WO2022198456A1 - 一种软启动电路及变换器 - Google Patents

一种软启动电路及变换器 Download PDF

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Publication number
WO2022198456A1
WO2022198456A1 PCT/CN2021/082456 CN2021082456W WO2022198456A1 WO 2022198456 A1 WO2022198456 A1 WO 2022198456A1 CN 2021082456 W CN2021082456 W CN 2021082456W WO 2022198456 A1 WO2022198456 A1 WO 2022198456A1
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WO
WIPO (PCT)
Prior art keywords
circuit
soft
relay
switch tube
rectifier circuit
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Application number
PCT/CN2021/082456
Other languages
English (en)
French (fr)
Inventor
庞晋永
刘洋
姜振廷
胡彪
Original Assignee
华为数字能源技术有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 华为数字能源技术有限公司 filed Critical 华为数字能源技术有限公司
Priority to PCT/CN2021/082456 priority Critical patent/WO2022198456A1/zh
Priority to EP21932087.6A priority patent/EP4318906A4/en
Priority to CN202180004091.4A priority patent/CN114051689A/zh
Publication of WO2022198456A1 publication Critical patent/WO2022198456A1/zh

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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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/36—Means for starting or stopping converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/001—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection limiting speed of change of electric quantities, e.g. soft switching on or off
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208—Arrangements for improving power factor of AC input
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208—Arrangements for improving power factor of AC input
    • H02M1/4216—Arrangements for improving power factor of AC input operating from a three-phase input voltage
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208—Arrangements for improving power factor of AC input
    • H02M1/4233—Arrangements for improving power factor of AC input using a bridge converter comprising active switches
    • 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
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • 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
    • 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
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02T90/10—Technologies relating to charging of electric vehicles
    • Y02T90/16—Information or communication technologies improving the operation of electric vehicles

Definitions

  • the present application relates to the technical field of power supplies, and in particular, to a soft-start circuit and a converter.
  • a rectifier circuit As an alternating current (AC)/direct current (DC) converter, a rectifier circuit is widely used in many scenarios.
  • a rectifier circuit may be included in the DC charging pile, which is used to rectify the AC power output by the power grid to obtain DC power, so as to charge the power battery.
  • an on-board charger OBC
  • AC/DC converters are also included in data centers and communication power supplies.
  • the input side of the PFC circuit is connected to the power grid, for example, it can be connected to the 380V AC power grid.
  • the voltage of the bus capacitor is zero; after the PFC circuit is powered on, the bus capacitor will be impacted by the power grid, which is likely to cause device damage. Therefore, in practical applications, a soft-start circuit is usually configured for the PFC circuit to prevent a large inrush current during power-on.
  • a soft-start circuit provided in the prior art may be shown in FIG. 1 .
  • the soft-start circuit includes a parallel resistor R1 and a relay K1, as well as a parallel resistor R2 and a relay K2; R1 and K1 are connected in series on phase A, R2 and K2 are connected in series on phase B, and C1 and C2 is the bus capacitor.
  • the AC output from the power grid charges C1 and C2 through R1 and R2; when the bus capacitor voltage reaches a certain value, the auxiliary power supply works (the auxiliary power supply can be operated at C2 Power is taken at the connection point P with the positive bus, when C2 is charged to a certain voltage value, the auxiliary power supply starts); after the auxiliary power supply works, it can supply power to the control circuit, so that the control circuit can control the state of K1 and K2; when the control circuit detects When the bus capacitor voltage reaches the preset rectified voltage value, the control circuit controls K1 and K2 to turn on, and the PFC circuit works normally. Soft start can be achieved in the above manner.
  • the soft-start circuit includes two relays and two resistors, which requires a large number of components, which affects the cost and volume of the soft-start circuit.
  • Embodiments of the present application provide a soft-start circuit and a converter, which are used to reduce the number of components in the soft-start circuit, and reduce cost and volume.
  • an embodiment of the present application provides a soft-start circuit.
  • the soft start circuit is located between the rectifier circuit and the bus capacitor, and is used to realize the soft start of the rectifier circuit.
  • the soft start circuit includes a switch tube and a relay. The relay is connected in parallel with the switch tube, the relay is in an open state before the rectifier circuit is powered on, and the relay is closed after the rectifier circuit is powered on and the voltage value of the bus capacitor reaches a preset voltage value.
  • the switch tube can be a metal-oxide semiconductor field effect transistor MOSFET, an insulated gate bipolar transistor IGBT or a triode.
  • the relays can be AC relays, DC relays or contactors.
  • the switch tube and the relay are in a disconnected state by default, and the voltage on the bus capacitor is zero.
