Pitch servo driver with controllable rectifier input and driving method thereof

Abstract

The present invention provides a variable pitch servo driver with controllable rectifier input and a driving method thereof, wherein the driver comprises a three-phase alternating current detection unit, a controllable rectifier module, a power-on buffer unit, an auxiliary power supply, a control unit and an energy storage capacitor, wherein the input ends of the three-phase alternating current detection unit, the controllable rectifier module and the power-on buffer unit are all connected to the three-phase alternating current, the output end of the power-on buffer unit is connected to the output end of the controllable rectifier module, the output end of the controllable rectifier module is connected to the energy storage capacitor and further connected to the input end of the auxiliary power supply, the output end of the auxiliary power supply is connected to the power input end of the control unit, and the control unit is connected to the controllable rectifier module to provide a rectification control signal. Compared with an uncontrollable diode rectifier circuit, the DC bus voltage of the controllable rectifier is relatively stable, which is conducive to the stable control of the driver output.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power generation, and in particular to a servo driver and a driving method thereof used in a wind power generation pitch control system. Background Art

[0002] At present, the mainstream rectifier circuit of the variable pitch servo drive is composed of 6 diodes to form an uncontrollable three-phase full-bridge rectifier bridge, which is then rectified into a relatively stable DC power after capacitor filtering. The relationship between the rectified DC voltage Udc and the input three-phase AC voltage Uac is Udc=√2*Uac. It can be seen from the formula that the DC bus voltage Udc after rectification and filtering and the grid input three-phase AC voltage Uac are in a linear relationship. The DC bus voltage Udc will decrease or increase with the decrease of the input three-phase AC voltage Uac. When the DC bus voltage Udc is high to the upper limit of the safety voltage set by the driver, the driver will report an input overvoltage / bus overvoltage fault and stop working. From the above, it can be seen that the main problem of this circuit is that the rectified DC bus voltage Udc is uncontrollable. When the power grid is unstable, the driver is prone to abnormal bus voltage and report a fault.

[0003] my country's wind power industry is booming, and the installed capacity is steadily increasing, which has made important contributions to the effective use of green energy, clear water and blue sky, and sustainable development in my country. However, most wind turbines are installed in remote areas with harsh natural conditions, especially in mountainous areas. The power grids in these remote areas generally have problems with unstable power grids and poor power quality. The variable pitch system is an important component of wind turbines, and the servo drive is the core component of the variable pitch. At present, the input rectification of the variable pitch drive is mostly uncontrollable. When the grid voltage fluctuates too much or the harmonic pollution is serious, the bus voltage of the drive will exceed the normal voltage range, and the drive will frequently report input overvoltage / bus overvoltage faults, which will not only affect normal power generation but also pose a safety hazard. For this reason, it is urgent to develop a variable pitch servo drive with controllable rectification input to solve this problem. Summary of the invention

[0004] In view of the deficiencies of the current prior art, an object of the present invention is to provide a safer variable pitch servo driver with a controllable rectifier input and a driving method thereof.

[0005] To achieve the above object, the embodiments of the present invention adopt the following technical solutions:

[0006] A variable pitch servo driver with a controllable rectifier input, the driver comprising a three-phase AC detection unit, a controllable rectifier module, a power-on buffer unit, an auxiliary power supply, a control unit and an energy storage capacitor, the input ends of the three-phase AC detection unit, the controllable rectifier module and the power-on buffer unit are all connected to the three-phase AC, the output end of the power-on buffer unit is connected to the output end of the controllable rectifier module, the output end of the controllable rectifier module is connected to the energy storage capacitor and further connected to the input end of the auxiliary power supply, the output end of the auxiliary power supply is connected to the power input end of the control unit, the control unit is connected to the controllable rectifier module to provide a rectification control signal, the control unit is also connected to the power-on buffer unit to provide a delayed switching signal, and the control unit is also connected to the three-phase AC detection unit to receive the three-phase AC detection signal provided by the three-phase AC detection unit.

