Inverter and control circuit thereof

Abstract

The utility model provides a kind of inverter and its control circuit, the control circuit includes: driving power supply, with the one end of the alternating side three-phase relay coil of inverter, the one end of alternating side N line relay coil is connected;First drive switch tube, first end is connected with the other end of three-phase relay coil, second end ground connection;Second drive switch tube, first end is connected with the other end of N line relay coil, second end ground connection;Controller, with the control end of driving power supply, first drive switch tube's, second drive switch tube's respectively, for output enable signal to driving power supply and output drive signal to first drive switch tube and second drive switch tube.The utility model can realize the action time sequence and attraction speed independent control of the alternating side three-phase relay coil and N line relay coil of inverter, to realize the quick switching of grid-connected and off-grid without relying on external N line thyristor, and the structure of entire circuit is simple, low in cost.

Description

Technical Field

[0001] This utility model relates to the field of power electronics technology, specifically to a control circuit for an inverter and an inverter. Background Technology

[0002] Photovoltaic inverters or energy storage inverters typically include three-phase relays and neutral (N) line relays on the AC side. To ensure fast and reliable engagement and low continuous power consumption, dual power supply is generally used in related technologies. When the relay is engaged, it is powered by a DC power supply through a controllable switch, and during the holding period, it is powered by the output of a BUCK circuit (step-down DC-DC converter circuit).

[0003] However, in the above method, the coil drive voltages of the three-phase relays and the neutral (N) line relays are the same, making it impossible for them to operate independently. Therefore, direct switching between grid-connected and off-grid operation is not possible. To achieve direct switching, a double switch circuit and a buck circuit are required, resulting in a complex structure, numerous components, and high cost. Even with a double switch circuit and buck circuit, the operating timing and pull-in speed of the three-phase relays and the neutral (N) line relays cannot be independently controlled, thus preventing the neutral (N) line relay from operating rapidly during grid-connected and off-grid switching. Utility Model Content

[0004] To solve the above-mentioned technical problems, this utility model provides a control circuit for an inverter.

[0005] This utility model also proposes an inverter.

[0006] The technical solution adopted in this utility model is as follows:

[0007] This utility model proposes a control circuit for an inverter, comprising: a drive power supply, wherein a first drive terminal of the drive power supply is connected to one end of a three-phase relay coil on the AC side of the inverter, and a second drive terminal of the drive power supply is connected to one end of a neutral (N) line relay coil on the AC side of the inverter; a first drive switch, wherein a first terminal of the first drive switch is connected to the other end of the three-phase relay coil, and a second terminal of the first drive switch is grounded; a second drive switch, wherein a first terminal of the second drive switch is connected to the other end of the neutral (N) line relay coil, and a second terminal of the second drive switch is grounded; and a controller, wherein the controller is connected to the drive power supply, the control terminal of the first drive switch, and the control terminal of the second drive switch, respectively, and the controller is used to output an enable signal to the drive power supply and output a drive signal to the first drive switch and the second drive switch, so that the drive power supply energizes the three-phase relay coil or the neutral (N) line relay coil according to the enable signal, and the first drive switch and the second drive switch are de-energized according to the drive signal to de-energize the three-phase relay coil or the neutral (N) line relay coil.

[0008] The control circuit of the inverter described above in this utility model also has the following additional technical features:

[0009] Specifically, the driving power supply includes: a first power supply circuit and a second power supply circuit, the input terminals of the first power supply circuit and the second power supply circuit being connected to a preset power supply, the first power supply circuit and the second power supply circuit being used to convert the DC power output by the preset power supply into voltage respectively; and a switching circuit, the first input terminal of the switching circuit being connected to the output terminal of the first power supply circuit, the second input terminal of the switching circuit being connected to the output terminal of the second power supply circuit, the first output terminal of the switching circuit serving as the first driving terminal of the driving power supply, the second output terminal of the switching circuit serving as the second driving terminal of the driving power supply, and the switching circuit being used to output the DC power output by the first power supply circuit or the second power supply circuit to the first driving switch or the second driving switch transistor.

[0010] Further, the first power supply circuit includes: a first voltage converter and a first holding control module. The input terminal of the first voltage converter is connected to a preset power supply, the output terminal of the first voltage converter is connected to the first input terminal of the switching circuit, the feedback terminal of the first voltage converter is connected to the first terminal of the first holding control module, the second terminal of the first holding control module is connected to the output terminal of the first voltage converter, and the control terminal of the first holding control module is connected to the first enable signal output terminal of the controller. The first holding control module is used to control the first voltage converter to output a first voltage to the switching circuit when receiving the first enable signal, and to control the first voltage converter to output a second voltage to the switching circuit when stopping receiving the first enable signal, wherein the second voltage is less than the first voltage.

[0011] Further, the second power supply circuit includes: a second voltage converter and a second holding control module. The input terminal of the second voltage converter is connected to a preset power supply, the output terminal of the second voltage converter is connected to the second input terminal of the switching circuit, the feedback terminal of the second voltage converter is connected to the first terminal of the second holding control module, the second terminal of the second holding control module is connected to the output terminal of the second voltage converter, and the control terminal of the second holding control module is connected to the second enable signal output terminal of the controller. The second holding control module is used to control the second voltage converter to output a third voltage to the switching circuit when receiving a second enable signal, and to control the second voltage converter to output a fourth voltage to the switching circuit when stopping receiving the second enable signal, wherein the fourth voltage is less than the third voltage.

