CN109103907B - Control method and device of three-phase unbalance compensation device - Google Patents
Control method and device of three-phase unbalance compensation device Download PDFInfo
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- CN109103907B CN109103907B CN201811121440.7A CN201811121440A CN109103907B CN 109103907 B CN109103907 B CN 109103907B CN 201811121440 A CN201811121440 A CN 201811121440A CN 109103907 B CN109103907 B CN 109103907B
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- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
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Abstract
The embodiment of the invention provides a control method and a control device of a three-phase unbalance compensation device, and relates to the technical field of power electronics. The method comprises the following steps: receiving an effective value of phase A current, an effective value of phase B current and an effective value of phase C current sent by a current acquisition unit; respectively calculating a first compensation value, a second compensation value and a third compensation value according to the effective value of the phase-A current, the effective value of the phase-B current and the effective value of the phase-C current; when the first switch unit is in a working state, if the absolute value of the first compensation value is smaller than a first preset value, controlling the first switch unit to stop working; when the second switch unit is in a working state, if the absolute value of the second compensation value is smaller than the first preset value, controlling the second switch unit to stop working; and when the third switching unit is in a working state, if the absolute value of the third compensation value is smaller than the first preset value, controlling the third switching unit to stop working. The method effectively reduces the self loss of the three-phase unbalance compensation device.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a control method and a control device of a three-phase unbalance compensation device.
Background
In urban residents and rural power grid power supply systems of low-voltage three-phase four-wire system, as most of power consumers are single-phase loads or single-phase and three-phase loads are mixed, and the loads are different in size and power utilization time, the long-term imbalance of the three-phase loads of the low-voltage power supply system is caused, the copper loss of circuits and transformers is increased, the iron loss of the transformers is increased, the power of the transformers is reduced, the safe operation of the transformers can be influenced even, and finally, the imbalance of three-phase voltage can be caused.
With the development of the power electronic industry, the three-phase imbalance compensation device based on the power electronic technology can solve the three-phase imbalance caused by the imbalance of the load. However, the three-phase unbalanced device reduces neutral current and loss of the voltage transformer, and meanwhile, the three-phase unbalanced device also brings certain loss. The three-phase compensation current that unbalanced three-phase regulation and compensation arrangement sent can not equal naturally, when load change, can appear certain phase current output and be close to the condition of zero, and if this looks switch tube designs according to conventional theory under this condition, this looks switch tube still is in operating condition, and this looks switch tube can be because of switching loss and the conduction loss that switching action produced, and this looks need not adjust and compensate mutually. The small compensation current of a certain phase of the three-phase system does not help the compensation of the whole system, but the loss is increased and the efficiency is reduced.
Disclosure of Invention
The invention aims to provide a control method and a control device of a three-phase unbalance compensation device, which can control at least one corresponding switch unit to stop working when the compensation current of at least one phase of a load approaches zero, thereby effectively reducing the self-loss of the device.
In order to achieve the above purpose, the embodiment of the present invention adopts the following technical solutions:
in a first aspect, an embodiment of the present invention provides a control method for a three-phase imbalance compensation device, which is applied to the three-phase imbalance compensation device, where the three-phase imbalance compensation device includes a first switch unit, a second switch unit, a third switch unit, a current collection unit, and a controller, the controller is electrically connected to the first switch unit, the second switch unit, the third switch unit, and the current collection unit, the first switch unit, the second switch unit, and the third switch unit are electrically connected to an a phase, a B phase, and a C phase of a load, respectively, the current collection unit is connected to the a phase, the B phase, and the C phase of the load, and the current collection unit is configured to collect an a-phase current, and a C-phase current of the load to obtain an a-phase current effective value, and a-phase current effective value, the method comprises the following steps: receiving the effective value of the phase A current, the effective value of the phase B current and the effective value of the phase C current sent by the current acquisition unit; respectively calculating a first compensation value, a second compensation value and a third compensation value according to the effective value of the phase A current, the effective value of the phase B current and the effective value of the phase C current; when the first switch unit is in a working state, if the absolute value of the first compensation value is smaller than a first preset value, controlling the first switch unit to stop working; when the second switch unit is in a working state, if the absolute value of the second compensation value is smaller than the first preset value, controlling the second switch unit to stop working; and when the third switching unit is in a working state, if the absolute value of the third compensation value is smaller than the first preset value, controlling the third switching unit to stop working.
