Three-phase voltage commutation method and voltage phase converter

Abstract

The invention discloses a three-phase voltage commutation method and a voltage phase converter, and belongs to the technical field of electric power, and the method comprises the steps: determining a reference transition voltage which coincides with a first phase voltage at a first moment and coincides with a second phase voltage at a second moment; determining a commutation transition interval based on the first moment and the second moment, and boosting the first phase voltage based on the reference transition voltage in the commutation transition interval to obtain a first phase boost voltage; chopping the first phase boost voltage based on the reference transition voltage and generating a cut-off signal at a second moment, and switching the first phase voltage to a second phase voltage based on the cut-off signal; the first phase voltage is boosted and chopped by taking the reference transition voltage as a standard, so that stable commutation can be realized; the commutation transition interval is determined according to the first moment and the second moment and changes periodically, so that the commutation transition interval can be adjusted, and the precision requirement on time in the commutation process is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power, and particularly to a three-phase voltage commutation method and a voltage commutator. Background Art

[0002] Three-phase imbalance refers to the deviation of the amplitudes or phases of three-phase voltages or currents, resulting in power imbalance in the power grid and affecting the stable operation of the power system. In a three-phase AC generator, the voltage waveforms of the three phases are staggered by 120 degrees from each other to achieve the power supply of three-phase electricity and the drive of three-phase motors. However, in practical applications, due to the possible instantaneous change of the voltage waveform of the power grid, the phases of the three-phase voltage waveforms will also change. At this time, if voltage commutation is not performed in a timely manner, the balance of three-phase electricity may be broken, which may further lead to stability problems of the power grid. Therefore, voltage commutation is an important means to ensure the balance of three-phase electricity.

[0003] Currently, commutation is mainly carried out through an intelligent commutation switch. The intelligent commutation switch mainly has three structures, specifically including: 1. Pure mechanical commutation: This commutation method uses a relay switch to switch phases, which will not cause inter-phase short-circuit problems. However, the high temperature generated by arcing is likely to damage the contacts of the relay, thereby reducing the service life of the relay. 2. Power electronic commutation structure: This commutation method uses a power electronic switch instead of a relay, which can improve the commutation speed. There is no arcing during commutation, and the speed is fast and the service life is long. However, the power electronic device has a relatively weak anti-short-circuit impact ability. 3. Hybrid commutation structure: In order to combine the advantages of the above two commutation devices, the power electronic commutation device is cooperated with a relay for switching operations. This method can achieve seamless commutation with 0 ms of equal voltage, there is no voltage mutation and power failure, but there is a phase mutation. Because the commutation speed is relatively fast, the requirement for the commutation time accuracy is very high, and the control is relatively complex.

[0004] Therefore, in the process of three-phase voltage commutation in the prior art, there is a problem that it is difficult to control due to the high requirement for time accuracy. Summary of the Invention

[0005] In view of this, it is necessary to provide a three-phase voltage commutation method and a voltage commutator to solve the problem that in the process of three-phase voltage commutation in the prior art, it is difficult to control due to the high requirement for time accuracy.

[0006] To solve the above problems, in the first aspect, the present invention provides a three-phase voltage commutation method, including: Determine a reference transition voltage, which coincides with the first-phase voltage at the first moment and coincides with the second-phase voltage at the second moment; Determine a commutation transition interval based on the first moment and the second moment, and in the commutation transition interval, boost the first-phase voltage based on the reference transition voltage to obtain a first-phase boosted voltage; Chop the boosted voltage of the first phase based on the reference transition voltage and generate a cut-off signal at the second moment, and switch the first-phase voltage to the second-phase voltage based on the cut-off signal.

[0007] In a possible implementation, in the commutation transition interval, boost the voltage of the first phase based on the reference transition voltage to obtain the boosted voltage of the first phase, including: In the commutation transition interval, boost the voltage of the first phase based on the maximum and minimum values of the reference transition voltage, so that the maximum value curve of the first-phase voltage is greater than the maximum value of the reference transition voltage, and the minimum value curve of the first-phase voltage is greater than the minimum value of the reference transition voltage, to obtain the boosted voltage of the first phase.

[0008] In a possible implementation, chop the boosted voltage of the first phase based on the reference transition voltage, including: In the commutation transition interval, perform PWM chopping on the boosted voltage of the first phase to overlap the waveform diagram of the boosted voltage of the first phase with the waveform diagram of the reference transition voltage.

