CN112072911A - Bus capacitor voltage regulating circuit, frequency converter and air conditioner - Google Patents
Bus capacitor voltage regulating circuit, frequency converter and air conditioner Download PDFInfo
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- CN112072911A CN112072911A CN202010952478.XA CN202010952478A CN112072911A CN 112072911 A CN112072911 A CN 112072911A CN 202010952478 A CN202010952478 A CN 202010952478A CN 112072911 A CN112072911 A CN 112072911A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/06—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using resistors or capacitors, e.g. potential divider
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
Abstract
The invention provides a bus capacitor voltage regulating circuit, a frequency converter and an air conditioner, wherein the bus capacitor comprises a first capacitor and a second capacitor which are connected in series between a positive bus and a negative bus, and the bus capacitor voltage regulating circuit comprises: the voltage division circuit is connected between the positive bus and the negative bus and is used for generating divided voltage; and the voltage regulating circuit is connected with the positive bus, the negative bus, the voltage dividing circuit, the first capacitor and the second capacitor, and is switched on or switched off according to the divided voltage so as to regulate the voltage of the first capacitor or the voltage of the second capacitor. On one hand, the voltage of the first capacitor and the voltage of the second capacitor are averaged, the voltage-sharing effect is improved, and the failure of the high-voltage capacitor is avoided; on the other hand, the bus is prevented from being provided with the fixed resistor to cause the reduction of the system efficiency, and the increase of the power consumption of the fixed resistor to cause the temperature rise of system components under the condition of high-voltage input is prevented.
Description
Technical Field
The invention relates to the technical field of circuits, in particular to a bus capacitor voltage regulating circuit, a frequency converter and an air conditioner.
Background
In a three-phase variable frequency driving system, a three-phase uncontrolled rectification topology or a three-phase Power Factor Correction (PFC) rectification topology is commonly used, the bus voltage obtained after rectification is generally over 540V level, and the withstand voltage of a common electrolytic capacitor is not more than 450V, so that the bus capacitor in the three-phase system needs to be improved in a series connection mode. However, since the positive and negative bus capacitors cannot be completely consistent, the voltages of the upper and lower bus capacitors are not uniform in practical use. If the problem of uneven voltage is not restrained, the bus capacitor with high voltage can be seriously failed.
In the related technology, power resistors are respectively connected in parallel at two ends of an upper bus capacitor and a lower bus capacitor, and the purpose of automatic voltage equalization is achieved by discharging the bus capacitors through the resistors. However, this method essentially increases a load to the bus bar, which reduces the efficiency of the system, and in addition, when a high voltage is input, the power consumption of the resistor increases, which causes unnecessary trouble in heat dissipation of the resistor itself and the devices around the resistor.
Disclosure of Invention
The invention mainly aims to provide a bus capacitor voltage regulating circuit, a frequency converter and an air conditioner, and aims to solve the problems of high loss and high cost caused by a common resistor voltage-sharing mode of the conventional three-phase system.
In order to achieve the above object, the present invention provides a bus capacitor voltage regulating circuit, wherein the bus capacitor includes a first capacitor and a second capacitor connected in series between a positive bus and a negative bus, and the bus capacitor voltage regulating circuit includes: the voltage division circuit is connected between the positive bus and the negative bus and is used for generating divided voltage; and the voltage regulating circuit is connected with the positive bus, the negative bus, the voltage dividing circuit, the first capacitor and the second capacitor, and is switched on or switched off according to the divided voltage so as to regulate the voltage of the first capacitor or the voltage of the second capacitor.
Further, the voltage dividing circuit includes: a first resistor; and the second resistor and the first resistor are connected in series between the positive bus and the negative bus, and the voltage between the first resistor and the second resistor is recorded as a divided voltage.
Further, the voltage regulating circuit includes: the first end of the first voltage regulating circuit is connected with the positive bus, the second end of the first voltage regulating circuit is connected between the first resistor and the second resistor, and the third end of the first voltage regulating circuit is connected between the first capacitor and the second capacitor; and the first end of the second voltage regulating circuit is connected with the negative bus, the second end of the second voltage regulating circuit is connected between the first resistor and the second resistor, and the third end of the second voltage regulating circuit is connected between the first capacitor and the second capacitor.
