Thyristor activator and its control method
The thyristor starter system addresses common-mode noise issues by controlling the firing phases and timings of thyristors in inverters and converters, achieving stable operation and noise suppression.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- TMEIC CORP (100 00)
- Filing Date
- 2023-03-07
- Publication Date
- 2026-05-25
AI Technical Summary
Thyristor starting devices for synchronous machines face issues with common-mode noise due to simultaneous turn-on surges in the inverter and converter.
A thyristor starter system with a converter, DC reactor, and inverter, equipped with a position detector, control units, and a timing control circuit to manage the firing phases and timings of thyristors, preventing simultaneous firing to suppress common-mode noise.
The system effectively suppresses common-mode noise and prevents malfunctions by controlling the firing timing of thyristors in the inverter and converter, ensuring stable operation.
Smart Images
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Abstract
Description
Technical Field
[0006] , ,
[0001] The present disclosure relates to a thyristor starting device.
Background Art
[0002] Thyristor starting devices for starting synchronous machines such as generators and motors have been developed. The thyristor starting device includes a converter that converts AC power into DC power, a DC reactor that smooths the DC power, and an inverter that converts the DC power supplied from the converter via the DC reactor into variable-frequency AC power and supplies it to the synchronous machine. By controlling the AC power supplied to the synchronous machine, a stopped synchronous machine can be started and driven at a predetermined rotational speed (see Patent Document 1).
[0003] When an inverter or the like is composed of thyristors or the like, it is known that switching surges occur. In this regard, various methods for suppressing such surges have been proposed (see Patent Document 2).
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Patent Document 2
Summary of the Invention
Problems to be Solved by the Invention
[0005] On the other hand, when the thyristors of the inverter and the converter are simultaneously ignited, common-mode noise may occur due to turn-on surges.
[0006] An object of the present disclosure is to solve the above problems and realize a thyristor starting device and its control method capable of suppressing common-mode noise caused by turn-on surges. [Means for solving the problem]
[0007] According to one embodiment, a thyristor starter for starting a synchronous machine comprises a converter that converts AC power to DC power, a DC reactor that smooths the DC power, an inverter that converts the DC power supplied from the converter through the DC reactor into variable frequency AC power and supplies it to the synchronous machine, a position detector that detects the rotor position of the synchronous machine, a first control unit that controls the firing phase of a thyristor in the inverter based on the detection signal of the position detector, a second control unit that controls the firing phase of a thyristor in the converter based on the detection signal of the position detector so that the DC current flowing through the DC reactor matches the current command value, and a timing control circuit that controls the timing between the firing of a thyristor in the inverter and the firing of a thyristor in the converter.
[0008] Preferably, the timing control circuit stops the firing of the thyristor in the converter or inverter when the timing of the firing of the thyristor in the inverter and the firing of the thyristor in the converter overlap.
[0009] Preferably, the timing control circuit includes a gate prevention circuit that, if the timing of the thyristor firing in the inverter and the thyristor firing in the converter overlap, continues the firing if the thyristor firing in the converter or inverter has already started.
[0010] According to one embodiment, a control method for a thyristor starter for starting a synchronous machine, the thyristor starter includes a converter that converts AC power to DC power, a DC reactor that smooths the DC power, and an inverter that converts the DC power supplied from the converter through the DC reactor into variable frequency AC power and supplies it to the synchronous machine, and comprises the steps of detecting the rotor position of the synchronous machine, controlling the firing phase of a thyristor in the inverter based on the detection signal, controlling the firing phase of a thyristor in the converter based on the detection signal so that the DC current flowing through the DC reactor matches the current command value, and controlling the timing between the firing of a thyristor in the inverter and the firing of a thyristor in the converter. [Effects of the Invention]
[0011] The thyristor starter and its control method according to this disclosure are capable of suppressing common-mode noise caused by turn-on surges. [Brief explanation of the drawing]
[0012] [Figure 1] This is a circuit block diagram showing the configuration of a thyristor starter 100 according to Embodiment 1. [Figure 2] This diagram illustrates common-mode noise when the timing of thyristor firing in an inverter and thyristor firing in a converter overlap, according to the comparative example. [Figure 3] This diagram illustrates the configuration of the timing control circuit 18 according to Embodiment 1. [Figure 4] This diagram illustrates the operation of the timing control circuit 18 according to Embodiment 1. [Figure 5] This figure illustrates the configuration of a timing control circuit 18 according to a modified example of Embodiment 1. [Figure 6] This is a circuit block diagram showing the configuration of a thyristor starter 100# according to Embodiment 2. [Modes for carrying out the invention]
[0013] The embodiments will be described below with reference to the figures.