[0009] In a possible implementation, determining the reference transition voltage further includes: Obtain the maximum and minimum values of the bearing voltage of the external load; Correspondingly determine the maximum and minimum values of the reference transition voltage based on the maximum and minimum values of the bearing voltage.

[0010] In a possible implementation, after switching the first-phase voltage to the second-phase voltage based on the cut-off signal, it further includes: Judge whether the power supply voltage of the external load is successfully switched from the first-phase voltage to the second-phase voltage; When the power supply voltage of the external load is not successfully switched from the first-phase voltage to the second-phase voltage, send a phase conversion failure instruction to the control circuit.

[0011] In a possible implementation, the voltage amplitude of the reference transition voltage is equal to the voltage amplitude of the three-phase voltage, and the ratio of the reference transition voltage frequency of the reference transition voltage to the power frequency voltage of the three-phase voltage commutator is within a preset range.

[0012] In a possible implementation, the preset range includes (0.9, 1.1).

[0013] In a second aspect, the present invention further provides a three-phase voltage commutator, including: a control circuit, a boosting circuit, and a chopping circuit, and the control circuit is respectively connected to the boosting circuit and the chopping circuit; Wherein, the control circuit is used to determine the reference transition voltage, and the reference transition voltage coincides with the first-phase voltage at the first moment and coincides with the second-phase voltage at the second moment; The boost circuit is used to determine a commutation transition interval based on a first moment and a second moment, and within the commutation transition interval, boost a first-phase voltage based on a reference transition voltage to obtain a first-phase boosted voltage; The chopper circuit is used to chop the first-phase boosted voltage based on the reference transition voltage and generate a cut-off signal at the second moment; The control circuit is further used to switch the first-phase voltage to a second-phase voltage based on the cut-off signal.

[0014] In a possible implementation manner, the three-phase voltage commutator further includes an external load; Wherein, the external load is respectively connected to the control circuit, the first-phase voltage and the second-phase voltage; The control circuit is further used to control the external load to switch from the first-phase voltage to the second-phase voltage.

[0015] In a possible implementation manner, the three-phase voltage commutator further includes a detection circuit; Wherein, the detection circuit is respectively connected to the control circuit and the external load, and is used to detect whether the power supply voltage of the external load has successfully switched from the first-phase voltage to the second-phase voltage; When the power supply voltage of the external load has not successfully switched from the first-phase voltage to the second-phase voltage, a phase conversion failure instruction is sent to the control circuit.

[0016] The beneficial effects of adopting the above embodiments are as follows: The present invention provides a three-phase voltage commutation method. By using the reference transition voltage as a reference standard to boost the first-phase voltage, the first-phase voltage can completely envelope the reference transition voltage, thereby ensuring that the required voltage can be obtained when chopping the first-phase boosted voltage subsequently, and realizing stable commutation; Specifically, the commutation transition interval of the present application is determined according to the coincidence moment of the reference transition voltage and the first-phase voltage / second-phase voltage, and the reference transition voltage can be adjusted as needed. Therefore, the commutation start time can be adjusted; In addition, the first moment and the second moment change periodically and can be dynamically adjusted according to actual needs, greatly reducing the accuracy requirement for time during the commutation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic flowchart of an embodiment of the three-phase voltage commutation method provided by the present invention; Figure 2 It is a waveform diagram of an embodiment of the reference transition voltage, phase A voltage and phase B voltage provided by the present invention; Figure 3 It is a result schematic diagram of an embodiment of the three-phase voltage maximum and minimum value waveforms and the reference transition voltage waveform provided by the present invention; Figure 4Comparison diagram of the results of the maximum value of the first-phase boost voltage and the reference transition voltage provided by the present invention; Figure 5 Waveform diagram of the first-phase voltage after chopping provided by the present invention; Figure 6 Structural schematic diagram of the first embodiment of the three-phase voltage commutator provided by the present invention; Figure 7 Circuit diagram of the boost circuit provided by the present invention; Figure 8 Circuit diagram of the chopping circuit provided by the present invention. Detailed implementation manners

[0018] The preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. The accompanying drawings form a part of the present invention and are used together with the embodiments of the present invention to explain the principles of the present invention, rather than to limit the scope of the present invention.