[0007] Furthermore, the controllable rectifier module includes a rectifier bridge, the lower bridge arm of the rectifier bridge is three uncontrollable diodes, and the upper bridge arm of the rectifier bridge is three thyristors, which respectively receive rectification control signals provided by the control unit.

[0008] Furthermore, the power-on buffer unit includes three diodes, a first resistor and a controllable switch, the positive poles of the three diodes are respectively connected to the three-phase alternating current, the negative poles of the three diodes are all connected to the first end of the first resistor, the second end of the first resistor is connected to the first end of the controllable switch, the second end of the controllable switch is connected to the controllable rectifier module, the controllable switch also has a signal input end to receive the delayed switch signal, and the controllable switch is in a normally closed state.

[0009] Furthermore, the energy storage capacitor is connected in parallel to both ends of the output end of the controllable rectifier module.

[0010] Furthermore, the control unit is also connected to the output end of the controllable rectifier module through a DC bus voltage detection unit to detect the DC bus voltage output by the controllable rectifier module.

[0011] A driving method for a variable pitch servo driver with a controllable rectifier input adopts the driver as described above, and the driving method comprises the following steps:

[0012] Step S1, connecting three-phase alternating current, the three-phase alternating current passes through the power-on buffer unit and the controllable rectifier module to form a closed loop, and the DC bus voltage output by the controllable rectifier module and the energy storage capacitor are powered up;

[0013] Step S2, when the DC bus voltage reaches or exceeds the minimum operating voltage of the auxiliary power supply, the auxiliary power supply starts to work and outputs the low-voltage DC voltage required by the control unit and the three-phase AC power detection unit;

[0014] Step S3, the control unit and the three-phase AC power detection unit obtain the required low-voltage DC voltage and start working;

[0015] Step S4, the control unit outputs a rectification control signal according to the three-phase AC power detection signal provided by the three-phase AC power detection unit to drive the controllable rectification module to work normally, and the controllable rectification module starts to supply power to the system;

[0016] Step S5, the control unit outputs a delayed switch signal to control the power-on buffer unit to be disconnected from the controllable rectifier module;

[0017] Step S6, the control unit adjusts the rectification control signal in real time through the three-phase AC detection signal provided in real time by the three-phase AC detection unit, so that the controllable rectification module outputs a stable DC bus voltage;

[0018] Step S7, when the DC bus voltage cannot be stabilized within a normal range, the control unit controls the controllable rectifier module to shut down through the rectification control signal, and controls the driver to stop outputting an overvoltage fault report, and then outputs the delayed switching signal to control the power-on buffer unit to connect to the controllable rectifier module, and repeats steps S2-S6.

[0019] Furthermore, the controlled rectifier module includes a rectifier bridge, the lower bridge arm of the rectifier bridge is three uncontrollable diodes, and the upper bridge arm of the rectifier bridge is three thyristors, which respectively receive rectification control signals provided by the control unit; in the step S1, the power-on buffer unit and the controlled rectifier module form a closed loop, and the power-on buffer unit and the lower bridge arm of the rectifier bridge in the controlled rectifier module form a closed loop; in the step S7, the power-on buffer unit is connected to the controlled rectifier module, and the power-on buffer unit and the lower bridge arm of the rectifier bridge in the controlled rectifier module are connected.

[0020] Furthermore, the power-on buffer unit includes three diodes, a first resistor and a controllable switch, the positive poles of the three diodes are respectively connected to the three-phase alternating current, the negative poles of the three diodes are all connected to the first end of the first resistor, the second end of the first resistor is connected to the first end of the controllable switch, the second end of the controllable switch is connected to the controllable rectifier module, the controllable switch also has a signal input end to receive the delayed switch signal, and the controllable switch is in a normally closed state.

[0021] Furthermore, the three-phase AC power detection signal includes a three-phase AC power voltage and a phase angle; and the rectification control signal is used to control the phase angle of the rectifier bridge conduction.