  • the input current of the rectifier circuit charges the bus capacitor through the switch tube.
  • the switch tube can be in a high-resistance state through the control signal of the switch tube, so when the bus capacitor is charged, the current flowing through the bus capacitor will not be too large, which can prevent the bus capacitor from being damaged by the impact of the power grid.
  • the relay is closed, the switch tube is bypassed, and the soft start of the rectifier circuit is realized.
  • the preset voltage value of the bus capacitor may be the rated output voltage value of the rectifier circuit, that is, the rectifier value of the rectifier circuit.
  • the soft-start circuit is located between the rectifier circuit and the bus capacitor.
  • the specific implementation methods may be: 1.
  • the soft-start circuit is located on the positive bus; 2.
  • the soft-start circuit is located on the negative bus; 3.
  • the soft-start The circuit is in series with the bus capacitor.
  • the rectifier circuit can be any of the following: a three-phase three-level power factor correction PFC circuit; a three-phase two-level PFC circuit; a single-phase PFC circuit.
  • the soft-start circuit provided by the first aspect may further include a resistor, and the resistor is connected in series with the switch tube to limit the current of the switch tube.
  • control signal of the switch tube is a pulse width modulated PWM wave.
  • the switch tube can be in a high resistance state by configuring the control signal of the switch tube, and the switch tube can be controlled by PWM wave, so that the switch tube can be turned on and off alternately, showing a high resistance state, which plays a current limiting role.
  • the closing of the relay is controlled by a control circuit.
  • the relay can be closed by the control circuit after the rectification circuit is started up.
  • control circuit can be powered by an auxiliary power supply, and the auxiliary power supply takes power at the input end of the rectifier circuit.
  • the rectifier circuit when the rectifier circuit is powered on, the voltage of the auxiliary power supply point rises rapidly to reach the starting voltage of the auxiliary power supply, and the auxiliary power supply starts.
  • the input voltage can be converted into the working voltage of the control circuit, thereby supplying power to the control circuit.
  • the control signal of the switch tube can be controlled, so as to limit the current of the branch of the switch tube.
  • an embodiment of the present application provides a converter, which includes a rectifier circuit and the soft-start circuit provided in the first aspect and any possible designs thereof.
  • the soft start circuit is used to realize the soft start of the rectifier circuit;
  • the rectifier circuit is used to rectify the input alternating current to obtain the direct current.
  • FIG. 1 is a schematic structural diagram of a soft-start circuit provided by the prior art
  • FIG. 2 is a schematic structural diagram of a first soft-start circuit provided by an embodiment of the present application
  • FIG. 3 is a schematic structural diagram of a second soft-start circuit according to an embodiment of the present application.
  • FIG. 4 is a schematic structural diagram of a third soft-start circuit provided by an embodiment of the present application.
  • FIG. 5 is a schematic structural diagram of a fourth soft-start circuit provided by an embodiment of the present application.
  • FIG. 6 is a schematic structural diagram of a fifth soft-start circuit provided by an embodiment of the present application.
  • FIG. 7 is a schematic structural diagram of a sixth soft-start circuit provided by an embodiment of the present application.
  • FIG. 8 is a schematic structural diagram of a seventh soft-start circuit according to an embodiment of the present application.
  • FIG. 9 is a schematic structural diagram of an eighth soft-start circuit provided by an embodiment of the present application.
  • FIG. 10 is a schematic structural diagram of a converter according to an embodiment of the present application.
  • An embodiment of the present application provides a soft-start circuit.
  • the soft-start circuit is located between the rectifier circuit and the bus capacitor, and is used to realize the soft-start of the rectifier circuit.
  • the soft start circuit 200 includes a switch tube 201 and a relay 202 .
  • the relay 202 is connected in parallel with the switch tube 201 , the relay 202 is in an open state before the rectifier circuit is powered on, and the relay 202 is closed after the rectifier circuit is powered on and the voltage value of the bus capacitor reaches a preset voltage value.
  • the switch tube 201 can be, for example, a metal-oxide-semiconductor field-effect transistor (MOSFET), a gallium nitride (gallium nitride, GaN) transistor, an insulated gate bipolar transistor ( Insulated gate bipolar transist, IGBT), bipolar junction transistor (bipolar junction transistor, BJT), triode, etc.
  • the relay 202 may be, for example, an AC relay, a DC relay, a contactor, or the like.
  • the specific structure of the rectifier circuit is not limited in the embodiments of the present application, and the rectifier circuit may be a three-phase three-level PFC circuit, a three-phase two-level PFC circuit, or a single-phase PFC circuit.
  • the specific structure of the above-mentioned rectifier circuit belongs to the prior art, and is not repeated in the embodiments of the present application.
