Primary-secondary side coordinated control circuit and method based on isolated grid-connected inverter

Abstract

The present invention relates to a primary-secondary coordinated control circuit and method based on an isolated grid-connected inverter, and belongs to the technical field of inverters. The primary-secondary coordinated control circuit and method of the present invention can collect VH voltage signals through the secondary side to determine whether the VH voltage exceeds a threshold value; and when the threshold value is exceeded, the primary side device is controlled to stop functioning, thereby avoiding damage caused by the impact of the high voltage value on VH on the MOS tube; further, the half-wave where the grid waveform is located can be determined, and the corresponding half-wave drive control device can be used to control the function, thereby preventing damage to the equipment caused by the simultaneous opening of the upper and lower half-wave drives. The primary-secondary coordinated control circuit and method based on the isolated grid-connected inverter of the present invention are simple to implement and have a wide range of applications.

Description

Technical Field

[0001] The present invention relates to the field of inverter technology, and in particular to the field of inverter control method technology, and specifically refers to a primary-secondary side collaborative control circuit and method based on an isolated grid-connected inverter. Background Art

[0002] In the application of isolated grid-connected inverter, when the primary side stops generating power due to some abnormality, the corresponding power generation voltage VH is lower than the grid voltage, so that the secondary thyristor is turned off, but there is still a certain voltage on VH, and the MOS tube is in the on state (the VH waveform is similar to the corresponding thyristor waveform); but the energy on VH is not released. In the next cycle, the secondary side drives the thyristor to turn on normally, and there is a higher voltage value on VH. At the moment when the secondary thyristor is turned on, there will be a large current impact. If this abnormality is triggered frequently and repeatedly, the secondary MOS tube is easily damaged due to multiple impacts.

[0003] Therefore, providing a new primary-secondary side coordinated control method that can avoid damage to the MOS tube caused by the impact of the high voltage value on VH has become an urgent problem to be solved in the inverter field. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and to provide a primary-secondary side cooperative control circuit and method based on an isolated grid-connected inverter, which can effectively avoid damage to the MOS tube caused by the impact of the high voltage value on VH.

[0005] In order to achieve the above-mentioned purpose, the primary-secondary side cooperative control circuit based on the isolated grid-connected inverter of the present invention has the following structure:

[0006] The primary-secondary coordinated control circuit based on the isolated grid-connected inverter includes a primary circuit connected to a DC power supply device and a secondary circuit connected to an AC power grid. The primary circuit and the secondary circuit are respectively connected to a primary control chip and a secondary control chip.

[0007] The secondary side control chip is used to collect the power generation voltage VH voltage signal of the DC power supply device in the corresponding secondary side circuit, and determine whether the VH voltage signal exceeds a threshold value; when the VH voltage signal exceeds the threshold value, the DC power supply device is controlled to stop generating power through the primary side control chip, and when the VH voltage signal does not exceed the threshold value, the DC power supply device is controlled to generate power through the primary side control chip.

[0008] In the primary-secondary side cooperative control circuit based on the isolated grid-connected inverter, the secondary side control chip is used to collect the power generation voltage VH voltage signal of the DC power supply device in the corresponding secondary side circuit when the AC power grid waveform passes through the zero point, and determine whether the difference between the VH voltage signal and the value of 0 at this time is greater than a threshold.

[0009] In the primary-secondary coordinated control circuit based on the isolated grid-connected inverter, the secondary side control chip is also used to detect the waveform of the AC power grid, and according to whether the waveform is in the positive half-wave or the negative half-wave; the primary side control chip is also used to control the DC power supply device to generate power by using the corresponding positive half-wave drive or negative half-wave drive according to the half-wave where the waveform is located.

[0010] In the primary-secondary side cooperative control circuit based on the isolated grid-connected inverter, the secondary side control chip is specifically used to detect the AC grid waveform and generate an angle value according to the AC grid waveform, and a section of the angle value corresponding to the zero-crossing point of the AC grid waveform is the zero-crossing angle section;

[0011] In a half wave before the zero-crossing angle interval, the primary control chip controls the DC power supply device to generate power by using the corresponding half wave drive;

[0012] In the zero-crossing angle interval, the primary control chip controls the DC power supply device to stop generating power, thereby increasing the dead time;

[0013] During the next half wave after the zero-crossing angle interval, another half wave is used to drive and control the DC power supply device to generate power.