[0019] The intelligent commutation switch is a kind of power controller with high precision, high speed and high reliability, and has various functions and advantages. It is widely used in various power equipment and provides strong support for the forward and reverse rotation control of motors in the fields of industrial automation, mechanical equipment, etc. During use and maintenance, relevant specifications and operation requirements should be followed to ensure the normal operation and use safety of the equipment.

[0020] Currently, during the commutation process using an intelligent commutation switch, the voltage phase is switched at the intersection of the first-phase voltage and the second-phase voltage. There are not only phase mutations, but also very high requirements for time accuracy, resulting in difficulty in better controlling the commutation.

[0021] In order to solve the problem in the prior art that it is difficult to control during the three-phase voltage commutation process due to high requirements for time accuracy, the present invention provides a three-phase voltage commutation method and a voltage commutator, which will be described in detail below respectively.

[0022] As Figure 1 shown, Figure 1 Flow schematic diagram of an embodiment of the three-phase voltage commutation method provided by the present invention, including: S101: Determine the reference transition voltage, which coincides with the first-phase voltage at the first moment and coincides with the second-phase voltage at the second moment; It should be noted that the transition voltage refers to a temporary voltage change phenomenon that occurs in the circuit under certain specific circumstances. In this application, by setting the reference transition voltage as a reference benchmark, the phase change process of the voltage is accurately guided to guide the voltage to smoothly commutate. Generally, the reference transition voltage is also a regularly changing voltage, which is not limited here.

[0023] The first-phase voltage refers to the phase voltage before phase commutation, and the second-phase voltage refers to the target phase voltage to be achieved by phase commutation. In a specific embodiment, for the A, B, and C phase voltages in three-phase voltage, the first-phase voltage can be any one of the A, B, and C phase voltages, and the second-phase voltage can be any one of the other two corresponding ones, which will not be elaborated here.

[0024] It should be noted that the basis for determining the intersection of the reference transition voltage and the first-phase voltage / second-phase voltage is: when the derivatives of the expressions of the reference transition voltage value and the first-phase voltage / second-phase voltage value are consistent at a certain moment, it is determined that at this moment, the reference transition voltage intersects with the first-phase voltage / second-phase voltage.

[0025] Furthermore, the first intersection point of the reference transition voltage and the first-phase voltage can all be used as the commutation starting point, that is, the first moment; after the commutation starting point, the second intersection point of the reference transition voltage and the second-phase voltage can all be used as the commutation termination point, that is, the second moment, but preferably the second intersection point closest to the commutation starting point is used as the commutation termination point. The commutation transition interval refers to the interval between the first moment and the second moment.

[0026] S102: Determine the commutation transition interval based on the first moment and the second moment, and in the commutation transition interval, boost the first-phase voltage based on the reference transition voltage to obtain the first-phase boosted voltage; S103: Chop the first-phase boosted voltage based on the reference transition voltage and generate a cut-off signal at the second moment, and switch the first-phase voltage to the second-phase voltage based on the cut-off signal.

[0027] In this embodiment, by using the reference transition voltage as a reference standard to boost the first-phase voltage, the first-phase voltage can completely envelope the reference transition voltage, so as to ensure that the required voltage can be obtained when chopping the first-phase boosted voltage subsequently, realizing stable commutation; specifically, the commutation transition interval of the present application is determined according to the coincidence moment of the reference transition voltage and the first-phase voltage / second-phase voltage, and the reference transition voltage can be adjusted as needed. Therefore, the commutation starting time can be adjusted; in addition, the first moment and the second moment change periodically and can be dynamically adjusted according to actual needs, greatly reducing the accuracy requirement for time during the commutation process.

[0028] Furthermore, since the reference transition voltage changes smoothly and is similar to the change of the first-phase voltage itself, the present application can achieve smooth commutation without sudden changes.

[0029] In some embodiments of the present invention, in S101, the voltage amplitude of the reference transition voltage is equal to the voltage amplitude of the three-phase voltage, and the ratio of the reference transition voltage frequency of the reference transition voltage to the power frequency voltage of the three-phase voltage converter is within a preset range.

[0030] In some embodiments of the present invention, the above preset range includes (0.9, 1.1).