  • the soft-start circuit 200 is located between the rectifier circuit and the bus capacitor. Specifically, the soft-start circuit 200 may be located on the positive bus, may be located on the negative bus, or may be connected in series with the bus capacitor.
  • the soft-start circuit 200 is located on the positive bus; in the example of FIG. 4 , the soft-start circuit 200 is located on the negative bus ; In the example of FIG. 5, the soft-start circuit 200 is connected in series with the bus capacitor. In addition, in the example of FIG. 5, the soft-start circuit 200 is connected in series with the bus capacitor C2. In another possible design, the soft-start circuit 200 may also be connected in series with the bus capacitor C1.
  • the soft-start circuit 200 is connected in series with the bus capacitor, the current flowing through the relay 202 is only the ripple current on the bus capacitor, and the relay 202 can select a relay with a smaller current specification.
  • the working principle of the soft-start circuit 200 is described below by taking FIG. 3 as an example: before the rectifier circuit (ie, the three-phase PFC circuit in FIG. 3 ) is powered on, the switch tube 201 and the relay 202 are in a disconnected state by default, and the bus capacitors C1 and The voltage on C2 is all zero. After the rectifier circuit is powered on, the input current of the rectifier circuit charges the bus capacitors C1 and C2 through the switch tube 201 . In practical applications, the switch tube 201 can be in a high-impedance state through the control signal of the switch tube 201. Therefore, when charging C1 and C2, the current flowing through C1 and C2 will not be too large, which can avoid the occurrence of bus capacitance due to damage.
  • the preset voltage value of the bus capacitor may be the rated output voltage value of the rectifier circuit, that is, the rectifier value of the rectifier circuit.
  • the soft-start of the rectifier circuit can be realized only by the switch tube 201 and the relay 202.
  • the components required by the soft-start circuit 200 The number of components is small, which reduces the cost and volume of the soft-start circuit 200 .
  • a resistor needs to be configured in the soft-start circuit.
  • the resistor is connected in series with the phase line, and needs to withstand a large current impact when the rectifier circuit is powered on, so the resistor adopts a cement resistor.
  • the volume of the cement resistor is large, which also increases the volume of the soft-start circuit to a certain extent.
  • the switch tube 201 is controlled by the control signal of the switch tube 201, so that the switch tube is in a high resistance state, which plays a current limiting role.
  • the volume of the switch tube 201 is much smaller than that of the cement resistor, so the volume of the soft-start circuit 200 can be further reduced.
  • the control signal of the switch tube 201 can be configured so that the switch tube 201 is in a high resistance state.
  • the control signal of the switch tube 201 is input from the control terminal of the switch tube 201.
  • the control terminal of the switch tube 201 is the gate of the MOSFET.
  • the control signal of the switch tube 201 may be a pulse width modulation (pulse width modulation, PWM) wave.
  • PWM pulse width modulation
  • the PWM wave can be regarded as a square wave with an adjustable duty cycle.
  • a resistor may also be connected in parallel with the branch of the switch tube 201, and the switch tube 201 is current-limited through the resistor.
  • the structure of the soft-start circuit 200 may be as shown in FIG. 6 .
  • Q1 represents a switch tube
  • K1 represents a relay
  • R1 represents a resistor.
  • Using a parallel resistor to achieve current limiting can further reduce the current flowing through the switch tube 201 .
  • the switch tube 201 can still use the PWM wave as the control signal.
  • the switch tube may not use the PWM wave as the control signal: the switch tube 201 is in a closed state before the rectifier circuit is powered on; after the rectifier circuit is powered on, the input circuit charges the bus capacitor through the resistor R1 ; After the voltage on the bus capacitor reaches the preset voltage value, the switch tube 201 is disconnected, K1 is closed, and the rectifier circuit works normally. Adopting this control method can reduce the control difficulty of the switch tube 201 .
  • the opening and closing of the relay 202 needs to be controlled, and the input signal (control signal) of the switch tube 201 also needs to be controlled.
  • the opening and closing of the relay 202 and the control signal of the switch tube 201 can be controlled by the control circuit.
  • the control circuit can be powered by an auxiliary power supply, and the auxiliary power supply can be powered from the input end of the rectifier circuit.
  • the auxiliary power supply can be powered at point P in FIG. 3 . Then, when the rectifier circuit is powered on, the voltage of the auxiliary power supply point rises rapidly to reach the starting voltage of the auxiliary power supply, and the auxiliary power supply starts. After the auxiliary power supply is started, the input voltage can be converted into the working voltage of the control circuit, thereby supplying power to the control circuit. After the control circuit is started, the input signal (control signal) of the switch tube 201 can be controlled, so as to limit the current of the branch of the switch tube 201 . After the voltage of the bus capacitor reaches the preset voltage value, the control circuit controls the relay 202 to close.