Further, the first voltage regulating circuit includes: the first end of the first power tube is connected with the positive bus, and the second end of the first power tube is connected between the first resistor and the second resistor; and one end of the third resistor is connected with the third end of the first power tube, and the other end of the third resistor is connected between the first capacitor and the second capacitor.
Further, the first voltage regulating circuit further includes: and the first protection circuit is connected between the second end of the first power tube and the third end of the first power tube.
Further, the first voltage regulating circuit further includes: and one end of the first diode is connected between the first capacitor and the second capacitor, and the other end of the first diode is connected with the third resistor.
Further, the second voltage regulating circuit includes: the first end of the second power tube is connected with the negative bus, and the second end of the second power tube is connected between the first resistor and the second resistor; and one end of the fourth resistor is connected with the third end of the second power tube, and the other end of the fourth resistor is connected between the first capacitor and the second capacitor.
Further, the second voltage regulating circuit further includes: and the second protection circuit is connected between the second end of the second power tube and the third end of the second power tube.
Further, the second voltage regulating circuit further includes: and one end of the second diode is connected between the first capacitor and the second capacitor, and the other end of the second diode is connected with the fourth resistor.
The invention also provides a frequency converter which comprises the bus capacitor voltage regulating circuit.
The invention also provides an air conditioner, which comprises the bus capacitor voltage regulating circuit; or the frequency converter described above.
In the technical scheme of the invention, the voltage division circuit generates the divided voltage according to the bus voltage, and the voltage regulation circuit is switched on or switched off according to the voltage difference between the divided voltage and the voltage of the first capacitor or the voltage difference between the divided voltage and the voltage of the second capacitor. On one hand, when the voltage difference is large, namely the voltage of the first capacitor and the voltage of the second capacitor are uneven, the voltage regulating circuit is conducted, and the first capacitor or the second capacitor discharges to the resistor in the voltage regulating circuit, so that the voltage of the first capacitor and the voltage of the second capacitor are even, the voltage equalizing effect is improved, and the failure of the high-voltage capacitor is avoided; on the other hand, after the voltage of the first capacitor and the voltage of the second capacitor are averaged, the voltage regulating circuit is turned off, the first capacitor or the second capacitor stops discharging to the resistor in the voltage regulating circuit, the problem that the efficiency of the system is reduced due to the fact that the bus is provided with the fixed resistor (namely, the resistor which is always connected in the circuit) is avoided, and the problem that the temperature of components of the system is increased due to the fact that the power consumption of the fixed resistor is increased under the condition of high-voltage input is avoided.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a schematic diagram of a bus capacitor voltage regulator circuit according to an embodiment of the present invention;
fig. 2 is a second schematic diagram of the bus capacitor voltage regulating circuit according to the embodiment of the invention.
The reference numbers illustrate:
| reference numerals | Name (R) | Reference numerals | Name (R) |
| 102 | |
104 | Voltage regulating |
| 1042 | First voltage regulating |
1044 | Second voltage regulating |
| 106 | |
108 | Negative bus |
| C1 | First capacitor | C2 | Second capacitor |
| R1 | A first resistor | R2 | Second resistance |
| R3 | Third resistance | R4 | Fourth resistor |
| T1 | First power tube | T2 | Second power tube |
| D11 | First protection circuit | D22 | Second protection circuit |
| D1 | First diode | D2 | Second diode |
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
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. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.
In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "connected," "secured," and the like are to be construed broadly, and for example, "secured" may be a fixed connection, a removable connection, or an integral part; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In addition, the technical solutions in the embodiments of the present invention may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination of technical solutions should not be considered to exist, and is not within the protection scope of the present invention.
In an embodiment of the first aspect of the present invention, a bus capacitor voltage regulating circuit is provided, which is described in detail with reference to fig. 1 and 2, wherein the bus capacitor includes a first capacitor C1 and a second capacitor C2 connected in series between the positive bus 106 and the negative bus 108.
As shown in fig. 1, the bus capacitor voltage regulator circuit includes:
a voltage dividing circuit 102, one end of the voltage dividing circuit 102 is connected to the positive bus 106, the other end of the voltage dividing circuit 102 is connected to the negative bus 108, the voltage dividing circuit 102 is used for generating a divided voltage, and the divided voltage is determined according to the bus voltage;
and the voltage regulating circuit 104 is connected with the positive bus 106, the negative bus 108, the voltage dividing circuit 102, the first capacitor C1 and the second capacitor C2, and the voltage regulating circuit 104 is switched on or off according to a voltage difference between the divided voltage and the voltage of the first capacitor or the voltage of the second capacitor so as to regulate the voltage of the first capacitor C1 or the voltage of the second capacitor C2.