[0012] Specifically, the first holding control module or the second holding control module includes: a feedback switching control unit, the control terminal of which is connected to the enable terminal of the controller, and the output terminal of which is connected to the feedback terminal of the first voltage converter or the second voltage converter; a first feedback circuit and a second feedback circuit, one end of which is connected to the feedback switching control unit, and the other end of which is connected to the output terminal of the first voltage converter or the second voltage converter.

[0013] Further, the first feedback circuit includes: a first resistor and a second resistor; the second feedback circuit includes: a third resistor; the feedback switching control unit includes: a first MOSFET, a fourth resistor, a fifth resistor, and a first capacitor, wherein one end of the first resistor is connected to the output terminal of the first voltage converter or the second voltage converter, one end of the second resistor is connected to the other end of the first resistor, the two ends of the second resistor and the first resistor are connected as a voltage divider terminal of the first feedback circuit and connected to the feedback terminal of the first voltage converter or the second voltage converter, the other end of the second resistor is grounded, one end of the third resistor is connected to the voltage divider terminal, the first end of the first MOSFET is connected to the other end of the third resistor, the second end of the first MOSFET is grounded, one end of the fourth resistor is connected to the control terminal of the first MOSFET, the other end of the fourth resistor is grounded, one end of the fifth resistor is connected to the control terminal of the first MOSFET, the other end of the fifth resistor is connected to the first enable signal output terminal or the second enable signal output terminal of the controller, and the first capacitor is connected in parallel with the fourth resistor.

[0014] This utility model also proposes an inverter, including the control circuit of the inverter described above.

[0015] The beneficial effects of this utility model are:

[0016] This invention enables independent control of the operating timing and pull-in speed of the AC side three-phase relay coil and the N-line relay coil of the inverter, so as to achieve rapid switching between grid-connected and off-grid without relying on an external N-line thyristor. The entire circuit adopts a simple structure and low cost. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the control circuit of an inverter according to an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of the structure of a drive power supply according to an embodiment of the present invention;

[0019] Figure 3 This is a circuit topology diagram of the driving power supply according to the first example of this utility model;

[0020] Figure 4 This is a circuit topology diagram of the driving power supply according to the second example of this utility model;

[0021] Figure 5 This is a circuit topology diagram of the driving power supply according to the third example of this utility model;

[0022] Figure 6This is a schematic diagram of the structure of a first power supply circuit and a second power supply circuit according to an embodiment of the present utility model;

[0023] Figure 7 This is a schematic diagram of the structure of a first holding control module or a second holding control module according to an embodiment of the present invention;

[0024] Figure 8 This is a circuit topology diagram of a first holding control module or a second holding control module according to a specific example of the present invention. Detailed Implementation

[0025] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0026] Figure 1 This is a schematic diagram of the control circuit of an inverter according to an embodiment of the present invention, as shown below. Figure 1 As shown, the control circuit includes: a drive power supply 1, a first drive switch S1, a second drive switch S2, and a controller 2.

[0027] In this configuration, the first drive terminal VCC_Replay_P of the drive power supply 1 is connected to one end of the three-phase relay coil SA on the AC side of the inverter, and the second drive terminal VCC_Replay_N of the drive power supply is connected to one end of the N-line relay coil SN on the AC side of the inverter. The first terminal of the first drive switch S1 is connected to the other end of the three-phase relay coil SA, and the second terminal of the first drive switch S1 is grounded. The first terminal of the second drive switch S2 is connected to the other end of the N-line relay coil SN, and the second terminal of the second drive switch S2 is grounded. The controller 2 is connected to the drive power supply 1, the control terminal of the first drive switch S1, and the control terminal of the second drive switch S2. The controller 2 is used to output an enable signal to the drive power supply 1 and output a drive signal to the first drive switch S1 and the second drive switch S2, so that the drive power supply 1 drives one end of the three-phase relay coil SA or the N-line relay coil SN to be powered according to the enable signal. The first drive switch S1 and the second drive switch S2 are turned on according to the drive signal to drive the three-phase relay coil SA or the N-line relay coil SN to be energized. The first drive switch S1 and the second drive switch S2 are disconnected according to the drive signal to drive the three-phase relay coil SA / N and the line relay coil SN to de-energize.

[0028] Specifically, the AC side of the inverter includes three-phase relays and a neutral (N) line relay. Figure 1 Taking the example where the three-phase relay, neutral line relay, first drive switch S1 and second drive switch S2 are omitted as one, controller 2 is an inverter controller that can drive the inverter's conversion circuit. Controller 2 can also output enable signals to the drive power supply, as well as the first drive switch S1 and second switch S2 that output drive signals. The enable signals include the first enable signal EN1 and the second enable signal EN2. VCC is the preset power supply.

[0029] When the three-phase relay needs to be engaged, controller 2 first outputs a first enable signal EN1 to drive power supply 1. Drive power supply 1 outputs the rated operating voltage of the three-phase relay coil SA, energizing one end of SA. Controller 2 then outputs a drive signal to the first drive switch S1, which turns on, thereby controlling the three-phase relay coil SA to engage at the rated speed. After a certain delay time tr_1, controller 2 disconnects the first enable signal EN1 output to drive power supply while maintaining the drive signal output to the three-phase relay coil SA. Drive power supply 1 outputs a step-down holding voltage for the three-phase relay coil SA, enabling the three-phase relay to remain closed with low power consumption. When the three-phase relay needs to be disengaged, controller 2 disconnects the drive signal output to S1, de-energizing the three-phase relay coil SA and causing it to disengage.

