (inductor). One or more control devices may control the gate of the MOSFET, which is a power switch, at least in part based on the amount of current supplied to the inductor. For example, in embodiments of the present invention in which the power switch is a MOSFET, the control devices can control the gate of the MOSFET at least in part based on the amount of current supplied to the inductor. A current sensor, for example, a resistor, a current transformer, a current converter, a Hall effect device or other current sensor, can be connected in series between a MOSFET transistor and an inductor. The current sensor may be configured to detect the current supplied to the inductor and to provide a signal indicative of the amount of current to the control device that controls the gate.

[0025] As noted above, a control device that controls the gate can be configured to control the gate of the MOSFET using a PWM modulation method. Thus, the control device that controls the gate can be configured to adjust the duty cycle of the signal supplied to the gate of the MOSFET, at least in part based on a signal reflecting the magnitude of the current. In this document, “duty cycle” is the ratio of the time when the signal pulse is in the active (for example, “high”) state to the full period of signal modulation. In particular, for each modulation period of the pulse signal, the control device that controls the gate can be configured to lower the signal pulse when the measured current reaches the current threshold, as a result of which the power switch opens. In embodiments of the present invention, the threshold current value may be between about 0.7 Amperes and about 1.5 Amperes. In this document, the term “about”, when used in connection with numerical values, should be interpreted as implying that it is within 30% of the indicated numerical value. When the power switch is open, no current flows through the current limiting device. In this case, at the beginning of the immediately following modulation period, the signal pulse can be brought to a high state, as a result of which the power switch will be closed. When the power switch is closed, the current flowing through the current-limiting device to the capacitor bank begins to increase. When the current reaches the threshold value of the current again, the signal pulse can be brought to a low state, as a result of which the power switch will be opened.

[0026] Throughout the pre-charging procedure, the voltage on the capacitor bank increases. The voltage monitoring on the capacitor bank may be performed. When the voltage on the capacitor bank reaches the threshold voltage value, the pre-charging procedure may be terminated. For example, the voltage threshold may be between about 60% and about 95% of the input DC voltage. Thus, when the measured value on the capacitor bank reaches a threshold voltage value, a bypass contactor can be closed so that no current flows through the current limiting device.

[0027] Next, with reference to the attached drawings, embodiments of the present invention will be described in more detail. For example, in FIG. 1 shows a perspective view of one embodiment of a wind turbine 10. In accordance with the illustration, the wind turbine 10 includes mainly a tower 12 standing on a supporting surface 14, a nacelle 16 mounted on a tower 12, and a rotor 18 connected to the nacelle 16. The rotor 18 includes a rotating hub 20 and at least one rotor blade 22 connected to the hub 20 and out of it. For example, in the illustrated embodiment of the present invention, the rotor 18 includes three rotor blades 22. However, in one alternative embodiment of the present invention, the rotor 18 may include more or less than three rotor blades 22. All rotor blades 22 can be distributed around a circle around the hub 20 and can contribute to the rotation of the rotor 18, providing the conversion of kinetic wind energy into useful mechanical energy and then into electric energy. For example, the hub 20 may have a rotational connection with an electric generator located inside the nacelle 16, and provide for the generation of electrical energy.

[0028] The wind turbine 10 may also comprise a turbine control system that includes a turbine controller 26 located in the nacelle 16 or elsewhere and connected to the wind turbine 10. In general, the turbine controller 26 may include one or more processor devices . So, in some of the embodiments of the present invention, the turbine controller 26 may include appropriate machine-readable instructions that, when executed by one or more processor devices, configure the controller 26 to perform various functions, such as receiving, transmitting and / or executing wind turbine control signals . In this case, the turbine controller 26 itself can be generally configured to control various operating modes (for example, start or stop sequences) and / or components of the wind turbine 10.