In this embodiment, the voltage dividing circuit 102 generates a divided voltage according to the bus voltage, and the voltage regulating circuit 104 is turned on or off according to a voltage difference between the divided voltage and the voltage of the first capacitor C1 or according to a voltage difference between the divided voltage and the voltage of the second capacitor C2. On one hand, when the voltage difference between the divided voltage and the voltage of the first capacitor C1 is larger, or the voltage difference between the divided voltage and the voltage of the second capacitor C2 is larger, that is, the voltage of the first capacitor C1 is unbalanced with the voltage of the second capacitor C2, at this time, the voltage regulating circuit 104 is turned on, and the first capacitor C1 or the second capacitor C2 discharges to the resistor in the voltage regulating circuit 104, so that the voltage of the first capacitor C1 is balanced with the voltage of the second capacitor C2, the voltage equalizing effect is improved, and the high-voltage capacitor is prevented from failing; on the other hand, after the voltage of the first capacitor C1 and the voltage of the second capacitor C2 are balanced, the voltage regulating circuit 104 is turned off, the first capacitor C1 or the second capacitor C2 stops discharging to the resistor in the voltage regulating circuit 104, so that the problem that the efficiency of the system is reduced due to the fact that a bus is provided with a fixed resistor (namely, a resistor which is always connected in the circuit) is avoided, and the problem that the temperature of components of the system is increased due to the fact that the power consumption of the fixed resistor is increased under the condition of high-voltage input is avoided.
It should be noted that the first capacitor C1 and the second capacitor C2 are usually capacitors of the same type, and the first capacitor C1 and the second capacitor C2 both have insulation resistances therein, and the insulation resistances of different individual capacitors have a certain difference, so that the voltage of the first capacitor C1 is different from the voltage of the second capacitor C2. According to the embodiment of the invention, the voltage regulating circuit 104 is used for realizing that the capacitor is discharged only when no voltage is equalized, and the discharging path is automatically cut off when the voltage is equalized, so that the system loss is reduced, the cost is reduced to a certain extent, and the heat dissipation design requirement is reduced.
The first capacitor C1 may be an equivalent capacitor of a plurality of parallel capacitors, and the second capacitor C2 may be an equivalent capacitor of a plurality of parallel capacitors.
It should be noted that the capacitance value of the first capacitor C1 and the capacitance value of the second capacitor C2 are equal or unequal. The state of voltage balance or voltage equalization between the voltage of the first capacitor C1 and the voltage of the second capacitor C2 means that when the capacitance value of the first capacitor C1 is equal to the capacitance value of the second capacitor C2, the voltage of the first capacitor C1 and the voltage of the second capacitor C2 are adjusted to be equal to each other by turning on the voltage adjusting circuit 104; when the capacitance values of the first capacitor C1 and the second capacitor C2 are not equal to each other, the voltage of the first capacitor C1 and the voltage of the second capacitor C2 are adjusted to voltage values corresponding to the respective capacitance values by turning on the voltage adjusting circuit 104.
Further, as shown in fig. 2, the voltage dividing circuit 102 includes:
a first resistor R1;
the second resistor R2, the second resistor R2 and the first resistor R1 are connected in series between the positive bus 106 and the negative bus 108, and the voltage between the first resistor R1 and the second resistor R2 is referred to as a divided voltage.
In this embodiment, voltage divider circuit 102 is a multi-resistor circuit connected between positive bus 106 and negative bus 108, providing a bus midpoint voltage, providing on and off charge and discharge loops for voltage regulator circuit 104. Specifically, the first resistor R1 and the second resistor R2 of the voltage dividing circuit 102 are sequentially connected between the positive bus 106 and the negative bus 108, and the first resistor R1 and the second resistor R2 divide the bus voltage to obtain the voltage at the center point between the first resistor R1 and the second resistor R2, that is, the divided voltage. Further, whether voltage sharing is carried out or not is determined according to the divided voltage, under the condition that voltage sharing is not carried out, discharging of a capacitor with a relatively high voltage is achieved through the voltage regulating circuit 104, voltage sharing is achieved, and a discharging path is automatically cut off by the voltage regulating circuit 104 after voltage sharing is carried out, so that system loss is reduced, cost is reduced to a certain extent, and heat dissipation design requirements are reduced.