In a second aspect, an embodiment of the present invention further provides a control device of a three-phase imbalance compensation device, which is applied to the three-phase imbalance compensation device, the three-phase imbalance compensation device includes a first switch unit, a second switch unit, a third switch unit, a current collection unit and a controller, the controller is electrically connected to the first switch unit, the second switch unit, the third switch unit and the current collection unit, the first switch unit, the second switch unit and the third switch unit are respectively electrically connected to a phase a, a phase B and a phase C of a load, the current collection unit is connected to the phase a, the phase B and the phase C of the load, the current collection unit is configured to collect a phase current, a phase current and a phase current of the load to obtain an effective value of the phase a current, an effective value of the phase B current and an effective value of the phase C current, the device comprises: the receiving module is used for receiving the A-phase current effective value, the B-phase current effective value and the C-phase current effective value sent by the current acquisition unit; the calculation module is used for calculating a first compensation value, a second compensation value and a third compensation value according to the A-phase current effective value, the B-phase current effective value and the C-phase current effective value respectively; the first control module is used for controlling the first switch unit to stop working if the absolute value of the first compensation value is smaller than a first preset value when the first switch unit is in a working state; the second control module is used for controlling the second switch unit to stop working if the absolute value of the second compensation value is smaller than the first preset value when the second switch unit is in a working state; and the third control module is used for controlling the third switching unit to stop working if the absolute value of the third compensation value is smaller than the first preset value when the third switching unit is in a working state.
According to the control method and the control device of the three-phase unbalance compensation device, when the absolute value of the compensation value of at least one of the A phase, the B phase and the C phase is detected to be smaller than a first preset value, namely the compensation value of at least one of the A phase, the B phase and the C phase approaches to zero, at least one corresponding switch unit with the compensation value approaching to zero is controlled to stop working, the switching loss and the conduction loss of the switch unit are effectively reduced under the condition that no hardware cost is increased, the efficiency of the three-phase unbalance compensation device is improved, and the energy-saving effect is achieved.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 is a schematic diagram illustrating an application environment of a control method and a device of a three-phase imbalance compensation device according to an embodiment of the present invention;
fig. 2 is a schematic circuit diagram of a three-phase imbalance compensation apparatus according to an embodiment of the present invention;
fig. 3 is a schematic flow chart illustrating a control method of a three-phase imbalance compensation device according to an embodiment of the present invention;
fig. 4 is a block diagram showing a configuration of a control device of a three-phase imbalance compensation device according to an embodiment of the present invention.
Icon: 1-a three-phase unbalance compensation device; 11-a first switching unit; 12-a second switching unit; 13-a third switching unit; 14-a current collection unit; 15-a controller; 2-load; 3-a power grid; 4-a control device of the three-phase unbalance compensation device; 41-a receiving module; 42-a calculation module; 43-a first control module; 44-a second control module; 45-a third control module; CT1 — first current transformer; CT2 — second current transformer; CT 3-third current transformer; sa 1-first switching tube; sa 2-second switching tube; sa 3-third switching tube; sa 4-fourth switching tube; sb 1-fifth switching tube; sb 2-sixth switching tube; sb 3-seventh switching tube; sb 4-eighth switching tube; sc 1-ninth switching tube; sc 2-tenth switching tube; sc 3-eleventh switch tube; sc 4-a twelfth switching tube; l1 — first inductance; l2 — second inductance; l3 — third inductance; l4 — fourth inductance; l5-fifth inductance; l6-sixth inductance; c1 — first capacitance; c2 — second capacitance; c11 — third capacitance; c12-fourth capacitance; c13 — fifth capacitance; h1 — first hall sensor; h2 — second hall sensor; h3-third hall sensor.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures. Meanwhile, in the description of the present invention, the terms "first", "second", and the like are used only for distinguishing the description, and are not to be construed as indicating or implying relative importance.
The control method and the control device of the three-phase unbalance compensation device provided by the embodiment of the invention can be applied to the application environment shown in fig. 1. As shown in fig. 1, the control method and apparatus are applied to a three-phase unbalance compensation apparatus 1, where the three-phase unbalance compensation apparatus 1 includes a first switch unit 11, a second switch unit 12, a third switch unit 13, a current collection unit 14 and a controller 15, the controller 15 is electrically connected to the first switch unit 11, the second switch unit 12, the third switch unit 13 and the current collection unit 14, the first switch unit 11, the second switch unit 12 and the third switch unit 13 are electrically connected to a phase a, a phase B and a phase C of a load 2, respectively, the current collection unit 14 is connected to the phase a, the phase B and the phase C of the load 2, and the phase a, the phase B and the phase C of the load 2 are provided by a power grid 3.
In this embodiment, the three-phase imbalance compensation apparatus 1 may adopt a T-type three-level topology. As shown in fig. 2, the first switching unit 11 includes a first switching tube Sa1, a second switching tube Sa2, a third switching tube Sa3 and a fourth switching tube Sa4, the second switching unit 12 includes a fifth switching tube Sb1, a sixth switching tube Sb2, a seventh switching tube Sb3 and an eighth switching tube Sb4, and the third switching unit 13 includes a ninth switching tube Sc1, a tenth switching tube Sc2, an eleventh switching tube Sc3 and a twelfth switching tube Sc 4. Wherein, all the switch tubes can adopt Insulated Gate Bipolar Transistors (IGBT).
