CN213213320U - Constant-current pre-charging circuit and frequency conversion device - Google Patents
Constant-current pre-charging circuit and frequency conversion device Download PDFInfo
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- CN213213320U CN213213320U CN202022256189.4U CN202022256189U CN213213320U CN 213213320 U CN213213320 U CN 213213320U CN 202022256189 U CN202022256189 U CN 202022256189U CN 213213320 U CN213213320 U CN 213213320U
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Abstract
The utility model provides a constant current is charging circuit and frequency conversion device in advance, constant current is charging circuit in advance includes: a precharge switch unit connected to the charging capacitor; the voltage stabilizing unit is connected with the pre-charging switch unit; a current detection unit connected to the precharge switching unit; and the driving voltage control unit is respectively connected with the current detection unit and the pre-charging switch unit. The frequency conversion device comprises: the constant-current pre-charging circuit comprises a constant-current pre-charging circuit, a rectifying circuit, an inverter circuit and a charging capacitor; the rectifying circuit is respectively connected with the three-phase alternating current power supply and the constant current pre-charging circuit; the constant-current pre-charging circuit is respectively connected with the charging capacitor and the inverter circuit. The utility model provides a small and with low costs constant current is charging circuit in advance.
Description
Technical Field
The utility model belongs to the technical field of power electronics, a precharge circuit is related to, especially relate to a constant current precharge circuit and frequency conversion device.
Background
At present, the application of converting alternating current to direct current and then charging a bus large capacitor in the field of commercial three-phase frequency converters is very wide, when the frequency converter is powered on, due to the working principle of a capacitor, the voltage at two ends of an energy storage element capacitor on the direct current bus is 0, a large impact current can be generated at the moment, and if a pre-charging circuit is not provided, a diode or a relay of a rectifier can cause the damage of devices in the circuit; the power supply voltage drop increases, creating interference to the grid. After the pre-charging resistor is added, the bus capacitor is pre-charged through the pre-charging loop, so that the current of the main circuit when the main circuit is switched on can be controlled within a safe range, elements of the rectifier are protected from being damaged due to instant short-circuit current of the capacitor, and normal operation of a system is ensured.
In order to overcome the defect of excessive charging current, the scheme in the prior art mainly uses more pre-charging resistors packaged by high-power cement, the scheme is high in cost and large in occupied circuit board area, fixing glue needs to be applied or a special plastic support needs to be made to fix the high-volume pre-charging resistors, and further the production process is complex.
Therefore, how to provide a small-sized and low-cost constant current pre-charge circuit has become an urgent technical problem to be solved by those skilled in the art.
SUMMERY OF THE UTILITY MODEL
In view of the above-mentioned shortcomings of the prior art, it is an object of the present invention to provide a small and low-cost constant current pre-charging circuit.
In order to achieve the above objects and other related objects, an aspect of the present invention is to provide a constant current pre-charge circuit, including: a precharge switch unit connected to the charging capacitor; the voltage stabilizing unit is connected with the pre-charging switch unit; a current detection unit connected to the precharge switching unit; and the driving voltage control unit is respectively connected with the current detection unit and the pre-charging switch unit.
In an embodiment of the present invention, the pre-charge switch unit includes a MOS transistor; and the drain electrode of the MOS tube is connected with one end of the charging capacitor, and the other end of the charging capacitor is connected with one end of the rectification output.
In an embodiment of the present invention, the voltage stabilizing unit includes a voltage regulator tube, a first resistor and a second resistor; the cathode of the voltage-stabilizing tube is respectively connected with one end of the first resistor and one end of the second resistor; the other end of the first resistor is connected with one end of the rectification output, and the other end of the second resistor is connected with the grid electrode of the MOS tube; and the anode of the voltage stabilizing tube is connected with the other end of the rectification output.
In an embodiment of the present invention, the current detection unit includes a current detection resistor, one end of the current detection resistor is connected to the source of the MOS transistor, and the other end is connected to the other end of the rectification output.
In an embodiment of the present invention, the driving voltage control unit includes a three-terminal voltage regulator; the cathode of the three-terminal voltage stabilizer is connected with the grid of the MOS tube, the anode of the three-terminal voltage stabilizer is connected with the other end of the rectification output, and the reference electrode of the three-terminal voltage stabilizer is connected with the source electrode of the MOS tube.
