A control circuit, system and fan of a variable pitch motor

Abstract

The present invention discloses a control circuit, system and fan of a variable pitch motor, and relates to the technical field of variable pitch motors. The control circuit of the variable pitch motor includes an energy feedback device and a variable pitch driver corresponding to the variable pitch motor. The variable pitch driver includes a rectifier unit, a DC bus, a first bus capacitor and an inverter unit; wherein the rectifier unit of the variable pitch driver rectifies the AC power in the power grid into DC power, and then inverts the DC power into AC power through the inverter unit to drive the variable pitch motor to operate. When the voltage of the DC bus is greater than a first preset voltage threshold, the energy feedback device inverts the voltage on the DC bus into AC power and outputs it to the power grid. In this way, the energy is fed back to the power grid for reuse through the energy feedback device, avoiding the energy being wasted by the way of resistance heating consumption. While improving the control efficiency of the variable pitch motor, the ambient temperature in the hub is also reduced, and the service life of the components inside the variable pitch control system is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of variable pitch motors, and in particular to a control circuit, system and fan of a variable pitch motor. Background Art

[0002] The variable pitch control system uses power electronics technology to control the variable pitch motor in the wind turbine, and achieves precise control of the pitch angle of the blades on the wind turbine, so that the wind turbine can obtain the maximum wind energy during operation. At present, in the process of variable pitch motor control, since the load direction of the blades on the wind turbine changes in real time with the wind load and the position of the wind rotor, and the speed of the variable pitch motor also accelerates and decelerates with the main control command, this allows the variable pitch motor to work in both electric mode and power generation mode.

[0003] Please refer to Figure 1 , Figure 1 The diagram is a circuit topology diagram of a variable pitch drive in the related art. When the variable pitch motor works in the power generation mode, the electric energy generated by the variable pitch motor will be fed back to the bus capacitor on the DC bus through the inverter unit of the drive for storage. As the fed-back energy increases, the voltage of the bus capacitor increases. After the voltage increases to a certain threshold, the energy on the bus capacitor is consumed through the braking resistor, and the heat consumed by the resistor generates heat, resulting in energy waste. In addition, since the hub space where the variable pitch control system is located is relatively close, the electric energy consumed by the braking resistor will be converted into heat energy and accumulated inside the hub, thus affecting the temperature of the environment inside the hub, thereby shortening the service life of the components inside the variable pitch control system. Summary of the invention

[0004] The object of the present invention is to provide a control circuit, system and fan for a pitch motor, which can feed back to the power grid for repeated utilization through an energy feedback device when the voltage of the DC bus is greater than a preset voltage threshold, thereby avoiding energy being wasted through resistance heat consumption. While improving the control efficiency of the pitch motor, it also reduces the ambient temperature inside the hub and increases the service life of components inside the pitch control system.

[0005] In order to solve the above technical problems, the present invention provides a control circuit of a pitch motor, comprising an energy feedback device and a pitch driver corresponding to the pitch motor, wherein the pitch driver comprises a rectifier unit, a DC bus, a first bus capacitor and an inverter unit;

[0006] For any of the pitch drive, the AC end of the rectifier unit is connected to the power grid, and the DC end is connected to the DC end of the inverter unit through the DC bus;

[0007] The first bus capacitor is connected in parallel between the DC bus bars;

[0008] The AC end of the inverter unit is connected to the corresponding pitch motor;

[0009] The input end of the energy feedback device is connected to the DC bus in each pitch drive, and the output end is connected to the power grid, and is used for inverting the voltage on the DC bus into AC power and outputting it to the power grid when the voltage of the DC bus is greater than a first preset voltage threshold.

[0010] Optionally, the energy feedback device includes:

[0011] A feedback unit, wherein the input end of the feedback unit is connected to the DC bus in each pitch drive, and the AC end is connected to the power grid, and is used for inverting the voltage on the DC bus into AC power and outputting it to the power grid when the voltage of the DC bus is greater than a preset threshold;

[0012] A second bus capacitor is connected in parallel with the input end of the feedback unit.

[0013] Optionally, also include:

[0014] A reactor, wherein a first end of the reactor is connected to the output end of the energy feedback device, and a second end of the reactor is connected to the power grid.

[0015] Optionally, also include:

[0016] A backup power supply module is connected to the DC terminal of the inverter unit and is used to provide power to each pitch drive when the power grid is abnormal.