Further, the three-phase imbalance compensation device 1 further includes a first capacitor C1, a second capacitor C2, a third capacitor C11, a fourth capacitor C12, a fifth capacitor C13, a first inductor L1, a second inductor L2, a third inductor L3, a fourth inductor L4, a fifth inductor L5, a sixth inductor L6, a first hall sensor H1, a second hall sensor H2, and a third hall sensor H3.
One end of the fourth inductor L4 is electrically connected with a phase a of the load 2, the other end of the fourth inductor L4 is electrically connected with one end of the first inductor L1 and one end of the third capacitor C11, the other end of the first inductor L1 is electrically connected with the source of the first switching tube Sa1, the drain of the third switching tube Sa3 and the drain of the fourth switching tube Sa4, the drain of the first switching tube Sa1 is electrically connected with one end of the first capacitor C1, the drain of the fifth switching tube Sb1 and the drain of the ninth switching tube Sc1, the source of the third switching tube Sa3 is electrically connected with the source of the second switching tube 2, the drain of the second switching tube Sa2 is electrically connected with the other end of the first capacitor C1, one end of the second capacitor C2, the drain of the sixth switching tube Sb2 and the drain of the tenth switching tube Sc2, the other end of the second capacitor C2 is electrically connected with the source of the fourth switching tube Sa4, the source of the eighth switching tube Sb 599 and the twelfth switching tube Sb 599, one end of a fifth inductor L5 is electrically connected with a phase B of the load 2, the other end of the fifth inductor L5 is electrically connected with one end of a second inductor L2 and one end of a fourth capacitor C12, the other end of the second inductor L2 is electrically connected with a source of a fifth switching tube Sb1, a drain of a seventh switching tube Sb3 and a drain of an eighth switching tube Sb4, a source of the seventh switching tube Sb3 is electrically connected with a source of a sixth switching tube Sb2, one end of a sixth inductor L6 is electrically connected with a phase C of the load 2, the other end of a sixth inductor L6 is electrically connected with one end of a third inductor L3 and one end of a fifth capacitor C13, the other end of the third inductor L3 is electrically connected with a source of a ninth switching tube Sc1, a drain of an eleventh switching tube Sc3 and a drain of a twelfth switching tube Sc4, a source of the eleventh switching tube Sc3 is electrically connected with a source of a tenth switching tube Sc 5, and the other end of the first capacitor C2 and the other end of the first capacitor C57323, The other end of the third capacitor C11, the other end of the fourth capacitor C12 and the other end of the fifth capacitor C13 are all electrically connected to N phase of the load 2, the first hall sensor H1 is sleeved at one end of the first inductor L1, the second hall sensor H2 is sleeved at one end of the second inductor L2, and the third hall sensor H3 is sleeved at one end of the third inductor L3.
In this embodiment, the gate of the first switching tube Sa1, the gate of the second switching tube Sa2, the gate of the third switching tube Sa3, the gate of the fourth switching tube Sa4, the gate of the fifth switching tube Sb1, the gate of the sixth switching tube Sb2, the gate of the seventh switching tube Sb3, the gate of the eighth switching tube Sb4, the gate of the ninth switching tube Sc1, the gate of the tenth switching tube Sc2, the gate of the eleventh switching tube Sc3, and the gate of the twelfth switching tube Sc4 may all be electrically connected to a DSP chip, and the DSP chip is electrically connected to the controller 15; the gate of the first switching tube Sa1, the gate of the second switching tube Sa2, the gate of the third switching tube Sa3, the gate of the fourth switching tube Sa4, the gate of the fifth switching tube Sb1, the gate of the sixth switching tube Sb2, the gate of the seventh switching tube Sb3, the gate of the eighth switching tube Sb4, the gate of the ninth switching tube Sc1, the gate of the tenth switching tube Sc2, the gate of the eleventh switching tube Sc3 and the gate of the twelfth switching tube Sc4 may all be directly electrically connected to the controller 15.