In an embodiment of the present invention, the constant current pre-charging circuit further includes: a state switching unit; and the first end of the state switching unit is connected with the drain electrode of the MOS tube, and the second end of the state switching unit is connected with the other end of the rectification output.
In an embodiment of the present invention, the constant current pre-charging circuit further includes: a main control unit; and the main control unit is connected with the third end of the state switching unit.
The utility model discloses another aspect provides a frequency conversion device, frequency conversion device includes: the constant-current pre-charging circuit, the rectifying circuit, the inverter circuit and the charging capacitor are connected in series; the rectifying circuit is respectively connected with the three-phase alternating current power supply and the constant current pre-charging circuit; the constant-current pre-charging circuit is respectively connected with the charging capacitor and the inverter circuit.
In an embodiment of the present invention, the rectifying circuit includes a first diode, a second diode, a third diode, a fourth diode, a fifth diode, and a sixth diode; the cathode of the first diode, the cathode of the third diode and the cathode of the fifth diode are all connected with one end of the rectification output, the anode of the second diode, the anode of the fourth diode and the anode of the sixth diode are all connected with the other end of the rectification output, the anode of the first diode is connected with the cathode of the second diode and serves as a first input end of the three-phase alternating current power supply, the anode of the third diode is connected with the cathode of the fourth diode and serves as a second input end of the three-phase alternating current power supply, and the anode of the fifth diode is connected with the cathode of the sixth diode and serves as a third input end of the three-phase alternating current power supply; the inverter circuit comprises a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor and a sixth transistor; the drain electrode of the first transistor, the drain electrode of the third transistor and the drain electrode of the fifth transistor are all connected with one end of the rectification output, the source electrode of the second transistor, the source electrode of the fourth transistor and the source electrode of the sixth transistor are all connected with the other end of the rectification output, the source electrode of the first transistor is connected with the drain electrode of the second transistor and serves as a first inversion output end, the source electrode of the third transistor is connected with the drain electrode of the fourth transistor and serves as a second inversion output end, and the source electrode of the fifth transistor is connected with the drain electrode of the sixth transistor and serves as a third inversion output end.
As above, constant current precharge circuit, the following beneficial effect has:
the constant-current pre-charging of the bus capacitor can be realized through 1 MOS (Metal Oxide Semiconductor) transistor, 1 precise voltage-stabilizing source, a current detection resistor and a voltage-stabilizing tube, and the constant-current pre-charging circuit is small in size and low in cost. The MOS tube is switched on through the voltage stabilizing tube to charge the charging capacitor, and the working state of the MOS tube is controlled by the precise voltage stabilizing tube through the voltage converted by the current detection resistor, so that the constant-current pre-charging process is realized.
Drawings
Fig. 1 is a schematic diagram illustrating a circuit connection of a constant current precharge circuit according to an embodiment of the present invention.
Fig. 2 is a schematic circuit diagram of a constant current precharge circuit according to another embodiment of the present invention.
Fig. 3 is a diagram of a constant current precharge circuit according to an embodiment of the present invention.
Fig. 4 is a schematic circuit diagram of a frequency converter according to an embodiment of the present invention.
Description of the element reference numerals
1 constant current pre-charging circuit
11 precharge switch unit
12 voltage stabilizing unit
13 Current detecting unit
14 drive voltage control unit
15 state switching unit
16 Main control unit
2 rectification circuit
3 inverter circuit
4 charging capacitor
Detailed Description
The following description is provided for illustrative purposes, and other advantages and features of the present invention will become apparent to those skilled in the art from the following detailed description.
Please refer to the attached drawings. It should be understood that the structures, ratios, sizes, etc. shown in the drawings attached to the present specification are only used for matching with the contents disclosed in the specification, so as to be known and read by those skilled in the art, and are not used for limiting the limit conditions that the present invention can be implemented, so that the present invention has no technical essential meaning, and any modification of the structures, changes of the ratio relationship, or adjustment of the size should still fall within the scope that the technical contents disclosed in the present invention can cover without affecting the efficacy that the present invention can produce and the purpose that the present invention can achieve. Meanwhile, the terms such as "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for convenience of description, and are not intended to limit the scope of the present invention, and changes or adjustments of the relative relationship thereof may be made without substantial technical changes, and the present invention is also regarded as the scope of the present invention.