[0031] Specifically, in order to clearly express the relationship between the reference transition voltage and the three-phase voltage, first, define the amplitude of the three-phase voltage as 220V, the frequency as 50Hz, and the phase difference as 120°. Then, its expression can be defined as:

[0032] Among them, V A is the calculation formula for the voltage of phase A, V B is the calculation formula for the voltage of phase B, V C is the calculation formula for the voltage of phase C.

[0033] Taking the switching from the voltage of phase A to the voltage of phase B as an example, first, select a voltage that is slightly larger than the power frequency of the three-phase voltage and has the same voltage amplitude as the three-phase voltage as the reference transition voltage according to the selection requirements of the reference transition voltage , and its expression is as follows:

[0034] As Figure 2 shown, Figure 2 is a waveform diagram of an embodiment of the reference transition voltage, the voltage of phase A, and the voltage of phase B provided by the present invention. Among them, at 0.02s, the derivatives of the expressions of the reference transition voltage and the voltage of phase A are the same, that is, the reference transition voltage and the voltage of phase A intersect at 0.02s. In order to avoid commutation mutation, the commutation is selected to start at 0.02s; in addition, at 0.153s, the derivatives of the expressions of the reference transition voltage and the voltage of phase B are the same, that is, the reference transition voltage and the voltage of phase B intersect at 0.153s. In order to avoid commutation mutation, the commutation is selected to end at 0.153s.

[0035] In this embodiment, by setting a reference transition voltage as a reference standard, since the frequency of the reference transition voltage is different from that of the three-phase voltage, there will always be periodic intersection points between the reference transition voltage, the phase-A voltage, and the phase-B voltage. To avoid voltage mutations during the commutation process, based on the derivative of the expression as a reference, the position where the change trends of the reference transition voltage and the phase-A voltage are the same is used as the commutation start flag, and the position where the change trends of the reference transition voltage and the phase-B voltage are the same is used as the commutation end flag. This can not only ensure the smoothness and stability of commutation, but also, since the frequency of the reference transition voltage is not much different from that of the three-phase voltage, can ensure the power supply stability during the commutation process as much as possible.

[0036] Based on the above embodiment, during the commutation process, when the reference transition voltage is 55 Hz, the voltage frequency of the entire circuit will slowly deviate from the power frequency, but after a certain time, it will slowly approach the power frequency voltage again, that is, it will slowly change from 50 Hz to 55 Hz and then change back to 50 Hz.

[0037] Obviously, since the intersection points between the reference transition voltage, the phase-A voltage, and the phase-B voltage in this application change periodically, when a commutation fails or there are requirements for the commutation time, the commutation time can be adaptively adjusted as needed to reduce the requirement for time accuracy during the commutation process, which will not be elaborated here.

[0038] In some other embodiments of the present invention, the reference transition voltage can also be adaptively adjusted according to actual needs without affecting the normal operation of the circuit, such as increasing or decreasing the voltage amplitude of the reference transition voltage, etc., which is not limited here.

[0039] In some embodiments of the present invention, after determining the commutation transition interval, since the waveforms of the maximum and minimum values of the three-phase voltage cannot completely envelope the waveform of the reference transition voltage, as Figure 3 shown, Figure 3 is a schematic diagram of the results of an embodiment of the waveforms of the maximum and minimum values of the three-phase voltage and the reference transition voltage provided by the present invention, where 301 refers to the waveform of the maximum and minimum values of the three-phase voltage, and 302 refers to the waveform of the reference transition voltage.

[0040] That is to say, based on the current three-phase voltage, it is impossible to directly make the first-phase voltage change according to the waveform of the reference transition voltage.

[0041] Therefore, in S102, in order to make the first-phase voltage change according to the waveform of the reference transition voltage, it is necessary to boost the first-phase voltage to obtain the first-phase boosted voltage. Specifically, based on the maximum and minimum values of the reference transition voltage, the first-phase voltage is boosted so that the maximum value curve of the first-phase voltage is greater than the maximum value of the reference transition voltage, and the minimum value curve of the first-phase voltage is greater than the minimum value of the reference transition voltage, thereby obtaining the first-phase boosted voltage.

[0042] Specifically, in order to clearly describe the change of the first-phase voltage, as Figure 4 shown, Figure 4 FIG. 4 is a comparison diagram of the results of an embodiment of the maximum and minimum values of the first-phase boosted voltage and the reference transition voltage provided by the present invention. 401 refers to the waveform diagram of the maximum and minimum values of the first-phase boosted voltage, and 402 refers to the waveform diagram of the reference transition voltage.

