Trigger signal and driving circuit of thyristor for non-controlled rectification of direct current bus voltage

Abstract

The application discloses a thyristor trigger signal and driving circuit for non-controlled rectification of a direct-current bus voltage, comprising a voltage comparison unit, a pulse wave generation unit, a trigger signal unit and a driving unit; the voltage comparison unit is used for judging a thyristor opening time and sending an output effective level signal to the trigger signal unit; the pulse wave generation unit is used for generating a frequency-adjustable pulse wave and sending the pulse wave to the trigger signal unit; the trigger signal unit is used for synthesizing a trigger signal based on the effective level signal and the trigger signal and sending the trigger signal to the driving unit; and the driving unit is used for controlling conduction of the thyristor based on the trigger signal. The application greatly improves reliability of the thyristor driving, avoids problems of power waste and large loss of a driving power supply, and can be applied to high-power frequency converter products in batches.

Description

Technical Field

[0001] This invention relates to the field of power electronics and electrical drive equipment technology, and more specifically to a thyristor trigger signal and drive circuit for uncontrolled rectification of DC bus voltage. Background Technology

[0002] With the acceleration of my country's industrialization process, rectifier control devices are being used more and more. Rectifier devices come in two types: those with controllable DC bus voltage and those with uncontrollable DC bus voltage.

[0003] For uncontrollable rectifiers, thyristors are typically used in the upper bridge arm and rectifier diodes in the lower bridge arm to achieve uncontrolled rectification of the DC bus voltage. There are two main control methods: one is a software-triggered control scheme, which has the disadvantage of requiring an MCU for judgment and wave generation, making it unable to quickly respond to abnormal fluctuations in the power grid, and the circuit design is relatively complicated with a high degree of dependence on software; the other is a pure hardware control scheme, which has high power loss of the drive power supply, wastes energy and has low reliability.

[0004] Therefore, for purely hardware methods, this application provides a thyristor trigger signal and drive circuit for uncontrolled rectification of DC bus voltage, which can avoid the problems of insufficient reliability and large power waste of the drive power supply in previous hardware solutions. Summary of the Invention

[0005] In view of this, the present invention provides a thyristor trigger signal and driving circuit for DC bus voltage uncontrolled rectification, which greatly improves the reliability of thyristor driving and avoids the problems of wasted power and high loss of driving power supply.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The thyristor trigger signal and drive circuit for DC bus voltage uncontrolled rectification includes: a voltage comparison unit, a pulse wave generation unit, a trigger signal unit, and a drive unit;

[0008] The voltage comparison unit is used to determine the turn-on time of the thyristor and sends the output valid level signal to the trigger signal unit;

[0009] The pulse wave generation unit is used to generate frequency-adjustable pulse waves and send them to the trigger signal unit;

[0010] The trigger signal unit is used to synthesize a trigger signal based on the effective level signal and the trigger signal, and then send the trigger signal to the drive unit;

[0011] The drive unit is used to control the conduction of the thyristor based on the trigger signal.

[0012] Preferably, the voltage comparison unit includes a hysteresis comparator, a voltage divider and limiting circuit, and a reference voltage circuit;

[0013] The reference voltage circuit is used to generate a reference voltage and send the reference voltage to the inverting input of the hysteresis comparator;

[0014] The voltage divider and limiting circuit is used to perform current limiting, voltage division, and amplitude limiting protection on the input grid voltage and sends the data to the non-inverting input of the hysteresis comparator.

[0015] A hysteresis comparator is used to compare the voltage at the non-inverting input terminal with the voltage at the inverting input terminal and outputs a valid level signal.

[0016] Preferably, the pulse wave generating unit includes a pulse wave starting circuit, a Schmitt inverter U3B, a periodic rectangular wave generator circuit, and a Schmitt inverter U3C;

[0017] The pulse wave start circuit is used to receive the system start signal. When the system is ready, the SCR_SETUP signal changes from high level to low level and outputs high level V1 through the Schmitt inverter U3C.

[0018] The periodic rectangular wave generator circuit is used to generate periodic rectangular waveforms, and after shaping the periodic rectangular waveforms by the Schmitt inverter U3B, it outputs a high level V2.