The constant-current pre-charging circuit provided by the embodiment can realize the constant-current pre-charging of the bus capacitor through the 1 MOS tube, the 1 precise voltage stabilizing source, the current detection resistor and the voltage stabilizing tube, and is small in size and low in cost.
Please refer to fig. 1 and fig. 2, which respectively show a circuit connection diagram of the constant current pre-charge circuit in one embodiment of the present invention and a circuit connection diagram of the constant current pre-charge circuit in another embodiment of the present invention. As shown in fig. 2, the constant current precharge circuit 1 includes: a precharge switching unit 11, a voltage stabilizing unit 12, a current detecting unit 13, a driving voltage control unit 14, a state switching unit 15, and a main control unit 16.
The precharge switching unit 11 is connected to the charging capacitor.
Please refer to fig. 3, which shows a precharge circuit diagram of the constant current precharge circuit according to an embodiment of the present invention. As shown in fig. 3, in the present embodiment, the precharge switching unit includes a MOS transistor MOS 1; the drain of the MOS transistor MOS1 is connected to one end of the charging capacitor C1, and the other end of the charging capacitor C1 is connected to one end of the rectified output.
It should be noted that, the MOS transistor, whether it is an NMOS transistor or a PMOS transistor, is protected by the present invention through the circuit structure corresponding to the gate level thereof.
The voltage stabilization unit 12 is connected to the precharge switching unit 11.
In the present embodiment, the voltage regulator unit includes a voltage regulator tube Z1, a first resistor R1, and a second resistor R2.
The cathode of the voltage stabilizing Z1 tube is respectively connected with one end of the first resistor R1 and one end of the second resistor R2.
The other end of the first resistor R1 is connected with one end of the rectification output, and the other end of the second resistor R2 is connected with the grid of the MOS tube MOS 1.
And the anode of the voltage-stabilizing tube Z1 is connected with the other end of the rectified output.
The current detection unit 13 is connected to the precharge switching unit 11.
In this embodiment, the current detection unit includes a current detection resistor R3, one end of the current detection resistor R3 is connected to the source of the MOS transistor MOS1, and the other end is connected to the other end of the rectified output.
The driving voltage control unit 14 is connected to the current detection unit 13 and the precharge switching unit 11, respectively.
In this embodiment, the driving voltage control unit includes a three-terminal regulator TL 431; the cathode of the three-terminal voltage regulator device TL431 is connected with the grid of the MOS transistor MOS1, the anode of the three-terminal voltage regulator device TL431 is connected with the other end of the rectification output, and the reference electrode of the three-terminal voltage regulator device TL is connected with the source electrode of the MOS transistor MOS 1.
It should be noted that TL431 is only the device adopted in an embodiment of the present invention, in another embodiment, other precise voltage stabilization source devices, devices and integrated circuits except TL431, which can adjust the gate voltage of the MOS transistor according to the voltage drop of the current detection resistor, are also within the scope of the present invention.
The state switching unit 15 has a first end connected to the drain of the MOS transistor MOS1, and a second end connected to the other end of the rectified output.
Specifically, the state switching unit 15 may be a relay, a switch tube, or another device that can receive a control signal and perform state switching.
The main control unit 16 is connected to the third end of the state switching unit 15.
Specifically, the main control Unit 16 is an MCU (micro controller Unit, micro control Unit or single chip microcomputer). The MCU receives the charging voltage of the charging capacitor C1 detected by the voltage detection circuit, compares the charging voltage with a preset value, and sends a control signal to switch the state of the state switching unit 15 when it is determined that the charging of the capacitor is completed (i.e. the detected voltage value reaches 90% of the full charge capacity of the charging capacitor), so as to short-circuit the pre-charging switch unit and the current detection unit.
It should be noted that, the first resistor, the second resistor, the current detection resistor and other equivalent devices in the present invention may be single devices or equivalent forms of multiple devices connected in series and in parallel.