It should be noted that, functionally, the first resistor R1 and the second resistor R2 are used to supply current only for turning on or off the voltage regulator circuit 104, so that power loss is greatly reduced compared with the voltage equalizing manner of parallel resistors in the related art.
It should be noted that, the resistance values of the first resistor R1 and the second resistor R2 are equal or unequal, and when the capacitance value of the first capacitor C1 is equal to the capacitance value of the second capacitor C2, the resistance values of the first resistor R1 and the second resistor R2 are equal; when the capacitance values of the first capacitor C1 and the second capacitor C2 are not equal, the resistance values of the first resistor R1 and the second resistor R2 are not equal, but in the case of non-equal, the resistance value of the first resistor R1 is related to the capacitance value of the first capacitor C1, and the resistance value of the second resistor R2 is related to the capacitance value of the second capacitor C2.
Further, as shown in fig. 2, the voltage regulating circuit 104 includes:
a first end of the first voltage regulating circuit 1042 is connected with the positive bus 106, a second end of the first voltage regulating circuit 1042 is connected between a first resistor R1 and a second resistor R2, and a third end of the first voltage regulating circuit 1042 is connected between a first capacitor C1 and a second capacitor C2;
a second voltage regulating circuit 1044, a first end of the second voltage regulating circuit 1044 is connected to the negative bus 108, a second end of the second voltage regulating circuit 1044 is connected between the first resistor R1 and the second resistor R2, and a third end of the second voltage regulating circuit 1044 is connected between the first capacitor C1 and the second capacitor C2.
In this embodiment, as shown in fig. 2, a point a is provided between the first resistor R1 and the second resistor R2, a point B is provided on the positive bus 106, a point C is provided between the first capacitor C1 and the second capacitor C2, a point D is provided on the negative bus 108, the first voltage regulating circuit 1042 is connected to the point a, the point B, and the point C, respectively, and the second voltage regulating circuit 1044 is connected to the point a, the point C, and the point D, respectively.
When the voltage at the point a is greater than the voltage at the point C, specifically, when the voltage difference between the voltage at the point a and the voltage at the point C is greater than the preset starting voltage, it is indicated that the voltage of the first capacitor C1 is greater than the voltage of the second capacitor C2, and the voltage is not uniform, then the first voltage regulating circuit 1042 is automatically turned on, the resistor in the first voltage regulating circuit 1042 is connected in parallel with the first capacitor C1, and then the first capacitor C1 discharges the resistor in the first voltage regulating circuit 1042, so as to implement the voltage reduction of the first capacitor C1, and further balance the voltage of the first capacitor C1 with the voltage of the second capacitor C2. And when the voltage at point a is greater than the voltage at point C, the second voltage regulating circuit 1044 is in an off state.
When the voltage at the point C is greater than the voltage at the point a, specifically, when the absolute value of the voltage difference between the voltage at the point a and the voltage at the point C is greater than the preset starting voltage, it indicates that the voltage of the second capacitor C2 is greater than the voltage of the first capacitor C1, and the voltage is not uniform, then the second voltage regulating circuit 1044 is automatically turned on, the resistor in the second voltage regulating circuit 1044 is connected in parallel with the second capacitor C2, and then the second capacitor C2 discharges the resistor in the second voltage regulating circuit 1044, so that the voltage drop of the second capacitor C2 is realized, and further, the voltage of the first capacitor C1 is balanced with the voltage of the second capacitor C2. And when the voltage at the point C is greater than the voltage at the point a, the first voltage regulating circuit 1042 is in an off state.
Further, as shown in fig. 2, the first voltage regulating circuit 1042 includes:
a first power tube T1, a first end of the first power tube T1 is connected with the positive bus 106, and a second end of the first power tube T1 is connected between the first resistor R1 and the second resistor R2;
a third resistor R3, a first end of the third resistor R3 is connected to a third end of the first power transistor T1, a second end of the third resistor R3 is connected between the first capacitor C1 and the second capacitor C2, and the third resistor R3 discharges to the first capacitor C1 when the first power transistor T1 is turned on.