[0043] In this embodiment, by controlling the maximum and minimum value changes of the first-phase voltage in the commutation transition interval, the maximum and minimum value diagram of the first-phase boosted voltage completely envelopes the reference transition voltage, so as to facilitate subsequent adjustment of the voltage value of the first-phase boosted voltage.

[0044] It should be noted that when adjusting the voltage value of the first-phase boosted voltage, it is easier to adjust from a value with a larger absolute value to a value with a smaller absolute value, but it is more difficult to adjust from a value with a smaller absolute value to a value with a larger absolute value. Therefore, it is necessary to ensure that each maximum and minimum value of the reference transition voltage is within the maximum and minimum value change range of the first-phase boosted voltage.

[0045] In some embodiments of the present invention, in S103, after obtaining the first-phase boosted voltage, in order to make the first-phase voltage change according to the waveform of the reference transition voltage, it is also necessary to perform PWM chopping on the first-phase boosted voltage in the commutation transition interval to overlap the waveform diagram of the first-phase boosted voltage with the waveform diagram of the reference transition voltage.

[0046] It should be noted that PWM chopping, that is, Pulse Width Modulation chopping technology, is a technology that controls the magnitude of voltage or current by changing the pulse width of a signal. Its basic principle is to compare the control signal with a triangular wave (or other carrier signals), and control the on and off of the switching tube through the comparison result, thereby realizing the control of the current or voltage of the circuit. Specifically, when the control signal is higher than the voltage of the triangular wave, the switching tube is turned on; when the control signal is lower than the voltage of the triangular wave, the switching tube is turned off. In this way, by adjusting the magnitude and frequency of the control signal, the on and off time of the switching tube can be controlled, and thus the purpose of controlling the circuit current or voltage can be achieved.

[0047] Specifically, in order to clearly describe the change of the first-phase voltage after chopping, asFigure 5 As shown Figure 5 Figure 1 is a waveform diagram of an embodiment after the first-phase voltage is chopped in the present invention. Obviously, the first-phase voltage starts commutation at 0.02 s. Although the frequency of the voltage is increased, the maximum value is consistent with the maximum values of the three-phase voltages, and it also changes in a regular waveform. The commutation ends at 0.153 s, completing the step of switching from phase A to phase B.

[0048] In this embodiment, the boosted first-phase boosted voltage is chopped by PWM chopping technology, so that the first-phase boosted voltage can change according to the waveform of the reference transition voltage, so that the first-phase voltage can directly intersect with the second-phase voltage to realize the switching of the first-phase voltage to the second-phase voltage.

[0049] In summary, in this application, by using the reference transition voltage as a reference, the first-phase voltage is boosted and PWM chopped, so that the first-phase voltage can change according to the law of the reference transition voltage, realizing the switching of the first-phase voltage to the second-phase voltage.

[0050] In some embodiments of the present invention, in order to determine the reference transition voltage, first, the maximum value of the bearing voltage of the external load is obtained; then, the maximum value of the reference transition voltage is correspondingly determined based on the maximum value of the bearing voltage.

[0051] In this embodiment, by obtaining the maximum value of the bearing voltage of the external load, which is the power supply object of the entire circuit, the maximum voltage value that the entire circuit can withstand is obtained, and the maximum value of the reference transition voltage is controlled with this maximum voltage value as a reference quantity, avoiding problems of damaging the external load due to commutation.

[0052] In some embodiments of the present invention, in order to detect the completion of the commutation process, after the first-phase voltage is switched to the second-phase voltage based on the cut-off signal, it is also necessary to determine whether the power supply voltage of the external load has successfully switched from the first-phase voltage to the second-phase voltage; and when the power supply voltage of the external load has not successfully switched from the first-phase voltage to the second-phase voltage, a phase conversion failure instruction is sent to the control circuit.

[0053] In this embodiment, by using the power supply voltage of the external load as a reference quantity to detect the completion of the commutation process, the result of the commutation can be effectively monitored, improving the reliability of the commutation.

