CN212381111U - Three-level power conversion circuit capable of being precharged by flying capacitor - Google Patents
Three-level power conversion circuit capable of being precharged by flying capacitor Download PDFInfo
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- CN212381111U CN212381111U CN202020403549.6U CN202020403549U CN212381111U CN 212381111 U CN212381111 U CN 212381111U CN 202020403549 U CN202020403549 U CN 202020403549U CN 212381111 U CN212381111 U CN 212381111U
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Abstract
The utility model discloses a three level power conversion circuit that can supply flying electric capacity to precharge increases a voltage control circuit on basic circuit topology, and voltage control circuit contains an electric capacity C2, a switch S1, and flying electric capacity Cf and switch tube Q2 ' S common terminal is connected to this voltage control circuit ' S first end, and the input negative pole is connected to this voltage control circuit ' S second end. The voltage at one side of the capacitor C1 is the input voltage Vin; the voltage on the resistor RL side is the output voltage Vout. The utility model discloses utilize electric capacity voltage can not break the principle and electric capacity series connection partial pressure principle suddenly, increase an electric capacity C2 and connect in parallel at a switch tube both ends, solved the switch tube and born input voltage's problem alone when going up electricity. In order not to affect normal operation, a switch S1 is connected in series in the added capacitor C2 loop, and the capacitor loop is disconnected when the main circuit works normally.
Description
Technical Field
The utility model relates to a can supply three level power conversion circuit of flying capacitor precharge belongs to power electronic technology field.
Background
A DC/DC circuit is a circuit that steps up or down a direct current, and its input and output are both direct currents. The DC/DC circuit has wide application in the fields of energy storage, electric automobiles, new energy, electric power systems and the like. The topology form of the DC/DC circuit can be divided into two-level topology and multi-level topology according to the state of the output level. With the rise of system voltage, the requirement for withstand voltage of related devices is also gradually raised, and in view of the influence of semiconductor device process performance and other aspects, the multilevel technology becomes a research hotspot for realizing high-voltage power change at a lower cost due to the fact that devices with lower voltage grades can be utilized.
The flying capacitor three-level power conversion circuit is a common basic circuit topology, the input and the output of the flying capacitor three-level power conversion circuit are common negative or positive, and the flying capacitor three-level power conversion circuit is also beneficial to the optimization design of other auxiliary devices in a system, such as a lightning protection device, an inductor and the like, so that the topology is more and more applied to actual products.
However, in practical use, as shown in fig. 1, in an exemplary flying capacitor three-level boost circuit, during normal operation, the voltage of the flying capacitor Cf is about half of the output voltage Vout, so that the voltages of the switching tubes Q1 and Q2, the diodes D1, D2, D3, and D4 are clamped to about half of the output voltage Vout, but at the time of powering on the circuit, the voltage of the flying capacitor is substantially 0, and the switching tube Q2 alone will bear the entire input voltage, so that there is a risk of breakdown and damage, and therefore, the flying capacitor is in the non-power state at the time of powering on is a problem that needs to be solved for the flying capacitor three-level boost circuit.
In order to solve the problem that the flying capacitor is in a non-electric state at the power-on moment, so that the switching tube Q2 bears the whole input voltage, the prior art generally adopts three solutions:
firstly, a power switch is added in a current loop of an input main circuit, the switch is in a disconnected state before power-on, a buffer resistor or an additional auxiliary power supply is used for charging a flying capacitor, the flying capacitor is charged to a design voltage, and then the power switch is closed, although the problem can be solved, when the circuit works normally, the power switch also flows large current, so that the loss is increased, the cost is increased, and the system conversion efficiency is also reduced;
secondly, a power switch is added in the flying capacitor loop, the switch is in an off state before power-on, an auxiliary power supply is additionally added to charge the flying capacitor, the flying capacitor is charged to a design voltage, and then the power switch is closed, although the problem can be solved, when the circuit works normally, the power switch can also flow large current, so that the loss is increased, the cost is increased, and the system conversion efficiency is also reduced;
before power-on, an additional auxiliary power supply is provided, the input voltage and the flying capacitor voltage are monitored in real time, the switching tube Q2 is controlled to be switched on and off according to the change of the input voltage and the flying capacitor voltage, the flying capacitor is directly charged by the input voltage, although the problem can be solved, the additional auxiliary power supply is required before power-on, the standby power consumption is increased, the control logic is complex, and the flying capacitor is not beneficial to popularization and use.
Disclosure of Invention
The to-be-solved technical problem of the utility model is: how to avoid the flying capacitor to be in the non-electric state at the moment of electrifying, and the problem that the switching tube bears the whole input voltage alone is prevented.