In this embodiment, the first voltage regulating circuit 1042 includes a first power transistor T1 and a third resistor R3, the first power transistor T1 implements a switching function, when the first power transistor T1 is turned on, the third resistor R3 is connected in parallel with the first capacitor C1, and the first capacitor C1 discharges to the third resistor R3, thereby implementing voltage reduction; when the first power tube T1 is turned off, the third resistor R3 is not connected to the circuit, thereby reducing system loss, and to some extent, reducing cost and reducing heat dissipation design requirements.
Specifically, when the voltage at the point a is greater than the voltage at the point C, the first power transistor T1 is turned on; in the case that the voltage at the point C is greater than the voltage at the point a, the first power transistor T1 is turned off.
In an embodiment, the first power transistor T1 may be a MOS (Metal Oxide Semiconductor) transistor, a triode, or the like.
When the first power transistor T1 is an MOS transistor, the first power transistor T1 is an N-channel MOS transistor, the first end of the first power transistor T1 is a drain, the second end of the first power transistor T1 is a gate, and the third end of the first power transistor T1 is a source. The drain voltage of the first power transistor T1 is the voltage at point B, the gate voltage of the first power transistor T1 is the voltage at point a, and the source of the first power transistor T1 is connected between the first capacitor C1 and the second capacitor C2 through the third resistor R3, that is, at point C. When the gate voltage of the first power transistor T1 is greater than the source voltage of the first power transistor T1, it indicates that the voltage across the first capacitor C1 is greater than the voltage across the second capacitor C2, the first power transistor T1 is turned on, the third resistor R3 is connected in parallel with the first capacitor C1, and the first capacitor C1 discharges to the third resistor R3, so that voltage reduction is achieved. Under the condition that the grid voltage of the first power tube T1 is not larger than the source voltage of the first power tube T1, the first power tube T1 is turned off, and the third resistor R3 is turned off, so that the system loss is reduced, and the heat dissipation design requirement is reduced.
When the first power transistor T1 is a triode, the first terminal of the first power transistor T1 is a collector, the second terminal of the first power transistor T1 is a base, and the third terminal of the first power transistor T1 is an emitter. The collector voltage of the first power transistor T1 is the voltage at point B, the base voltage of the first power transistor T1 is the voltage at point a, and the emitter of the first power transistor T1 is connected between the first capacitor C1 and the second capacitor C2 through the third resistor R3, that is, at point C. When the base voltage of the first power tube T1 is greater than the emitter voltage of the first power tube T1, it indicates that the voltage across the first capacitor C1 is greater than the voltage across the second capacitor C2, the first power tube T1 is turned on, the third resistor R3 is connected in parallel with the first capacitor C1, and the first capacitor C1 discharges to the third resistor R3, so that voltage reduction is achieved. Under the condition that the base voltage of the first power tube T1 is not larger than the emitter voltage of the first power tube T1, the first power tube T1 is turned off, and the third resistor R3 is turned off, so that the system loss is reduced, and the heat dissipation design requirement is reduced.
In addition, it should be noted that the resistance of the third resistor R3 may be set according to actual requirements, or may be an adjustable resistor. Therefore, the bus capacitor with different capacities can be subjected to voltage reduction, and the problem that the capacity of the bus capacitor in the related technology needs to be reduced by connecting more resistors in parallel after the power is increased, so that the cost of the resistors is increased is avoided.
Further, as shown in fig. 2, the first voltage regulating circuit 1042 further includes:
and the first protection circuit D11 and the first protection circuit D11 are connected between the second end of the first power tube T1 and the first end of the third resistor R3.
In this embodiment, the first protection circuit D11 is connected between the second terminal of the first power transistor T1 and the third terminal of the first power transistor T1, and is used to limit the gate voltage of the first power transistor T1 within a certain range, so as to protect the first power transistor T1 from breakdown, thereby improving the service life of the first power transistor T1.
The first protection circuit D11 may be a zener diode, an anode of the zener diode is connected to the third terminal of the first power transistor T1, and a cathode of the zener diode is connected to the second terminal of the first power transistor T1.
When the first power transistor T1 is a MOS transistor, the anode of the zener diode is connected to the source of the first power transistor T1, and the cathode of the zener diode is connected to the gate of the first power transistor T1. When the first power transistor T1 is a triode, the anode of the zener diode is connected to the emitter of the first power transistor T1, and the cathode of the zener diode is connected to the base of the first power transistor T1.