[0022] Furthermore, the control unit is also connected to the output end of the controllable rectifier module through a DC bus voltage detection unit to detect the DC bus voltage output by the controllable rectifier module and generate the rectification control signal.

[0023] The present invention discloses a variable pitch servo driver with controllable rectifier input and a driving method thereof, wherein the rectifier bridge adopts thyristor, and through cooperation with the power-on buffer unit and the auxiliary power supply, when the DC bus voltage exceeds the normal range, the rectifier bridge is turned off, and the output is stopped to report an overvoltage fault (i.e., no fault is reported), and the system is slowly restored to normal by the temporary power supply of the power-on buffer unit and the auxiliary power supply, and then the rectifier bridge is turned on to work normally. Compared with the uncontrollable diode rectifier circuit, the DC bus voltage of the controllable rectifier is more stable, which is conducive to the stable control of the driver output; and the adaptability of the driver to the power grid is increased, which can reduce the driver failure rate caused by the instability of the power grid, improve safety, and increase the power generation time to reduce losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be 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 paying creative work.

[0025] Figure 1 This is a structural block diagram of a pitch servo driver with a controllable rectifier input according to an embodiment of the present invention;

[0026] Figure 2 The present invention is a flowchart of a driving method of a pitch servo drive having a controllable rectifier as an input according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0028] See also Figure 1As shown, an embodiment of the present invention is a variable pitch servo driver with a controllable rectifier input, the driver comprising a three-phase AC detection unit, a controllable rectifier module, a power-on buffer unit, an auxiliary power supply, a control unit and an energy storage capacitor, the input ends of the three-phase AC detection unit, the controllable rectifier module and the power-on buffer unit are all connected to the three-phase AC, the output end of the power-on buffer unit is connected to the output end of the controllable rectifier module, the output end of the controllable rectifier module is connected to the energy storage capacitor and further connected to the input end of the auxiliary power supply, the output end of the auxiliary power supply is connected to the power input end of the control unit, the control unit is connected to the controllable rectifier module to provide a rectification control signal, the control unit is also connected to the power-on buffer unit to provide a delayed switching signal, and the control unit is also connected to the three-phase AC detection unit to receive the three-phase AC detection signal provided by the three-phase AC detection unit.

[0029] The controllable rectifier module includes a rectifier bridge B1, the lower bridge arm of the rectifier bridge B1 is three uncontrollable diodes, and the upper bridge arm of the rectifier bridge B1 is three thyristors, which respectively receive rectifier control signals SCR_DRVA, SCR_DRVB, and SCR_DRVC provided by the control unit.

[0030] The power-on buffer unit includes three diodes D1, D2, D3, a first resistor R1 and a controllable switch K1. The positive electrodes of the three diodes D1, D2, and D3 are respectively connected to the three-phase alternating currents LA, LB, and LC. The negative electrodes of the three diodes D1, D2, and D3 are all connected to the first end of the first resistor R1. The second end of the first resistor R1 is connected to the first end of the controllable switch K1. The second end of the controllable switch K1 is connected to the controllable rectifier module. The controllable switch K1 also has a signal input end to receive the delayed switch signal RELAY1_DRV. The controllable switch K1 is in a normally closed state. Of course, the controllable switch K1 also has a ground terminal GND.

[0031] The energy storage capacitor C1 is connected in parallel to two ends DC+ and DC- of the output end of the controllable rectifier module.

[0032] The control unit is also connected to the output end of the controllable rectifier module through a DC bus voltage detection unit to detect the DC bus voltage DC+ output by the controllable rectifier module. Of course, the DC bus voltage detection unit is also connected to the auxiliary power supply, which provides the working voltage.