In order to solve the technical problem, the technical solution of the present invention is to provide a three-level power conversion circuit for precharging flying capacitor, including a capacitor C1, one end of the capacitor C1 is connected with one end of an inductor L1, the other end of the inductor L1 is connected with one end of a diode D3, the other end of the diode D3 is connected with one end of a diode D4, the other end of a diode D4 is connected with one end of a capacitor C3, the other end of the capacitor C3 is connected with the other end of a capacitor C1, the other end of the inductor L1 and the other end of a capacitor C1 are respectively connected with two ends of a switch tube Q1 and a switch tube Q2 which are connected in series, the common end between the switch tube Q1 and the switch tube Q2 is connected with one end of a flying capacitor Cf, the other end of the flying capacitor Cf is connected with the common end between the diode D3 and the diode D4, two ends of the capacitor C3 are connected in parallel with a resistor RL, and the two ends of the switch tube Q2 or two ends of the switch tube Q599 are connected with a capacitor C And a switch S1.
Preferably, the switch S1 is a relay and/or a semiconductor switch tube based on electromagnetic principle.
Preferably, the semiconductor switch tube is one or a combination of a triode, an insulated gate bipolar transistor IGBT and a field effect switch MOSFET.
Preferably, the voltage at one side of the capacitor C1 is the input voltage Vin; the voltage on the resistor RL side is the output voltage Vout.
Preferably, a current limiting resistor R is connected in series in a branch where the switch S1 and the capacitor C2 are connected together in series.
The utility model discloses utilize electric capacity voltage can not break the principle and electric capacity series connection partial pressure principle suddenly, increase an electric capacity C2 and connect in parallel at a switch tube both ends, simultaneously again for flying electric capacity Cf charges and provide the current path, the series circuit has been constituteed with it, charge together, two electric capacities bear whole input voltage jointly, the voltage at the parallelly connected switch tube both ends of voltage control circuit also can follow 0 and begin to climb, it is unanimous with electric capacity C2 both ends voltage holding that increases, consequently, go up electric in-process switch tube Q1 and switch tube Q2 and also bear input voltage jointly, the problem of bearing input voltage alone when having solved the switch tube and going up the electricity. In order not to affect normal operation, a switch S1 is connected in series in the added capacitor C2 loop, and the capacitor loop is disconnected when the main circuit works normally.
Drawings
FIG. 1 is a schematic diagram of a conventional flying capacitor three-level boost circuit;
FIG. 2a is a schematic diagram of a three-level power conversion circuit for pre-charging flying capacitor (the second terminal of the voltage control circuit is connected to the negative input terminal);
FIG. 2b is a schematic diagram of a three-level power conversion circuit for pre-charging flying capacitor (the second terminal of the voltage control circuit is connected to the input anode, and the switch loop is connected in series to the current limiting resistor R1);
FIG. 3a is a schematic diagram of a three-level power conversion circuit for pre-charging flying capacitor (the second terminal of the voltage control circuit is connected to the input anode);
FIG. 3b is a schematic diagram of a three-level power conversion circuit for pre-charging flying capacitor (the second terminal of the voltage control circuit is connected to the input anode, and the switch loop is connected in series to the current limiting resistor R1);
FIG. 4 is a schematic diagram of a default closed state of switch S1 in a three-level power conversion circuit for pre-charging flying capacitors;
FIG. 5 is a schematic current flow diagram of a three-level power conversion circuit for precharging flying capacitors during normal operation of the circuit (switch S1 is turned off);
fig. 6 is a schematic diagram of an equivalent circuit of a three-level power conversion circuit for precharging a flying capacitor after the capacitor is charged.
Detailed Description
In order to make the present invention more comprehensible, preferred embodiments are described in detail below with reference to the accompanying drawings.
Example 1
The utility model relates to a can supply three level power conversion circuit of flying electric capacity precharge for flying electric capacity is in the electroless state constantly on solving, leads to switch tube Q2 to bear whole input voltage problem alone. The utility model discloses increase a voltage control circuit on basic circuit topology, as shown in fig. 2a, flying capacitor three-level power conversion circuit includes electric capacity C1, electric capacity C1's one end is connected with inductance L1's one end, inductance L1's the other end is connected with diode D3's one end, diode D3's the other end is connected with diode D4's one end, diode D4's the other end is connected with electric capacity C3's one end, electric capacity C3's the other end is connected with electric capacity C1's the other end, inductance L1's the other end and electric capacity C1 are connected the both ends of switch tube Q1 and switch tube Q2 that series connection is in the same place respectively, the one end of flying capacitor Cf is connected to the common terminal between switch tube Q1 and the switch tube Q2, the common terminal between diode D3 and the diode D4 is connected to the other end of flying capacitor C3's both ends in parallel connection have resistance RL; the voltage control circuit comprises a capacitor C2 and a switch S1, wherein a first end of the voltage control circuit is connected with the common end of the flying capacitor Cf and the switching tube Q2, and a second end of the voltage control circuit is connected with the negative pole of the input. The voltage at one side of the capacitor C1 is the input voltage Vin; the voltage on the resistor RL side is the output voltage Vout. The collector and the emitter of the switching tube Q1 are respectively connected with the cathode and the anode of the diode D1, and the collector and the emitter of the switching tube Q2 are respectively connected with the cathode and the anode of the diode D2.