[0017] Optionally, also include:

[0018] A first anti-reverse diode, wherein the anode of the first anti-reverse diode is connected to the positive DC bus of the DC bus, and the cathode of the first anti-reverse diode is connected to the positive input terminal of the energy feedback device;

[0019] A second anti-reverse diode, wherein the anode of the second anti-reverse diode is connected to the negative input terminal of the energy feedback device, and the cathode of the second anti-reverse diode is connected to the negative DC bus of the DC bus.

[0020] Optionally, also include:

[0021] A fuse is connected between the DC bus and the energy feedback device, and is used to disconnect the circuit between the DC bus and the energy feedback device when the current of the DC bus of the energy feedback device is greater than a preset current threshold.

[0022] Optionally, also include:

[0023] A braking unit is connected in parallel with the input end of the energy feedback device and is used to discharge the voltage on the DC bus of the energy feedback device when the voltage of the DC bus of the energy feedback device is greater than a second preset voltage threshold and the energy feedback device fails.

[0024] Optionally, the braking unit includes:

[0025] Braking resistor;

[0026] A switch, wherein the switch is connected in series with the braking resistor and the series circuit is connected in parallel with the input end of the energy feedback device, and is used to be turned on when the voltage of the DC bus of the energy feedback device is greater than a second preset voltage threshold and the energy feedback device fails.

[0027] The present invention also provides a control system for a variable pitch motor, comprising a variable pitch motor and a control circuit for the variable pitch motor as described above, wherein the control circuit for the variable pitch motor is connected to the variable pitch motor.

[0028] The present invention further provides a wind turbine, comprising blades and a control system of the variable pitch motor as described above, wherein the control system of the variable pitch motor is connected to the blades.

[0029] The present invention provides a control circuit, system and fan of a pitch motor. The control circuit of the pitch motor includes an energy feedback device and a pitch driver corresponding to the pitch motor. The pitch driver includes a rectifier unit, a DC bus, a first bus capacitor and an inverter unit. The rectifier unit of the pitch driver rectifies the AC power in the power grid into DC power, and then inverts the DC power into AC power through the inverter unit to drive the pitch motor to operate. When the voltage of the DC bus is greater than the first preset voltage threshold, the energy feedback device inverts the voltage on the DC bus into AC power and outputs it to the power grid. In this way, when the voltage of the DC bus is greater than the preset voltage threshold, the energy feedback device is fed back to the power grid for reuse, thereby avoiding energy being wasted in the form of resistance heating consumption. While improving the control efficiency of the pitch motor, the ambient temperature in the hub is also reduced, thereby improving the service life of components inside the pitch control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the prior art and the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 A circuit topology diagram of a variable pitch drive in the related art;

[0032] Figure 2 A schematic diagram of the structure of a control circuit of a pitch motor provided by the present invention;

[0033] Figure 3 A schematic diagram of the structure of a specific control system of a pitch motor provided by the present invention;

[0034] Figure 4 A schematic diagram of the topology of an energy feedback device provided by the present invention. DETAILED DESCRIPTION

[0035] The core of the present invention is to provide a control circuit, system and fan for a pitch motor, which can feed back to the power grid for repeated use through an energy feedback device when the voltage of the DC bus is greater than a preset voltage threshold, thereby avoiding energy being wasted through resistance heat consumption. While improving the control efficiency of the pitch motor, it also reduces the ambient temperature inside the hub and increases the service life of components inside the pitch control system.

[0036] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] At present, when the variable pitch motor works in the power generation mode, the electric energy generated by the variable pitch motor will be fed back to the bus capacitor on the DC bus through the inverter unit of the driver for storage. As the feedback energy increases, the voltage of the bus capacitor increases. After the voltage increases to a certain threshold, the energy on the bus capacitor is consumed through the braking resistor, and the heat consumption through the resistor generates heat, resulting in energy waste. In addition, since the hub space where the variable pitch control system is located is relatively close, the electric energy consumed by the braking resistor will be converted into heat energy and accumulated inside the hub, thus affecting the temperature of the environment inside the hub, thereby shortening the service life of the components inside the variable pitch control system.

[0038] In order to solve the above technical problem, the present invention provides a control circuit for a variable pitch motor.