[0019] Preferably, the trigger signal unit is a 2-input AND gate.

[0020] Preferably, the hysteresis comparator includes a comparator U1A, a positive feedback resistor R6, and a pull-up resistor R7. The positive feedback resistor R6 is provided between the non-inverting input terminal and the output terminal of the comparator U1A, and the output terminal of the comparator U1A is connected to the pull-up resistor R7.

[0021] The voltage divider and limiting circuit includes resistors R1, R2, R3 and diode ZD1. Resistor R1 is connected to the non-inverting input of comparator U1A, and the connection point between resistor R1 and the non-inverting input of comparator U1A is connected to VCC1 through resistor R2. The connection point between resistor R1 and the non-inverting input of comparator U1A is connected to GND through resistor R3 and diode ZD1 respectively.

[0022] The reference voltage circuit includes capacitor C1, resistor R5 and resistor R4. The two ends of capacitor C1 are connected to GND and the inverting input of comparator U1A, respectively. The inverting input of comparator U1A is connected to VCC1 through resistor R4, and the inverting input of comparator U1A is connected to GND through resistor R5.

[0023] Preferably, the periodic rectangular wave generator circuit includes a Schmitt inverter U3A, resistor R11, resistor R12, and diode D1. The output terminal of Schmitt inverter U3A is connected to the input terminal of Schmitt inverter U3B. The input terminal of Schmitt inverter U3A is connected to capacitor C2. The connection node between the output terminal of Schmitt inverter U3A and the input terminal of Schmitt inverter U3B is connected to capacitor C2 through resistor R11. The connection node between the output terminal of Schmitt inverter U3A and the input terminal of Schmitt inverter U3B is connected to capacitor C2 through resistor R12 and diode D1 in sequence. Capacitor C2 is connected to GND.

[0024] The pulse wave start-up circuit includes an optocoupler U4, resistors R8, R9, and R10. Pin 1 of optocoupler U4 is connected to VCC2 through resistor R8. Pin 1 of optocoupler U4 is connected to a low-level SCR_SETUP signal through resistor R9. Pin 4 of optocoupler U4 is connected to the input of Schmitt inverter U3C, and the connection node between pin 4 of optocoupler U4 and the input of Schmitt inverter U3C is connected to VCC1 through resistor R10. Pin 3 of optocoupler U4 is connected to GND.

[0025] Preferably, the driving unit includes a NOMS transistor Q1, a POMS transistor Q2, resistors R13, R14, R15, R16, R17, and R18. Resistor R15 is connected between the gate (G) and source (S) of NOMS transistor Q1. Resistor R14 is connected to the gate (G) of NOMS transistor Q1. The drain (D) of NOMS transistor Q1 and the gate (G) of POMS transistor Q2 are both connected to VCC1 through resistor R13. The source (S) of POMS transistor Q2 is connected to VCC1. The drain (D) of POMS transistor Q2 is connected to the input terminal of the thyristor through resistor R16. The other input terminal of the thyristor is connected to GND through resistor R17, and resistor R18 is connected in parallel with the thyristor.

[0026] Preferably, it also includes an auxiliary power supply unit, which is electrically connected to the voltage comparison unit, the pulse wave generation unit, the trigger signal unit and the drive unit, respectively, and is used to supply power to each unit.

[0027] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a thyristor trigger signal and drive circuit for uncontrolled rectification of DC bus voltage. It uses a pure hardware control scheme and a highly distinctive thyristor trigger signal generation and drive circuit to realize uncontrolled rectification of DC bus voltage, which greatly improves the reliability of thyristor drive and avoids the problems of wasted drive power and high loss. It can be applied in batches to high-power frequency converter products. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the overall structure of the thyristor trigger signal and drive circuit for DC bus voltage uncontrolled rectification provided by the present invention.

[0030] Figure 2 The specific circuit diagrams of the pulse wave generation unit, voltage comparison unit, and trigger signal unit provided by the present invention are shown below.

[0031] Figure 3 The specific circuit diagram of the driving unit provided by the present invention.