  • the control circuit since the control circuit can control the relay to close after the bus capacitor is charged to the rectified voltage value, the soft-start process of the rectifier circuit does not actually require the participation of the control circuit before closing the relay. .
  • the control circuit needs to control the control signal of the switch tube 201 . Therefore, compared with the prior art shown in FIG. 1 , in the embodiment of the present application, the power taking point of the auxiliary power supply is in front, so that the auxiliary power supply can be started after the rectifier circuit is powered on, thereby triggering the control circuit to work normally, and the switching tube 201 The control signal is controlled to realize soft start.
  • the rectifier circuit may be a three-phase three-level PFC circuit, a three-phase two-level PFC circuit, or a single-phase PFC circuit.
  • the rectifier circuit adopts the three-phase three-level PFC circuit topology as an example for introduction. The following is an example of the rectifier circuit using the three-phase two-level PFC circuit topology and the single-phase PFC circuit topology.
  • the soft-start circuit 200 provided by the embodiment of the present application may be as shown in FIG. 7 .
  • Q1 represents the switch tube 201
  • K1 represents the relay 202 .
  • the soft-start circuit 200 provided by the embodiment of the present application may be as shown in FIG. 8 .
  • Q1 represents the switch tube 201
  • K1 represents the relay 202 .
  • the soft-start of the rectifier circuit can be realized only by the switch tube 201 and the relay 202.
  • the soft-start circuit 200 has The number of components required is less, and the cost and volume of the soft-start circuit 200 are reduced.
  • the switch tube 201 is controlled by the control signal of the switch tube 201, so that the switch tube 201 is in a high resistance state, which plays a current limiting role.
  • the volume of the switch tube 201 is much smaller than that of the cement resistors, so the volume of the soft-start circuit 200 can be further reduced.
  • the soft-start circuit 200 provided in this embodiment of the present application can be applied to various scenarios in which a rectifier circuit is configured, so as to realize the soft-start of the rectifier circuit.
  • the embodiments of the present application do not specifically limit the application scenarios of the soft-start circuit 200, for example, it can be applied to entities such as a DC charging pile, an OBC, a data center, or a communication power supply.
  • the DC charging pile may include multiple conversion modules, each conversion module includes a rectification circuit and a conversion circuit, and the rectification circuit is used to rectify the input AC power (mains power). , to obtain the first direct current; the conversion circuit is used to perform DC/DC conversion on the first direct current to obtain the second direct current, and the second direct current is used to charge the power battery.
  • each conversion module further includes a soft-start circuit 200, the soft-start circuit 200 is located between the DC bus and the bus capacitor, and is used to realize the soft-start of the rectifier circuit.
  • the OBC may include a plurality of conversion modules, each conversion module includes a rectifier circuit and a conversion circuit, and the rectifier circuit is used to rectify the AC power output by the AC charging pile to obtain the first Direct current; the conversion circuit is used to perform DC/DC conversion on the first direct current to obtain the second direct current, and the second direct current is used to charge the power battery.
  • each conversion module further includes a soft-start circuit 200, the soft-start circuit 200 is located between the DC bus and the bus capacitor, and is used to realize the soft-start of the rectifier circuit.
  • the soft start circuit As shown in FIG. 9 , taking the Vienna circuit topology as an example for the rectifier circuit, the soft start circuit provided by the embodiment of the present application can be set on the positive bus, and the soft start circuit includes a parallel switch tube Q1 and a relay K1 .
  • K1 and Q1 are both disconnected, and the voltages on the bus capacitors C1 and C2 are both zero; after the three-phase voltage is connected, the auxiliary power supply works to supply power to the control circuit; the control circuit outputs PWM to Q1 wave to limit the current of Q1; the AC rectified voltage charges the bus capacitors C1 and C2 through Q1; when the voltage value of the bus capacitor reaches the rectified value of the input voltage, K1 is turned on, Q1 is bypassed, and Q1 is turned off, thereby achieve the effect of soft start.
  • the embodiments of the present application also provide a converter.
  • the converter 1000 includes a rectifier circuit 1001 and the aforementioned soft-start circuit 200 .
  • the soft-start circuit 200 is used to implement the soft-start of the rectifier circuit 1001; the rectifier circuit 1001 is used to rectify the input alternating current to obtain direct current.