[0014] Figure 1 is a circuit block diagram showing the configuration of a thyristor starter 100 according to Embodiment 1. Referring to Figure 1, the thyristor starter 100 according to Embodiment 1 starts the synchronous machine 20 by accelerating the stopped synchronous machine 20 to a predetermined rotational speed.
[0015] The synchronous machine 20 includes a stator having armature windings ATU, ATV, ATW, and a rotor having field windings 22. The synchronous machine 20 is coupled to, for example, a gas turbine in a thermal power plant and is rotationally driven by the gas turbine. In the following description, a predetermined rotational speed will also be referred to as the "rated rotational speed".
[0016] The thyristor starter 100 is connected to the secondary side of the transformer TR. The primary side of the transformer TR is connected to the AC power supply 30. The transformer TR converts the three-phase AC voltage supplied from the AC power supply 30 into a three-phase AC voltage of a predetermined voltage value and supplies it to the thyristor starter 100.
[0017] The thyristor starter 100 comprises a converter 1, a DC reactor 3, and an inverter 2. Converter 1 is a three-phase full-wave rectifier containing at least six thyristors RP, SP, TP, RN, SN, and TN. The cathodes of thyristors RP, SP, and TP are all connected to the positive output terminal 1a, and their anodes are connected to the input terminals 1c, 1d, and 1e, respectively. The cathodes of thyristors RN, SN, and TN are connected to the input terminals 1c, 1d, and 1e, respectively, and their anodes are all connected to the negative output terminal 1b. Converter 1 converts three-phase AC power from transformer TR into variable voltage DC power.
[0018] The DC reactor 3 is connected between the positive output terminal 1a of the converter 1 and the positive output terminal 2a of the inverter 2. The DC reactor 3 smoothes the DC current Id output from the converter 1. The negative output terminal 1b of the converter 1 and the negative output terminal 2b of the inverter 2 are connected to each other. Another DC reactor 3 may be connected between the negative output terminal 1b of the converter 1 and the negative output terminal 2b of the inverter 2.
[0019] The three output terminals 2c, 2d, 2e of the inverter 2 are respectively connected to the three armature windings ATU, ATV, ATW of the synchronous machine 20. The inverter 2 is a three-phase separately excited inverter including at least six thyristors U, V, W, X, Y, Z. The anodes of the thyristors U, V, W are all connected to the positive input terminal 2a, and their cathodes are respectively connected to the output terminals 2c, 2d, 2e; The anodes of the thyristors X, Y, Z are respectively connected to the output terminals 2c, 2d, 2e, and their cathodes are all connected to the negative input terminal 2b.
[0020] The thyristor starter 100 further includes current converters 4, 5, a voltage detector 6, a position detector 7, a current detector 9, an inverter control unit 10, a converter control unit 13, and a timing control circuit 18.
[0021] The current converter 4 detects the three-phase alternating current flowing from the transformer TR to the converter 1, and gives a signal indicating the detected value to the current detector 9. Based on the signal from the current converter 4, the current detector 9 calculates a DC current Id♯ proportional to the DC current Id output from the converter 1, and gives a signal indicating the calculated value to the converter control unit 13. Specifically, the current detector 9 has a full-wave rectifier type diode rectifier, rectifies the detected three-phase alternating current, and converts it into the DC current Id♯.
[0022] The current converter 5 detects the current flowing from the inverter 2 to the armature windings ATU, ATV, ATW of the synchronous machine 20, and gives a signal indicating the detected value to the position detector 7.
[0023] The voltage detector 6 detects the instantaneous values of the three-phase AC voltages VU, VV, and VW supplied from the inverter 2 to the synchronous machine 20, and provides a signal indicating the detected value to the position detector 7. Specifically, the voltage detector 6 detects two of the line voltages of the three-phase AC voltage in the armature windings ATU, ATV, and ATW of the synchronous machine 20 (in Figure 1, these are the AC voltages between the U-phase and V-phase, VU-VV, and the AC voltages between the V-phase and W-phase, VV-VW). The voltage detector 6 may also be configured to detect three line voltages (AC voltages between the U-phase and V-phase, VU-VV, VV-VW, and VW-VU).