[0054] In order to better implement the three-phase voltage commutation method in the embodiments of the present invention, correspondingly, on the basis of the three-phase voltage commutation method, the embodiments of the present invention also provide a three-phase voltage commutator, as Figure 6 shown Figure 6Schematic diagram of the structure of the first embodiment of the three-phase voltage commutator provided by the present invention. The three-phase voltage commutator 600 includes: a control circuit 601, a boost circuit 602, and a chopper circuit 603. The control circuit 601 is respectively connected to the boost circuit 602 and the chopper circuit 603; Among them, the control circuit 601 is used to determine a reference transition voltage, which coincides with the first-phase voltage at the first moment and coincides with the second-phase voltage at the second moment; The boost circuit 602 is used to determine a commutation transition interval based on the first moment and the second moment, and in the commutation transition interval, boost the first-phase voltage based on the reference transition voltage to obtain a first-phase boosted voltage; The chopper circuit 603 is used to chop the first-phase boosted voltage based on the reference transition voltage and generate a cut-off signal at the second moment; The control circuit 601 is further used to switch the first-phase voltage to the second-phase voltage based on the cut-off signal.

[0055] In some embodiments of the present invention, as Figure 7 shown, Figure 7 Schematic diagram of the circuit of an embodiment of the boost circuit provided by the present invention. Among them, taking phase A as an example, L A is a boost inductor, S A1 and S A2 are AC switches, which can be regarded as two MOS transistors connected in reverse series. The control waveforms of these two switches are complementary, the switching frequency is high enough, and the on and off times are well controlled, that is, the charging and discharging times. Through the filter capacitor, a stable output voltage can be obtained. Since the input voltage is a power frequency voltage, the switching frequency is much greater than the frequency of the input voltage. When the input voltage is a positive voltage, when S A1 conducts and S A2 turns off, the inductor L A is grounded, and at this time the inductor is charged. Since the current of the inductor cannot change suddenly, if S A2 conducts and S A1 turns off at this time, the inductor will generate a self-induced electromotive force, and this self-induced electromotive force will be superimposed on the input voltage to raise the output voltage. The situation is similar when the input voltage is a reverse voltage.

[0056] In this embodiment, the boost circuit 602 uses the principle of boost voltage to boost the three-phase voltage to a usable voltage value. The boost link is a large harmonic source for the power grid. Using the boost circuit can also improve the input current waveform, reduce the input current harmonic content, improve the power factor, and stabilize the output voltage. Boosting with an inductor can obtain a stable output voltage, strong load-carrying capacity, and will not be interfered by various forms of loads.

[0057] In some embodiments of the present invention, asFigure 8 As shown Figure 8 is a circuit diagram of an embodiment of the chopper circuit provided by the present invention, where S A3 is the AC switch of phase A S B3 is the AC switch of phase B S C3 is the AC switch of phase C, and R L is the voltage stabilizing resistor

[0058] Set the reference transition voltage as the reference voltage. The reference transition voltage is divided into two modes: positive voltage and negative voltage. In the positive voltage mode, the output voltage minus the reference value passes through the PID controller and is limited to generate a PWM control signal. At the same time, the boosted voltage is compared. When the electrical value of a certain phase is the largest, the PWM control signal controls the switch of that phase to perform chopping. In the negative voltage mode, the reference value minus the output voltage passes through the PID controller and is limited to generate a control signal. At the same time, the boosted voltage is compared. When the voltage value of a certain phase is the smallest, the control signal controls that phase to perform chopping, while the switches of other phases are all turned off

[0059] It should be noted that the PID controller (Proportional-Integral-Derivative Controller), whose full name is Proportional-Integral-Derivative Controller, is a very common feedback loop component in industrial control applications. The PID controller consists of three main parts: a proportional unit (P), an integral unit (I), and a derivative unit (D). Its working principle is based on the difference between the current state of the controlled object and the set value to adjust the output signal, making the difference approach zero

[0060] In some embodiments of the present invention, the three-phase voltage commutator 600 further includes an external load 604 wherein, the external load 604 is respectively connected to the control circuit 601, the first-phase voltage, and the second-phase voltage The control circuit 601 is further configured to control the external load 604 to switch from the first-phase voltage to the second-phase voltage