[0014] In the primary-secondary coordinated control circuit based on the isolated grid-connected inverter, the secondary control chip is specifically used to detect the AC grid waveform and determine the half-wave values ​​vg1 and vg2 of the two AC grid samples in real time;

[0015] When vg1-vg2>0, the AC power grid is in a positive half-wave, and the primary control chip uses the positive half-wave drive to control the DC power supply device to work;

[0016] When vg1-vg2<0, the AC power grid is in a negative half-wave, and the primary control chip uses the negative half-wave drive to control the DC power supply device to generate power.

[0017] The present invention also provides a primary-secondary coordinated control method based on an isolated grid-connected inverter, wherein the isolated grid-connected inverter comprises a primary circuit connected to a DC power supply device and a secondary circuit connected to an AC power grid, wherein the primary circuit and the secondary circuit are respectively connected to a primary control chip and a secondary control chip, and the method comprises the following steps:

[0018] (2-1) The secondary control chip collects the power generation voltage VH voltage signal of the DC power supply device in the corresponding secondary circuit, and determines whether the VH voltage signal exceeds a threshold;

[0019] (2-2) When the VH voltage signal exceeds a threshold value, the DC power supply device is controlled by the primary control chip to stop functioning; when the VH voltage signal does not exceed the threshold value, the DC power supply device is controlled by the primary control chip to function.

[0020] In the primary-secondary side coordinated control method based on the isolated grid-connected inverter, the step (2-1) is specifically as follows:

[0021] When the AC power grid waveform passes through zero, the secondary control chip collects the power generation voltage VH voltage signal of the DC power supply device in the corresponding secondary circuit, and determines whether the difference between the VH voltage signal and the value of 0 is greater than a threshold.

[0022] The primary-secondary side coordinated control method based on the isolated grid-connected inverter also includes:

[0023] (1) The secondary control chip detects the waveform of the AC power grid and determines whether the waveform is in the positive half-wave or the negative half-wave. The primary control chip controls the DC power supply device to generate power by using the corresponding positive half-wave drive or negative half-wave drive according to the half-wave where the waveform is located.

[0024] In the primary-secondary side coordinated control method based on the isolated grid-connected inverter, the step (1) specifically includes:

[0025] The secondary control chip described in (1a-1) detects the AC grid waveform and generates an angle value according to the AC grid waveform. The zero-crossing point of the AC grid waveform corresponds to an interval of the angle value as the zero-crossing point angle interval.

[0026] (1a-2) In a half-wave before the zero-crossing angle interval, the primary control chip uses the corresponding half-wave drive to control the DC power supply device to generate power;

[0027] In the zero-crossing angle interval, the primary control chip controls the DC power supply device to stop generating power, thereby increasing the dead time;

[0028] During the next half wave after the zero-crossing angle interval, another half wave is used to drive and control the DC power supply device to generate power.

[0029] In the primary-secondary side coordinated control method based on the isolated grid-connected inverter, the step (1) specifically includes:

[0030] The secondary side control chip (1b-1) is specifically used to detect the AC grid waveform and determine the half-wave values ​​vg1 and vg2 of the two AC grid samples in real time;

[0031] (1b-2) When vg1-vg2>0, the AC power grid is in a positive half-wave, and the primary control chip uses the positive half-wave drive to control the DC power supply device to generate power;

[0032] When vg1-vg2<0, the AC power grid is in a negative half-wave, and the primary control chip uses the negative half-wave drive to control the DC power supply device to generate power.

[0033] The primary-secondary coordinated control circuit and method based on the isolated grid-connected inverter of the invention can collect the VH voltage signal to determine whether it exceeds the threshold; and when it exceeds the threshold, the control device stops working, thereby avoiding damage caused by the impact of the high voltage value on VH on the MOS tube. Further, the half-wave of the grid waveform can be determined, and the corresponding half-wave drive control device can be used to control the device to work, thereby preventing damage to the device caused by the simultaneous opening of the upper and lower half-wave drives. The primary-secondary coordinated control circuit and method based on the isolated grid-connected inverter of the invention are simple to implement and have a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a circuit structure schematic diagram of a primary-secondary side cooperative control circuit based on an isolated grid-connected inverter of the present invention;

[0035] Figure 2 It is a flow chart of the steps of the primary-secondary side cooperative control method based on the isolated grid-connected inverter of the present invention. DETAILED DESCRIPTION

[0036] In order to more clearly understand the technical content of the present invention, the following embodiments are given in detail.

[0037] See also Figure 1 As shown, it is a circuit structure schematic diagram of the primary-secondary side cooperative control circuit based on the isolated grid-connected inverter of the present invention.