[0029] For example, the controller 26 may be configured to control the angle, or rotation angle, of each of the rotor blades 22 (for example, an angle that determines the spatial position of the rotor blades 22 relative to the wind direction 28) to control the load on the rotor blades 22 by adjusting the angular position of at least one of the rotor blades 22 with respect to the wind. For example, the turbine controller 26 can control the angle of inclination of the rotor blades 22 either individually or simultaneously, by transmitting the corresponding signals, or commands, to various angle drives or angle adjustment mechanisms, for example, the angle adjustment engine 32 (FIG. 2) a wind turbine 10. In particular, the rotor blades 22 can be pivotally mounted on the hub 20 using one or more tilt angle bearings (not shown in the drawing), while the tilt angle can be adjusted by rotating the blades 22 around the axis 34 of the blade using motors 32 adjust the angle of inclination.

[0030] In this case, when the wind direction 28 changes, the turbine controller 26 can be configured to control the direction of the nacelle 16 in the yaw angle by turning around the yaw axis 36 to arrange the rotor blades 22 in accordance with the wind direction 28, which allows controlling loads acting on the wind turbine 10. For example, the turbine controller 26 can be configured to transmit control signals or commands to the yaw control mechanism 38 (FIG. 2) of the wind turbine, whereby the nacelle 16 can rotate around the yaw axis 30.

[0031] Additionally, the turbine controller 26 may be configured to control the torque of the generator 24 (FIG. 2). For example, the turbine controller 26 can be configured to transmit signals or commands to the generator 24 in order to modulate the magnetic flux generated in the generator 24, which allows you to adjust the required torque in the generator 24. Such a temporary reduction in the power of the generator 24 can reduce the speed of rotation of the blades 22 rotor, and accordingly, to reduce the aerodynamic loads acting on them, as well as the reactive forces acting on various other components of the wind turbine 10.

[0032] FIG. 2 shows a simplified internal view of one embodiment of a nacelle 16 of a wind turbine 10. In accordance with the illustration, a generator 24 can be placed inside the nacelle 16. In general, the generator 24 can be connected to the rotor 18 of the wind turbine 10 in order to obtain electrical energy from rotational energy generated by the rotor 18. For example, the rotor 18 may include a rotor main shaft 40 connected to the hub 20 and rotating with it. The generator 24 may in this case be connected to the rotor shaft 40 so that the rotation of the rotor 40 drives the generator 24. For example, in the illustrated embodiment of the present invention, the generator comprises a generator shaft 42 rotationally coupled to the rotor shaft 40 by means of a transmission 44. However, it should be understood that in other embodiments of the present invention, the generator shaft 42 may be rotationally coupled directly to the rotor shaft 40. Alternatively, generator 24 may be directly rotationally coupled to rotor shaft 40 (often referred to as a “direct drive wind turbine”).

[0033] It should be understood that the rotor shaft 40 can generally be supported in the nacelle by a support frame or support plate 46 mounted on top of a wind turbine tower 12. For example, the shaft 40 may be supported by a support plate 46 by means of a pair of support bearings mounted on the support plate 46.

[0034] Also, as already noted herein, a turbine controller 26 may be placed inside the nacelle 16 of the wind turbine 10. For example, in accordance with the illustrated embodiment of the present invention, the turbine controller 26 may be located in a control stand 52 mounted in one of the parts of the nacelle 16. However, in other embodiments of the present invention, the turbine controller 26 may be located in any other suitable place on the wind turbine 10 and / or inside it, or at any appropriate location remote from the wind turbine 10. Moreover, in accordance with the previous description, the turbine controller 26 can be connected, with the possibility of communication, with various components of the wind turbine 10 and can general control of a wind turbine and / or its components. For example, the turbine controller 26 can be connected, with the possibility of communication, with the mechanism (or mechanisms) 38 of the yaw drive of the wind turbine 10 in order to control the direction of the yaw angle and / or change the direction of the nacelle 16 in the yaw angle relative to direction 28 (Fig. 1 ) wind. Similarly, the turbine controller 26 can also be connected, with the possibility of communication, with each of the wind turbine angle adjustment engines 32 (one of which is shown in the drawing) to control the angle or change the angle of the rotor blades 22 relative to the wind direction 28. For example, the turbine controller 26 may be configured to transmit a signal or control command to each of the tilt adjustment motors 32, as a result of which one or more actuators (not shown) of the tilt adjustment motor 32 can be used to rotate the blades 22 relative to hubs 20.

