Variable pitch servo driver and variable pitch system

Abstract

The invention provides a variable pitch servo driver and a variable pitch system, and the variable pitch servo driver comprises a driving module and an energy recovery module. The driving module comprises a plurality of drivers and a direct current bus electrically connected with the drivers, and each driver comprises a power generation mode and an electric mode; the driver is used for converting the obtained mechanical energy into electric energy in the power generation mode, or the driver is used for converting the obtained electric energy into mechanical energy in the electric mode; and the energy recovery module is electrically connected to the direct current bus and is used for recovering the pumped voltage in the direct current bus under the power generation state of at least one driver. According to the variable pitch servo driver provided by the invention, the pumping energy is fed back to the power grid in time without influencing the normal functions and hardware architecture of the driver, and the use cost is reduced.

Description

Technical Field

[0001] The present disclosure relates to the field of wind turbine design, and in particular to a variable pitch servo driver and a variable pitch system. Background Art

[0002] Currently, IPC (Individual Pitch Control) is a control technology for wind turbines. Its core is to issue different pitch control instructions according to the actual load of each blade, control the change of the pitch angle, and enable each blade to obtain a different target position.

[0003] Currently, IPC has been used in batches for load shedding of the entire machine. However, when the blades move frequently, the DC bus voltage of the pitch drive is pumped up due to the continuous energy feedback from the blades to the pitch system, which in turn causes the power demand of the bleeder resistor to increase continuously, causing a series of problems such as heat and reliability. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the defect of DC bus voltage pumping in the prior art and to provide a variable pitch servo drive and a variable pitch system.

[0005] The present invention solves the above technical problems through the following technical solutions:

[0006] According to a first aspect of the present disclosure, there is provided a pitch servo drive, the pitch servo drive comprising a drive module and an energy recovery module;

[0007] The drive module includes a plurality of drivers and a DC bus electrically connecting the drivers, and the driver includes a power generation mode and a motoring mode;

[0008] The driver is used to convert the obtained mechanical energy into electrical energy in the power generation mode, or the driver is used to convert the obtained electrical energy into mechanical energy in the motoring mode;

[0009] The energy recovery module is electrically connected to the DC bus and is used to recover the voltage pumped up in the DC bus when at least one of the drivers is in a power generation state.

[0010] Preferably, the energy recovery module comprises an inverter unit and a transformer unit which are electrically connected in sequence, and the transformer unit is connected to an electric storage device or a power grid;

[0011] Wherein, the inverter unit is used to convert the pumped voltage in the DC bus into a first voltage;

[0012] The voltage transformation unit is used to transform the first voltage into target electric energy, and output the target electric energy to the power storage device or the power grid.

[0013] Preferably, the voltage transformation unit includes a transformer.

[0014] Preferably, the inverter unit includes a three-phase inverter.

[0015] Preferably, the three-phase inverter comprises a three-phase inverter circuit;

[0016] Each phase inverter circuit includes a relay unit and a power unit which are electrically connected in sequence.

[0017] Preferably, the relay unit comprises a slow-on resistor and a contact switch connected in parallel at both ends of the slow-on resistor;

[0018] The relay unit is used to protect the inverter circuit, and the contact switch is configured to be opened in a first state and closed in a second state.

[0019] Preferably,

[0020] The input ends of the three power units are all electrically connected to the positive voltage end of the DC bus;

[0021] The output ends of the three power units are electrically connected to the negative voltage end of the DC bus;

[0022] One end of the relay unit is electrically connected to the connection between the two power units, and the other end of the relay unit is electrically connected to the transformer unit.

[0023] Preferably, any of the power units comprises a first power subunit and a second power subunit connected in series;

[0024] The first power subunit includes a first power transistor and a first diode; wherein the source of the first power transistor is electrically connected to the anode of the first diode, the drain of the first power transistor and the cathode of the first diode are both electrically connected to the positive voltage end of the DC bus, and the gate of the first power transistor is electrically connected to the control circuit;

[0025] The second power subunit includes a second power transistor and a second diode, wherein the source of the second power transistor and the anode of the second diode are both electrically connected to the negative voltage end of the DC bus, the drain of the second power transistor and the cathode of the second diode are both electrically connected to the source of the first power transistor, and the gate of the second power transistor is electrically connected to the control circuit.

[0026] Preferably, the pitch servo driver further comprises a plurality of isolation modules; each isolation module corresponds to one driver;

[0027] Different isolation modules are used to isolate different drivers from each other;

[0028] and / or,

[0029] A plurality of the drivers correspond to a plurality of the energy recovery modules, or a plurality of the drivers correspond to one energy recovery module.