[0030] When the N-line relay needs to be engaged, controller 2 first outputs a second enable signal EN2 to drive power supply 1. Drive power supply 1 outputs a voltage k times the operating voltage of the N-line relay coil SN, where 1 ≤ k ≤ 2, and the value of k is determined by the N-line relay drive power supply setting parameters. Controller 2 then outputs a drive signal to turn on the second drive switch S2, controlling the N-line relay to engage at a faster speed. After a certain delay time tr_2, controller 2 disconnects the second enable signal EN2 output to drive power supply 1 while maintaining the drive signal output to the second drive switch S2. Drive power supply 1 outputs a reduced holding voltage for the N-line relay coil SN, allowing the N-line relay to remain closed with low power consumption. When the N-line relay needs to be disengaged, controller 2 disconnects the drive signal output to the second drive switch S2, de-energizing the N-line relay coil SN and causing it to disengage. This enables rapid operation of the N-line relay.

[0031] The control circuit of the inverter described above utilizes a relatively simple, low-cost, and highly reliable circuit structure, which enables separate control of the neutral (N) line relay and the phase line relay, independent control of grid-connected and off-grid operation, and rapid operation of the neutral (N) line relay during grid-connected and off-grid switching.

[0032] In this utility model, such as Figure 2As shown, the driving power supply 1 may include: a first power supply circuit 11, a second power supply circuit 12, and a switching circuit 13.

[0033] The input terminals of the first power supply circuit 11 and the second power supply circuit 12 are connected to the preset power supply VCC. The first power supply circuit 11 and the second power supply circuit 12 are used to convert the DC power output from the preset power supply VCC into voltages respectively. The first input terminal of the switching circuit 13 is connected to the output terminal of the first power supply circuit 11, and the second input terminal of the switching circuit 13 is connected to the output terminal of the second power supply circuit 12. The first output terminal of the switching circuit 13 serves as the first driving terminal VCC_Replay_P of the driving power supply 1, and the second output terminal of the switching circuit 13 serves as the second driving terminal VCC_Replay_N of the driving power supply. The switching circuit 13 is used to output the DC power output from the first power supply circuit 11 or the second power supply circuit 12 to the first driving switch S1 or the second driving switch S2.

[0034] Specifically, such as Figure 2 As shown, when the three-phase relay needs to be engaged, the controller 2 first outputs the first enable signal EN1 to the drive power supply 1. The first power supply circuit 11 of the drive power supply 1 outputs the rated operating voltage of the three-phase relay coil SA. The switching circuit 13 outputs the rated operating voltage to the first drive switch S1, and one end of the SA coil is energized. The controller 2 then outputs a drive signal to the first drive switch S1, and the first drive switch S1 is turned on, thereby controlling the three-phase relay coil SA to engage at the rated speed. After a certain delay time tr_1, the controller 2 disconnects the first enable signal EN1 output to the drive power supply and maintains the drive signal output to the first drive switch S1. The first power supply circuit 11 outputs the reduced holding voltage of the three-phase relay coil SA, and the three-phase relay can remain closed with low power consumption. When the N-line relay needs to be engaged, the controller 2 first outputs a second enable signal EN2 to the drive power supply 1. The second power supply circuit 12 of the drive power supply 1 outputs k times the working voltage of the N-line relay coil SN, where 1≤k≤2. The value of k is determined by the setting parameters of the three-phase relay and the N-line relay drive power supply. The switching circuit 13 outputs k times the working voltage to one end of the SN coil. The controller 2 then outputs a drive signal to the second drive switch S2 to turn on, controlling the N-line relay to engage at a faster speed. After a certain delay time tr_2, the controller 2 disconnects the second enable signal EN2 output to the drive power supply 1 and maintains the drive signal output to the second drive switch S2. The second power supply circuit 12 outputs a reduced holding voltage for the N-line relay coil SN, enabling the N-line relay to remain closed with low power consumption.

[0035] It is understood that a three-phase relay is not necessarily a single relay; it can be two relays on the same phase connected in series, or one or two relays for each of phases A, B, and C; the neutral (N) line relay may also consist of two relays connected in series. This invention is described using only one three-phase relay and one neutral (N) line relay for ease of description.

[0036] For the specific circuit topology of drive power supply 1, please refer to Figure 3 , Figure 4 and Figure 5 As shown. As a first example of this utility model, as... Figure 3 As shown, the driving power supply 1 may include: a first BUCK circuit, a first resistor R1, a second resistor R2, a third resistor R3, a first MOSFET Q1, a fourth resistor R4, a fifth resistor R5, a first capacitor C1, a second BUCK circuit, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a second MOSFET Q2, a ninth resistor R9, a tenth resistor R10, and a second capacitor C2.