[0032] Figure 4 A schematic diagram of the overall circuit of another embodiment of the present invention. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] This invention discloses a thyristor trigger signal and driving circuit for DC bus voltage uncontrolled rectification, such as... Figure 1 As shown, it includes: a voltage comparison unit, a pulse wave generation unit, a trigger signal unit, and a drive unit;

[0035] The voltage comparison unit is used to determine the turn-on time of the thyristor. When the anode voltage of the thyristor is higher than the cathode voltage, that is, when the input AC voltage is higher than the positive terminal voltage of the bus, the voltage comparison unit outputs a valid level signal and sends the output valid level signal to the trigger signal unit.

[0036] The pulse wave generation unit is used to generate frequency-adjustable pulse waves and send them to the trigger signal unit;

[0037] The trigger signal unit is used to synthesize a trigger signal based on the effective level signal and the trigger signal, and then send the trigger signal to the drive unit;

[0038] The drive unit is used to control the conduction of the thyristor based on the trigger signal.

[0039] In this embodiment, the voltage comparison unit includes a hysteresis comparator, a voltage divider and limiting circuit, and a reference voltage circuit;

[0040] The reference voltage circuit is used to generate a reference voltage and send the reference voltage to the inverting input of the hysteresis comparator;

[0041] The voltage divider and limiting circuit is used to perform current limiting, voltage division, and amplitude limiting protection on the input grid voltage and sends the data to the non-inverting input of the hysteresis comparator.

[0042] A hysteresis comparator is used to compare the voltage at the non-inverting input terminal with the voltage at the inverting input terminal and outputs a valid level signal.

[0043] Specifically, such as Figure 2 As shown, the hysteresis comparator includes comparator U1A, positive feedback resistor R6 and pull-up resistor R7. Positive feedback resistor R6 is set between the non-inverting input terminal and the output terminal of comparator U1A, and pull-up resistor R7 is connected to the output terminal of comparator U1A.

[0044] The voltage divider and limiting circuit includes resistors R1, R2, R3, and diode ZD1. Resistor R1 is connected to the non-inverting input of comparator U1A, and the connection point between resistor R1 and the non-inverting input of comparator U1A is connected to VCC1 through resistor R2 to ensure that the voltage input to the non-inverting input of comparator U1A is always positive. The connection point between resistor R1 and the non-inverting input of comparator U1A is connected to GND through resistor R3 and diode ZD1, respectively.

[0045] The reference voltage circuit includes capacitor C1, resistor R5 and resistor R4. Resistors R5 and R4 act as voltage dividers. The two ends of capacitor C1 are connected to GND and the inverting input of comparator U1A, respectively. The inverting input of comparator U1A is connected to VCC1 through resistor R4, and the inverting input of comparator U1A is connected to GND through resistor R5.

[0046] When the voltage V+ at the non-inverting input of comparator U1A is higher than the voltage REF1 at its inverting input, the comparator outputs a high level. In this embodiment, the input R phase is used as an example (the other two phases are the same). This generates a drive signal to trigger the thyristor of the R phase to the bridge, indicating that the magnitude relationship between the input grid R phase and the positive voltage of the bus is about to meet the condition for the thyristor to turn on. When the voltage V+ at the non-inverting input of comparator U1A is lower than the voltage REF1 at its inverting input, the comparator always outputs a low level, blocking the thyristor drive.

[0047] In this embodiment, the pulse wave generation unit includes a pulse wave activation circuit, a Schmitt inverter U3B, a periodic rectangular wave generator circuit, and a Schmitt inverter U3C;

[0048] The pulse wave start circuit is used to receive the system start signal. When the system is ready, the SCR_SETUP signal changes from high level to low level and outputs high level V1 through the Schmitt inverter U3C.

[0049] The periodic rectangular wave generator circuit is used to generate periodic rectangular waveforms, and after shaping the periodic rectangular waveforms by the Schmitt inverter U3B, it outputs a high level V2.