[0030] Preferably, the isolation module includes a diode;

[0031] Wherein, the anode of the diode is electrically connected to the corresponding output terminal of the driver, and the cathode of the diode is electrically connected to the input terminal of the energy recovery module.

[0032] According to a second aspect of the present disclosure, a pitch system is provided, wherein the pitch system comprises the pitch servo drive according to the first aspect of the present disclosure.

[0033] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present disclosure.

[0034] The positive and progressive effects of this disclosure are:

[0035] The variable pitch servo drive provided by the present invention adds an energy recovery module in parallel to the DC bus without changing the original drive architecture. When the DC bus voltage of the variable pitch servo drive has been pumped up but has not exceeded the discharge point, the energy recovery module is started, thereby inverting the DC power on the DC bus into industrial frequency AC power, and sending it to the power grid through a transformer to completely avoid pumping up the bus voltage, thereby improving energy utilization while protecting the safety of the variable pitch servo drive. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a structural diagram of a currently common variable pitch servo drive;

[0037] Figure 2 This is a module schematic diagram of the pitch servo drive provided in Embodiment 1 of the present disclosure;

[0038] Figure 3 This is a schematic diagram of the structure of the pitch servo driver provided in Embodiment 1 of the present disclosure;

[0039] Figure 4 This is a schematic diagram of the structure of multiple drivers corresponding to multiple energy recovery modules in Embodiment 1 of the present disclosure;

[0040] Figure 5 It is a structural schematic diagram of a plurality of drivers corresponding to one energy recovery module in Embodiment 1 of the present disclosure. DETAILED DESCRIPTION

[0041] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples.

[0042] Prefixes such as "first" and "second" are used in the embodiments of the present disclosure only to distinguish different description objects, and have no limiting effect on the position, order, priority, quantity or content of the described objects. The use of prefixes such as ordinal numbers to distinguish description objects in the embodiments of the present disclosure does not constitute a limitation on the described objects. For the statement of the described objects, please refer to the description in the context of the claims or embodiments, and no unnecessary limitation should be constituted due to the use of such prefixes. In addition, in the description of the present embodiment, unless otherwise specified, the meaning of "plurality" is two or more.

[0043] like Figure 1 As shown, the current common variable pitch servo drive uses a diode to separate the backup power supply and the DC bus. If the DC bus voltage pump rises to the discharge threshold, the discharge circuit will be opened to discharge the energy into the brake resistor. Frequent discharges can easily cause the temperature of the brake resistor to rise and reduce its life. At the same time, the heat of the resistor causes the temperature inside the wheel hub to increase, shortening the life of electronic devices.

[0044] In view of this, the present disclosure provides a variable pitch servo drive and a variable pitch system to realize timely feedback of pumped energy to the power grid without affecting the normal function and hardware architecture of the drive, thereby improving the life of electronic components.

[0045] Example 1

[0046] like Figure 2 As shown, the pitch servo driver provided in this embodiment includes a drive module 100 and an energy recovery module 200;

[0047] The drive module 100 includes a plurality of drivers and a DC bus electrically connecting the drivers, wherein the driver includes a power generation mode and a motoring mode;

[0048] The driver is used to convert the obtained mechanical energy into electrical energy in the power generation mode, or the driver is used to convert the obtained electrical energy into mechanical energy in the motoring mode;

[0049] The energy recovery module 200 is electrically connected to the DC bus and is used to recover the voltage pumped up in the DC bus when at least one of the drivers is in a power generation state.

[0050] The variable pitch servo drive provided by the present invention adds an energy recovery module in parallel to the DC bus without changing the original drive architecture. When the DC bus voltage of the variable pitch servo drive has been pumped up but has not exceeded the discharge point, the energy recovery module is started, thereby inverting the DC power on the DC bus into industrial frequency AC power, and sending it to the power grid through a transformer to completely avoid pumping up the bus voltage, thereby improving energy utilization while protecting the safety of the variable pitch servo drive.

[0051] like Figure 2 As shown, in this embodiment, the energy recovery module 200 includes an inverter unit 201 and a transformer unit 202 which are electrically connected in sequence, and the transformer unit 202 is connected to an electric storage device or a power grid;

[0052] The inverter unit 201 is used to convert the pumped voltage in the DC bus into a first voltage;

[0053] The voltage transformation unit 202 is used to transform the first voltage into target electric energy, and output the target electric energy to the power storage device or the power grid.

[0054] In one embodiment, the voltage transformation unit 202 includes a transformer. The transformer is provided to change the voltage output by the inverter unit, so that the changed voltage meets the standard of the power grid, thereby completing the energy recovery of the power grid from electric energy.