[0035] FIG. 3 is a perspective view illustrating an example of a control system 100 of the tilt adjustment engine 32 in accordance with embodiments of the present invention. In accordance with the illustration, the system 100 may include a Converter 101 DC to DC. The converter 101 may include a control circuit 102. The control circuit 102 may comprise machine-readable instructions that, when executed by one or more processors, provide, by one or more processors, various control routines, for example, the implementation of the pre-charging process of a capacitor bank 104 associated with system 100. In embodiments of the present invention, the control circuit 102 may correspond to a turbine controller 26 or an independent and separate control device (s).

[0036] The system 100 may further comprise a direct current input source 106 configured to supply a direct current voltage to the tilt adjustment motor 32 through the converter 101. In particular, the source 106 can be configured to supply a direct current voltage through the pre-charging circuit 108 and through an inverter bridge 110 to a tilt adjustment motor 32. As noted above, the pre-charging circuit 108 may be configured to limit the amount of current flowing into the capacitor bank 104. The capacitor bank 104 may be configured to reduce ripple of the DC voltage on the tilt angle adjustment motor 32 during operation. In accordance with the following more detailed description, the pre-charging circuit 108 may include one or more current-limiting elements or devices configured to prevent current from flowing through the pre-charging circuit 108. The pre-charging circuit 108 may also include one or more control devices configured to control the operation of the pre-charging circuit 108. Thus, one or more control devices can be independent and separate from the control circuit 102 of the devices or can be part of it or be otherwise associated with the control circuit 102.

[0037] The converter 101 may be configured to direct current through the pre-charging circuit 108 during one or more pre-charging procedures. Thus, the converter 101 may further comprise a bypass contactor 112 for removing current bypassing the pre-charging circuit 108 when the pre-charging procedure is completed. For example, the control circuit 102 may be configured to terminate the pre-charging process by applying a control command to close the shunt contactor 112 when the voltage on the capacitor bank 104 reaches a voltage threshold value, whereby current is drawn through the shunt contactor 112.

[0038] FIG. 4 is a block diagram of one embodiment of respective components that may be part of a control circuit 102 and / or one or more control devices 108 in a precharge circuit 108 in accordance with examples of aspects of the present invention. In accordance with the illustration, the control circuit 102 may include one or more processors 212 and corresponding memory devices 214 configured to execute software-implemented functions (for example, performing methods, steps, calculations, and the like described herein)

[0039] In this document, the term "processor" is understood not only as integrated circuits, which in the technical field are understood as incoming computers, but also controllers, microcontrollers, micro-computers, programmable logic controllers (PLCs), custom integrated circuits and other programmable circuits. Moreover, the storage device (or devices) 214 in the general case may include a storage element (or elements) including, without limitation to the above, computer-readable non-volatile media (for example, flash memory), floppy disks, read-only memory on a compact discs (compact disc-read only memory, CD-ROM), magneto-optical disks (magneto-optical disk, MOD), digital versatile discs (digital versatile disc, DVD) and / or other suitable storage elements.

[0040] Such a storage device (or devices) 214 can generally be configured to store appropriate machine-readable instructions, which when executed by a processor (or processors) 212 configure a control circuit 102 to perform various functions including, but not limited to, direct or indirect receiving signals from one or more sensors (for example, current sensors, wind speed sensors, turbine speed sensors) reflecting various input conditions, measuring the voltage on a capacitor bank, controlling the pre-charging process of a capacitor bank, and / or various other relevant functions implemented using software.