[0050] Specifically, such as Figure 2 As shown, the periodic rectangular wave generator circuit includes a Schmitt inverter U3A, resistors R11 and R12, and diode D1. The output of Schmitt inverter U3A is connected to the input of Schmitt inverter U3B, and the input of Schmitt inverter U3A is connected to capacitor C2. The period and duty cycle of the rectangular wave can be flexibly adjusted by R11, R12, and C2. The connection between the output of Schmitt inverter U3A and the input of Schmitt inverter U3B is connected to capacitor C2 through resistor R11. The connection between the output of Schmitt inverter U3A and the input of Schmitt inverter U3B is connected to capacitor C2 through resistor R12 and diode D1 in sequence. Capacitor C2 is connected to GND.

[0051] The pulse wave start-up circuit includes an optocoupler U4, resistors R8, R9, and R10. Pin 1 of optocoupler U4 is connected to VCC2 through resistor R8. Pin 1 of optocoupler U4 is connected to a low-level SCR_SETUP signal through resistor R9. Pin 4 of optocoupler U4 is connected to the input of Schmitt inverter U3C, and the connection node between pin 4 of optocoupler U4 and the input of Schmitt inverter U3C is connected to VCC1 through resistor R10. Pin 3 of optocoupler U4 is connected to GND.

[0052] In this embodiment, the trigger signal unit is a 2-input AND gate, whose inputs are respectively from the V3 signal of the voltage comparison unit and the V4 signal of the pulse wave generation unit.

[0053] In this embodiment, as Figure 3As shown, the driving unit includes a NOMS transistor Q1, a POMS transistor Q2, resistors R13, R14, R15, R16, R17, and R18. Resistors R16 and R17 are current-limiting resistors. The signal input to the driving unit, i.e., the trigger signal SCR_R, controls the conduction of Q2. Resistor R18 is a parallel driving resistor for the thyristor to ensure that the thyristor has sufficient driving voltage. Resistor R15 is connected between the gate (G) and source (S) of NOMS transistor Q1. Resistor R14 is connected to the gate (G) of NOMS transistor Q1. The drain (D) of NOMS transistor Q1 and the gate (G) of POMS transistor Q2 are both connected to VCC1 through resistor R13. The source (S) of POMS transistor Q2 is connected to VCC1. The drain (D) of POMS transistor Q2 is connected to the input terminal of the thyristor through resistor R16. The other input terminal of the thyristor is connected to GND through resistor R17, and resistor R18 is connected in parallel with the thyristor.

[0054] In this embodiment, as Figure 4 As shown, it also includes an auxiliary power supply unit, which is electrically connected to the voltage comparison unit, pulse wave generation unit, trigger signal unit and drive unit respectively, and is used to supply power to each unit.

[0055] In this invention, the trigger signal for the thyristor is a pulse wave, which serves two purposes: First, similar to the principle of a dual trigger pulse for a thyristor, the continuous trigger signal ensures reliable triggering of the thyristor; second, in conjunction with the drive circuit, the pulse wave controls the switching on and off of the MOS transistor in the drive circuit, intermittently controlling the input and output of the thyristor's drive power supply, thereby avoiding the waste of drive power energy.