[0024] In this way, by detecting at least two of the line voltages among the AC voltages between the U-phase and V-phase (VU-VV), the AC voltages between the V-phase and W-phase (VV-VW), and the AC voltages between the W-phase and U-phase (VW-VU), the AC voltages of the U-phase, V-phase, and W-phase can be calculated. This conversion from line voltages to phase voltages is performed by the voltage detector 6 or the position detector 7.
[0025] The position detector 7 detects the position of the rotor of the synchronous machine 20 based on signals from the current transformer 5 and the voltage detector 6, and provides a signal indicating the detected value to the inverter control unit 10 and the converter control unit 13.
[0026] The inverter control unit 10 controls the firing phase of the inverter 2 based on the signal from the position detector 7. Specifically, the inverter control unit 10 includes a control angle calculation unit 11 and a gate pulse generator 12. The control angle calculation unit 11 calculates the phase control angle (firing angle) γ based on the detected rotor position of the synchronous machine 20 and provides the calculated phase control angle γ to the gate pulse generator 12. The gate pulse generator 12 generates a gate pulse (firing command) to be given to the gate of the thyristor of the inverter 2 based on the phase control angle γ received from the control angle calculation unit 11. The inverter control unit 10 corresponds to one embodiment of the "first control unit".
[0027] The converter control unit 13 controls the firing phase of the converter 1 based on the signal from the position detector 7 and the signal from the current detector 9. Specifically, the converter control unit 13 controls the firing phase of the converter 1 so that the DC current Id♯ detected by the current detector 9 matches the current command value Id*. Since the DC current Id♯ is proportional to the DC current Id, matching the DC current Id♯ to the current command value Id* is equivalent to matching the DC current Id to the current command value Id*. The converter control unit 13 corresponds to one embodiment of the "second control unit".
[0028] Specifically, the converter control unit 13 includes a speed control unit 14, a current control unit 15, a control angle calculation unit 16, and a gate pulse generator 17. The speed control unit 14 calculates the rotational speed of the synchronous machine 20 based on the detected rotor position of the synchronous machine 20. Based on the calculated rotational speed, the speed control unit 14 generates a current command value Id*, which is the target value of the DC current Id.
[0029] The current control unit 15 performs control calculations to make the DC current Id♯ follow the current command value Id* and generates the voltage command value VDC1*. For example, the current control unit 15 calculates the deviation ΔId between the current command value Id* and the DC current Id♯, and generates the voltage command value VDC1* by performing a proportional-integral (PI) operation on the calculated deviation ΔId. The current control unit 15 may also be configured to perform proportional-integral-differential (PID) operations.
[0030] The voltage command value VDC1* corresponds to a control command that specifies the DC voltage VDC1 that converter 1 should output. Converter 1 controls the DC voltage VDC1 so that it is greater than the DC voltage VDC2 on the input terminals 2a and 2b of inverter 2 by the amount of the voltage drop due to the DC reactor 3. This controls the DC current Id.
[0031] The control angle calculation unit 16 controls the phase control angle α based on the voltage command value VDC1* provided by the current control unit 15. The control angle calculation unit 16 then provides the calculated phase control angle α to the gate pulse generator 17.
[0032] The gate pulse generator 17 generates gate pulses (firing commands) to be applied to the gates of the thyristors of the converter 1 based on the phase control angle α received from the control angle calculation unit 16. By switching control of the converter 1 according to the gate pulses generated by the gate pulse generator 17, a DC current Id according to the current command value Id* is output from the converter 1.
[0033] The timing control circuit 18 is provided in correspondence with the converter 1 and controls the timing between the gate pulse (firing command) given to the gate of the thyristor in the inverter 2 and the gate pulse (firing command) of the thyristor in the converter 1.
[0034] Figure 2 illustrates common-mode noise caused by turn-on surge when the timing of thyristor firing in an inverter and thyristor firing in a converter overlap, according to the comparative example.
[0035] Refer to Figure 2, which shows the case where the timing of the gate pulse (firing command) of the thyristor on the converter side and the gate pulse (firing command) of the thyristor on the inverter side overlap (dotted line timing).
[0036] In this case, as shown in the figure, common-mode noise is generated because the voltage between the anode and cathode of the thyristors of the converter and inverter fluctuates simultaneously due to the turn-on surge.
[0037] In this example, the common-mode noise is superimposed on the control signal line electrically connected to the converter or inverter. In particular, this superimposed common-mode noise becomes larger when the switching timings of the inverter and converter overlap.
[0038] This can cause common-mode noise to be generated in the control signal line, potentially leading to malfunctions.