Please refer to fig. 4, which is a schematic circuit diagram of a frequency converter according to an embodiment of the present invention. As shown in fig. 4, the frequency conversion device of the present invention comprises: the constant current pre-charging circuit comprises a constant current pre-charging circuit 1, a rectifying circuit 2, an inverter circuit 3 and a charging capacitor 4.
The rectifying circuit 2 is respectively connected with a three-phase alternating current power supply and the constant current pre-charging circuit 1; the constant-current pre-charging circuit 1 is respectively connected with the charging capacitor 4 and the inverter circuit 3.
With reference to fig. 2, the rectifying circuit 2 includes a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5 and a sixth diode D6.
A cathode of the first diode D1, a cathode of the third diode D3, and a cathode of the fifth diode D5 are all connected to one end of the rectified output, an anode of the second diode D2, an anode of the fourth diode D4, and an anode of the sixth diode D6 are all connected to the other end of the rectified output, an anode of the first diode D1 is connected to a cathode of the second diode D2 and serves as a first input terminal L1 of the three-phase ac power supply, an anode of the third diode D3 is connected to a cathode of the fourth diode D4 and serves as a second input terminal L2 of the three-phase ac power supply, and an anode of the fifth diode D5 is connected to a cathode of the sixth diode D6 and serves as a third input terminal L3 of the three-phase ac power supply.
With continued reference to fig. 2, the inverter circuit 3 includes a first Transistor IGBT1(Insulated Gate Bipolar Transistor), a second Transistor IGBT2, a third Transistor IGBT3, a fourth Transistor IGBT4, a fifth Transistor IGBT5, and a sixth Transistor IGBT 6.
A drain of the first transistor IGBT1, a drain of the third transistor IGBT3, and a drain of the fifth transistor IGBT5 are all connected to one end of the rectified output, a source of the second transistor IGBT2, a source of the fourth transistor IGBT4, and a source of the sixth transistor IGBT6 are all connected to the other end of the rectified output, a source of the first transistor IGBT1 is connected to a drain of the second transistor IGBT2 and serves as a first inverting output terminal U, a source of the third transistor IGBT3 is connected to a drain of the fourth transistor IGBT4 and serves as a second inverting output terminal V, and a source of the fifth transistor IGBT5 is connected to a drain of the sixth transistor IGBT6 and serves as a third inverting output terminal W.
The working principle of the constant-current pre-charging circuit applied to the frequency conversion device is as follows: D1-D6 are three-phase rectifier diodes, C1 is a direct current filter capacitor, IGBTs 1-6 form a three-phase inverter, S1 is a relay contact, a first resistor R1 and a 15V voltage regulator tube Z1 provide power for a circuit, MOS1 is a pre-charging switch, R3 is a current detection resistor, and TL431 controls the driving voltage of MOS 1. When the frequency converter is powered on, 15V voltage is generated on a voltage regulator tube Z1 to enable an MOS1 to be switched on and charge a capacitor C1, a charging current flows through an R3, when the voltage drop of a current detection resistor R3 is larger than 2.5V (reference voltage inside a TL 431), the voltage between the cathode and the anode of the TL431 is rapidly reduced, the gate voltage of the MOS1 is reduced, the MOS1 works in a linear region, the voltage drop of the R3 is stabilized at 2.5V until the capacitor C1 is charged completely, and after the voltage of a capacitor C1 is detected by an MCU to reach a preset value, the relay S1 is controlled to be closed, and the charging is finished. Wherein, the charging current is equal to 2.5V/R3, and constant current pre-charging is realized.
To sum up, the utility model provides a constant current is charging circuit in advance can realize bus capacitor's constant current in advance through 1 MOS pipe, 1 accurate steady voltage source, current detection resistance, stabilivolt, and is small and with low costs. The MOS tube is switched on through the voltage stabilizing tube to charge the charging capacitor, and the working state of the MOS tube is controlled by the precise voltage stabilizing tube through the voltage converted by the current detection resistor, so that the constant-current pre-charging process is realized. Effectively overcomes various defects in the prior art and has high industrial utilization value.
The above embodiments are merely illustrative of the principles and effects of the present invention, and are not to be construed as limiting the invention. Modifications and variations can be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which may be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (9)
1. A constant current precharge circuit, comprising:
a precharge switch unit connected to the charging capacitor;
the voltage stabilizing unit is connected with the pre-charging switch unit;
a current detection unit connected to the precharge switching unit;
and the driving voltage control unit is respectively connected with the current detection unit and the pre-charging switch unit.