Further, as shown in fig. 2, the first voltage regulating circuit 1042 further includes:
and a first diode D1, one end of the first diode D1 is connected between the first capacitor C1 and the second capacitor C2, and the other end of the first diode D1 is connected with the third resistor R3.
In this embodiment, the anode of the first diode D1 is connected to the third resistor R3, and the cathode of the first diode D1 is connected between the first capacitor C1 and the second capacitor C2. The first diode D1 is used to prevent current from flowing through the first protection circuit D11 during non-uniform voltage, and to prevent the first protection circuit D11 from being turned on by mistake in the same direction.
Further, as shown in fig. 2, the second voltage regulation circuit 1044 includes:
a second power tube T2, a first end of the second power tube T2 is connected with the negative bus 108, and a second end of the second power tube T2 is connected between the first resistor R1 and the second resistor R2;
a fourth resistor R4, a first end of the fourth resistor R4 is connected to the third end of the second power transistor T2, a second end of the fourth resistor R4 is connected between the first capacitor C1 and the second capacitor C2, and the fourth resistor R4 discharges to the second capacitor C2 when the second power transistor T2 is turned on.
In this embodiment, the second voltage regulation circuit 1044 includes a second power transistor T2 and a fourth resistor R4, the second power transistor T2 implements a switching function, when the second power transistor T2 is turned on, the fourth resistor R4 is connected in parallel with the second capacitor C2, and the second capacitor C2 discharges to the fourth resistor R4, thereby implementing a voltage reduction; when the second power tube T2 is turned off, the fourth resistor R4 is not connected to the circuit, thereby reducing the system loss, and to a certain extent, reducing the cost and reducing the heat dissipation design requirement.
Specifically, when the voltage at the point C is greater than the voltage at the point a, the second power transistor T2 is turned on; in the case where the voltage at the point a is greater than the voltage at the point C, the second power transistor T2 is turned off.
In a specific embodiment, the second power transistor T2 may be a MOS transistor, a triode, or the like.
When the second power transistor T2 is a MOS transistor, the second power transistor T2 is a P-channel MOS transistor, the first end of the second power transistor T2 is a drain, the second end of the second power transistor T2 is a gate, and the third end of the second power transistor T2 is a source. The drain voltage of the second power transistor T2 is the voltage at the point D, the gate voltage of the second power transistor T2 is the voltage at the point a, and the source of the second power transistor T2 is connected between the first capacitor C1 and the second capacitor C2 through the fourth resistor R4, that is, at the point C. When the source voltage of the second power tube T2 is greater than the gate voltage of the second power tube T2, it indicates that the voltage across the second capacitor C2 is greater than the voltage across the first capacitor C1, the second power tube T2 is turned on, the fourth resistor R4 is connected in parallel with the second capacitor C2, and the second capacitor C2 discharges to the fourth resistor R4, so that voltage reduction is achieved. Under the condition that the source voltage of the second power tube T2 is not greater than the gate voltage of the second power tube T2, the second power tube T2 is turned off, and the fourth resistor R4 is turned off, so that the system loss is reduced, and the heat dissipation design requirement is reduced.
When the second power transistor T2 is a triode, the first terminal of the second power transistor T2 is a collector, the second terminal of the second power transistor T2 is a base, and the third terminal of the second power transistor T2 is an emitter. The collector voltage of the second power transistor T2 is the voltage at point D, the base voltage of the second power transistor T2 is the voltage at point a, and the emitter of the second power transistor T2 is connected between the first capacitor C1 and the second capacitor C2 through the fourth resistor R4, that is, at point C. When the base voltage of the second power tube T2 is greater than the emitter voltage of the second power tube T2, it indicates that the voltage across the second capacitor C2 is greater than the voltage across the first capacitor C1, the second power tube T2 is turned on, the fourth resistor R4 is connected in parallel with the second capacitor C2, and the second capacitor C2 discharges to the fourth resistor R4, so that voltage reduction is achieved. Under the condition that the base voltage of the second power tube T2 is not larger than the emitter voltage of the second power tube T2, the second power tube T2 is turned off, and the fourth resistor R4 is turned off, so that the system loss is reduced, and the heat dissipation design requirement is reduced.