[0038] In one embodiment, the primary-secondary coordinated control circuit based on the isolated grid-connected inverter includes a primary circuit connected to a DC power supply device and a secondary circuit connected to an AC power grid, wherein the primary circuit and the secondary circuit are respectively connected to a primary control chip and a secondary control chip;

[0039] The secondary side control chip is used to collect the power generation voltage VH voltage signal of the DC power supply device in the corresponding secondary side circuit, and determine whether the VH voltage signal exceeds a threshold value; when the VH voltage signal exceeds the threshold value, the DC power supply device is controlled to stop generating power through the primary side control chip, and when the VH voltage signal does not exceed the threshold value, the DC power supply device is controlled to generate power through the primary side control chip.

[0040] In a preferred embodiment, the secondary side control chip is used to collect the power generation voltage VH voltage signal of the DC power supply device in the corresponding secondary side circuit when the AC power grid waveform passes through the zero point, and determine whether the difference between the VH voltage signal and the value of 0 at this time is greater than a threshold.

[0041] In another preferred embodiment, the secondary side control chip is also used to detect the waveform of the AC power grid, and according to whether the waveform is in the positive half-wave or the negative half-wave; the primary side control chip is also used to control the DC power supply device to operate using the corresponding positive half-wave drive or negative half-wave drive according to the half-wave in which the waveform is located.

[0042] In a more preferred embodiment, the secondary control chip is specifically used to detect the AC grid waveform and generate an angle value according to the AC grid waveform, and a section of the angle value corresponding to the zero-crossing point of the AC grid waveform is the zero-crossing angle section;

[0043] In a half wave before the zero-crossing angle interval, the primary control chip controls the DC power supply device to generate power by using the corresponding half wave drive;

[0044] In the zero-crossing angle interval, the primary control chip controls the DC power supply device to stop generating power, thereby increasing the dead time;

[0045] During the next half wave after the zero-crossing angle interval, another half wave is used to drive and control the DC power supply device to generate power.

[0046] In another more preferred embodiment, the secondary side control chip is specifically used to detect the AC grid waveform and determine the half-wave values ​​vg1 and vg2 of the two previous and next AC grid samples in real time;

[0047] When vg1-vg2>0, the AC power grid is in a positive half-wave, and the primary control chip uses the positive half-wave drive to control the DC power supply device to work;

[0048] When vg1-vg2<0, the AC power grid is in a negative half-wave, and the primary control chip uses the negative half-wave drive to control the DC power supply device to generate power.

[0049] The present invention also provides a primary-secondary coordinated control method based on an isolated grid-connected inverter, wherein the isolated grid-connected inverter comprises a primary circuit connected to a DC power supply device and a secondary circuit connected to an AC power grid, wherein the primary circuit and the secondary circuit are respectively connected to a primary control chip and a secondary control chip, wherein the method is as follows Figure 2 As shown, the following steps are included:

[0050] (2-1) The secondary control chip collects the power generation voltage VH voltage signal of the DC power supply device in the corresponding secondary circuit, and determines whether the VH voltage signal exceeds a threshold;

[0051] (2-2) When the VH voltage signal exceeds a threshold value, the DC power supply device is controlled by the primary control chip to stop functioning; when the VH voltage signal does not exceed the threshold value, the DC power supply device is controlled by the primary control chip to function.

[0052] In a preferred embodiment, the step (2-1) is specifically:

[0053] When the AC power grid waveform passes through zero, the secondary control chip collects the power generation voltage VH voltage signal of the DC power supply device in the corresponding secondary circuit, and determines whether the difference between the VH voltage signal and the value of 0 is greater than a threshold.

[0054] In another preferred embodiment, the method further comprises:

[0055] (1) The secondary control chip detects the waveform of the AC power grid and determines whether the waveform is in the positive half-wave or the negative half-wave. The primary control chip controls the DC power supply device to generate power by using the corresponding positive half-wave drive or negative half-wave drive according to the half-wave where the waveform is located.

[0056] In a more preferred embodiment, the step (1) may specifically include:

[0057] The secondary control chip described in (1a-1) detects the AC grid waveform and generates an angle value according to the AC grid waveform. The zero-crossing point of the AC grid waveform corresponds to an interval of the angle value as the zero-crossing point angle interval.

[0058] (1a-2) In a half-wave before the zero-crossing angle interval, the primary control chip uses the corresponding half-wave drive to control the DC power supply device to generate power;

[0059] In the zero-crossing angle interval, the primary control chip controls the DC power supply device to stop generating power, thereby increasing the dead time;

[0060] During the next half wave after the zero-crossing angle interval, another half wave is used to drive and control the DC power supply device to generate power.