[0039] Figure 3 is a diagram illustrating the configuration of the timing control circuit 18 according to Embodiment 1.
[0040] Referring to Figure 3, the timing control circuit 18 includes an AND gate 182, a NAND gate 184, and a one-shot pulse generation circuit 186.
[0041] The one-shot pulse generation circuit 186 outputs a predetermined one-shot pulse signal to the NAND circuit 184 when it receives a gate pulse (firing command) input from the inverter 2, for example.
[0042] The NAND circuit 184 receives the gate pulse (firing command) from the converter 1 and the output signal from the one-shot pulse generation circuit 186, and outputs the result of the NAND logic operation to the AND circuit 182.
[0043] The AND circuit 182 receives the gate pulse (firing command) from the converter 1 and the output signal from the NAND circuit 184 as inputs, and outputs the result of the AND logic operation as a gate pulse (firing command).
[0044] Figure 4 is a diagram illustrating the operation of the timing control circuit 18 according to Embodiment 1.
[0045] Referring to Figure 4(A), the case where a gate pulse from converter 1 is input to the timing control circuit 18 will be explained. In this case, the case where no gate pulse from inverter 2 is input will be explained.
[0046] The NAND circuit 184 outputs the result of the NAND logic operation ("1") to the AND circuit 182.
[0047] The AND circuit 182 receives the output signal ("1") from the NAND circuit 184 and the gate pulse ("1") from the converter 1 and outputs a gate pulse (firing command) ("1").
[0048] Referring to Figure 4(B), the case where gate pulses from converter 1 and inverter 2 are input to the timing control circuit 18 will be described next.
[0049] The NAND circuit 184 outputs the result of the NAND logic operation ("0") to the AND circuit 182.
[0050] The AND circuit 182 receives the output signal ("1") from the NAND circuit 184 and the gate pulse ("1") from the converter 1 and outputs a gate pulse (firing command) ("0").
[0051] In other words, the AND gate 182 does not output a gate pulse (firing command) ("1") to the converter 1.
[0052] This makes it possible to avoid simultaneous firing by stopping the output of the gate pulse (firing command) of the converter-side thyristor and the inverter-side thyristor when their timings overlap, thereby suppressing the generation of common-mode noise caused by turn-on surges.
[0053] Referring to Figure 4(C), if no gate pulses from converter 1 and inverter 2 are input to the timing control circuit 18, the state remains unchanged.
[0054] In this example, the configuration was explained using logic circuits with AND and NAND gates, but it is also possible to achieve a similar configuration using flip-flop circuits as needed.
[0055] With this configuration, by providing the timing control circuit 18, it is possible to avoid a situation where gate pulses are simultaneously input to the converter or inverter and they turn on at the same time. This makes it possible to avoid the generation of common-mode noise caused by turn-on surges, suppress the superposition of common-mode noise on the control signal line, and prevent malfunctions.
[0056] Figure 5 is a diagram illustrating the configuration of a timing control circuit 18 according to a modified example of Embodiment 1.
[0057] Referring to Figure 5, the timing control circuit 18 according to a modified example of Embodiment 1 differs in that it further includes an under-gate prevention circuit 188.
[0058] The under-gate prevention circuit 188 operates in response to the output of the AND gate 182.
[0059] Specifically, the under-gate prevention circuit 188 is a circuit that continues to output a gate pulse to converter 1 even if the gate pulse to converter 1 stops after it has been output.
[0060] For example, if a gate pulse from inverter 2 is input immediately after a gate pulse is output to converter 1, the output of the AND circuit 182 will be stopped by the input of the gate pulse from inverter 2. In this case, there is a possibility that the gate pulse to converter 1 will not be input to the thyristor for an appropriate period of time.
[0061] Therefore, the under-gate prevention circuit 188 maintains a state such that a gate pulse is output to the converter 1 for an appropriate amount of time, even if the output signal from the AND circuit 182 changes in that case. This makes it possible to operate the converter 1 stably without causing it to become unstable.
[0062] Furthermore, in this case, since there is a timing difference between the gate pulse to converter 1 and the gate pulse from inverter 2, it is considered possible to suppress the generation of common-mode noise caused by the turn-on surge. Therefore, by suppressing the generation of common-mode noise, it is possible to prevent noise from being superimposed on the control signal line and avoid malfunctions.