[0037] In this circuit, the power input pin IN and enable pin EN of the first BUCK circuit are connected to the first preset power supply VCC1, and the output pin OUT of the first BUCK circuit serves as the first driving terminal VCC_Replay_P of the driving power supply; one end of the first resistor R1 is connected to the output pin OUT of the first BUCK circuit; one end of the second resistor R2 is connected to the other end of the first resistor R1 and the feedback pin FB of the first BUCK circuit, and the other end of the second resistor R2 is grounded; one end of the third resistor R3 is connected to the feedback pin FB of the first BUCK circuit; the first terminal of the first MOSFET Q1 is connected to the other end of the third resistor R3, and the second terminal of the first MOSFET Q1 is grounded; one end of the fourth resistor R4 is connected to the control terminal of the first MOSFET Q1, and the other end of the fourth resistor R4 is grounded; one end of the fifth resistor R5 is connected to the control terminal of the first MOSFET Q1, and the other end of the fifth resistor R5 is connected to the first enable signal output terminal EN1 of the controller 2; the first capacitor C1 is connected in parallel with the fourth resistor R4. The power input pin IN and enable pin EN of the second BUCK circuit are connected to the first preset power supply VCC1. The output pin OUT of the second BUCK circuit serves as the second driving terminal VCC_Replay_N of the driving power supply 1. One end of the sixth resistor R6 is connected to the output pin OUT of the second BUCK circuit. One end of the seventh resistor R7 is connected to the other end of the sixth resistor R6 and the feedback pin FB of the second BUCK circuit. The other end of the seventh resistor R7 is grounded. One end of the eighth resistor R8 is connected to the feedback pin FB of the second BUCK circuit. The first end of the second MOSFET Q2 is connected to the other end of the eighth resistor R8. The second end of the second MOSFET Q2 is grounded. One end of the ninth resistor R9 is connected to the control terminal of the second MOSFET Q2. The other end of the ninth resistor R9 is connected to the second enable signal output terminal of the controller 2. One end of the tenth resistor R10 is connected to the control terminal of the second MOSFET Q2. The other end of the tenth resistor R10 is grounded. The second capacitor C2 is connected in parallel with the tenth resistor R10.

[0038] Specifically, VCC1 is a power supply higher than the rated voltage of the three-phase relay coil SA and the neutral (N) relay coil SN. For example, if the rated coil voltage is 12V, then VCC1 = 24V. For SA, its pull-in voltage is VCC_Relay_P = VCC / 2, and its holding voltage is VCC_Relay_P = VCC / 2 - ΔV1. ΔV1 is the difference between the pull-in voltage and the holding voltage of the neutral (N) relay coil SN, for example, 5V. This allows the three-phase relay coil SA to pull in at its rated speed with a suitable speed to prevent severe rebound and voltage drop during holding. For the neutral (N) relay coil SN, its pull-in voltage is VCC_Relay_N = VCC + ΔV2, and its holding voltage is VCC_Relay_N = VCC / 2 - ΔV1. ΔV2 is the voltage increase required to accelerate the pull-in of the neutral (N) relay, specifically determined according to the engineering design. This allows the neutral (N) relay to pull in at the fastest speed and maintain its holding voltage at a reduced rate. Without considering relay self-tests or the same number of self-tests for three-phase relays and neutral (N) line relays, three-phase relays need to engage during normal grid connection, remain engaged during grid connection, and disengage during shutdown. The number of operations within their lifespan is the same as the number of inverter startups, which is a relatively large value. Therefore, a suitable operating speed and using VCC_Relay_P = VCC - ΔV1 for engagement are beneficial for improving lifespan. Neutral (N) line relays close instantly during grid-to-off-grid transitions and require rapid closing to shorten the grid-to-off-grid transition time for seamless switching. However, the number of grid-to-off-grid transitions within the inverter's lifespan is small, so lifespan is a secondary parameter and speed is the primary parameter.

[0039] When controller 2 outputs the EN1 signal, Q1 is turned on. The voltage divider between R3 and R2 (connected in parallel) and R1 serves as the feedback value for FB. At this time, VCC_Relay_P is the rated voltage of the coil. When controller 2 stops outputting the EN1 signal, Q1 is turned off. The voltage divider between R2 and R1 serves as the feedback value for FB. At this time, VCC_Relay_P is in a step-down holding mode. When controller 2 outputs the EN2 signal, Q2 is turned on. The voltage divider between R8 and R7 (connected in parallel) and R6 serves as the feedback value for FB. At this time, VCC_Relay_N is the rated voltage of the coil, VCC + ΔV2. When controller 2 stops outputting the EN2 signal, Q2 is turned off. The voltage divider between R7 and R6 serves as the feedback value for FB. At this time, VCC_Relay_N is in a step-down holding mode. By adjusting the values ​​of R3 and R8, ΔV1 and ΔV2 can be arbitrarily adjusted.

[0040] This section only describes the drive power supply inputs for the three-phase relays and neutral (N) relays on the AC side of the inverter. The activation of the three-phase and N relays requires the drive power supply to first output voltage as the coil voltage, and then control the activation and deactivation of the relay inputs via S1 and S2. Subsequent embodiments will also only illustrate the drive power supply and control of the phase and N relays.

[0041] As a second example of this utility model, such as Figure 4As shown, the driving power supply 1 includes: a third BUCK circuit, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a third MOSFET Q3, a fourteenth resistor R14, a third capacitor C3, a fifteenth resistor R15, a fourth MOSFET Q4, a sixteenth resistor R16, a first diode D1, a seventeenth resistor Q17, a fifth MOSFET Q5, an eighteenth resistor R18, a nineteenth resistor R19, and a fourth capacitor C4.