[0061] In another more preferred embodiment, optionally, the step (1) may specifically include:

[0062] The secondary side control chip (1b-1) is specifically used to detect the AC grid waveform and determine the half-wave values ​​vg1 and vg2 of the two AC grid samples in real time;

[0063] (1b-2) When vg1-vg2>0, the AC power grid is in a positive half-wave, and the primary control chip uses the positive half-wave drive to control the DC power supply device to generate power;

[0064] When vg1-vg2<0, the AC power grid is in a negative half-wave, and the primary control chip uses the negative half-wave drive to control the DC power supply device to generate power.

[0065] In the application of the present invention, in order to avoid damage caused by the impact of the high voltage value on VH on the MOS tube, the sampling of the VH signal by the secondary control chip can be increased, and then the secondary drive and primary drive on / off logic can be optimized by judging the amplitude of the VH signal. The specific method is:

[0066] VH is the voltage of the device, and the voltage waveform changes synchronously with the grid waveform. When the grid waveform passes through the zero point, the grid waveform is 0. Under normal circumstances, the VH waveform is also 0 at this time. Therefore, it can be judged by sampling the VH voltage value at the zero point. If the value is greater than the threshold of the zero-crossing VH under normal circumstances, it is considered that the device is not operating normally at this time, and the device needs to stop operating until the VH voltage value is less than the threshold and then it can operate normally.

[0067] The secondary side program can be further optimized. Specifically, you can choose to increase the dead time or increase the difference judgment of vg1 and vg2 to ensure that the drive is turned on at the corresponding half-wave.

[0068] Method 1: Increase dead time:

[0069] The device will detect the grid waveform to generate an angle value. The zero crossing point of the grid waveform corresponds to a range of angle values. In this range, the device will turn off the power driver and wait until the next half-wave to start another set of drivers. Increasing the dead time means increasing the driver shutdown interval without affecting the normal operation of the device to prevent the upper and lower half-wave drivers from being turned on at the same time, causing damage to the device.

[0070] Method 2: Add the difference between vg1 and vg2:

[0071] vg1 and vg2 are the values ​​of the two half-waves sampled by the power grid. When the power grid is in the positive half-wave, vg1-vg2>0, and when the power grid is in the negative half-wave, vg1-vg2<0. Therefore, the difference between the two can be used to determine which half-wave the power grid is in to prevent abnormal drive startup.

[0072] The primary-secondary coordinated control circuit and method based on the isolated grid-connected inverter of the invention can collect the VH voltage signal to determine whether it exceeds the threshold; and when it exceeds the threshold, the control device stops working, thereby avoiding damage caused by the impact of the high voltage value on VH on the MOS tube. Further, the half-wave of the grid waveform can be determined, and the corresponding half-wave drive control device can be used to control the device to work, thereby preventing damage to the device caused by the simultaneous opening of the upper and lower half-wave drives. The primary-secondary coordinated control circuit and method based on the isolated grid-connected inverter of the invention are simple to implement and have a wide range of applications.

[0073] In this specification, the present invention has been described with reference to specific embodiments thereof. However, it is apparent that various modifications and variations may be made without departing from the spirit and scope of the present invention. Therefore, the specification and drawings should be regarded as illustrative rather than restrictive.

Claims

1. A primary-secondary coordinated control circuit based on an isolated grid-connected inverter, comprising a primary circuit connected to a DC power supply device and a secondary circuit connected to an AC power grid, characterized in that: The primary circuit and the secondary circuit are respectively connected to a primary control chip and a secondary control chip; The secondary side control chip is used to collect the power generation voltage VH voltage signal of the DC power supply device in the corresponding secondary side circuit, and determine whether the VH voltage signal exceeds a threshold value; when the VH voltage signal exceeds the threshold value, the DC power supply device is controlled to stop generating power through the primary side control chip, and when the VH voltage signal does not exceed the threshold value, the DC power supply device is controlled to generate power through the primary side control chip.

2. The primary-secondary side cooperative control circuit based on the isolated grid-connected inverter according to claim 1, characterized in that: The secondary side control chip is used to collect the power generation voltage VH voltage signal of the DC power supply device in the corresponding secondary side circuit when the AC power grid waveform passes through the zero point, and determine whether the difference between the VH voltage signal and the value of 0 is greater than a threshold value.