[0039] Specifically, see Figure 2 As shown, Figure 2 A schematic diagram of a control circuit of a pitch motor provided by the present invention. The control circuit of the pitch motor includes an energy feedback device 1 and a pitch driver 2 corresponding to a pitch motor 6, wherein the pitch driver 2 includes a rectifier unit 3, a DC bus DC, a first bus capacitor 4 and an inverter unit 5;

[0040] For any pitch drive 2, the AC end of the rectifier unit 3 is connected to the power grid L, and the DC end is connected to the DC end of the inverter unit 5 through the DC bus DC;

[0041] The first bus capacitor 4 is connected in parallel between the DC bus bars DC;

[0042] The AC end of the inverter unit 5 is connected to the corresponding pitch motor 6;

[0043] The input end of the energy feedback device 1 is connected to the DC bus DC in each pitch drive 2, and the output end is connected to the power grid L, and is used to invert the voltage on the DC bus DC into AC power and output it to the power grid L when the voltage of the DC bus DC is greater than a first preset voltage threshold.

[0044] The control circuit of the variable pitch motor includes an energy feedback device 1 and a variable pitch driver 2, and the variable pitch driver 2 includes a rectifier unit 3, a DC bus DC, a first bus capacitor 4 and an inverter unit 5. Among them, the rectifier unit 3 can be a three-phase bridge full-controlled rectifier circuit, and the inverter unit 5 can be a three-phase bridge inverter circuit. The variable pitch control system controls the variable pitch motor 6 in the wind turbine through power electronics technology to achieve precise control of the blade angle of the blades on the wind turbine, so that the running wind turbine can obtain wind energy to the maximum extent. At present, in the control process of the variable pitch motor 6, since the load direction of the blades on the wind turbine changes in real time with the wind load and the position of the wind wheel, and the speed of the variable pitch motor 6 also has an acceleration and deceleration process with the main control command, this enables the variable pitch motor 6 to work in both electric mode and power generation mode.

[0045] In this example, when the pitch motor 6 works in the power generation mode, the electric energy generated by the pitch motor 6 will be fed back to the first bus capacitor 4 on the DC bus DC through the inverter unit 5 of the pitch drive 2 for storage. As the fed-back energy increases, the voltage of the first bus capacitor 4 increases. When the first bus capacitor 4 is too high, the temperature of the capacitor will rise rapidly. If it is in an overvoltage state for a long time, the insulation performance of the capacitor may be reduced, and even cause the capacitor to break down or explode. In addition, excessive voltage will increase the dielectric loss of the capacitor, causing it to heat up severely and accelerate insulation aging. In order to ensure the normal operation of the entire system and increase the service life of each device, when the voltage of the DC bus DC is greater than the first preset voltage threshold, the energy of the DC bus DC needs to be discharged. The present application uses an energy feedback device 1 to invert the voltage on the DC bus DC into alternating current and output it to the power grid L so that the power grid L can reuse it.

[0046] Specifically, the control circuit of the variable pitch motor converts the industrial frequency AC power input from the power grid L into a power supply with controllable amplitude and frequency through each variable pitch driver 2, and drives each variable pitch motor 6 to run at the set speed to complete normal variable pitch control. Under the independent variable pitch control strategy, the variable pitch motor 6 rotates according to a nearly sinusoidal law, and will frequently accelerate and decelerate. During the acceleration process, the variable pitch motor 6 is in an electric state and consumes the energy of the power grid L. During the deceleration process, the variable pitch motor 6 will be in a power generation state. The energy generated by the variable pitch motor 6 in the power generation state is fed back to the DC bus DC through the inverter unit 5 of the variable pitch driver 2. At this time, the voltage of the DC bus DC of the variable pitch driver 2 increases, and the energy feedback device 1 starts to work, and feeds back the energy generated by the variable pitch motor 6 to the power grid L. The present invention converts the braking energy originally consumed by resistor heating into energy that can be fed back to the power grid L for recycling through the energy feedback device 1, thereby achieving efficient operation of the control circuit of the variable pitch motor and reducing the ambient temperature in the wheel hub.

[0047] It can be seen that the rectifier unit 3 of the pitch drive 2 rectifies the AC power in the power grid L into DC power, and then inverts the DC power into AC power through the inverter unit 5 to drive the pitch motor 6 to operate. When the voltage of the DC bus DC is greater than the preset first voltage threshold, the energy feedback device 1 inverts the voltage on the DC bus DC into AC power and outputs it to the power grid L. In this way, when the voltage of the DC bus DC is greater than the first preset voltage threshold, the energy feedback device 1 feeds back to the power grid L for repeated use, avoiding energy wasting through resistance heating consumption, while improving the control efficiency of the pitch motor 6, it also reduces the ambient temperature in the hub, and improves the service life of the components inside the pitch control system.