In addition, it should be noted that the resistance of the fourth resistor R4 may be set according to actual requirements, or may be an adjustable resistor. Therefore, the bus capacitor with different capacities can be subjected to voltage reduction, and the problem that the capacity of the bus capacitor in the related technology needs to be reduced by connecting more resistors in parallel after the power is increased, so that the cost of the resistors is increased is avoided.
Further, as shown in fig. 2, the second voltage regulation circuit 1044 further includes:
and a second protection circuit D22, the second protection circuit D22 being connected between the second terminal of the second power transistor T2 and the first terminal of the fourth resistor R4.
In this embodiment, the second protection circuit D22 is connected between the second terminal of the second power transistor T2 and the third terminal of the second power transistor T2, and is used to limit the gate voltage of the second power transistor T2 within a certain range, so as to protect the second power transistor T2 from breakdown, thereby improving the service life of the second power transistor T2.
The second protection circuit D22 may be a zener diode, an anode of the zener diode is connected to the second terminal of the second power transistor T2, and a cathode of the zener diode is connected to the third terminal of the second power transistor T2.
When the first power transistor T1 is a MOS transistor, the anode of the zener diode is connected to the gate of the first power transistor T1, and the cathode of the zener diode is connected to the drain of the first power transistor T1. When the first power transistor T1 is a triode, the anode of the zener diode is connected to the base of the first power transistor T1, and the cathode of the zener diode is connected to the collector of the first power transistor T1. Further, as shown in fig. 2, the second voltage regulation circuit 1044 further includes:
one end of a second diode D2, one end of a second diode D2 is connected between the first capacitor C1 and the second capacitor C2, and the other end of the second diode D2 is connected to the fourth resistor R4.
In this embodiment, the anode of the second diode D2 is connected between the first capacitor C1 and the second capacitor C2, and the cathode of the second diode D2 is connected to the fourth resistor R4. The second diode D2 is used to avoid current flowing through the second protection circuit D22 during non-uniform voltage, and to avoid the second protection circuit D22 from being turned on by mistake in the same direction.
It should be noted that in the embodiment of the present invention, a voltage regulating circuit is correspondingly disposed in each of the first capacitor C1 and the second capacitor C2, specifically, the first capacitor C1 corresponds to the first voltage regulating circuit 1042, and the third resistor R3 is connected or not connected to the circuit by turning on or off the first power transistor T1 in the first voltage regulating circuit 1042. The second capacitor C2 corresponds to the second voltage regulating circuit 1044, and the fourth resistor R4 is connected or not connected to the circuit by turning on or off the second power tube T2 in the second voltage regulating circuit 1044. That is to say, just when the electric capacity needs to carry out the step-down of parallel resistance, incorporate the resistance into the circuit, otherwise do not insert parallel resistance, not only can realize the quick step-down of corresponding electric capacity, can also play the effect that reduces the consumption.
In addition, compared with a scheme that the parallel resistance of one of the first capacitor C1 and the second capacitor C2 is adjusted to be switched in, and the other capacitor is switched in all the time, the power consumption of the circuit can be reduced to a greater extent.
The embodiment of the invention provides a bus capacitor voltage regulating circuit aiming at the problems of high loss and high cost caused by a common resistance voltage-sharing mode of the existing three-phase system.
In an embodiment of the second aspect of the present invention, a frequency converter is provided, which includes the bus capacitor voltage regulating circuit.
The frequency converter provided by the invention includes the bus capacitor voltage regulating circuit of the embodiment of the first aspect, so that the frequency converter includes all the beneficial effects of the bus capacitor voltage regulating circuit of the embodiment of the first aspect, and details are not repeated herein.
In an embodiment of a third aspect of the present invention, an air conditioner is provided, including the bus capacitor voltage regulating circuit of the embodiment of the first aspect; or the frequency converter of the embodiment of the second aspect described above.
The air conditioner provided by the invention includes the bus capacitor voltage regulating circuit of the embodiment of the first aspect or the inverter of the embodiment of the second aspect, so that the air conditioner includes all the beneficial effects of the bus capacitor voltage regulating circuit of the embodiment of the first aspect, and details are not repeated herein.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (11)
1. A bus capacitor voltage regulator circuit, wherein the bus capacitor includes a first capacitor and a second capacitor connected in series between a positive bus and a negative bus, the bus capacitor voltage regulator circuit comprising:
the voltage division circuit is connected between the positive bus and the negative bus and is used for generating divided voltage;
and the voltage regulating circuit is connected with the positive bus, the negative bus, the voltage dividing circuit, the first capacitor and the second capacitor, and the voltage regulating circuit is switched on or switched off according to the divided voltage so as to regulate the voltage of the first capacitor or the voltage of the second capacitor.