In this embodiment, the anode of the capacitor C1 is connected in series with the capacitor C3 through the inductor L1, the diode D3, and the diode D4 in sequence.
The switch S1 is closed before the main circuit operates, and automatically switched to an open state after the main circuit operates, and both the forward current and the reverse current are blocked.
The switch S1 may be a relay based on electromagnetic principle, or a semiconductor switch tube, such as a triode, an insulated gate bipolar transistor IGBT, a field effect switch MOSFET, or the like, or a combination of multiple switches.
The utility model discloses utilize electric capacity voltage can not sudden change principle and electric capacity series connection partial pressure principle, electric capacity C2 that increases connects in parallel at switch tube Q2 both ends through switch S1, simultaneously again for flying electric capacity Cf charges and provides the current path, the series circuit has been constituteed with it, charge together, two electric capacities (flying electric capacity Cf and electric capacity C2 promptly) bear whole input voltage jointly, the voltage at corresponding switch tube Q2 both ends also can be from 0 beginning to climb, it is unanimous with electric capacity C2 both ends voltage holding that increases, consequently, it also bears input voltage jointly to go up electric in-process switch tube Q1 and switch tube Q2, the problem of bearing input voltage alone when having solved switch tube Q2 and going up electricity, in order not to influence normal operating, switch S1 establishes ties in the electric capacity C2 return circuit that increases, when the main circuit normally works, break off this electric capacity return circuit.
As shown in fig. 4, the switch S1 is in a closed state by default, before the circuit is powered on, the voltages of the capacitor C1, the capacitor C2 and the flying capacitor Cf are substantially 0v, during the power on process, the input voltage forms one of current loops through the inductor L1, the diode D3, the flying capacitor Cf, the added capacitor C2 and the switch S1, the current loop is as shown by a dotted line in fig. 2a, the capacitor voltage rises from zero, and finally the sum of the voltage of the capacitor C2 and the voltage of the flying capacitor Cf is equal to the whole input voltage Vin.
As shown in fig. 5, when the circuit normally operates, the switch S1 is turned off, and the current loop flows through the flying capacitor Cf without flowing through the capacitor C2 and the switch S1, which does not affect the normal operation of the circuit and does not reduce the system conversion efficiency.
According to the capacitance value calculation method of the capacitor C2, from power-on to power-on, the voltages of the switching tube Q1 and the switching tube Q2 are related to the flying capacitor Cf and the capacitor C2 which are connected in parallel, the inductor L1 and the diode can be equivalently short-circuited, and after the capacitor is charged, the equivalent circuit schematic diagram can be simplified as shown in FIG. 6. According to the capacitor series connection, the charge quantity is equal, and then:
Vin*C＝VQ2*C2……………………(1)
wherein C is the total capacitance value of the capacitor series connection (C2, Cf series connection);
according to the condition that the reciprocal of the total capacitance value of the series circuit is equal to the sum of the reciprocals of the capacitance values of all capacitors in the series circuit, the following steps are provided:
from the formulas (1) and (2), it can be obtained
For example, the voltage resistance of the switching tube Q2 is 1000V, the voltage resistance Vq2 is 900V, the input voltage Vin is 1500V, the capacitance of the flying capacitor Cf is 20uF, and the known data is substituted into (3) to calculate, so that the capacitance of C2 is about 13.3 uF.
In practice, capacitance values with similar values are obtained, and a capacitor with the withstand voltage of about 1000V is selected.
Example 2
In this embodiment, as shown in fig. 3a, the capacitor C2 and the switch S1 connected in series are connected in parallel to two ends of the switching tube Q1. The negative electrode of the capacitor C1 is connected in series with the capacitor C3 through the inductor L1, the diode D3, and the diode D4 in this order.
The rest is the same as in example 1.
Example 3
In this embodiment, as shown in fig. 2b, the branch where the switch S1 is located is serially connected to the current limiting resistor R, that is, the capacitor C2, the switch S1 and the current limiting resistor R are serially connected to two ends of the switch Q2 in parallel.
The rest is the same as in example 1.
Example 4
In this embodiment, as shown in fig. 3b, the branch where the switch S1 is located is serially connected to the current limiting resistor R, that is, the capacitor C2, the switch S1 and the current limiting resistor R are serially connected to two ends of the switch Q1 in parallel.