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  • Power Engineering (AREA)
  • Rectifiers (AREA)

Abstract

一种软启动电路及变换器，用以减少软启动电路中元器件的数量，降低成本和体积。该软启动电路位于整流电路与母线电容之间，用于实现整流电路的软启动。该软启动电路包括开关管和继电器。继电器与开关管并联，继电器在整流电路上电之前处于断开状态，继电器在整流电路上电之后、且母线电容的电压值达到预设电压值时闭合。

Description

一种软启动电路及变换器 技术领域
本申请涉及电源技术领域，尤其涉及一种软启动电路及变换器。
背景技术
整流电路作为一种交流(alternating current，AC)/直流(direct current，DC)变换器，在很多场景中得到广泛应用。比如，直流充电桩中可以包括整流电路，用于对电网输出的交流电进行整流，得到直流电，从而为动力电池充电。再比如，车载充电器(on board charger，OBC)中也可以包括整流电路，用于将输入的交流电转换成直流电，从而为动力电池充电。此外，数据中心、通信电源中也包含AC/DC变换器。
以直流充电桩中的功率因数校正(power factor correction，PFC)电路这一整流电路为例，PFC电路的输入侧接电网，例如可以接380V交流电网。在PFC电路上电前，母线电容的电压为零；PFC电路上电后，母线电容会受到电网冲击，易造成器件损坏。因此，实际应用中通常会为PFC电路配置软启动电路，以防止上电时出现较大的冲击电流。
现有技术中提供的一种软启动电路可以如图1所示。以应用于三相PFC电路为例，软启动电路包括并联的电阻R1和继电器K1，以及并联的电阻R2和继电器K2；R1和K1串接在A相，R2和K2串接在B相，C1和C2为母线电容。在初始状态，即PFC电路上电前，K1和K2处于断开状态，母线电容C1、C2上的电压均为0；PFC电路上电后，输入回路中的电阻R1、R2可以起到限制输入电流的作用，防止电网中的大电流对C1和C2产生冲击，电网输出的交流电通过R1、R2给C1、C2充电；当母线电容电压达到一定值的时候，辅助电源工作(辅助电源可以在C2与正母线的连接点P处取电，当C2充电至一定电压值时，辅助电源启动)；辅助电源工作后，可以为控制电路供电，使得控制电路控制K1和K2的状态；当控制电路检测到母线电容电压达到预设的整流电压值时，控制电路控制K1、K2开启，PFC电路正常工作。通过上述方式可以实现软启动。
现有技术所提供的方案中，软启动电路包括两个继电器和两个电阻，所需的元器件数量较多，影响软启动电路的成本和体积。
发明内容
本申请实施例提供了一种软启动电路及变换器，用以减少软启动电路中元器件的数量，降低成本和体积。
第一方面，本申请实施例提供一种软启动电路。软启动电路位于整流电路与母线电容之间，用于实现整流电路的软启动，软启动电路包括开关管和继电器。继电器与开关管并联，继电器在整流电路上电之前处于断开状态，继电器在整流电路上电之后、且母线电容的电压值达到预设电压值时闭合。
其中，开关管可以为金属-氧化物半导体场效应晶体管MOSFET、绝缘栅双极型晶体管IGBT或三极管。继电器可以为交流继电器、直流继电器或接触器。
采用第一方面提供的软启动电路，整流电路上电前，开关管和继电器默认处于断开状态，母线电容上的电压均为零。整流电路上电后，整流电路的输入电流经过开关管向母线 电容充电。实际应用中，可以通过开关管的控制信号使得开关管处于高阻状态，因而在对母线电容进行充电时，流经母线电容的电流不会过大，可以避免出现母线电容因受到电网冲击而损坏的情况；当母线电容上的电压达到预设电压值后，继电器闭合，开关管被旁路，实现整流电路的软启动。其中，母线电容的预设电压值可以是整流电路的额定输出电压值，即整流电路的整流值。采用第一方面提供的软启动电路，仅通过开关管和继电器两个器件即可实现整流电路的软启动，与现有技术中的方案相比，软启动电路所需的元器件数量较少，降低了软启动电路的成本和体积。
在一种可能的设计中，软启动电路位于整流电路与母线电容之间，具体实现方式可以是：1、软启动电路位于正母线上；2、软启动电路位于负母线上；3、软启动电路与母线电容串联。
在一种可能的设计中，整流电路可以为以下任一种：三相三电平功率因数校正PFC电路；三相两电平PFC电路；单相PFC电路。
此外，第一方面提供的软启动电路还可以包括电阻，电阻与开关管串联，用于对开关管进行限流。
采用上述方案，在整流电路启动时，可以进一步减小流经开关管的电流。