[0048] Based on the above embodiments:

[0049] The present invention takes the three variable pitch motors 6 of the axis A motor 10, the axis B motor 11 and the axis C motor 12 as an example, please refer to Figure 3 As shown, Figure 3 A schematic structural diagram of a specific control system of a pitch motor provided by the present invention.

[0050] The control system of the variable pitch motor specifically consists of a power grid L, an energy feedback device 1, an axis A driver 7, an axis B driver 8, an axis C driver 9, an axis A motor 10, an axis B motor 11, an axis C motor 12, a backup power supply module 13, a braking unit 14, an inductor 15, a positive DC bus DC+, a negative DC bus DC-, a first anti-reverse A diode D1, a first anti-reverse B diode D2, a first anti-reverse C diode D3, a second anti-reverse A diode D4, a second anti-reverse B diode D5, a second anti-reverse C diode D6, a first fuse FU1, a second fuse FU2 and a third fuse FU3. Among them, the AC input ends of the axis A driver 7, the axis B driver 8 and the axis C driver 9 are respectively connected to the power grid L, the DC input ends are respectively connected to the backup power supply module 13, and the output ends are respectively connected to the three pitch motors 6 one by one. The positive DC bus DC+ of the three pitch drivers 2 are respectively connected to the positive input end of the energy feedback device 1 through the first anti-reverse diode and the fuse connected in series, and the positive DC bus DC+ of the three pitch drivers 2 are respectively connected to the negative input end of the energy feedback device 1 through the second anti-reverse diode, the braking unit 14 is connected in parallel with the input end of the energy feedback device 1, and the output end of the energy feedback device 1 is connected to the power grid L.

[0051] As an optional embodiment, the energy feedback device 1 includes:

[0052] A feedback unit 16, the input end of which is connected to the DC bus DC in each pitch drive 2, and the AC end of which is connected to the power grid L, for inverting the voltage on the DC bus DC into AC power and outputting it to the power grid L when the voltage of the DC bus DC is greater than a preset threshold;

[0053] The second bus capacitor 17 is connected in parallel with the input end of the feedback unit 16 .

[0054] Please refer to Figure 4 , Figure 4The schematic diagram of the structure of the topology of an energy feedback device provided by the present invention is that the input end of the feedback unit 16 is connected to the DC bus DC in each pitch drive 2, the AC end is connected to the power grid L, and the second bus capacitor 17 is connected in parallel with the input end of the feedback unit 16. When the control circuit of the pitch motor is working, when the pitch motor 6 is in acceleration or uniform speed operation, the rectifier unit 3 of the pitch drive 2 rectifies the AC power supply of the power grid L into a DC power supply and stores it in the DC bus DC. The post-stage inverter unit 5 outputs AC power with variable frequency and amplitude through PWM (Pulse Width Modulation) control technology to drive the pitch motor 6 to operate as required. When the pitch motor 6 is in a deceleration braking state, the braking energy generated is fed back to the DC bus DC through the inverter unit 5, and the energy generated by the braking will be modulated into power frequency electricity with the same amplitude and frequency as the power grid L through the feedback unit 16, and incorporated into the power grid L. The second bus capacitor 17 mainly maintains a stable DC voltage by filtering and storing energy.

[0055] It can be seen that the present invention converts the braking energy originally consumed by resistor heating into energy that can be fed back to the power grid L for recycling through the feedback unit 16, thereby achieving efficient operation of the control circuit of the variable pitch motor, while reducing the ambient temperature inside the hub, and providing a stable working environment for the control circuit of the variable pitch motor.

[0056] As an optional embodiment, it also includes:

[0057] The reactor 15 has a first end connected to the output end of the energy feedback device 1 , and a second end connected to the power grid L.

[0058] In this embodiment, the reactor 15 plays a role in stabilizing the current when the energy feedback device 1 inverts the voltage on the DC bus DC into AC power and outputs it to the power grid L, by converting electrical energy into magnetic energy for storage and releasing energy when needed. This characteristic enables the reactor 15 to effectively suppress the rapid change of the current fed back by the energy feedback device 1, thereby maintaining the current stability in the circuit.