[0041] Additionally, the control circuit 102 may also include a communication interface 247 for providing communication between the control circuit 102 and various components of the wind turbine 10. The interface may include one or more circuits, connectors, outputs, contacts, conductors or other components for transmission and reception control signals. In this case, also, the control circuit 102 may include an interface 244 of sensors (for example, one or more analog-to-digital converters) to ensure the conversion of signals transmitted from sensors (for example, sensors 120, 122 and 124) into signals that can be sensed and processed by processors 212.

[0042] FIG. 5 is a perspective view illustrating an example of a pre-charging circuit control system 200 for a capacitor bank in a blade angle adjustment drive in accordance with embodiments of the present invention. Thus, in particular, the system 300 may correspond, at least in part, to the pre-charging circuit 108 shown in FIG. 3. As noted above, the system 300 may include a current limiting device, for example, an inductor 302 connected to a power switch 304. The power switch 304 can be controlled by a pulse width modulation (PWM) signal supplied by the control device 306. The control device 306 may include various suitable components, for example, one or more components, shown as being related to the control circuit 102 in FIG. 4. You need to understand that the power switch 304 can be controlled using various other methods. The system 300 may also include an isolated DC power supply 308 and / or a DC / DC converter for receiving voltage from the DC input source 106 and for generating an isolated voltage signal (eg, IP15) for the control device 306. An insulated key 310 may be installed between the control device 306 and the power supply 308. The key 310 may be an optocoupler, a photorelay, or any other suitable insulated key. The key 310 may optionally be placed in an open state or in a closed state, and may be controlled or otherwise driven by a control circuit 102 in accordance with embodiments of the present invention.

[0043] In particular, the control circuit 102 may be configured to control the state of the key 310 at least partially based on the voltage 314 on the capacitor bank. For example, voltage monitoring on the capacitor bank 104 may be performed and / or otherwise measured, and a signal indicative of the voltage may be supplied to the control circuit 102. When the voltage 314 on the capacitor bank 104 reaches a voltage threshold value, the control circuit 102 can be configured to provide one or more command signals to a key 310 that enable the key 310 to be switched to an open state, which opens the circuit between the power source 308 and the control device 306. The control circuit 102 may be further configured to provide a control command to the bypass contactor 112 (for example, in accordance with the illustration of FIG. 3) to enable the bypass contactor 112 to be closed.

[0044] The control circuit 102 may also be configured to determine the capacitance of the capacitor bank 104. Thus, the control circuit may also receive a signal reflecting the charging current 316 supplied to the capacitor bank 104. In embodiments of the present invention, a signal reflecting the charging current 316, may be the average value of the charging current supplied to the capacitor bank 104. In accordance with the illustration, the charging current supplied to the capacitor bank 104 can be measured using a current sensor 318. The current sensor 318 may include any suitable current measuring device, such as a resistor, current transformer, current transducer, Hall effect device, or any other suitable current sensor. A signal reflecting the charging current can be supplied to the control circuit 102 through a differential amplifier, for example, a differential operational amplifier 320. Thus, the differential operational amplifier 320 can be configured to convert the differential voltage signal supplied by the current sensor 318 to a unipolar signal 316 and for supplying a unipolar signal 316 to the control circuit 102. The control circuit 102 may then determine the capacitance of the capacitor bank 104 at least based on the average value of the current signal 316 and / or voltage 314.