在一种可能的设计中，开关管的控制信号为脉冲宽度调制PWM波。
采用上述方案，可以通过配置开关管的控制信号使得开关管处于高阻状态，通过PWM波控制开关管，可以使得开关管交替导通和关断，呈现高阻状态，起到限流作用。
在一种可能的设计中，继电器的闭合由控制电路控制。
采用上述方案，可以在整流电路启动完成后，通过控制电路闭合继电器。
进一步地，控制电路可以由辅助电源供电，辅助电源在整流电路的输入端取电。
采用上述方案，在整流电路上电时，辅助电源取电点的电压快速上升，达到辅助电源的启动电压，辅助电源启动。辅助电源启动后可以将输入的电压变换成控制电路的工作电压，从而为控制电路供电。控制电路启动后，即可对开关管的控制信号进行控制，从而对开关管的支路进行限流。
第二方面，本申请实施例提供一种变换器，该变换器包括整流电路以及上述第一方面及其任一可能的设计中提供的软启动电路。其中，软启动电路用于实现整流电路的软启动；整流电路用于对输入的交流电进行整流，得到直流电。
另外，应理解，第二方面及其任一种可能设计方式所带来的技术效果可参见第一方面中不同设计方式所带来的技术效果，此处不再赘述。
附图说明
图1为现有技术提供的一种软启动电路的结构示意图；
图2为本申请实施例提供的第一种软启动电路的结构示意图；
图3为本申请实施例提供的第二种软启动电路的结构示意图；
图4为本申请实施例提供的第三种软启动电路的结构示意图；
图5为本申请实施例提供的第四种软启动电路的结构示意图；
图6为本申请实施例提供的第五种软启动电路的结构示意图；
图7为本申请实施例提供的第六种软启动电路的结构示意图；
图8为本申请实施例提供的第七种软启动电路的结构示意图；
图9为本申请实施例提供的第八种软启动电路的结构示意图；
图10为本申请实施例提供的一种变换器的结构示意图。
具体实施方式
下面将结合附图对本申请实施例作进一步地详细描述。
需要说明的是，本申请实施例中，多个是指两个或两个以上。另外，在本申请的描述中，“第一”、“第二”等词汇，仅用于区分描述的目的，而不能理解为指示或暗示相对重要性，也不能理解为指示或暗示顺序。本申请实施例中所提到的“耦合”，是指电学连接，具体可以包括直接连接或者间接连接两种方式。
本申请实施例提供一种软启动电路，软启动电路位于整流电路和母线电容之间，用于实现整流电路的软启动。如图2所示，软启动电路200包括开关管201和继电器202。其中，继电器202与开关管201并联，继电器202在整流电路上电之前处于断开状态，继电器202在整流电路上电之后、且母线电容的电压值达到预设电压值时闭合。
实际应用中，开关管201例如可以是金属-氧化物半导体场效应晶体管(metal-oxide-semiconductor field-effect transistor，MOSFET)、氮化镓(gallium nitride，GaN)晶体管、绝缘栅双极型晶体管(insulated gate bipolar transist，IGBT)、双极结型晶体管(bipolar junction transistor，BJT)、三极管等。继电器202例如可以是交流继电器、直流继电器、接触器等。
此外，本申请实施例中对整流电路的具体结构不做限定，整流电路可以为三相三电平PFC电路、三相两电平PFC电路或单相PFC电路。上述整流电路的具体结构属于现有技术，本申请实施例中不再赘述。
本申请实施例中，软启动电路200位于整流电路和母线电容之间。具体地，软启动电路200可以位于正母线上，可以位于负母线上，也可以与母线电容串联。
以整流电路为图1所示的三相三电平PFC电路为例，在图3的示例中，软启动电路200位于正母线上；在图4的示例中，软启动电路200位于负母线上；在图5的示例中，软启动电路200与母线电容串联。此外，在图5的示例中，软启动电路200与母线电容C2串联，在另一种可能的设计中，软启动电路200也可以与母线电容C1串联。
若软启动电路200与母线电容串联，流经继电器202上的电流仅为母线电容上的纹波电流，继电器202可以选择电流规格较小的继电器。
下面以图3为例对软启动电路200的工作原理进行介绍：整流电路(即图3中的三相PFC电路)上电前，开关管201和继电器202默认处于断开状态，母线电容C1和C2上的电压均为零。整流电路上电后，整流电路的输入电流经过开关管201向母线电容C1和C2充电。实际应用中，可以通过开关管201的控制信号使得开关管201处于高阻状态，因而在对C1和C2进行充电时，流经C1和C2的电流不会过大，可以避免出现母线电容因受到电网冲击而损坏的情况；当母线电容C1和C2上的电压达到预设电压值后，继电器202闭合，开关管201被旁路，实现整流电路的软启动。其中，母线电容的预设电压值可以是整流电路的额定输出电压值，即整流电路的整流值。