[0061] Furthermore, in order to ensure the reliability of commutation and avoid losses to the external load 604 due to commutation, the three-phase voltage commutator 600 further includes a detection circuit 605 wherein, the detection circuit 605 is respectively connected to the control circuit 601 and the external load 604, and is used to detect whether the supply voltage of the external load 604 has successfully switched from the first-phase voltage to the second-phase voltage When the supply voltage of the external load 604 has not successfully switched from the first-phase voltage to the second-phase voltage, a phase conversion failure instruction is sent to the control circuit 601

[0062] The three-phase voltage commutation method and the voltage commutation device provided by the present invention have been introduced in detail above. Specific examples are used in this text to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those skilled in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A three-phase voltage commutation method, characterized in that: include: Determine a reference transition voltage, wherein the reference transition voltage coincides with the first phase voltage at a first moment and coincides with the second phase voltage at a second moment; Determine a commutation transition interval based on a first moment and a second moment, and in the commutation transition interval, boost the first phase voltage based on the reference transition voltage to obtain a first phase boost voltage; The first-phase boosted voltage is chopped based on the reference transition voltage and a cutoff signal is generated at the second time, and the first-phase voltage is switched to the second-phase voltage based on the cutoff signal.

2. The three-phase voltage commutation method according to claim 1, characterized in that: The step of boosting the first phase voltage based on the reference transition voltage in the commutation transition interval to obtain a first phase boosted voltage comprises: In the commutation transition interval, the first phase voltage is boosted based on the maximum and minimum values ​​of the reference transition voltage, so that the maximum value curve of the first phase voltage is greater than the maximum value of the reference transition voltage, and the minimum value curve of the first phase voltage is greater than the minimum value of the reference transition voltage, thereby obtaining the first phase boosted voltage.

3. The three-phase voltage commutation method according to claim 1, characterized in that: The chopping the first-phase boost voltage based on the reference transition voltage comprises: In the phase switching transition interval, the first phase boost voltage is subjected to PWM chopping, and a waveform diagram of the first phase boost voltage is overlapped with a waveform diagram of the reference transition voltage.

4. The three-phase voltage commutation method according to claim 1, characterized in that: The determining of the reference transition voltage further includes: Get the maximum load voltage of the external load; The maximum value of the reference transition voltage is determined based on the maximum value of the load voltage.

5. The three-phase voltage commutation method according to claim 4, characterized in that: After switching the first phase voltage to the second phase voltage based on the cutoff signal, the method further includes: determining whether the power supply voltage of the external load is successfully switched from the first phase voltage to the second phase voltage; When the power supply voltage of the external load fails to switch from the first phase voltage to the second phase voltage, a phase switching failure instruction is sent to the control circuit.

6. The three-phase voltage commutation method according to claim 1, characterized in that: The voltage amplitude of the reference transition voltage is equal to the voltage amplitude of the three-phase voltage, and the ratio of the reference transition voltage frequency of the reference transition voltage to the voltage power frequency of the three-phase voltage converter is within a preset range.

7. The three-phase voltage commutation method according to claim 6, characterized in that: The preset range includes (0.9, 1.1).

8. A three-phase voltage converter, characterized in that: include: A control circuit, a boost circuit and a chopper circuit, wherein the control circuit is connected to the boost circuit and the chopper circuit respectively; Wherein, the control circuit is used to determine a reference transition voltage, wherein the reference transition voltage coincides with the first phase voltage at a first moment and coincides with the second phase voltage at a second moment; The boost circuit is used to determine a commutation transition interval based on a first moment and a second moment, and in the commutation transition interval, boost the first phase voltage based on the reference transition voltage to obtain a first phase boost voltage; The chopper circuit is used to chop the first phase boost voltage based on the reference transition voltage and generate a cutoff signal at the second time; The control circuit is further configured to switch the first phase voltage to the second phase voltage based on the cutoff signal.

9. The three-phase voltage converter according to claim 8, characterized in that: It also includes external loads; Wherein, the external load is connected to the control circuit, the first phase voltage and the second phase voltage respectively; The control circuit is further configured to control the external load to switch from the first phase voltage to the second phase voltage.

10. The three-phase voltage converter according to claim 9, characterized in that: Also includes a detection circuit; Wherein, the detection circuit is connected to the control circuit and the external load respectively, and is used to detect whether the power supply voltage of the external load is successfully switched from the first phase voltage to the second phase voltage; When the power supply voltage of the external load fails to switch from the first phase voltage to the second phase voltage, a phase switching failure instruction is sent to the control circuit.

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