In this embodiment, the controller 15 may directly generate an SPWM wave to drive the 12 switching tubes to be turned on and off, so as to control the inductive current provided by the three-phase imbalance device to the load 2, thereby achieving the purpose of compensating the current imbalance and the reactive power at the side of the load 2; the controller 15 can also control the DSP chip to generate SPWM waves to drive the 12 switching tubes to be switched on and switched off, so that the inductive current provided by the three-phase unbalance device to the load 2 is controlled, and the purposes of compensating unbalance current and reactive power on the side of the load 2 are achieved. The first inductor L1, the second inductor L2, the third inductor L3, the fourth inductor L4, the fifth inductor L5, the sixth inductor L6, the third capacitor C11, the fourth capacitor C12 and the fifth capacitor C13 form three groups of LCL filters to realize a filtering function; the first capacitor C1 and the second capacitor C2 are positive and negative direct current bus capacitor groups; the first hall sensor H1 is used for acquiring the compensation current provided by the three-phase unbalance compensation device 1 to the a phase, the second hall sensor H2 is used for acquiring the compensation current provided by the three-phase unbalance compensation device 1 to the B phase, and the third hall sensor H3 is used for acquiring the compensation current provided by the three-phase unbalance compensation device 1 to the C phase.
In this embodiment, the current collecting unit 14 is configured to collect the a-phase current, the B-phase current, and the C-phase current of the load 2 to obtain an effective value of the a-phase current, an effective value of the B-phase current, and an effective value of the C-phase current. The current collecting unit 14 includes a first current transformer CT1, a second current transformer CT2 and a third current transformer CT3, the first current transformer CT1 is sleeved on the a-phase electric wire of the load 2, the second current transformer CT2 is sleeved on the B-phase electric wire of the load 2, and the third current transformer CT3 is sleeved on the C-phase electric wire of the load 2; the first current transformer CT1 is used for collecting the A-phase current of the load 2 to obtain an effective value of the A-phase current; the second current transformer CT2 is used for collecting the B-phase current of the load 2 to obtain an effective value of the B-phase current; the third current transformer CT3 is used for collecting the C-phase current of the load 2 to obtain an effective value of the C-phase current.
Fig. 3 is a schematic flow chart of a control method of the three-phase imbalance compensation apparatus 1 according to the embodiment of the present invention. It should be noted that the control method of the three-phase imbalance compensation device 1 according to the embodiment of the present invention is not limited by the specific sequence shown in fig. 2 and described below. It should be understood that, in other embodiments, the order of some steps in the control method of the three-phase imbalance compensation device 1 according to the present invention may be interchanged according to actual needs, or some steps may be omitted or deleted, and the specific flow shown in fig. 2 will be described in detail below.
Step S101, receiving the effective value of the phase a current, the effective value of the phase B current, and the effective value of the phase C current sent by the current collecting unit 14.
In this embodiment, the controller 15 receives the effective value of the a-phase current sent by the first current transformer CT1, the effective value of the B-phase current sent by the second current transformer CT2, and the effective value of the C-phase current sent by the third current transformer CT 3.
And step S102, respectively calculating a first compensation value, a second compensation value and a third compensation value according to the effective value of the phase A current, the effective value of the phase B current and the effective value of the phase C current.
In this embodiment, an average current effective value is calculated according to the a-phase current effective value, the B-phase current effective value and the C-phase current effective value; and respectively carrying out subtraction processing on the effective value of the phase current A, the effective value of the phase current B and the effective value of the phase current C and the effective value of the average current to obtain the first compensation value, the second compensation value and the third compensation value.
It can be understood that the first current transformer CT1 detects that the effective value of the a-phase current of the load 2 is 50A, the second current transformer CT2 detects that the effective value of the B-phase current of the load 2 is 100A, the third current transformer CT3 detects that the effective value of the C-phase current of the load 2 is 150A, and the average effective value of the current calculated by the controller 15 according to the effective values of the currents of the three phases is 100A, then the first compensation value is 50A, the second compensation value is 0A, and the third compensation value is-50A.
Step S103, when the first switch unit 11 is in a working state, if the absolute value of the first compensation value is smaller than a first preset value, controlling the first switch unit 11 to stop working.
In this embodiment, the controller 15 records a status flag bit of the first switch unit 11, and the controller 15 respectively determines whether the first switch unit 11 is in a working state according to a value of the status flag bit of the first switch unit 11, and determines that the first switch unit 11 is in the working state when the value of the status flag bit is a third preset value; and when the value of the status flag bit is a fourth preset value, judging that the status flag bit is not in a working state. The third preset value may be set to 0, the fourth preset value may be set to 1, and the fact that the first switching unit 11 is not in the working state may be understood as that the first switching unit 11 is in the sleep state.
It can be understood that, when the controller 15 detects that the value of the status flag of the first switch unit 11 is 0 (i.e., the controller 15 or the DSP chip sends the SPWM wave to the first switch unit 11), the absolute value of the first compensation value is compared with the first preset value, and if the absolute value of the first compensation value is smaller than the first preset value, it is determined that the compensation current of the phase a of the load 2 approaches zero, and the controller 15 controls the first switch unit 11 to stop working, i.e., stops sending the SPWM wave to the first switch unit 11. Wherein the first preset value may be set to 2A.