采用本申请实施例提供的软启动电路200，仅通过开关管201和继电器202两个器件即可实现整流电路的软启动，与现有技术中的方案相比，软启动电路200所需的元器件数量较少，降低了软启动电路200的成本和体积。
此外，在图1所示的现有技术中，软启动电路中需配置电阻。电阻串联在相线上，在整流电路上电时需要承受较大的电流冲击，因而该电阻采用水泥电阻。水泥电阻的体积较大，在一定程度上也增加了软启动电路的体积。而本申请实施例中，通过开关管201的控制信号控制开关管201，使得开关管呈现高阻状态，起到限流作用。开关管201的体积远小于水泥电阻的体积，因而可以进一步减小软启动电路200的体积。
如前所述，本申请实施例中可以通过配置开关管201的控制信号使得开关管201处于高阻状态。开关管201的控制信号从开关管201的控制端输入，例如开关管201为MOSFET时，开关管201的控制端为MOSFET的栅极。具体地，开关管201的控制信号可以为脉冲宽度调制(pulse width modulation，PWM)波。PWM波可以视为占空比可调的方波，通过PWM波控制开关管201，可以使得开关管201交替导通和关断，呈现高阻状态，起到限流作用。
在另一种实现方式中，也可以在开关管201的支路上并联电阻，通过该电阻对开关管201进行限流。仍以图3的示例为例，在开关管201支路上并联电阻后，软启动电路200的结构可以如图6所示。在图6中，Q1表示开关管，K1表示继电器，R1表示电阻。
采用并联电阻的方式实现限流，可以进一步减小流经开关管201的电流。
并联电阻后，开关管201仍可采用PWM波作为控制信号。或者，在另一种实现方式中，开关管也可以不采用PWM波作为控制信号：开关管201在整流电路上电前处于闭合状态；整流电路上电后，输入电路经电阻R1向母线电容充电；在母线电容上的电压达到预设电压值后开关管201断开，K1闭合，整流电路正常工作。采用这种控制方式可以降低开关管201的控制难度。
本申请实施例中，实现整流电路的软启动需要对继电器202的断开和闭合进行控制，也需要对开关管201的输入信号(控制信号)进行控制。具体地，继电器202的断开和闭合以及开关管201的控制信号均可以通过控制电路进行控制。
实际应用中，控制电路可以由辅助电源供电，辅助电源可以在整流电路的输入端取电。比如，仍以图3所示的拓扑为例，辅助电源可以在图3中的P点处取电。那么，在整流电路上电时，辅助电源取电点的电压快速上升，达到辅助电源的启动电压，辅助电源启动。辅助电源启动后可以将输入的电压变换成控制电路的工作电压，从而为控制电路供电。控制电路启动后，即可对开关管201的输入信号(控制信号)进行控制，从而对开关管201的支路进行限流。在母线电容的电压达到预设电压值后，控制电路控制继电器202闭合。
在图1所示的现有技术中，由于控制电路在母线电容充电至整流电压值之后控制继电器闭合即可，因而在闭合继电器之前，整流电路的软启动过程实际上并不需要控制电路的参与。与图1所示的现有技术不同的是，本申请实施例中，实现软启动的过程中，控制电路需要对开关管201的控制信号进行控制。因此，本申请实施例与图1所示的现有技术相比，辅助电源的取电点前置，使得整流电路上电后辅助电源即可启动，从而触发控制电路正常工作，对开关管201的控制信号进行控制，实现软启动。
如前所述，本申请实施例中，整流电路可以为三相三电平PFC电路、三相两电平PFC电路或者单相PFC电路。前面的示例中均以整流电路采用三相三电平PFC电路拓扑为例进行介绍，下面再列举一下整流电路采用三相两电平PFC电路拓扑和单相PFC电路拓扑的场景。
整流电路采用三相两电平PFC电路拓扑时，本申请实施例提供的软启动电路200可以 如图7所示。在图7的示例中，Q1表示开关管201，K1表示继电器202。
整流电路采用单相PFC电路拓扑时，本申请实施例提供的软启动电路200可以如图8所示。在图8的示例中，Q1表示开关管201，K1表示继电器202。
图7和图8所示的软启动电路200的工作原理与可以参见之前的描述，此处不再详细解释。
综上，采用本申请实施例提供的软启动电路200，仅通过开关管201和继电器202两个器件即可以实现整流电路的软启动，与现有技术中的方案相比，软启动电路200所需的元器件数量较少，降低了软启动电路200的成本和体积。此外，本申请实施例中，通过开关管201的控制信号控制开关管201，使得开关管201呈现高阻状态，起到限流作用。与现有技术中采用水泥电阻进行限流的方案相比，开关管201的体积远小于水泥电阻的体积，因而可以进一步减小软启动电路200的体积。