[0045] As noted above, the control device 306 can be configured to limit the current flowing into the inductor 302 during the pre-charging process. Thus, the current sensor 322 can be configured to monitor, measure and / or detect the current flowing into the inductor 302 and to provide a signal reflecting this current to the control device 306. In alternative embodiments of the present invention, signal 324 may be provided through a filter, such as a KS filter, to reduce the level of interference associated with signal 324. The control device 306 can generate a pulse train and transmit this pulse train to the power switch, thereby providing it closing or opening in accordance with the sequence of pulses. In embodiments of the present invention, device 306 may be configured to control the duty cycle of a pulse train, at least in part based on a current signal 324. In particular, the control device 306 may be configured to lower the pulse signal when the current signal 324 reaches the current threshold value, thereby shutting down the power switch 304, or otherwise transferring it to the open state. At the beginning of the immediately following modulation period, the pulse signal can be brought to a high state until the current signal 324 reaches the current threshold value again. Thus, for each modulation period of the pulse train generated by the control device 306, the power switch 304 can be closed until the current flowing through the power switch 340 reaches the threshold current value. In accordance with the more detailed description below, with reference to FIG. 6, in embodiments of the present invention, where the current limiting device of the pre-charging circuit is an inductive device (e.g., inductor 302), when the power switch 304 is opened, the inductor 302 can give off current, which makes it possible to make the charging current applied to the capacitor bank 104, approximately equal to the average value of the current flowing through the inductor 302. In similar embodiments of the present invention, the pre-charging circuit may also include a shunt diode 326 connected between the inductor 302 and ground. Diode 326 can be used to pass charging current when the power switch 304 is open.

[0046] FIG. 6 is a graph for an example of a current signal 324 in an inductive current limiting device in accordance with embodiments of the present invention. In particular, the current signal 324 may have an energy storage period 402 and an energy output period 404. The energy storage period 402 and the energy output period 404 can occur, at least in part, during each pulse train modulation period 406 generated, for example, by the control device 306. It should be understood that the modulation period 406 may have any suitable duration. In one particular implementation, the length of the modulation period 406 may be selected, at least in part, depending on the inductance value of the inductor 302.

[0047] According to the illustration, an energy storage period 402 can take place during the first part of the modulation period 406. In particular, the energy storage period 402 can occur when the power switch 304 is unlocked, after which the current flows through the inductor 302. The inductive properties of the inductor 302 provide the resistance of the inductor 302 to the current flow, which ensures a gradual increase in current through the inductor 302 as it accumulates energy. As noted above, when the current signal 324 reaches a current threshold value (for example, 1 Ampere), the control device 306 can open the power switch 304, thereby interrupting the current through the inductor 302. This causes the current to be output by the inductor 302 in accordance with the current signal 324 during the period 404 energy output. In accordance with the illustration, the inductor 302 can deliver current until the signal 324 reaches 0. Then, the signal 324 can remain at 0 until the start of the next modulation period, when the power switch 304 is closed and the inductor 302 begins to accumulate energy again. Thus, the load current (for example, the average value of the current applied to the capacitor bank 104) can be approximately half the threshold current value.

[0048] However, it should be understood that by the end of the modulation period 406, the current signal 324 may not reach 0. In this case, in accordance with embodiments of the present invention, the power switch 304 may remain open at the beginning of the next modulation period.

[0049] FIG. 7 is a flow chart of a method (500) for precharging a capacitor bank in accordance with embodiments of the present invention. Method (500) can be implemented, at least in part, using one or more control devices, for example, one or more of the controllers shown in FIG. 5. Moreover, for purposes of illustration and description, in FIG. The 7 steps are shown as being performed in a specific order. However, those skilled in the art, when using the present description, should understand that the steps of all the methods discussed herein, within the scope of the present invention, can be modified, expanded, omitted, reordered and / or adapted in various ways.

[0050] In step (502), method (500) may include starting the pre-charging process of the capacitor bank. A capacitor bank may comprise one or more capacitive capacitor devices connected in series and / or in parallel. The capacitor bank can be connected to a power switch and a current limiting device. In particular, the power switch and current limiting device can be connected in series between the power source and the capacitor bank. As noted above, the power switch and current limiting device can be configured to limit the peak current applied to the capacitor bank.