[0055] In one implementation, the inverter unit 201 includes a three-phase inverter.

[0056] like Figure 3 As shown, the three-phase inverter in this embodiment includes a three-phase inverter circuit; wherein each phase inverter circuit includes a relay unit 301 and a power unit 302 which are electrically connected in sequence.

[0057] In one implementation, the power unit may be an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor).

[0058] In this embodiment, a three-phase inverter is added in parallel to the DC bus. The three-phase inverter includes 6 power devices (such as IGBT). When the DC bus voltage of the driver has been pumped up but has not exceeded the discharge point, the three-phase inverter is started to invert the DC power on the DC bus into industrial frequency AC power, which is sent to the power grid through the auxiliary transformer, thereby completely avoiding the pumping of the bus voltage and replacing the role of the braking resistor.

[0059] The relay unit 301 in this embodiment includes a slow-on resistor and a contact switch connected in parallel at both ends of the slow-on resistor;

[0060] The relay unit 301 is used to protect the inverter circuit, and the contact switch is configured to be open in a first state and closed in a second state.

[0061] The first state is a state in which the contact switch is disconnected when a pump-up voltage appears in the DC bus, and the second state is a state in which the contact switch is closed after the DC bus voltage is stabilized.

[0062] Specifically, when a pump-up voltage appears on the DC bus, the contact switch is disconnected, and the voltage of the DC bus is ensured to rise slowly through the slow-up resistor to prevent impact on the DC bus capacitor; when the DC bus voltage is stable, the contact switch is closed, so that the energy recovery module works normally.

[0063] In this embodiment, a slow-on resistor and a contact switch are provided so that when a pump-up voltage appears on the DC bus, the contact switch is disconnected and the power-on current is limited by the slow-on resistor, thereby making the voltage change of the capacitor smoother; further, when the circuit is running stably, the contact switch is closed to reduce or eliminate the voltage drop caused by the slow-on resistor, thereby improving the efficiency of the circuit.

[0064] like Figure 3 As shown, the input ends of the three power units 302 in this embodiment are all electrically connected to the positive voltage end of the DC bus; the output ends of the three power units 302 are electrically connected to the negative voltage end of the DC bus; one end of the relay unit is electrically connected to the connection between the two power units, and the other end of the relay unit is electrically connected to the transformer unit; any power unit includes a first power subunit 302 and a second power subunit 3022 connected in series;

[0065] The first power subunit 3021 includes a first power transistor 30211 and a first diode 30212; wherein the source of the first power transistor 30211 is electrically connected to the anode of the first diode 30212, the drain of the first power transistor 30211 and the cathode of the first diode 30212 are both electrically connected to the positive voltage end of the DC bus, and the gate of the first power transistor 30211 is electrically connected to the control circuit;

[0066] The second power subunit 3022 includes a second power transistor 30221 and a second diode 30222, wherein the source of the second power transistor 30221 and the anode of the second diode 30222 are both electrically connected to the negative voltage end of the DC bus, the drain of the second power transistor 30221 and the cathode of the second diode 30222 are both electrically connected to the source of the first power transistor, and the gate of the second power transistor 30221 is electrically connected to the control circuit;

[0067] Wherein, the control circuit is used to provide a control voltage for the gate.

[0068] It should be noted that in this embodiment, there is no specific limitation on the models of power transistors and diodes.

[0069] The three relay units in this embodiment are three incoming line slow-on resistors and contactors K1, K2, and K3 connected in parallel. After the three-phase inverter is connected to the power grid, the slow-on resistors are first put into operation (K1, K2, and K3 are all in the disconnected state at this time), so as to ensure that the voltage of the DC bus rises slowly and prevent impact on the DC bus capacitor. When the voltage of the DC bus is stable (such as the DC bus voltage is about 565 volts), K1, K2, and K3 are closed, the slow-on resistors are bypassed, and the three-phase inverter enters the working state, further ensuring the stability of the circuit.

[0070] like Figure 4 As shown, in this embodiment, a plurality of the drivers may correspond to a plurality of the energy recovery modules, that is, the number of the drivers is consistent with the number of the energy recovery modules.

[0071] like Figure 5 As shown, in a preferred implementation, a plurality of the drivers may correspond to one energy recovery module, that is, a plurality of drivers may share one energy recovery module, thereby further reducing production costs.

[0072] like Figure 5 As shown, the pitch servo driver in this embodiment further includes a plurality of isolation modules 401; each isolation module 401 corresponds to a driver;

[0073] The isolation module 401 is used to isolate different drivers from each other.