[0042] In this circuit, the power input pin IN and enable pin EN of the third BUCK circuit are connected to the second preset power supply VCC2, and the output pin OUT of the third BUCK circuit serves as the first driving terminal VCC_Relay_P of the driving power supply; one end of the eleventh resistor R11 is connected to the output pin OUT of the third BUCK circuit, and the other end of the eleventh resistor R11 is connected to the feedback pin FB of the third BUCK circuit; one end of the twelfth resistor R12 is connected to the other end of the eleventh resistor R11, and the other end of the twelfth resistor R12 is grounded; one end of the thirteenth resistor R13 is connected to the other end of the eleventh resistor R11; the first terminal of the third MOSFET Q3 is connected to the other end of the thirteenth resistor R13, and the second terminal of the third MOSFET Q3 is grounded; one end of the fourteenth resistor R14 is connected to the control terminal of the third MOSFET Q3, and the other end of the fourteenth resistor R14 is grounded; the third capacitor C3 is connected in parallel with the fourteenth resistor R14; one end of the fifteenth resistor R15 is connected to the control terminal of the third MOSFET Q3, and the fifteenth resistor R15... The other end is connected to the first enable signal output terminal of controller 2; the first end of the fourth MOSFET Q4 is connected to the second preset power supply VCC2, and the second end of the fourth MOSFET Q4 serves as the second driving terminal VCC_Relay_N of the driving power supply; the sixteenth resistor R16 is connected between the first end of the fourth MOSFET Q4 and the control terminal; the anode of the first diode D1 is connected to the control terminal of the fourth MOSFET Q4, and the cathode of the first diode D1 is connected to the second end of the fourth MOSFET Q4; one end of the seventeenth resistor R17 is connected to the control terminal of the fourth MOSFET Q4; the first end of the fifth MOSFET Q5 is connected to the other end of the seventeenth resistor R17, and the second end of the fifth MOSFET Q5 is grounded; one end of the eighteenth resistor R18 is connected to the control terminal of the fifth MOSFET Q5, and the other end of the eighteenth resistor R18 is connected to the second enable signal output terminal of controller 2; one end of the nineteenth resistor R19 is connected to the control terminal of the fifth MOSFET Q5, and the other end of the nineteenth resistor R19 is grounded; the fourth capacitor C4 is connected in parallel with the nineteenth resistor R19.

[0043] Specifically, Figure 4In this configuration, VCC2 can be 24V. When the three-phase relay needs to be closed, the controller outputs the EN1 signal, Q3 is turned on, R12 and R13 are connected in parallel and then connected in series with R11 to divide the voltage, thus VCC_Relay_P outputs 12V, and SA is energized at the rated speed. After a delay time t_r1, the controller 2 stops outputting the first enable signal EN1, Q3 is turned off, R12 and R11 are connected in series to divide the voltage, thus VCC_Relay_P outputs 7V, and the three-phase relay coil SA is held at a reduced voltage.

[0044] When the N-line relay needs to be closed, controller 2 outputs the second enable signal EN2, Q5 turns on, and then Q4 turns on. VCC_Relay_N outputs 24V, and the N-line relay coil SN quickly engages. After a delay time t_r2, controller 2 stops outputting the second enable signal EN2, Q5 turns off, and then Q4 turns off. VCC_Relay_P is output to the N-line relay coil SN through the first diode D1, that is, VCC_Relay_N = 7 - 0.3V = 6.7V, and the N-line relay coil SN is maintained at a reduced voltage. When the three-phase relay and the neutral (N) relay need to be closed simultaneously, controller 2 outputs the first enable signal EN1 and the second enable signal EN2 simultaneously. As with the above logic, VCC_Relay_P = 12V, VCC_Relay_N = 24V. The three-phase relay coil SA is energized at the rated speed, and the neutral (N) relay coil SN is energized at an accelerated speed. After a delay time t_r2, controller 2 stops outputting the second enable signal EN. VCC_Relay_N = 12 - 0.4V = 11.7V can be maintained. After another (t_r1 - t_r2), the three-phase relay coil SA is maintained at a reduced voltage of 7V, and the neutral (N) relay coil SN is maintained at a reduced voltage.

[0045] In this invention, since the SN attraction speed is faster, t_r2 < t_r1.

[0046] As a third example of this utility model, such as Figure 5 As shown, the drive power supply 1 includes: a fourth BUCK circuit, a twentieth resistor R20, a twenty-first resistor R21, a second diode D2, a third diode D3, a sixth MOSFET Q6, a twenty-second resistor R22, a twenty-third resistor R23, a twenty-fourth resistor R24, a BOOST circuit, a twenty-fifth resistor R25, a seventh MOSFET Q7, a twenty-sixth resistor R26, a twenty-seventh resistor R27, and a fifth capacitor C5.