[0051] In step (504), method (500) may include applying a DC voltage for use in precharging a capacitor bank. The DC voltage can be supplied using a DC power source and can have any suitable voltage level.

[0052] In step (506), method (500) may include monitoring the amount of current flowing into the current limiting device. In particular, in those embodiments of the present invention where the current limiting device is an inductive device, the current through the inductive device can increase with time, at least in the initial period of time. For example, the current through the inductor can grow linearly in time. Current monitoring can be performed at least partially using a current sensor, for example, a resistor for measuring current or another current-measuring device. In particular, a current sensor may be connected in series between a power switch and a current limiting device. The current-limiting device can provide a signal indicative of the current that is applied to the current-limiting device to one or more control devices, for example, to one or more control devices shown in FIG. 5.

[0053] In step (508), method (500) may include controlling, optionally, operating a power switch at least in part based on a monitored current. In particular, the opening of the power switch can be ensured when the strength of the monitored current reaches the threshold current value. For example, the threshold value of the current may be between about 0.7 amperes and about 1.5 amperes. In embodiments of the present invention, the power key can be controlled using the PWM modulation method. So, the duty cycle of the PWM signal applied to the power switch can be adjusted when the monitored current reaches the threshold current value.

[0054] In step (510), method (500) may include monitoring a voltage on a capacitor bank. For example, the voltage on a capacitor bank may increase over time during the pre-charging process when current is applied to the capacitor bank. This voltage can be monitored, and a signal indicative of the monitored voltage can be supplied to one or more control devices.

[0055] In step (512), method (500) may include terminating the precharging process of the capacitor bank when the voltage reaches a voltage threshold value. In embodiments of the present invention, a threshold voltage value can be defined as constituting between about 60% and 95% of the DC voltage applied by the DC power source. Thus, when the voltage on the capacitor bank reaches the threshold voltage value, the power switch control signal can be turned off. In addition, or alternatively, when the voltage across the capacitor bank reaches a threshold voltage value, a bypass contactor may be closed, as a result of which electric current may be diverted from the pre-charging circuit (e.g., power switch and current limiting device). For example, a bypass contactor can be connected in parallel with a pre-charge circuit. Thus, current can flow into the capacitor bank through a shunt contactor.

[0056] Examples of aspects of the present invention are described by pre-charging a capacitor bank that is used in a wind turbine system, however, it should be understood that this consideration is for illustration only. In particular, those skilled in the art, when using the description provided herein, should understand that, within the scope of the present invention, the pre-charging methods discussed herein can be used in various other relevant applications. For example, the pre-charging methods discussed herein can be used in battery-powered electric vehicles, in electric drive systems, for motorized bicycles, and / or in various other relevant applications.

[0057] Specific examples are used herein to describe the invention, including the best embodiment. The purpose of these examples is to provide the possibility of practical application of the present invention by specialists in this field of technology, which may include the creation and use of any devices or systems, or the implementation of any methods according to the invention. The scope of the present invention is defined by the claims and may include other examples that may be found by those skilled in the art. All such additional examples fall within the scope of the claims if they include structural elements that do not differ from the literal description in the claims, or if they include equivalent structural elements with slight differences from the literal description in the claims.

Claims (43)