2. The constant-current precharge circuit according to claim 1,
the pre-charging switch unit comprises an MOS tube; and the drain electrode of the MOS tube is connected with one end of the charging capacitor, and the other end of the charging capacitor is connected with one end of the rectification output.
3. The constant-current pre-charging circuit according to claim 2, wherein the voltage stabilizing unit comprises a voltage regulator tube, a first resistor and a second resistor;
the cathode of the voltage-stabilizing tube is respectively connected with one end of the first resistor and one end of the second resistor;
the other end of the first resistor is connected with one end of the rectification output, and the other end of the second resistor is connected with the grid electrode of the MOS tube;
and the anode of the voltage stabilizing tube is connected with the other end of the rectification output.
4. The constant-current precharge circuit according to claim 2,
the current detection unit comprises a current detection resistor, one end of the current detection resistor is connected with the source electrode of the MOS tube, and the other end of the current detection resistor is connected with the other end of the rectification output.
5. The constant-current precharge circuit according to claim 2,
the driving voltage control unit comprises a three-terminal voltage stabilizing device; the cathode of the three-terminal voltage stabilizer is connected with the grid of the MOS tube, the anode of the three-terminal voltage stabilizer is connected with the other end of the rectification output, and the reference electrode of the three-terminal voltage stabilizer is connected with the source electrode of the MOS tube.
6. The constant-current precharge circuit according to claim 2, further comprising: a state switching unit;
and the first end of the state switching unit is connected with the drain electrode of the MOS tube, and the second end of the state switching unit is connected with the other end of the rectification output.
7. The constant-current precharge circuit according to claim 6, further comprising: a main control unit; and the main control unit is connected with the third end of the state switching unit.
8. A frequency conversion apparatus, characterized in that the frequency conversion apparatus comprises: the constant-current precharge circuit, the rectifier circuit, the inverter circuit, and the charging capacitor according to any one of claims 1 to 7;
the rectifying circuit is respectively connected with the three-phase alternating current power supply and the constant current pre-charging circuit; the constant-current pre-charging circuit is respectively connected with the charging capacitor and the inverter circuit.
9. Frequency conversion device according to claim 8,
the rectifying circuit comprises a first diode, a second diode, a third diode, a fourth diode, a fifth diode and a sixth diode;
the cathode of the first diode, the cathode of the third diode and the cathode of the fifth diode are all connected with one end of the rectification output, the anode of the second diode, the anode of the fourth diode and the anode of the sixth diode are all connected with the other end of the rectification output, the anode of the first diode is connected with the cathode of the second diode and serves as a first input end of the three-phase alternating current power supply, the anode of the third diode is connected with the cathode of the fourth diode and serves as a second input end of the three-phase alternating current power supply, and the anode of the fifth diode is connected with the cathode of the sixth diode and serves as a third input end of the three-phase alternating current power supply;
the inverter circuit comprises a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor and a sixth transistor;
the drain electrode of the first transistor, the drain electrode of the third transistor and the drain electrode of the fifth transistor are all connected with one end of the rectification output, the source electrode of the second transistor, the source electrode of the fourth transistor and the source electrode of the sixth transistor are all connected with the other end of the rectification output, the source electrode of the first transistor is connected with the drain electrode of the second transistor and serves as a first inversion output end, the source electrode of the third transistor is connected with the drain electrode of the fourth transistor and serves as a second inversion output end, and the source electrode of the fifth transistor is connected with the drain electrode of the sixth transistor and serves as a third inversion output end.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022256189.4U CN213213320U (en) | 2020-10-12 | 2020-10-12 | Constant-current pre-charging circuit and frequency conversion device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022256189.4U CN213213320U (en) | 2020-10-12 | 2020-10-12 | Constant-current pre-charging circuit and frequency conversion device |
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| Publication Number | Publication Date |
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| CN213213320U true CN213213320U (en) | 2021-05-14 |
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| CN202022256189.4U Active CN213213320U (en) | 2020-10-12 | 2020-10-12 | Constant-current pre-charging circuit and frequency conversion device |
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