The rest is the same as in example 2.
Claims (5)
1. A three-level power conversion circuit capable of being precharged by a flying capacitor comprises a capacitor C1, one end of a capacitor C1 is connected with one end of an inductor L1, the other end of the inductor L1 is connected with one end of a diode D3, the other end of a diode D3 is connected with one end of a diode D4, the other end of a diode D4 is connected with one end of a capacitor C3, the other end of a capacitor C3 is connected with the other end of the capacitor C1, the other end of the inductor L1 and the other end of the capacitor C1 are respectively connected with two ends of a switching tube Q1 and a switching tube Q2 which are connected together in series, a common end between the switching tube Q1 and the switching tube Q2 is connected with one end of a flying capacitor Cf, the other end of the flying capacitor Cf is connected with a common end between the diode D3 and a diode D4, two ends of a capacitor C3, the switch is characterized in that two ends of the switch tube Q2 or two ends of the switch tube Q1 are connected in parallel with a capacitor C2 and a switch S1 which are connected together in series.
2. The flying capacitor pre-charging three-level power conversion circuit as claimed in claim 1, wherein said switch S1 is an electromagnetic principle based relay and/or a semiconductor switch tube.
3. The flying capacitor pre-charging three-level power conversion circuit as claimed in claim 2, wherein said semiconductor switch is one or more of a combination of a triode, an Insulated Gate Bipolar Transistor (IGBT), and a field effect switch (MOSFET).
4. The flying capacitor pre-charge three-level power conversion circuit as claimed in claim 1, wherein the voltage on one side of said capacitor C1 is the input voltage Vin; the voltage on the resistor RL side is the output voltage Vout.
5. The flying capacitor pre-charge three-level power conversion circuit as claimed in claim 1, wherein said switch S1 and capacitor C2 are connected in series in a branch with a current limiting resistor R.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202020403549.6U CN212381111U (en) | 2020-03-25 | 2020-03-25 | Three-level power conversion circuit capable of being precharged by flying capacitor |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202020403549.6U CN212381111U (en) | 2020-03-25 | 2020-03-25 | Three-level power conversion circuit capable of being precharged by flying capacitor |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112865577A (en) * | 2021-01-29 | 2021-05-28 | 重庆大学 | Pre-charging circuit of hybrid multi-level converter (HCC) and control method thereof |
| CN113794373A (en) * | 2021-08-26 | 2021-12-14 | 华为技术有限公司 | Multi-level DC converter and power supply system |
| CN113992012A (en) * | 2021-11-30 | 2022-01-28 | 阳光电源股份有限公司 | Suspension capacitive Boost circuit, inverter and grid-connected power generation system |
| WO2023024848A1 (en) * | 2021-08-24 | 2023-03-02 | 中兴通讯股份有限公司 | Multi-level capacitive pre-charging circuit and power supply device |
| CN116345888A (en) * | 2023-05-30 | 2023-06-27 | 深圳市首航新能源股份有限公司 | Three-level converter, starting method thereof and electronic equipment |
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2020
- 2020-03-25 CN CN202020403549.6U patent/CN212381111U/en active Active
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112865577A (en) * | 2021-01-29 | 2021-05-28 | 重庆大学 | Pre-charging circuit of hybrid multi-level converter (HCC) and control method thereof |
| CN112865577B (en) * | 2021-01-29 | 2023-04-18 | 重庆大学 | Pre-charging circuit of hybrid multi-level converter (HCC) and control method thereof |
| WO2023024848A1 (en) * | 2021-08-24 | 2023-03-02 | 中兴通讯股份有限公司 | Multi-level capacitive pre-charging circuit and power supply device |
| CN113794373A (en) * | 2021-08-26 | 2021-12-14 | 华为技术有限公司 | Multi-level DC converter and power supply system |
| CN113794373B (en) * | 2021-08-26 | 2024-03-01 | 华为技术有限公司 | Multi-level direct current converter and power supply system |
| CN113992012A (en) * | 2021-11-30 | 2022-01-28 | 阳光电源股份有限公司 | Suspension capacitive Boost circuit, inverter and grid-connected power generation system |
| CN113992012B (en) * | 2021-11-30 | 2023-08-15 | 阳光电源股份有限公司 | Suspension capacitance type Boost circuit, inverter and grid-connected power generation system |
| CN116345888A (en) * | 2023-05-30 | 2023-06-27 | 深圳市首航新能源股份有限公司 | Three-level converter, starting method thereof and electronic equipment |
| CN116345888B (en) * | 2023-05-30 | 2023-08-29 | 深圳市首航新能源股份有限公司 | Three-level converter, starting method thereof and electronic equipment |
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