[0074] The isolation module in this embodiment includes a diode;

[0075] The anode of the diode is electrically connected to the output end of the corresponding driver, and the cathode of the diode is electrically connected to the input end of the energy recovery module.

[0076] By setting up an isolation module, the influence of reverse current is effectively prevented, and the mutual influence between the DC buses of the three drivers is prevented. Isolation diodes must be set between the energy feedback device and the three drivers to ensure that the three drivers are not connected to each other, further improving the stability of the circuit.

[0077] In one implementation manner, the inverter module in this embodiment includes three variable pitch servo drivers; the isolation module includes three diodes.

[0078] In this embodiment, since the three drivers do not pump up energy at the same time, the three drivers in the driving module in this embodiment share one energy recovery module, which further reduces the production cost.

[0079] Example 2

[0080] In this embodiment, a pitch control system is provided, and the pitch control system includes the pitch control servo drive described in Embodiment 1.

[0081] The variable pitch system provided by the present invention adds an energy recovery module in parallel to the DC bus without changing the original driver architecture. When the DC bus voltage of the variable pitch servo driver has been pumped up but has not exceeded the discharge point, the energy recovery module is started to invert the DC power on the DC bus into industrial frequency AC power, and then transforms it into AC power through a transformer to completely avoid pumping up the bus voltage, thereby improving energy utilization while protecting the safety of the variable pitch servo driver.

[0082] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A variable pitch servo drive, characterized in that: The pitch servo driver comprises a drive module and an energy recovery module; The drive module includes a plurality of drivers and a DC bus electrically connecting the drivers, and the driver includes a power generation mode and a motoring mode; The driver is used to convert the obtained mechanical energy into electrical energy in the power generation mode, or the driver is used to convert the obtained electrical energy into mechanical energy in the motoring mode; The energy recovery module is electrically connected to the DC bus and is used to recover the voltage pumped up in the DC bus when at least one of the drivers is in a power generation state.

2. The pitch servo drive according to claim 1, characterized in that: The energy recovery module comprises an inverter unit and a transformer unit which are electrically connected in sequence, and the transformer unit is connected to an electric storage device or a power grid; Wherein, the inverter unit is used to convert the pumped voltage in the DC bus into a first voltage; The voltage transformation unit is used to transform the first voltage into target electric energy, and output the target electric energy to the power storage device or the power grid.

3. The pitch servo driver according to claim 2, characterized in that: The voltage transformation unit includes a transformer; and / or, The inverter unit includes a three-phase inverter.

4. The pitch servo driver according to claim 3, characterized in that: The three-phase inverter includes a three-phase inverter circuit; Each phase inverter circuit includes a relay unit and a power unit which are electrically connected in sequence.

5. The pitch servo driver according to claim 4, characterized in that: The relay unit includes a slow-on resistor and a contact switch connected in parallel at both ends of the slow-on resistor; The relay unit is used to protect the inverter circuit, and the contact switch is configured to be opened in a first state and closed in a second state.

6. The pitch servo driver according to claim 4, characterized in that: The input ends of the three power units are all electrically connected to the positive voltage end of the DC bus; The output ends of the three power units are electrically connected to the negative voltage end of the DC bus; One end of the relay unit is electrically connected to a connection point between the two power units, and the other end of the relay unit is electrically connected to the transformer unit.

7. The pitch servo driver according to claim 6, characterized in that: Any of the power units comprises a first power subunit and a second power subunit connected in series; The first power subunit includes a first power transistor and a first diode; wherein the source of the first power transistor is electrically connected to the anode of the first diode, the drain of the first power transistor and the cathode of the first diode are both electrically connected to the positive voltage end of the DC bus, and the gate of the first power transistor is electrically connected to the control circuit; The second power subunit includes a second power transistor and a second diode, wherein the source of the second power transistor and the anode of the second diode are both electrically connected to the negative voltage end of the DC bus, the drain of the second power transistor and the cathode of the second diode are both electrically connected to the source of the first power transistor, and the gate of the second power transistor is electrically connected to the control circuit.

8. The pitch servo driver according to claim 1, characterized in that: The pitch servo driver further comprises a plurality of isolation modules; each isolation module corresponds to one driver; Different isolation modules are used to isolate different drivers from each other; and / or, A plurality of the drivers correspond to a plurality of the energy recovery modules, or a plurality of the drivers correspond to one energy recovery module.

9. The pitch servo driver according to claim 8, characterized in that: The isolation module includes a diode; Wherein, the anode of the diode is electrically connected to the corresponding output terminal of the driver, and the cathode of the diode is electrically connected to the input terminal of the energy recovery module.

10. A variable pitch system, characterized in that: The pitch system comprises a pitch servo drive according to any one of claims 1-9.

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