Further, in this embodiment, when the controller 15 controls the first switch unit 11 to stop working, the controller 15 may further change the value of the status flag bit of the first switch unit 11 from the third preset value to the fourth preset value. It is understood that the controller 15 controls the first switch unit 11 to stop working and changes the value of the status flag bit of the first switch unit 11 from 0 to 1.
Step S104, when the second switch unit 12 is in the working state, if the absolute value of the second compensation value is smaller than the first preset value, controlling the second switch unit 12 to stop working.
In this embodiment, the controller 15 records a status flag bit of the second switch unit 12, and the controller 15 respectively determines whether the second switch unit 12 is in a working state according to a value of the status flag bit of the second switch unit 12, and determines that the second switch unit 12 is in the working state when the value of the status flag bit is a third preset value; and when the value of the status flag bit is a fourth preset value, judging that the status flag bit is not in a working state.
It can be understood that, when the controller 15 detects that the value of the status flag of the second switch unit 12 is 0 (i.e., the controller 15 or the DSP chip sends the SPWM wave to the second switch unit 12), the absolute value of the second compensation value is compared with the first preset value, and if the absolute value of the second compensation value is smaller than the first preset value, it is determined that the compensation current of the B phase of the load 2 approaches zero, and the controller 15 controls the second switch unit 12 to stop working, i.e., stops sending the SPWM wave to the second switch unit 12.
Further, in this embodiment, when the controller 15 controls the second switch unit 12 to stop working, the controller 15 may further change the value of the status flag bit of the second switch unit 12 from the third preset value to the fourth preset value. It is understood that the controller 15 controls the second switch unit 12 to stop working and changes the value of the status flag bit of the second switch unit 12 from 0 to 1.
Step S105, when the third switching unit 13 is in the working state, if the absolute value of the third compensation value is smaller than the first preset value, controlling the third switching unit 13 to stop working.
In this embodiment, the controller 15 records a status flag bit of the third switching unit 13, and the controller 15 respectively determines whether the third switching unit 13 is in the working state according to a value of the status flag bit of the third switching unit 13, and determines that the third switching unit 13 is in the working state when the value of the status flag bit is a third preset value; and when the value of the status flag bit is a fourth preset value, judging that the status flag bit is not in a working state. The third preset value may be set to 0, and the fourth preset value may be set to 1.
It can be understood that, when the controller 15 detects that the value of the status flag of the third switching unit 13 is 0 (i.e., the controller 15 or the DSP chip sends the SPWM wave to the third switching unit 13), the absolute value of the third compensation value is compared with the first preset value, and if the absolute value of the third compensation value is smaller than the first preset value, it is determined that the compensation current of the C phase of the load 2 approaches zero, and the controller 15 controls the third switching unit 13 to stop working, i.e., stops sending the SPWM wave to the third switching unit 13.
Further, in this embodiment, when the controller 15 controls the third switching unit 13 to stop working, the controller 15 also changes the value of the status flag bit of the third switching unit 13 from the third preset value to the fourth preset value. It is understood that the controller 15 controls the third switching unit 13 to stop working and changes the value of the status flag bit of the third switching unit 13 from 0 to 1.
Step S106, when the first switch unit 11 is not in the working state, if the absolute value of the first compensation value is greater than a second preset value, controlling the first switch unit 11 to work.
In this embodiment, when the controller 15 detects that the value of the status flag of the first switch unit 11 is 1 (that is, the controller 15 or the DSP chip does not send the SPWM wave to the first switch unit 11), the absolute value of the first compensation value is compared with the second preset value, and if the absolute value of the first compensation value is greater than the second preset value, it is determined that the compensation current of the phase a of the load 2 is sufficiently large, and the phase a of the load 2 needs the first unit to provide the compensation current, so that the three-phase currents of the load 2 are balanced, and the controller 15 controls the first switch unit 11 to operate, that is, the SPWM wave is sent to the first switch unit 11. Wherein the second preset value may be set to 3A. Frequent entering and exiting of the operating state of the first switching unit 11 can be avoided by setting the second setting value.
Further, in this embodiment, when the controller 15 controls the first switch unit 11 to operate, the controller 15 may further change the value of the status flag bit of the first switch unit 11 from the fourth preset value to the third preset value. It is understood that the controller 15 controls the first switch unit 11 to operate and simultaneously changes the value of the status flag bit of the first switch unit 11 from 1 to 0.
Step S107, when the second switch unit 12 is not in the working state, if the absolute value of the second compensation value is greater than the second preset value, controlling the second switch unit 12 to work.