[0059] It can be seen that the reactor 15 can ensure stable output current during the process in which the energy feedback device 1 inverts the voltage on the DC bus DC into AC power and outputs it to the power grid L, ensure the normal operation of the control circuit of the variable pitch motor, and improve the overall performance of the system.

[0060] As an optional embodiment, it also includes:

[0061] The backup power supply module 13 is connected to the DC terminal of the inverter unit 5 and is used to provide power to each pitch drive 2 when the power grid L is abnormal.

[0062] In this embodiment, in order for the control circuit of the entire variable pitch motor to still work normally when an abnormality occurs in the power grid L, it is necessary to configure a backup power supply for each variable pitch drive 2, which means that each variable pitch drive 2 requires sufficient power supply to ensure its normal operation, and the backup power supply module 13 needs to meet the power supply requirements for all variable pitch drives 2. When an abnormality occurs in the input of the power grid L, the backup power supply module 13 can power the entire system and be used as a power source to drive the variable pitch motor 6 to complete the emergency pitching action when the power grid L is abnormal. It should be noted that the backup power supply module 13 is a DC backup power supply module; the backup power supply module 13 can be a backup power supply or three independent backup power supplies.

[0063] Among them, there is an anti-reverse diode between the backup power supply module 13 and the DC bus DC. When the voltage of the DC bus DC is higher than the voltage of the backup power supply module 13, the anti-reverse diode is not turned on, and the energy of the backup power supply module 13 cannot flow into the DC bus DC. When the voltage of the DC bus DC drops to a level lower than the voltage of the backup power supply module 13 due to an abnormal power grid situation, the anti-reverse diode is turned on, and the backup power supply module 13 provides energy for the variable pitch drive 2.

[0064] It can be seen that the backup power module 13 can be used as part of the redundant design to ensure that the system can continue to operate when a failure occurs in the power grid L. This redundant configuration improves the reliability of the system. Even if a single power supply fails, the backup power module 13 can continue to supply power, thereby avoiding the risk of downtime of various devices.

[0065] As an optional embodiment, it also includes:

[0066] A first anti-reverse diode, wherein the anode of the first anti-reverse diode is connected to the positive DC bus DC+ of the DC bus DC, and the cathode is connected to the positive input terminal of the energy feedback device 1;

[0067] A second anti-reverse diode, wherein the anode of the second anti-reverse diode is connected to the negative input terminal of the energy feedback device 1 , and the cathode of the second anti-reverse diode is connected to the negative DC bus DC- of the DC bus DC.

[0068] In this embodiment, in order to prevent the generation of circulating current between the pitch drives 2, resulting in additional power loss and thus reducing the overall efficiency of the system, the present application configures an anti-reverse diode between the positive input terminal and the negative input terminal of each pitch drive 2 and the energy feedback device 1 to avoid mutual influence between the pitch drives 2. Whenever a short circuit or other fault occurs in the bus of a single pitch drive 2, it will not cause abnormal operation of other pitch drives 2. At the same time, the energy of the pitch drive 2 with the highest bus voltage is preferentially fed back to the power grid L. This means that giving priority to feeding back the energy of the highest pitch drive 2 when the bus voltage is the highest to the power grid L can more effectively utilize wind energy, improve overall energy utilization efficiency, and promote the rational distribution and utilization of electric energy.

[0069] Specifically, when the three pitch motors 6 of the control circuit of the pitch motor are in the power generation state at the same time, the first anti-reverse diode D1 connected to the positive DC bus DC+ of the DC bus DC of an axis (taking the axis A motor 10 as an example) with the highest DC bus DC voltage among the three pitch drives 2 is turned on. According to the characteristics of the diode, at this time, the first anti-reverse diodes and the three second anti-reverse diodes connected to the positive DC bus DC+ of the other two pitch drives 2 are not turned on, and the energy on the voltage of the DC bus DC of the axis A motor 10 will not circulate to the axis B motor 11 or the axis C motor 12. At this time, the energy feedback device 1 feeds back the energy generated by the axis A motor 10 to the power grid L; as the energy feedback proceeds, The voltage of the DC bus DC of the axis A driver 7 corresponding to the axis A motor 10 gradually decreases. When it decreases to a voltage lower than that of the DC bus DC of the pitch drive 2 of the other axis (with the axis B motor 11), the first anti-reverse A diode D1 of the axis A motor 10 is turned off. At this time, the first anti-reverse B diode D2 of the axis B motor 11 is turned on. The first anti-reverse diode and the three second anti-reverse diodes of the axis A motor 10 and the axis C motor 12 are not turned on. The energy on the voltage of the DC bus DC of the axis B motor 11 will not circulate to the axis A motor 10 or the axis C motor 12. The energy feedback device 1 feeds back the energy generated by the axis B motor 11 to the power grid L. The same applies to the case when the bus voltage of the axis C driver 9 of the axis C motor 12 is the highest.