[0033] See also Figure 2 As shown, in one embodiment of the present invention, a driving method of a variable pitch servo driver with a controllable rectifier input is provided, using the driver as described above, and the driving method comprises the following steps:

[0034] Step S1, connecting three-phase alternating current, the three-phase alternating current forms a closed loop through the power-on buffer unit and the controllable rectifier module, and the DC bus voltage output by the controllable rectifier module and the energy storage capacitor are powered up;

[0035] Step S2, when the DC bus voltage reaches or exceeds the minimum operating voltage of the auxiliary power supply, the auxiliary power supply starts to work and outputs the low-voltage DC voltage required by the control unit and the three-phase AC power detection unit;

[0036] Step S3, the control unit and the three-phase AC power detection unit obtain the required low-voltage DC voltage and start working;

[0037] Step S4, the control unit outputs a rectification control signal according to the three-phase AC power detection signal provided by the three-phase AC power detection unit to drive the controllable rectification module to work normally, and the controllable rectification module starts to supply power to the system;

[0038] Step S5, the control unit outputs a delayed switch signal to control the power-on buffer unit to be disconnected from the controllable rectifier module;

[0039] Step S6, the control unit adjusts the rectification control signal in real time through the three-phase AC detection signal provided in real time by the three-phase AC detection unit, so that the controllable rectification module outputs a stable DC bus voltage;

[0040] Step S7, when the DC bus voltage cannot be stabilized within a normal range, the control unit controls the controllable rectifier module to shut down through the rectification control signal, and controls the driver to stop outputting an overvoltage fault report, and then outputs the delayed switching signal to control the power-on buffer unit to connect to the controllable rectifier module, and repeats steps S2-S6.

[0041] Among them, the controlled rectifier module includes a rectifier bridge B1, the lower bridge arm of the rectifier bridge B1 is three uncontrollable diodes, and the upper bridge arm of the rectifier bridge B1 is three thyristors, which respectively receive the rectification control signals SCR_DRVA, SCR_DRVB, and SCR_DRVC provided by the control unit; in the step S1, the power-on buffer unit and the controlled rectifier module form a closed loop, and the power-on buffer unit and the lower bridge arm of the rectifier bridge B1 in the controlled rectifier module form a closed loop; in the step S7, the power-on buffer unit is connected to the controlled rectifier module, and the power-on buffer unit and the lower bridge arm of the rectifier bridge B1 in the controlled rectifier module are connected.

[0042] The power-on buffer unit includes three diodes D1, D2, D3, a first resistor R1 and a controllable switch K1. The positive electrodes of the three diodes D1, D2, and D3 are respectively connected to the three-phase alternating currents LA, LB, and LC. The negative electrodes of the three diodes D1, D2, and D3 are all connected to the first end of the first resistor R1. The second end of the first resistor R1 is connected to the first end of the controllable switch K1. The second end of the controllable switch K1 is connected to the controllable rectifier module. The controllable switch K1 also has a signal input end to receive the delayed switch signal RELAY1_DRV. The controllable switch K1 is in a normally closed state. Of course, the controllable switch K1 also has a ground terminal GND.

[0043] The three-phase AC detection signal includes a three-phase AC voltage and a phase angle; the rectification control signal is used to control the phase angle of the rectification bridge B1.

[0044] The control unit is also connected to the output end of the controllable rectifier module through a DC bus voltage detection unit to detect the DC bus voltage DC+ output by the controllable rectifier module and generate the rectification control signal.

[0045] The present invention discloses a variable pitch servo driver with controllable rectifier input and a driving method thereof. The rectifier bridge adopts thyristor, and through cooperation with a power-on buffer unit and an auxiliary power supply, when the DC bus voltage exceeds the normal range, the rectifier bridge is turned off, and the output is stopped to report an overvoltage fault (i.e., no fault is reported). By temporarily supplying power to the power-on buffer unit and the auxiliary power supply, the system slowly returns to normal, and then the rectifier bridge is turned on to work normally. Compared with the uncontrollable diode rectifier circuit, the DC bus voltage of the controllable rectifier is more stable, which is conducive to the stable control of the driver output; and the adaptability of the driver to the power grid is increased, which can reduce the driver failure rate caused by the instability of the power grid, improve safety, and increase the power generation time to reduce losses.