需要说明的是，本申请实施例提供的软启动电路200可以应用多种配置有整流电路的场景，以实现整流电路的软启动。本申请实施例对软启动电路200的应用场景不做具体限定，例如可以应用于直流充电桩、OBC、数据中心或通信电源等实体中。
比如，当软启动电路200应用于直流充电桩时，直流充电桩中可以包括多个变换模块，每个变换模块包括整流电路和变换电路，整流电路用于对输入的交流电(市电)进行整流，得到第一直流电；变换电路用于对第一直流电进行DC/DC变换，得到第二直流电，第二直流电用于为动力电池充电。此外，每个变换模块中还包括软启动电路200，软启动电路200位于直流母线与母线电容之间，用于实现整流电路的软启动。
再比如，当软启动电路200应用于OBC时，OBC中可以包括多个变换模块，每个变换模块包括整流电路和变换电路，整流电路用于对交流充电桩输出的交流电进行整流，得到第一直流电；变换电路用于对第一直流电进行DC/DC变换，得到第二直流电，第二直流电用于为动力电池充电。此外，每个变换模块中还包括软启动电路200，软启动电路200位于直流母线与母线电容之间，用于实现整流电路的软启动。
下面，通过一个具体示例对本申请实施例提供的软启动电路的具体工作过程进行介绍。
如图9所示，以整流电路采用维也纳电路拓扑为例，本申请实施例提供的软启动电路可以设置在正母线上，软启动电路包括并联的开关管Q1和继电器K1。
三相电压接入前，K1和Q1都处于断开状态，母线电容C1和C2上的电压均为零；三相电压接入后，辅助电源工作，为控制电路供电；控制电路向Q1输出PWM波，以限制Q1的电流；交流整流后的电压通过Q1给母线电容C1和C2充电；当母线电容的电压值达到输入电压的整流值后，K1导通，将Q1旁路，Q1关闭，从而达到软启动的效果。
本申请实施例还提供一种变换器。如图10所示，变换器1000包括整流电路1001以及前述软启动电路200。软启动电路200用于实现整流电路1001的软启动；整流电路1001用于对输入的交流电进行整流，得到直流电。
需要说明的是，变换器1000中未详尽描述的实现方式及技术效果可以参见软启动电路200中的相关描述，此处不再赘述。
显然，本领域的技术人员可以对本申请实施例进行各种改动和变型而不脱离本申请实施例的范围。这样，倘若本申请实施例的这些修改和变型属于本申请权利要求及其等同技 术的范围之内，则本申请也意图包含这些改动和变型在内。

Claims (11)

  1. 一种软启动电路，其特征在于，所述软启动电路位于整流电路与母线电容之间，用于实现所述整流电路的软启动，所述软启动电路包括：
    开关管；
    继电器，所述继电器与所述开关管并联，所述继电器在所述整流电路上电之前处于断开状态，所述继电器在所述整流电路上电之后、且所述母线电容的电压值达到预设电压值时闭合。
  2. 如权利要求1所述的电路，其特征在于，在所述整流电路上电之后，所述整流电路的输入电流经过所述开关管向所述母线电容充电。
  3. 如权利要求1或2所述的电路，其特征在于，所述软启动电路位于正母线上；或者，所述软启动电路位于负母线上；或者，所述软启动电路与所述母线电容串联。
  4. 如权利要求1～3任一项所述的电路，其特征在于，所述整流电路为以下任一种：
    三相三电平功率因数校正PFC电路；
    三相两电平PFC电路；
    单相PFC电路。
  5. 如权利要求1～4任一项所述的电路，其特征在于，还包括：
    电阻，所述电阻与所述开关管串联，用于对所述开关管进行限流。
  6. 如权利要求1～5任一项所述的电路，其特征在于，所述开关管的控制信号为脉冲宽度调制PWM波。
  7. 如权利要求1～6任一项所述的电路，其特征在于，所述开关管为金属-氧化物半导体场效应晶体管MOSFET、绝缘栅双极型晶体管IGBT或三极管。
  8. 如权利要求1～7任一项所述的电路，其特征在于，所述继电器为交流继电器、直流继电器或接触器。
  9. 如权利要求1～8任一项所述的电路，其特征在于，所述继电器的闭合由控制电路控制。
  10. 如权利要求9所述的电路，其特征在于，所述控制电路由辅助电源供电，所述辅助电源在所述整流电路的输入端取电。
  11. 一种变换器，其特征在于，包括整流电路以及如权利要求1～10任一项所述的软启动电路；所述软启动电路用于实现所述整流电路的软启动；所述整流电路用于对输入的交 流电进行整流，得到直流电。
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