[0070] It should be noted that when the pitch motors 6 of the three axes are in the electric state, the inverter units 5 of the pitch drives 2 of the three axes are in the energy consumption state. At this time, the voltage of the DC bus DC of the pitch drives 2 of the three axes is not higher than the voltage of the DC bus DC of the energy feedback device 1, and the first anti-reverse diodes and the second anti-reverse diodes of the three axes are not turned on, and no energy is fed back to the power grid L. When the DC bus DC of the axis A motor 10 driver is abnormally short-circuited, due to the action of the first anti-reverse diode and the second anti-reverse diode, the pitch drives 2 corresponding to the axis B motor 11 and the axis C motor 12 will not be affected, and the control circuit of the pitch motor will continue to perform the pitch action to complete the pitching.

[0071] Among them, because the capacity of the DC bus capacitor is infinite in an ideal state, the voltage of the DC bus DC of the pitch drive 2 is equal to the voltage of the energy feedback device 1. However, in actual applications, the first bus capacitor is limited. If the pitch motor 6 is in a no-load state, the voltage of the DC bus DC of the pitch drive 2 is equal to the voltage of the DC bus of the energy feedback device 1. If there is a load, the voltage of the DC bus DC of the pitch drive 2 will be slightly lower than the voltage of the DC bus of the energy feedback device 1. Therefore, the voltage of the DC bus DC of the pitch drive 2 here is not higher than the voltage of the DC bus of the energy feedback device 1.

[0072] It can be seen that in this embodiment, anti-reverse diodes are configured between the positive input terminal and the negative input terminal of each pitch drive 2 and the energy feedback device 1 to avoid mutual influence between the pitch drives 2. At the same time, the three pitch drives 2 with the highest bus voltage give priority to feeding back energy to the power grid L, which can more effectively utilize wind energy, improve the overall energy utilization efficiency, and promote the rational distribution and utilization of electric energy.

[0073] As an optional embodiment, it also includes:

[0074] A fuse is connected between the DC bus DC and the energy feedback device 1 and is used to disconnect the circuit between the DC bus DC and the energy feedback device 1 when the current of the DC bus DC of the energy feedback device 1 is greater than a preset current threshold.

[0075] In this embodiment, when a short-circuit fault occurs in the DC bus DC of the energy feedback device 1, the DC bus DC of the pitch drive 2 will be short-circuited, damaging the pitch drive 2 and causing the three axes of the control circuit of the pitch motor to be unable to align at the same time. In order to avoid this situation, the present embodiment adds a fuse between each pitch drive 2 and the energy feedback device 1 to prevent the DC bus DC of the energy feedback device 1 from being short-circuited, causing the DC bus DC of the pitch drive 2 to be short-circuited. Specifically, when a short-circuit fault occurs in the DC bus DC of the energy feedback device 1, the fuses of the three axes will be blown due to the short circuit, isolating the short-circuit point and the pitch drive 2. After the pitch drive 2 is isolated from the fault source, a self-reset operation is performed according to the control method of the control circuit of the pitch motor. After the reset is completed, the pitch action continues to be performed to complete the aligning.

[0076] It can be seen that the role of the fuse in the energy feedback device 1 inverting the voltage on the DC bus DC into AC power and outputting it to the power grid L is mainly to provide short-circuit protection to ensure that the circuit is quickly cut off when a short circuit occurs, thereby protecting the entire control circuit from damage.

[0077] As an optional embodiment, it also includes:

[0078] The braking unit 14 is connected in parallel with the input end of the energy feedback device 1 and is used to discharge the voltage on the DC bus DC of the energy feedback device 1 when the voltage of the DC bus DC of the energy feedback device 1 is greater than the second preset voltage threshold and the energy feedback device 1 fails.