In this embodiment, when the controller 15 detects that the value of the status flag of the second switch unit 12 is 1 (that is, the controller 15 or the DSP chip does not send the SPWM wave to the second switch unit 12), the absolute value of the second compensation value is compared with the second preset value, and if the absolute value of the second compensation value is greater than the second preset value, it is determined that the compensation current of the B phase of the load 2 is sufficiently large, and the B phase of the load 2 needs to provide the compensation current by the second unit, so that the three-phase currents of the load 2 are balanced, and the controller 15 controls the second switch unit 12 to operate, that is, the SPWM wave is sent to the second switch unit 12. Frequent entering and exiting of the second switching unit 12 into the operating state can be avoided by setting the second setting value.
Further, in this embodiment, when the controller 15 controls the second switch unit 12 to operate, the controller 15 may further change the value of the status flag of the second switch unit 12 from the fourth preset value to the third preset value. It is understood that the controller 15 controls the second switch unit 12 to operate and simultaneously changes the value of the status flag bit of the second switch unit 12 from 1 to 0.
Step S108, when the third switching unit 13 is not in the working state, if the absolute value of the third compensation value is greater than the second preset value, the third switching unit 13 is controlled to work.
In this embodiment, when the controller 15 detects that the value of the status flag of the third switching unit 13 is 1 (i.e., the controller 15 or the DSP chip does not send the SPWM wave to the third switching unit 13), the absolute value of the third compensation value is compared with the second preset value, and if the absolute value of the third compensation value is greater than the second preset value, it is determined that the compensation current of the C phase of the load 2 is sufficiently large, and the C phase of the load 2 needs to be provided by the third unit to balance the three-phase currents of the load 2, and the controller 15 controls the third switching unit 13 to operate, i.e., send the SPWM wave to the third switching unit 13. Frequent entering and exiting of the third switching unit 13 into the operating state can be avoided by setting the second setting value.
Further, in this embodiment, when the controller 15 controls the third switching unit 13 to operate, the controller 15 also changes the value of the status flag bit of the third switching unit 13 from the fourth preset value to the third preset value. It is understood that the controller 15 controls the third switching unit 13 to operate while changing the value of the status flag bit of the third switching unit 13 from 1 to 0.
Fig. 4 is a schematic functional block diagram of a control device of the three-phase imbalance compensation device 1 according to the embodiment of the present invention. It should be noted that the basic principle and the technical effects of the control device of the three-phase imbalance compensation device 1 provided in the present embodiment are the same as those of the foregoing method embodiment, and for the sake of brief description, the corresponding contents in the foregoing method embodiment can be referred to for the parts not mentioned in the present embodiment. The control device of the three-phase imbalance compensation device 1 comprises a receiving module 41, a calculating module 42, a first control module 43, a second control module 44 and a third control module 45.
The receiving module 41 is configured to receive the effective value of the phase a current, the effective value of the phase B current, and the effective value of the phase C current sent by the current collecting unit 14.
It is understood that the receiving module 41 may perform the step S101.
The calculation module 42 is configured to calculate a first compensation value, a second compensation value, and a third compensation value according to the effective value of the phase a current, the effective value of the phase B current, and the effective value of the phase C current.
In the present embodiment, the calculation module 42 includes a first calculation unit and a second calculation unit.
The first calculating unit is used for calculating an average current effective value according to the A-phase current effective value, the B-phase current effective value and the C-phase current effective value; the second calculating unit is configured to subtract the average current effective value from the a-phase current effective value, the B-phase current effective value, and the C-phase current effective value to obtain the first compensation value, the second compensation value, and the third compensation value.
It is understood that the calculation module 42 may perform the step S102.
The first control module 43 is configured to, when the first switch unit 11 is in an operating state, control the first switch unit 11 to stop if an absolute value of the first compensation value is smaller than a first preset value; and is further configured to, when the first switch unit 11 is not in an operating state, control the first switch unit 11 to operate if the absolute value of the first compensation value is greater than a second preset value.
It is understood that the first control module 43 may perform the steps S103 and S106 described above.
The second control module 44 is configured to, when the second switch unit 12 is in an operating state, control the second switch unit 12 to stop operating if the absolute value of the second compensation value is smaller than the first preset value; and is further configured to control the second switch unit 12 to operate if the absolute value of the second compensation value is greater than the second preset value when the second switch unit 12 is not in the operating state.
It is understood that the second control module 44 may perform the steps S104 and S107 described above.
The third control module 45 is configured to, when the third switching unit 13 is in an operating state, control the third switching unit 13 to stop operating if the absolute value of the third compensation value is smaller than the first preset value; and is further configured to, when the third switching unit 13 is not in an operating state, control the third switching unit 13 to operate if the absolute value of the third compensation value is greater than the second preset value.