[0056] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0057] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A thyristor trigger signal and drive circuit for DC bus voltage uncontrolled rectification, characterized in that, include: Voltage comparison unit, pulse wave generation unit, trigger signal unit and drive unit; The voltage comparison unit is used to determine the turn-on time of the thyristor and sends the output valid level signal to the trigger signal unit; The pulse wave generation unit is used to generate frequency-adjustable pulse waves and send them to the trigger signal unit; The trigger signal unit is used to synthesize a trigger signal based on the effective level signal and the trigger signal, and then send the trigger signal to the drive unit; The drive unit is used to control the conduction of the thyristor based on the trigger signal; The pulse wave generation unit includes a pulse wave start-up circuit, a Schmitt inverter U3B, a periodic rectangular wave generator circuit, and a Schmitt inverter U3C; The pulse wave start circuit is used to receive the system start signal. When the system is ready, the SCR_SETUP signal changes from high level to low level and outputs high level V1 through the Schmitt inverter U3C. The periodic rectangular wave generator circuit is used to generate periodic rectangular waveforms, and the periodic rectangular waveforms are shaped by the Schmitt inverter U3B to output a high level V2. High-level signals V1 and V2 are output as an effective level signal V4 through an AND gate and sent to the trigger signal unit; The periodic rectangular wave generator circuit includes a Schmitt inverter U3A, resistor R11, resistor R12, and diode D1. The output of Schmitt inverter U3A is connected to the input of Schmitt inverter U3B. The input of Schmitt inverter U3A is connected to capacitor C2. The connection between the output of Schmitt inverter U3A and the input of Schmitt inverter U3B is connected to capacitor C2 through resistor R11. The connection between the output of Schmitt inverter U3A and the input of Schmitt inverter U3B is connected to capacitor C2 through resistor R12 and diode D1 in sequence. Capacitor C2 is connected to GND. The pulse wave start-up circuit includes an optocoupler U4, resistors R8, R9, and R10. Pin 1 of optocoupler U4 is connected to VCC2 through resistor R8. Pin 1 of optocoupler U4 is connected to a low-level SCR_SETUP signal through resistor R9. Pin 4 of optocoupler U4 is connected to the input of Schmitt inverter U3C, and the connection node between pin 4 of optocoupler U4 and the input of Schmitt inverter U3C is connected to VCC1 through resistor R10. Pin 3 of optocoupler U4 is connected to GND. The drive unit includes a NOMS transistor Q1, a POMS transistor Q2, resistors R13, R14, R15, R16, R17, and R18. Resistor R15 is connected between the gate (G) and source (S) of NOMS transistor Q1. Resistor R14 is connected to the gate (G) of NOMS transistor Q1. The drain (D) of NOMS transistor Q1 and the gate (G) of POMS transistor Q2 are both connected to VCC1 through resistor R13. The source (S) of POMS transistor Q2 is connected to VCC1. The drain (D) of POMS transistor Q2 is connected to the thyristor input terminal through resistor R16. The other input terminal of the thyristor is connected to GND through resistor R17, and resistor R18 is connected in parallel with the thyristor.

2. The thyristor trigger signal and drive circuit for DC bus voltage uncontrolled rectification according to claim 1, characterized in that, The voltage comparison unit includes a hysteresis comparator, a voltage divider and limiting circuit, and a reference voltage circuit; The reference voltage circuit is used to generate a reference voltage and send the reference voltage to the inverting input of the hysteresis comparator; The voltage divider and limiting circuit is used to perform current limiting, voltage division, and amplitude limiting protection on the input grid voltage and sends the data to the non-inverting input of the hysteresis comparator. A hysteresis comparator is used to compare the voltage at the non-inverting input terminal with the voltage at the inverting input terminal and outputs a valid level signal.

3. The thyristor trigger signal and drive circuit for DC bus voltage uncontrolled rectification according to claim 1, characterized in that, The trigger signal unit is a 2-input AND gate.

4. The thyristor trigger signal and drive circuit for DC bus voltage uncontrolled rectification according to claim 2, characterized in that, The hysteresis comparator includes comparator U1A, positive feedback resistor R6 and pull-up resistor R7. Positive feedback resistor R6 is set between the non-inverting input terminal and the output terminal of comparator U1A, and pull-up resistor R7 is connected to the output terminal of comparator U1A. The voltage divider and limiting circuit includes resistors R1, R2, R3 and diode ZD1. Resistor R1 is connected to the non-inverting input of comparator U1A, and the connection point between resistor R1 and the non-inverting input of comparator U1A is connected to VCC1 through resistor R2. The connection point between resistor R1 and the non-inverting input of comparator U1A is connected to GND through resistor R3 and diode ZD1 respectively. The reference voltage circuit includes capacitor C1, resistor R5 and resistor R4. The two ends of capacitor C1 are connected to GND and the inverting input of comparator U1A, respectively. The inverting input of comparator U1A is connected to VCC1 through resistor R4, and the inverting input of comparator U1A is connected to GND through resistor R5.

5. The thyristor trigger signal and drive circuit for DC bus voltage uncontrolled rectification according to claim 1, characterized in that, It also includes an auxiliary power supply unit, which is electrically connected to the voltage comparison unit, pulse wave generation unit, trigger signal unit and drive unit respectively, and is used to supply power to each unit.

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