3. The primary-secondary side cooperative control circuit based on the isolated grid-connected inverter according to claim 1, characterized in that: The secondary control chip is also used to detect the waveform of the AC power grid, and according to whether the waveform is in the positive half-wave or the negative half-wave; the primary control chip is also used to control the DC power supply device to generate power by using the corresponding positive half-wave drive or negative half-wave drive according to the half-wave where the waveform is located.

4. The primary-secondary side cooperative control circuit based on the isolated grid-connected inverter according to claim 3, characterized in that: The secondary side control chip is specifically used to detect the AC grid waveform and generate an angle value according to the AC grid waveform, and a section of the angle value corresponding to the zero crossing point of the AC grid waveform is the zero crossing angle section; In a half wave before the zero-crossing angle interval, the primary control chip controls the DC power supply device to generate power by using the corresponding half wave drive; In the zero-crossing angle interval, the primary control chip controls the DC power supply device to stop generating power, thereby increasing the dead time; During the next half wave after the zero-crossing angle interval, another half wave is used to drive and control the DC power supply device to generate power.

5. The primary-secondary side cooperative control circuit based on the isolated grid-connected inverter according to claim 3, characterized in that: The secondary side control chip is specifically used to detect the AC grid waveform and determine the half-wave values ​​vg1 and vg2 of the two AC grid samples in real time; When vg1-vg2>0, the AC power grid is in a positive half-wave, and the primary control chip uses the positive half-wave drive to control the DC power supply device to work; When vg1-vg2<0, the AC power grid is in a negative half-wave, and the primary control chip uses the negative half-wave drive to control the DC power supply device to generate power.

6. A primary-secondary coordinated control method based on an isolated grid-connected inverter, the isolated grid-connected inverter comprising a primary circuit connected to a DC power supply device and a secondary circuit connected to an AC power grid, the primary circuit and the secondary circuit are respectively connected to a primary control chip and a secondary control chip, characterized in that: The method comprises the following steps: (2-1) The secondary control chip collects the power generation voltage VH voltage signal of the DC power supply device in the corresponding secondary circuit, and determines whether the VH voltage signal exceeds a threshold; (2-2) When the VH voltage signal exceeds a threshold value, the DC power supply device is controlled by the primary control chip to stop functioning; when the VH voltage signal does not exceed the threshold value, the DC power supply device is controlled by the primary control chip to function.

7. The primary-secondary side coordinated control method based on the isolated grid-connected inverter according to claim 6, characterized in that: The step (2-1) is specifically as follows: When the AC power grid waveform passes through zero, the secondary control chip collects the power generation voltage VH voltage signal of the DC power supply device in the corresponding secondary circuit, and determines whether the difference between the VH voltage signal and the value of 0 is greater than a threshold.

8. The primary-secondary side coordinated control method based on the isolated grid-connected inverter according to claim 6, characterized in that: The method further includes: (1) The secondary control chip detects the waveform of the AC power grid and determines whether the waveform is in the positive half-wave or the negative half-wave. The primary control chip controls the DC power supply device to generate power by using the corresponding positive half-wave drive or negative half-wave drive according to the half-wave where the waveform is located.

9. The primary-secondary side coordinated control method based on the isolated grid-connected inverter according to claim 8, characterized in that: The step (1) specifically comprises: The secondary control chip described in (1a-1) detects the AC grid waveform and generates an angle value according to the AC grid waveform. The zero-crossing point of the AC grid waveform corresponds to an interval of the angle value as the zero-crossing point angle interval. (1a-2) In a half-wave before the zero-crossing angle interval, the primary control chip uses the corresponding half-wave drive to control the DC power supply device to generate power; In the zero-crossing angle interval, the primary control chip controls the DC power supply device to stop generating power, thereby increasing the dead time; During the next half wave after the zero-crossing angle interval, another half wave is used to drive and control the DC power supply device to generate power.

10. The primary-secondary side coordinated control method based on the isolated grid-connected inverter according to claim 8, characterized in that: The step (1) specifically comprises: The secondary side control chip (1b-1) is specifically used to detect the AC grid waveform and determine the half-wave values ​​vg1 and vg2 of the two AC grid samples in real time; (1b-2) When vg1-vg2>0, the AC power grid is in a positive half-wave, and the primary control chip uses the positive half-wave drive to control the DC power supply device to generate power; When vg1-vg2<0, the AC power grid is in a negative half-wave, and the primary control chip uses the negative half-wave drive to control the DC power supply device to generate power.

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