It is understood that the third control module 45 may perform the steps S105 and S108 described above.
In summary, in the control method and the control device for the three-phase imbalance compensation device provided in the embodiments of the present invention, the method receives the a-phase current effective value, the B-phase current effective value, and the C-phase current effective value sent by the current collection unit; respectively calculating a first compensation value, a second compensation value and a third compensation value according to the effective value of the phase-A current, the effective value of the phase-B current and the effective value of the phase-C current; when the first switch unit is in a working state, if the absolute value of the first compensation value is smaller than a first preset value, controlling the first switch unit to stop working; when the second switch unit is in a working state, if the absolute value of the second compensation value is smaller than the first preset value, controlling the second switch unit to stop working; and when the third switching unit is in a working state, if the absolute value of the third compensation value is smaller than the first preset value, controlling the third switching unit to stop working. Therefore, when the controller detects that the absolute value of the compensation value of at least one of the phases A, B and C is smaller than the first preset value, namely the compensation value of at least one of the phases A, B and C approaches zero, the controller controls at least one corresponding switch unit with the compensation value approaching zero to stop working, under the condition of not increasing any hardware cost, the switch loss and the conduction loss of the switch unit are effectively reduced, the efficiency of the three-phase unbalance compensation device is improved, and the energy-saving effect is achieved.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
Claims (8)
1. A control method of a three-phase unbalance compensation device is characterized in that the control method is applied to the three-phase unbalance compensation device, the three-phase unbalance compensation device comprises a first switch unit, a second switch unit, a third switch unit, a current acquisition unit and a controller, the controller is electrically connected with the first switch unit, the second switch unit, the third switch unit and the current acquisition unit, the first switch unit, the second switch unit and the third switch unit are respectively electrically connected with an A phase, a B phase and a C phase of a load, the current acquisition unit is connected with the A phase, the B phase and the C phase of the load, and the current acquisition unit is used for acquiring the A phase current, the B phase current and the C phase current of the load to obtain an A phase current effective value, a B phase current effective value and a C phase current effective value, the method comprises the following steps:
receiving the effective value of the phase A current, the effective value of the phase B current and the effective value of the phase C current sent by the current acquisition unit;
respectively calculating a first compensation value, a second compensation value and a third compensation value according to the effective value of the phase A current, the effective value of the phase B current and the effective value of the phase C current;
when the first switch unit is in a working state, if the absolute value of the first compensation value is smaller than a first preset value, controlling the first switch unit to stop working;
when the second switch unit is in a working state, if the absolute value of the second compensation value is smaller than the first preset value, controlling the second switch unit to stop working;
when the third switching unit is in a working state, if the absolute value of the third compensation value is smaller than the first preset value, controlling the third switching unit to stop working;
when the first switch unit is not in a working state, if the absolute value of the first compensation value is greater than a second preset value, controlling the first switch unit to work;
when the second switch unit is not in a working state, if the absolute value of the second compensation value is greater than the second preset value, controlling the second switch unit to work;
and when the third switching unit is not in a working state, if the absolute value of the third compensation value is greater than the second preset value, controlling the third switching unit to work.
2. The method according to claim 1, wherein a status flag bit of the first switch unit, a status flag bit of the second switch unit, and a status flag bit of the third switch unit are recorded in the controller, and the controller determines whether the first switch unit, the second switch unit, and the third switch unit are in an operating state according to values of the status flag bits of the first switch unit, the second switch unit, and the third switch unit, respectively, and determines that the first switch unit, the second switch unit, and the third switch unit are in the operating state when the value of the status flag bit is a third preset value; and when the value of the status flag bit is a fourth preset value, judging that the status flag bit is not in a working state.
3. The method for controlling a three-phase unbalance compensation apparatus according to claim 2, wherein after the step of controlling the first switching unit to stop operating if the absolute value of the first compensation value is smaller than a first preset value when the first switching unit is in the operating state, the method further comprises:
changing the value of the status flag bit of the first switch unit from the third preset value to the fourth preset value;
after the step of controlling the second switch unit to stop working if the absolute value of the second compensation value is smaller than the first preset value when the second switch unit is in a working state, the method further includes:
changing the value of the status flag bit of the second switch unit from the third preset value to the fourth preset value;
after the step of controlling the third switching unit to stop working if the absolute value of the third compensation value is smaller than the first preset value when the third switching unit is in a working state, the method further includes:
and changing the value of the status flag bit of the third switch unit from the third preset value to the fourth preset value.