[0079] In this embodiment, in order to prevent the energy of the energy feedback device 1 from accumulating on the DC bus DC of the pitch drive 2 when the energy feedback device 1 is abnormal, causing the DC bus DC voltage to be too high and damage the pitch drive 2, the present application configures a brake unit 14 in the control circuit of the pitch motor, in conjunction with the control method of the energy feedback device 1. Specifically, when an abnormality occurs in the energy feedback device 1, the energy generated by the braking of the pitch motor 6 cannot be fed back, resulting in a voltage increase of the DC bus DC of the energy feedback device 1. At this time, the brake unit 14 will be put into use, and the energy accumulated on the DC bus DC of the energy feedback device 1 will be discharged through the brake unit 14.

[0080] It can be seen that in this embodiment, a braking unit 14 is configured in the control circuit of the pitch motor so that when an abnormality occurs in the energy feedback device 1, the energy can be discharged through the braking unit 14, thereby avoiding energy accumulation on the DC bus DC of the pitch drive 2, causing the DC bus DC voltage to be too high to damage the pitch drive 2, thereby ensuring the normal operation of each device.

[0081] As an optional embodiment, the braking unit 14 includes:

[0082] Braking resistor;

[0083] A switch is connected in series with a braking resistor and the series circuit is connected in parallel with the input end of the energy feedback device 1, and is used to be turned on when the voltage of the DC bus DC of the energy feedback device 1 is greater than a second preset voltage threshold and the energy feedback device 1 fails.

[0084] In this embodiment, the above-mentioned braking unit includes a braking resistor and a switch. When an abnormality occurs in the energy feedback device 1, the switch is turned on or off according to the voltage value of the DC bus of the energy feedback device 1, controls the input and output of the braking resistor, and maintains the normal operation of the control circuit of the variable pitch motor when the energy feedback device 1 is abnormal.

[0085] Specifically, when an abnormality occurs in the energy feedback device 1, the energy generated by the braking of the pitch motor 6 cannot be fed back, resulting in an increase in the voltage of the DC bus DC of the energy feedback device 1. At this time, the switch is turned on or off according to the set second preset voltage threshold. When turned on, the energy accumulated on the DC bus DC of the energy feedback device 1 is discharged through the braking resistor to prevent the bus voltage from being too high and causing damage to the pitch drive 2. At the same time, the execution of the pitch protection action is guaranteed to realize a control method for hierarchical implementation of multiple strategies for a high-efficiency pitch control system.

[0086] It can be seen that this embodiment uses a braking resistor and a switch as a braking unit 14 in the control circuit of the pitch motor. When an abnormality occurs in the energy feedback device 1, the braking resistor is used to maintain the normal operation of the control circuit of the pitch motor under the abnormal condition of the energy feedback device 1. While protecting various devices from damage, the stability and energy efficiency of the system are improved.

[0087] The present invention further provides a control system for a pitch motor, including a pitch motor 6 and a control circuit for the pitch motor as described above, wherein the control circuit for the pitch motor is connected to the pitch motor 6 .

[0088] It should be noted that the control system of the variable pitch motor, as one of the core parts of the control system of a large motor unit, plays a very important role in the safe, stable and efficient operation of the unit. Through the control system of the variable pitch motor, the control of each variable pitch motor 6 can be realized, thereby adjusting the aerodynamic torque and power output captured by the wind wheel. This not only helps to optimize the absorption of wind energy under different wind speed conditions, but also effectively reduces the vibration and noise of the unit and prolongs the life of the equipment.

[0089] It can be seen that the control system of a variable pitch motor provided by the present invention can realize the control of each variable pitch motor 6, thereby adjusting the aerodynamic torque and power output captured by the wind wheel to ensure the safe, stable and efficient operation of each variable pitch motor 6.

[0090] The present invention also provides a wind turbine, comprising blades and a control system of the variable pitch motor as described above, wherein the control system of the variable pitch motor is connected to the blades.