[0047] In this circuit, the power input pin IN and enable pin EN of the fourth BUCK circuit are connected to the third preset power supply VCC3; one end of the twentieth resistor R20 is connected to the output pin OUT of the fourth BUCK circuit; one end of the twenty-first resistor R21 is connected to the other end of the twentieth resistor R20 and to the feedback pin FB of the fourth BUCK circuit, and the other end of the twenty-first resistor R21 is grounded; the anode of the second diode D2 is connected to the output pin OUT of the fourth BUCK circuit, and the cathode of the second diode D2 serves as the first driving terminal VCC_Relay_P of the driving power supply; the anode of the third diode D3 is connected to the anode of the second diode D2; the first terminal of the sixth MOSFET Q6 is connected to the third preset power supply VCC3, and the second terminal of the sixth MOSFET Q6 is connected to the cathode of the second diode D2; the twenty-second resistor R22 is connected between the first terminal and the control terminal of the sixth MOSFET Q6; one end of the twenty-third resistor R23 is connected to the control terminal of the sixth MOSFET Q6; the power input pin IN of the BOOST circuit is connected to the third preset power supply VCC3; one end ... The three preset power supplies VCC3 are connected. The output pin OUT of the BOOST circuit is connected to the cathode of the third diode D3 and serves as the second driving terminal VCC_Relay_N of the driving power supply. The enable pin EN of the BOOST circuit is connected to the second enable signal output terminal of the controller 2. One end of the twenty-fourth resistor R24 ​​is connected to the output pin OUT of the BOOST circuit. One end of the twenty-fifth resistor R25 is connected to the other end of the twenty-fourth resistor R24 ​​and the feedback pin FB of the BOOST circuit. The other end of the twenty-fifth resistor R25 is grounded. The first end of the seventh MOSFET Q7 is connected to the other end of the twenty-third resistor R23. The second end of the seventh MOSFET Q7 is grounded. One end of the twenty-sixth resistor R26 is connected to the control terminal of the seventh MOSFET Q7. The other end of the twenty-sixth resistor R26 is connected to the first enable signal output terminal of the controller 2. One end of the twenty-seventh resistor R27 is connected to the control terminal of the seventh MOSFET Q7. The other end of the twenty-seventh resistor R27 is grounded. The fifth capacitor C5 is connected in parallel with the twenty-seventh resistor R27.

[0048] Specifically, Figure 5In the circuit, VCC3 = 12V, the output of the fourth BUCK circuit is constant at VCC_Relay_HOLD = 7V and is always enabled; the BOOST circuit output is constant at 24V but requires the second enable signal EN2 for control. When the three-phase relay needs to be closed, the controller outputs the first enable signal EN1, Q7 turns on and then Q6 turns on, VCC_Relay_P outputs 12V, and the three-phase relay coil SA pulls in at the rated speed; after a delay time t_r1, the controller 2 stops outputting the first enable signal EN1, Q7 turns off and then Q6 turns off, VCC_Relay_P outputs 6.7V, and the three-phase relay coil SA is held at a reduced voltage. When the N-line relay needs to close, controller 2 outputs the second enable signal EN2, the BOOST circuit outputs 24V, VCC_Relay_N = 24V, and the N-line relay coil SN pulls in faster. After a delay time t_r2 (t_r2 < t_r1 because SN pulls in faster), controller 2 stops outputting the second enable signal EN2, the BOOST circuit shuts off, and VCC_Relay_HOLD is output to the N-line relay coil SN through the second diode D2, that is, VCC_Relay_N = 6.7V, and the N-line relay coil SN is held at a reduced voltage. When the three-phase relay and the neutral (N) relay need to close simultaneously, controller 2 outputs the first enable signal EN1 and the second enable signal EN2 simultaneously. As with the above logic, VCC_Relay_P = 12V and VCC_Relay_N = 24V. The three-phase relay coil SA closes at the rated speed, and the neutral (N) relay coil SN closes at an accelerated speed. After a delay time t_r2, controller 2 stops outputting the second enable signal EN2, and VCC_Relay_N = 6.7V can be maintained. After another (t_r1-t_r2), the three-phase relay coil SA is maintained at a reduced voltage of 6.7V.

[0049] In one embodiment of this utility model, such as Figure 6As shown, the first power supply circuit 11 may include: a first voltage converter 111 (e.g., a BUCK circuit) and a first holding control module 112. The input terminal of the first voltage converter 111 is connected to a preset power supply VCC, the output terminal of the first voltage converter 111 is connected to the first input terminal of the switching circuit 13, the feedback terminal FB of the first voltage converter 11 is connected to the first terminal of the first holding control module 112, the second terminal of the first holding control module 112 is connected to the output terminal of the first voltage converter 111, and the control terminal of the first holding control module 112 is connected to the first enable signal EN1 output terminal of the controller 2. The first holding control module 112 is used to control the first voltage converter 111 to output a first voltage to the switching circuit 13 when it receives the first enable signal EN1, and to control the first voltage converter 111 to output a second voltage to the switching circuit 13 when it stops receiving the first enable signal EN1. The second voltage is less than the first voltage, for example, the first voltage is 12V and the second voltage is 7V.

[0050] The second power supply circuit 12 includes: a second voltage converter 121 (e.g., a BUCK or BOOST circuit) and a second holding control module 122. The input terminal of the second voltage converter 121 is connected to a preset power supply VCC, the output terminal of the second voltage converter 121 is connected to the second input terminal of the switching circuit 13, the feedback terminal FB of the second voltage converter 121 is connected to the first terminal of the second holding control module 122, the second terminal of the second holding control module 122 is connected to the output terminal of the second voltage converter 121, and the control terminal of the second holding control module 122 is connected to the output terminal of the second enable signal EN2 of the controller 2. The second holding control module 122 is used to control the second voltage converter 121 to output a third voltage to the switching circuit 13 when it receives the second enable signal EN2, and to control the second voltage converter 121 to output a fourth voltage to the switching circuit 13 when it stops receiving the second enable signal EN2. The fourth voltage is less than the third voltage, for example, the third voltage is 24V and the third voltage is 6.7V.