4. The method for controlling an unbalance compensation apparatus for three phases according to claim 2, wherein after the step of controlling the first switching unit to operate if the absolute value of the first compensation value is greater than a second preset value when the first switching unit is not in an operating state, the method further comprises:
changing the value of the status flag bit of the first switch unit from the fourth preset value to the third preset value;
after the step of controlling the second switch unit to operate if the absolute value of the second compensation value is greater than the second preset value when the second switch unit is not in the operating state, the method further includes:
changing the value of the status flag bit of the second switch unit from the fourth preset value to the third preset value;
after the step of controlling the third switching unit to operate if the absolute value of the third compensation value is greater than the second preset value when the third switching unit is not in the operating state, the method further includes:
and changing the value of the status flag bit of the third switch unit from the fourth preset value to the third preset value.
5. The method of controlling a three-phase unbalance compensation apparatus according to claim 1, wherein the step of calculating a first compensation value, a second compensation value and a third compensation value based on the effective value of the a-phase current, the effective value of the B-phase current and the effective value of the C-phase current, respectively, comprises:
calculating to obtain an average current effective value according to the A-phase current effective value, the B-phase current effective value and the C-phase current effective value;
and respectively carrying out subtraction processing on the effective value of the phase current A, the effective value of the phase current B and the effective value of the phase current C and the effective value of the average current to obtain the first compensation value, the second compensation value and the third compensation value.
6. The control device of the three-phase unbalance compensation device is characterized by being applied to the three-phase unbalance compensation device, the three-phase unbalance compensation device comprises a first switch unit, a second switch unit, a third switch unit, a current acquisition unit and a controller, the controller is electrically connected with the first switch unit, the second switch unit, the third switch unit and the current acquisition unit, the first switch unit, the second switch unit and the third switch unit are respectively electrically connected with an A phase, a B phase and a C phase of a load, the current acquisition unit is connected with the A phase, the B phase and the C phase of the load, and the current acquisition unit is used for acquiring the A phase current, the B phase current and the C phase current of the load so as to obtain an A phase current effective value, a B phase current effective value and a C phase current effective value, the device comprises:
the receiving module is used for receiving the A-phase current effective value, the B-phase current effective value and the C-phase current effective value sent by the current acquisition unit;
the calculation module is used for calculating a first compensation value, a second compensation value and a third compensation value according to the A-phase current effective value, the B-phase current effective value and the C-phase current effective value respectively;
the first control module is used for controlling the first switch unit to stop working if the absolute value of the first compensation value is smaller than a first preset value when the first switch unit is in a working state;
the second control module is used for controlling the second switch unit to stop working if the absolute value of the second compensation value is smaller than the first preset value when the second switch unit is in a working state;
the third control module is used for controlling the third switching unit to stop working if the absolute value of the third compensation value is smaller than the first preset value when the third switching unit is in a working state;
the first control module is further configured to, when the first switch unit is not in a working state, control the first switch unit to work if an absolute value of the first compensation value is greater than a second preset value;
the second control module is further configured to, when the second switch unit is not in a working state, control the second switch unit to work if the absolute value of the second compensation value is greater than the second preset value;
the third control module is further configured to, when the third switching unit is not in the operating state, control the third switching unit to operate if the absolute value of the third compensation value is greater than the second preset value.
7. The apparatus of claim 6, wherein the controller records a status flag of the first switch unit, a status flag of the second switch unit, and a status flag of the third switch unit, and the controller determines whether the first switch unit, the second switch unit, and the third switch unit are in an operating state according to values of the status flags of the first switch unit, the second switch unit, and the third switch unit, respectively, and determines that the first switch unit, the second switch unit, and the third switch unit are in the operating state when the value of the status flag is a third preset value; and when the value of the status flag bit is a fourth preset value, judging that the status flag bit is not in a working state.
8. The control device of a three-phase unbalance compensation apparatus according to claim 7, wherein the calculation module includes:
the first calculation unit is used for calculating an average current effective value according to the A-phase current effective value, the B-phase current effective value and the C-phase current effective value;
and the second calculation unit is used for subtracting the average current effective value from the A-phase current effective value, the B-phase current effective value and the C-phase current effective value respectively to obtain the first compensation value, the second compensation value and the third compensation value.
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| CN204012736U (en) * | 2014-08-07 | 2014-12-10 | 国家电网公司 | A kind of three-phase imbalance adjusting device |
| CN105186545B (en) * | 2014-12-12 | 2018-08-07 | 艾思玛新能源技术（上海）有限公司苏州高新区分公司 | A kind of the current balance type control method and inverter of inverter |
| CN104767415B (en) * | 2015-03-27 | 2018-08-17 | 哈尔滨工程大学 | A kind of control method for parallel of three-phase four-leg inverter |
| CN106026140B (en) * | 2016-07-13 | 2020-01-03 | 深圳市泰昂能源科技股份有限公司 | Control device and method for three-phase unbalance and reactive compensation |
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