[0063] Figure 6 is a circuit block diagram showing the configuration of the thyristor starter 100# according to Embodiment 2. Referring to Figure 6, the thyristor starter 100# according to Embodiment 2 differs from the thyristor starter 100 according to Embodiment 1 in Figure 1 in that the timing control circuit 18 has been changed to a timing control circuit 19.
[0064] Specifically, the timing control circuit 19 is provided in correspondence with the inverter 2 and controls the timing between the gate pulse (firing command) given to the gate of the thyristor in the inverter 2 and the gate pulse (firing command) of the thyristor in the converter 1.
[0065] The other configurations are the same as those described in Embodiment 1.
[0066] Specifically, if the timing of the gate pulse (firing command) of the thyristor on the converter 1 side and the gate pulse (firing command) of the thyristor on the inverter 2 side overlap, the output of the gate pulse of inverter 2 can be stopped to avoid simultaneous firing and suppress the generation of common-mode noise.
[0067] With this configuration, by providing the timing control circuit 19, it is possible to avoid a situation where gate pulses are simultaneously input to the converter or inverter and they turn on at the same time. This makes it possible to avoid the generation of common-mode noise caused by turn-on surges, suppress the superposition of noise on the control signal line, and prevent malfunctions.
[0068] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]
[0069] 1 Converter, 2 Inverter, 3 DC reactor, 4,5 Current transformer, 6 Voltage detector, 7 Position detector, 9 Current detector, 10 Inverter control unit, 11,16 Control angle calculation unit, 12,17 Gate pulse generator, 13 Converter control unit, 14 Speed control unit, 15 Current control unit, 18,19 Timing control circuit, 20 Synchronous machine, 22 Field winding, 30 AC power supply, 100,100# Thyristor starter, 182 AND circuit, 184 NAND circuit, 186 One-shot pulse generation circuit, 188 Under-gate prevention circuit.
Claims
1. A thyristor starter for starting a synchronous machine, A converter that converts AC power to DC power, A DC reactor for smoothing the aforementioned DC power, An inverter that converts the DC power supplied from the converter via the DC reactor into variable frequency AC power and supplies it to the synchronous machine, A position detector for detecting the rotor position of the synchronous machine, A first control unit controls the firing phase of the thyristor in the inverter based on the detection signal of the position detector, A second control unit controls the firing phase of the thyristor in the converter so that the DC current flowing through the DC reactor matches the current command value, based on the detection signal of the position detector. The inverter is equipped with a timing control circuit that controls the timing of the firing of a thyristor in the inverter and the firing of a thyristor in the converter. The timing control circuit is a thyristor activating device that stops the activating of the thyristor in the converter or the inverter when the timing of the activating of the thyristor in the inverter and the activating of the thyristor in the converter overlap.
2. The thyristor activating device according to claim 1, wherein the timing control circuit includes a gate prevention circuit that continues ignition if the thyristor in the converter or inverter has already started igniting when the timing of ignition of the thyristor in the inverter and the thyristor in the converter overlap.
3. A method for controlling a thyristor starter for starting a synchronous machine, The thyristor starter includes a converter that converts AC power to DC power, a DC reactor that smooths the DC power, and an inverter that converts the DC power supplied from the converter through the DC reactor into variable frequency AC power and supplies it to the synchronous machine. The steps include detecting the rotor position of the synchronous machine, A step of controlling the firing phase of the thyristor in the inverter based on the detection signal, The steps include controlling the firing phase of the thyristor in the converter so that the DC current flowing through the DC reactor matches the current command value, based on the detection signal, The system includes a step of controlling the timing between the firing of a thyristor in the inverter and the firing of a thyristor in the converter. A control method for a thyristor starter, wherein the step of controlling the timing includes stopping the firing of the thyristor in the converter or the inverter when the timing of firing the thyristor in the inverter and the timing of firing the thyristor in the converter overlap.
4. A converter that converts AC power to DC power, A DC reactor for smoothing the aforementioned DC power, An inverter that converts the DC power supplied from the converter via the DC reactor into variable frequency AC power and supplies it to a synchronous machine, A position detector for detecting the rotor position of the synchronous machine, It includes a control unit, The control unit, Based on the detection signal from the position detector, the firing phase of the thyristor in the inverter is controlled. Based on the detection signal from the position detector, the firing phase of the thyristor in the converter is controlled so that the DC current flowing through the DC reactor matches the current command value. A thyristor activating device that stops the activating of the thyristor in the converter or the inverter when the thyristor in the inverter and the thyristor in the converter are activated simultaneously.