[0051] Specifically, such as Figure 6As shown, when the three-phase relay needs to be engaged, the controller 2 first outputs a first enable signal EN1 to the first holding control module 112. The first holding control module 112 controls the first voltage converter 111 to output the rated operating voltage of the three-phase relay coil SA. The switching circuit 13 outputs the rated operating voltage to the first drive switch S1, and SA is energized. The controller 2 then outputs a drive signal to the first drive switch S1, and the first drive switch S1 is turned on, thereby controlling the three-phase relay coil SA to engage at the rated speed. After a certain delay time tr_1, the controller 2 disconnects the first enable signal EN1 output to the drive power supply and maintains the drive signal output to the three-phase relay coil SA. The first holding control module 112 controls the first voltage converter 111 to output a stepped-down holding voltage for the three-phase relay coil SA, and the three-phase relay can remain closed with low power consumption.

[0052] When the N-line relay needs to be engaged, the controller 2 first outputs a second enable signal EN2 to the second holding control module 122. The second holding control module 122 controls the second voltage converter 121 to output k times the working voltage of the N-line relay coil SN. The switching circuit 13 outputs k times the working voltage to the second drive switch S2. The controller 2 then outputs a drive signal to the second drive switch S2 to turn it on, controlling the N-line relay to engage at a faster speed. After a certain delay time tr_2, the controller 2 disconnects the second enable signal EN2 output to the second holding control module 122 and maintains the drive signal output to the second drive switch S2. The second holding control module 122 controls the second voltage converter 121 to output a reduced holding voltage of the N-line relay coil SN, enabling the N-line relay to remain closed with low power consumption.

[0053] Furthermore, such as Figure 7 As shown, in one embodiment of this utility model, the first holding control module 112 or the second holding control module 122 includes: a feedback switching control unit 1121, a first feedback circuit 1122 and a second feedback circuit 1123. The control terminal of the feedback switching control unit 1121 is connected to the enable terminal (EN1 or EN2) of the controller, and the input terminal of the feedback switching control unit 1121 is connected to the feedback terminal FB of the first voltage converter 111 or the second voltage converter 121. One end of the first feedback circuit 1122 and the second feedback circuit 1123 is connected to the feedback switching control unit 1121, and the other end of the first feedback circuit 1122 and the second feedback circuit 1123 is connected to the output terminal of the first voltage converter 111 or the second voltage converter 121.

[0054] Specifically, such as Figure 7As shown, when the three-phase relay needs to be engaged, the controller 2 first outputs a first enable signal EN1 to the feedback switching control unit 1121 in the first power supply circuit 11. The feedback switching control unit 1121 controls the first feedback circuit 1122 to connect to the feedback terminal of the first voltage converter 111. The first feedback circuit 1122 outputs a first voltage, and the output terminal Vout of the first voltage converter 111 outputs the first voltage to the first drive switch S1, energizing SA. The controller 2 then outputs a drive signal to the first drive switch S1, turning on the first drive switch S1, thereby controlling the three-phase relay coil S. When relay A engages at its rated speed, after a certain delay time tr_1, controller 2 disconnects the first enable signal EN1 output to feedback switching control unit 1121 and maintains the drive signal output to the three-phase relay coil SA. Feedback switching control unit 1122 controls the second feedback circuit 1123 to connect to the feedback terminal of the first voltage converter 111. The second feedback circuit 1123 outputs a second voltage, and the output terminal Vout of the first voltage converter 111 outputs the second voltage to the first drive switch S1, outputting a stepped-down holding voltage for the three-phase relay coil. The three-phase relay can remain closed with low power consumption. The neutral (N) line relay engages similarly.

[0055] As an example, such as Figure 8 As shown, the first feedback circuit 1122 includes a first resistor R1 and a second resistor R2; the second feedback circuit 1123 includes a third resistor R3; the feedback switching control unit 1121 includes a first MOSFET Q1, a fourth resistor R4, a fifth resistor R5, and a first capacitor C1. One end of the first resistor R1 is connected to the output terminal of either the first voltage converter 111 or the second voltage converter 112; one end of the second resistor R2 is connected to the other end of the first resistor R1; and one end of the second resistor R3, together with the other end of the first resistor R1, serves as a voltage divider for the first feedback circuit and is connected to either the first voltage converter 111 or the second voltage converter 112. The feedback terminal of voltage converter 112 is connected, the other end of the second resistor R2 is grounded, one end of the third resistor R3 is connected to the voltage divider terminal, the first terminal of the first MOSFET Q1 is connected to the other end of the third resistor R3, the second terminal of the first MOSFET Q1 is grounded, one end of the fourth resistor R4 is connected to the control terminal of the first MOSFET Q1, the other end of the fourth resistor R4 is grounded, one end of the fifth resistor R5 is connected to the control terminal of the first MOSFET Q1, the other end of the fifth resistor R5 is connected to the first enable signal output terminal EN1 or the second enable signal output terminal EN2 of the controller, and the first capacitor C1 is connected in parallel with the fourth resistor R4.

[0056] Specifically, when controller 2 outputs the EN1 signal, Q1 is turned on, and the voltage divider between R3 and R2 and R1 serves as the feedback value for FB. At this time, VCC_Relay_P is the rated voltage of the coil. When controller 2 stops outputting the EN1 signal, Q1 is turned off, and the voltage divider between R2 and R1 serves as the feedback value for FB. At this time, VCC_Relay_P is in a step-down holding mode. The neutral (N) line relay is activated.

[0057] In summary, the control circuit of the inverter according to the embodiment of this utility model can realize independent control of the operating timing and pull-in speed of the AC side three-phase relay coil and the N-line relay coil of the inverter, so as to achieve rapid switching between grid connection and off-grid without relying on external N-line thyristors. Moreover, the entire circuit adopts a simple structure and low cost.