[0046] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A driving method for a variable pitch servo drive with a controllable rectifier input, using a drive, the drive comprising a three-phase AC detection unit, a controllable rectifier module, a power-on buffer unit, an auxiliary power supply, a control unit and an energy storage capacitor, the input ends of the three-phase AC detection unit, the controllable rectifier module and the power-on buffer unit are all connected to the three-phase AC, the output end of the power-on buffer unit is connected to the output end of the controllable rectifier module, the output end of the controllable rectifier module is connected to the energy storage capacitor and further connected to the input end of the auxiliary power supply, the output end of the auxiliary power supply is connected to the power input end of the control unit, the control unit is connected to the controllable rectifier module to provide a rectification control signal, the control unit is also connected to the power-on buffer unit to provide a delayed switching signal, the control unit is also connected to the three-phase AC detection unit to receive the three-phase AC detection signal provided by the three-phase AC detection unit, characterized in that The driving method comprises the following steps: Step S1, connecting three-phase alternating current, the three-phase alternating current forms a closed loop through the power-on buffer unit and the controllable rectifier module, and the DC bus voltage output by the controllable rectifier module and the energy storage capacitor are powered up; Step S2, when the DC bus voltage reaches or exceeds the minimum operating voltage of the auxiliary power supply, the auxiliary power supply starts to work and outputs the low-voltage DC voltage required by the control unit and the three-phase AC power detection unit; Step S3, the control unit and the three-phase AC power detection unit obtain the required low-voltage DC voltage and start working; Step S4, the control unit outputs a rectification control signal according to the three-phase AC power detection signal provided by the three-phase AC power detection unit to drive the controllable rectification module to work normally, and the controllable rectification module starts to supply power to the system; Step S5, the control unit outputs a delayed switch signal to control the power-on buffer unit to be disconnected from the controllable rectifier module; Step S6, the control unit adjusts the rectification control signal in real time through the three-phase AC detection signal provided in real time by the three-phase AC detection unit, so that the controllable rectification module outputs a stable DC bus voltage; Step S7, when the DC bus voltage cannot be stabilized within a normal range, the control unit controls the controllable rectifier module to shut down through the rectifier control signal, and controls the driver to stop outputting an overvoltage fault report, and then outputs the delayed switch signal to control the power-on buffer unit to connect to the controllable rectifier module, and repeats steps S2 to S6; The controlled rectifier module includes a rectifier bridge, the lower bridge arm of the rectifier bridge is three uncontrollable diodes, and the upper bridge arm of the rectifier bridge is three thyristors, which respectively receive the rectifier control signals provided by the control unit; in the step S1, the power-on buffer unit and the controlled rectifier module form a closed loop, that is, the power-on buffer unit and the lower bridge arm of the rectifier bridge in the controlled rectifier module form a closed loop; in the step S7, the power-on buffer unit is connected to the controlled rectifier module, that is, the power-on buffer unit and the lower bridge arm of the rectifier bridge in the controlled rectifier module are connected; The power-on buffer unit includes three diodes, a first resistor and a controllable switch, the positive electrodes of the three diodes are respectively connected to the three-phase alternating current, the negative electrodes of the three diodes are all connected to the first end of the first resistor, the second end of the first resistor is connected to the first end of the controllable switch, the second end of the controllable switch is connected to the controllable rectifier module, the controllable switch also has a signal input end for receiving the delayed switch signal, and the controllable switch is in a normally closed state.

2. The driving method according to claim 1, characterized in that: The three-phase AC detection signal includes a three-phase AC voltage and a phase angle; the rectification control signal is used to control the phase angle of the rectifier bridge.

3. The driving method according to claim 1, characterized in that: The control unit is also connected to the output end of the controllable rectifier module through a DC bus voltage detection unit to detect the DC bus voltage output by the controllable rectifier module and generate the rectification control signal.

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