2. The bus capacitance voltage regulator circuit according to claim 1, wherein the voltage divider circuit comprises:
a first resistor;
and the second resistor and the first resistor are connected in series between the positive bus and the negative bus, and the voltage between the first resistor and the second resistor is recorded as the divided voltage.
3. The bus capacitor voltage regulator circuit of claim 2, wherein the voltage regulator circuit comprises:
a first end of the first voltage regulating circuit is connected with the positive bus, a second end of the first voltage regulating circuit is connected between the first resistor and the second resistor, and a third end of the first voltage regulating circuit is connected between the first capacitor and the second capacitor;
and a first end of the second voltage regulating circuit is connected with the negative bus, a second end of the second voltage regulating circuit is connected between the first resistor and the second resistor, and a third end of the second voltage regulating circuit is connected between the first capacitor and the second capacitor.
4. The bus capacitor voltage regulator circuit of claim 3, wherein the first voltage regulator circuit comprises:
a first power tube, wherein a first end of the first power tube is connected with the positive bus, and a second end of the first power tube is connected between the first resistor and the second resistor;
and one end of the third resistor is connected with the third end of the first power tube, and the other end of the third resistor is connected between the first capacitor and the second capacitor.
5. The bus capacitor voltage regulator circuit of claim 4, wherein the first voltage regulator circuit further comprises:
the first protection circuit is connected between the second end of the first power tube and the third end of the first power tube.
6. The bus capacitor voltage regulator circuit of claim 4, wherein the first voltage regulator circuit further comprises:
and one end of the first diode is connected between the first capacitor and the second capacitor, and the other end of the first diode is connected with the third resistor.
7. The bus capacitor voltage regulator circuit according to any of claims 3-6, wherein the second voltage regulator circuit comprises:
a second power tube, wherein a first end of the second power tube is connected with the negative bus, and a second end of the second power tube is connected between the first resistor and the second resistor;
one end of the fourth resistor is connected with the third end of the second power tube, and the other end of the fourth resistor is connected between the first capacitor and the second capacitor.
8. The bus capacitor voltage regulator circuit of claim 7, wherein the second voltage regulator circuit further comprises:
and the second protection circuit is connected between the second end of the second power tube and the third end of the second power tube.
9. The bus capacitor voltage regulator circuit of claim 7, wherein the second voltage regulator circuit further comprises:
and one end of the second diode is connected between the first capacitor and the second capacitor, and the other end of the second diode is connected with the fourth resistor.
10. A frequency converter, comprising:
the bus capacitor voltage regulator circuit of any of claims 1-9.
11. An air conditioner, comprising:
the bus capacitance voltage regulator circuit of any one of claims 1 to 9; or
The frequency converter of claim 10.
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| CN202010952478.XA CN112072911B (en) | 2020-09-11 | 2020-09-11 | Bus capacitor voltage regulating circuit, frequency converter and air conditioner |
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| CN202010952478.XA CN112072911B (en) | 2020-09-11 | 2020-09-11 | Bus capacitor voltage regulating circuit, frequency converter and air conditioner |
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| CN112072911B CN112072911B (en) | 2022-05-17 |
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| CN111342432A (en) * | 2020-02-25 | 2020-06-26 | 深圳市禾望科技有限公司 | Photovoltaic inverter main circuit |
| CN211151522U (en) * | 2019-11-04 | 2020-07-31 | 苏州海鹏科技有限公司 | Photovoltaic inverter and direct current bus capacitor protection circuit thereof |
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| US6031738A (en) * | 1998-06-16 | 2000-02-29 | Wisconsin Alumni Research Foundation | DC bus voltage balancing and control in multilevel inverters |
| CN104391535A (en) * | 2014-11-21 | 2015-03-04 | 常熟开关制造有限公司(原常熟开关厂） | Method and device for equalizing voltage of DC bus capacitor |
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| CN112072911B (en) | 2022-05-17 |
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