[0058] This utility model also proposes an inverter, including the control circuit of the inverter described above.

[0059] According to the inverter of this utility model, the control circuit of the inverter can realize independent control of the operating timing and pull-in speed of the AC side three-phase relay coil and the N-line relay coil, so as to realize the rapid switching between grid connection and off-grid without relying on the external N-line thyristor. Moreover, the entire circuit adopts a simple structure and low cost.

[0060] In the description of this utility model, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0061] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0062] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0063] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A control circuit for an inverter, characterized in that, include: The driving power supply has a first driving terminal connected to one end of the three-phase relay coil on the AC side of the inverter, and a second driving terminal connected to one end of the neutral (N) line relay coil on the AC side of the inverter. The first driving switch transistor has its first end connected to the other end of the three-phase relay coil and its second end grounded. The second driving switch transistor has its first end connected to the other end of the N-line relay coil and its second end grounded. The controller is connected to the driving power supply, the control terminal of the first driving switch, and the control terminal of the second driving switch. The controller is used to output an enable signal to the driving power supply and a driving signal to the first driving switch and the second driving switch, so that the driving power supply drives the three-phase relay coil or the N-line relay coil to be energized according to the enable signal, and the first driving switch and the second driving switch disconnect according to the driving signal to drive the three-phase relay coil or the N-line relay coil to be de-energized.

2. The control circuit of the inverter according to claim 1, characterized in that, The driving power supply includes: A first power supply circuit and a second power supply circuit, the input terminals of the first power supply circuit and the second power supply circuit are connected to a preset power supply, and the first power supply circuit and the second power supply circuit are used to convert the DC power output by the preset power supply into voltage respectively. A switching circuit is provided, wherein the first input terminal of the switching circuit is connected to the output terminal of the first power supply circuit, the second input terminal of the switching circuit is connected to the output terminal of the second power supply circuit, the first output terminal of the switching circuit serves as the first driving terminal of the driving power supply, and the second output terminal of the switching circuit serves as the second driving terminal of the driving power supply. The switching circuit is used to output the DC power output by the first power supply circuit or the second power supply circuit to the first driving switch or the second driving switch transistor.

3. The control circuit of the inverter according to claim 2, characterized in that, in, The first power supply circuit includes: a first voltage converter and a first holding control module. The input terminal of the first voltage converter is connected to a preset power supply. The output terminal of the first voltage converter is connected to the first input terminal of the switching circuit. The feedback terminal of the first voltage converter is connected to the first terminal of the first holding control module. The second terminal of the first holding control module is connected to the output terminal of the first voltage converter. The control terminal of the first holding control module is connected to the first enable signal output terminal of the controller. The first holding control module is used to control the first voltage converter to output a first voltage to the switching circuit when it receives the first enable signal, and to control the first voltage converter to output a second voltage to the switching circuit when it stops receiving the first enable signal, wherein the second voltage is less than the first voltage.

4. The control circuit of the inverter according to claim 3, characterized in that, The second power supply circuit includes: a second voltage converter and a second holding control module. The input terminal of the second voltage converter is connected to a preset power supply, the output terminal of the second voltage converter is connected to the second input terminal of the switching circuit, the feedback terminal of the second voltage converter is connected to the first terminal of the second holding control module, the second terminal of the second holding control module is connected to the output terminal of the second voltage converter, and the control terminal of the second holding control module is connected to the second enable signal output terminal of the controller. The second holding control module is used to control the second voltage converter to output a third voltage to the switching circuit when receiving a second enable signal, and to control the second voltage converter to output a fourth voltage to the switching circuit when stopping receiving the second enable signal, wherein the fourth voltage is less than the third voltage.

5. The control circuit of the inverter according to claim 4, characterized in that, The first holding control module or the second holding control module includes: A feedback switching control unit, wherein the control terminal of the feedback switching control unit is connected to the enable terminal of the controller, and the output terminal of the feedback switching control unit is connected to the feedback terminal of the first voltage converter or the second voltage converter; A first feedback circuit and a second feedback circuit, one end of which is connected to the feedback switching control unit, and the other end of which is connected to the output terminal of the first voltage converter or the second voltage converter.

6. The control circuit of the inverter according to claim 5, characterized in that, The first feedback circuit includes: a first resistor and a second resistor; the second feedback circuit includes: a third resistor; the feedback switching control unit includes: a first MOSFET, a fourth resistor, a fifth resistor, and a first capacitor, wherein, One end of the first resistor is connected to the output terminal of the first voltage converter or the second voltage converter. One end of the second resistor is connected to the other end of the first resistor. The connection between the second end and the other end of the first resistor serves as the voltage divider terminal of the first feedback circuit and is connected to the feedback terminal of the first voltage converter or the second voltage converter. The other end of the second resistor is grounded. One end of the third resistor is connected to the voltage divider terminal. The first end of the first MOSFET is connected to the other end of the third resistor. The second end of the first MOSFET is grounded. One end of the fourth resistor is connected to the control terminal of the first MOSFET. The other end of the fourth resistor is grounded. One end of the fifth resistor is connected to the control terminal of the first MOSFET. The other end of the fifth resistor is connected to the first enable signal output terminal or the second enable signal output terminal EN2 of the controller. The first capacitor is connected in parallel with the fourth resistor.

7. An inverter, characterized in that, Includes the control circuit of the inverter according to any one of claims 1-6.

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