[0091] It should be noted that the control system of the variable pitch motor and the blades in the wind turbine work together to complete functions such as wind energy capture, power control and safety protection. The blades of the wind turbine mainly convert wind energy into mechanical energy by contacting the air, using the effects of pressure, turbulence and momentum to achieve power generation. The pitch of the wind turbine blades is adjusted by the control system of the variable pitch motor to adapt to the working requirements under different wind speeds, thereby optimizing the efficiency of wind power generation. The variable pitch control system is an important part of the wind turbine set, and its functions include normal operation control, status monitoring and safety protection. The variable pitch system controls the power output of the wind turbine by changing the pitch of the blades. When the wind speed exceeds the rated wind speed, the system will adjust the blade angle to reduce the axial load on the blades, and if necessary, shut down the wind turbine safely to avoid damage to the wind turbine due to overload.

[0092] It can be seen that the wind turbine provided by the present invention can optimize wind energy capture and power output by precisely adjusting the pitch of the blades through the control system of the variable pitch motor, and realize comprehensive monitoring and safety protection of the wind turbine.

[0093] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0094] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0095] Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present invention. The above description of the disclosed embodiments enables professional and technical personnel in the field to implement or use the present invention. Various modifications to these embodiments will be apparent to professional and technical personnel in the field, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features disclosed herein.

Claims

1. A control circuit for a pitch motor, characterized in that: It includes an energy feedback device and a pitch drive corresponding to the pitch motor one by one, and the pitch drive includes a rectifier unit, a DC bus, a first bus capacitor and an inverter unit; For any of the pitch drive, the AC end of the rectifier unit is connected to the power grid, and the DC end is connected to the DC end of the inverter unit through the DC bus; The first bus capacitor is connected in parallel between the DC buses; The AC end of the inverter unit is connected to the corresponding pitch motor; The input end of the energy feedback device is connected to the DC bus in each pitch drive, and the output end is connected to the power grid, and is used for inverting the voltage on the DC bus into AC power and outputting it to the power grid when the voltage of the DC bus is greater than a first preset voltage threshold.

2. The control circuit of the pitch motor according to claim 1, characterized in that: The energy feedback device comprises: A feedback unit, wherein the input end of the feedback unit is connected to the DC bus in each pitch drive, and the AC end is connected to the power grid, and is used for inverting the voltage on the DC bus into AC power and outputting it to the power grid when the voltage of the DC bus is greater than a preset threshold; A second bus capacitor is connected in parallel with the input end of the feedback unit.

3. The control circuit of the pitch motor according to claim 1, characterized in that: Also includes: A reactor, wherein a first end of the reactor is connected to the output end of the energy feedback device, and a second end of the reactor is connected to the power grid.

4. The control circuit of the pitch motor according to claim 1, characterized in that: Also includes: A backup power supply module is connected to the DC terminal of the inverter unit and is used to provide power to each pitch drive when the power grid is abnormal.

5. The control circuit of the pitch motor according to claim 1, characterized in that: Also includes: A first anti-reverse diode, wherein the anode of the first anti-reverse diode is connected to the positive DC bus of the DC bus, and the cathode of the first anti-reverse diode is connected to the positive input terminal of the energy feedback device; A second anti-reverse diode, wherein the anode of the second anti-reverse diode is connected to the negative input terminal of the energy feedback device, and the cathode of the second anti-reverse diode is connected to the negative DC bus of the DC bus.

6. The control circuit of the pitch motor according to claim 1, characterized in that: Also includes: A fuse is connected between the DC bus and the energy feedback device, and is used to disconnect the circuit between the DC bus and the energy feedback device when the current of the DC bus of the energy feedback device is greater than a preset current threshold.

7. The control circuit of the pitch motor according to any one of claims 1 to 6, characterized in that: Also includes: A braking unit is connected in parallel with the input end of the energy feedback device and is used to discharge the voltage on the DC bus of the energy feedback device when the voltage of the DC bus of the energy feedback device is greater than a second preset voltage threshold and the energy feedback device fails.

8. The control circuit of the pitch motor according to claim 7, characterized in that: The brake unit comprises: Braking resistor; A switch, wherein the switch is connected in series with the braking resistor and the series circuit is connected in parallel with the input end of the energy feedback device, and is used to be turned on when the voltage of the DC bus of the energy feedback device is greater than a second preset voltage threshold and the energy feedback device fails.

9. A control system for a pitch motor, characterized in that: It comprises a pitch motor and also comprises a control circuit of the pitch motor according to any one of claims 1 to 8, wherein the control circuit of the pitch motor is connected to the pitch motor.

10. A fan, characterized in that: It comprises a blade and a control system of a pitch motor as claimed in claim 9, wherein the control system of the pitch motor is connected to the blade.

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