1. A system for precharging a capacitor bank, including: a power switch connected in series with an input DC source; a current limiting device connected in series between a power switch and a capacitor bank comprising one or more capacitor devices; a first control device configured to control the operation of the power switch by: receiving one or more signals indicative of a charging current associated with a capacitor bank; and controlling the operation of the power switch at least partially based on the charging current; and a second control device configured to measure the voltage on the capacitor bank, and also to control the operation of the first control device at least partially based on the measured voltage on the capacitor bank. 2. The system of claim 1, wherein the power switch comprises a field effect transistor with a metal oxide semiconductor structure. 3. The system of claim 1, wherein the current limiting device comprises an inductive device. 4. The system of claim 3, further comprising a shunt diode connected between the power switch and ground. 5. The system of claim 1, wherein the first control device is a pulse width modulation controller, wherein controlling the operation of the power switch at least partially based on the charging current includes: comparing the received one or more signals indicative of a charging current with a threshold current value; and opening of the power switch when the signal indicating the charging current reaches the threshold current value. 6. The system of claim 1, further comprising a DC to DC converter configured to supply input electrical energy to the first control device. 7. The system of claim 6, further comprising an isolated switch included between the DC / DC converter and the first control device, wherein the second control device controls the operation of the first control device by supplying one or more control commands to the isolated key. 8. The system of claim 1, wherein the second control device is also configured to determine the capacitance of the capacitor bank at least in part based on the average value of the charging current and the measured voltage across the capacitor bank. 9. The system according to claim 8, in which the average value of the charging current is determined using a current-measuring element connected to a differential operational amplifier. 10. The system of claim 1, wherein the second control device is configured to control the operation of the first control device at least partially based on the measured voltage on the capacitor bank, by: comparing the measured voltage across the capacitor bank with a threshold voltage value; and stopping the first control device when the measured voltage across the capacitor bank reaches a voltage threshold value. 11. The system of claim 10, wherein the voltage threshold is a percentage of the voltage supplied by the input DC source. 12. The system of claim 10, further comprising a bypass contactor connected in parallel with the power switch and a current limiting device, so that when the bypass contactor is in the closed state, current from the input DC source is directed through the bypass contactor. 13. The system of claim 12, wherein the second control device is further configured to control the operation of the bypass contactor so that the bypass contactor is in a closed state when the voltage across the capacitor bank reaches a threshold voltage value. 14. The system of claim 1, wherein one or more signals indicative of a charging current are determined using a current sensing element. 15. A method of controlling pre-charging a capacitor bank comprising one or more capacitor devices, the capacitor bank being connected in series with a power switch and a current limiting device connected between the power source and the capacitor bank, the method comprising: supplying a DC input power source for use in pre-charging a capacitor bank; control of the direct current flowing into the current-limiting device; selectively controlling the operation of the power switch so that when the DC current reaches the threshold current value, the power switch is opened; voltage control on a capacitor bank; and when the voltage across the capacitor bank reaches the voltage threshold, stop pre-charging the capacitor bank so as to bypass the current limiting device. 16. The method of claim 15, wherein the selectively controlling the operation of the power switch so that when the DC current reaches the threshold current value, the power switch is opened, includes adjusting the duty cycle of the pulse sequence associated with the power switch when the DC current reaches the threshold value current. 17. The method according to p. 15, in which the termination of the pre-charging of the capacitor bank includes the submission to the shunt contactor of one or more control commands that ensure the operation of the shunt contactor in the closed state. 18. Wind turbine system, including: rotor; stator; an engine for adjusting the angle of inclination of one or more rotor blades associated with a wind turbine system; and one or more control devices configured to precharge the capacitor bank associated with the tilt adjustment motor by: start the process of pre-charging the capacitor bank; control the magnitude of the direct current flowing into the current-limiting device connected in series between the capacitor bank and the power source, selectively controlling the operation of the power switch in such a way that when the DC current reaches the threshold current value, the power switch is opened, which reduces the amount of current acting on the current limiting device; control voltage on a capacitor bank; and when the voltage on the capacitor bank reaches the threshold voltage value, termination of the pre-charging process. 19. The wind turbine system of claim 18, wherein the selectively controlling the operation of the power switch such that when the DC current reaches the threshold current value, the power switch is opened, includes adjusting the duty cycle of the pulse sequence associated with the power switch when the DC current reaches the threshold current values. 20. The wind turbine system according to claim 18, in which the termination of the pre-charging process includes the submission of one or more control commands to a bypass contactor connected in parallel with the current-limiting device, which ensures that the bypass contactor is closed, so that the current-limiting device is bypassed.

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