WO2014059736A1 - Dc/dc变换电路的输出电压检测电路 - Google Patents

Dc/dc变换电路的输出电压检测电路 Download PDF

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Publication number
WO2014059736A1
WO2014059736A1 PCT/CN2012/087798 CN2012087798W WO2014059736A1 WO 2014059736 A1 WO2014059736 A1 WO 2014059736A1 CN 2012087798 W CN2012087798 W CN 2012087798W WO 2014059736 A1 WO2014059736 A1 WO 2014059736A1
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WIPO (PCT)
Prior art keywords
resistor
voltage
circuit
output voltage
mosfet
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PCT/CN2012/087798
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English (en)
French (fr)
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张�林
刘皞星
付登萌
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联合汽车电子有限公司
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Publication of WO2014059736A1 publication Critical patent/WO2014059736A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/40—Testing power supplies
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/0084—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring voltage only
    • 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
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H02M3/33592—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
    • 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
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/337—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only in push-pull configuration
    • H02M3/3376—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only in push-pull configuration with automatic control of output voltage or current
    • 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
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0009—Devices or circuits for detecting current in a converter
    • 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

Definitions

  • the present invention relates to a power supply circuit, and more particularly to an output voltage detection circuit of a DC/DC conversion circuit.
  • DC/DC Transform Transforming an uncontrolled input DC voltage into another controlled output DC voltage is called DC/DC Transform.
  • Electric vehicle drive and regenerative braking system The DC/DC converter and the motor driver are important parts of the system energy flow.
  • the DC/DC converter converts the fixed DC voltage of the DC voltage source such as the battery and the DC motor into a controlled DC voltage output.
  • the switching type DC/DC conversion circuit adjusts the output voltage or maintains the output voltage constant by periodically controlling the on-off time or the on-off frequency of the switching device (power semiconductor device), and converts the fixed DC voltage into a controlled DC voltage. Output.
  • a common switching DC/DC (DC to DC) conversion circuit is shown in Figure 1, including a voltage conversion circuit, an inverter circuit, and a rectified output circuit; the input terminal of the voltage conversion circuit is connected to a DC voltage source Ud for controlling the The switching device is turned on and off to control the magnitude of the DC voltage Ui outputted to the inverter circuit, thereby controlling Switch type The output DC voltage Uo of the DC/DC circuit; the input terminal of the inverter circuit is connected to the output DC voltage Ui of the voltage conversion circuit for changing the output DC voltage Ui of the voltage conversion circuit to a high frequency AC voltage output.
  • the rectification output circuit is used for rectifying the high-frequency AC voltage outputted by the inverter circuit, and outputting the DC voltage Uo;
  • the voltage conversion circuit usually has a boost conversion circuit (Boost), a buck conversion circuit (Buck), and a lifting Pressure conversion circuit (Buck-Boost), Cook conversion circuit (Cuk), etc.; commonly used inverter circuits are full-bridge, half-bridge, push-pull.
  • the DC/DC converter circuit usually has an output voltage detection circuit and a battery at the voltage output end, a common on-board DC/DC converter circuit.
  • the output voltage detecting circuit includes a first resistor R1 and a second resistor R2.
  • the first resistor R1 and the second resistor R2 are connected in series to the DC/DC converter circuit.
  • the voltage output is positive and negative at both ends (both ends of the vehicle low voltage battery), and the voltage at the connection point of the first resistor R1 and the second resistor R2 and the voltage output of the DC/DC converter circuit is used as the detection voltage Uc.
  • the output voltage detecting circuit when the first resistor R1 and the second resistor R2 have a small value, since When the DC/DC converter circuit is not working, the output voltage of the low-voltage battery and the DC/DC converter circuit is not disconnected, and the low-voltage battery generates a large quiescent current through the first resistor R1 and the second resistor R2.
  • the values of the first resistor R1 and the second resistor R2 are large, although the quiescent current can be reduced, if the squeezing current is too large, the sampling resistor reduces the accuracy of the detection voltage.
  • This kind of output voltage detection circuit can not meet the vehicle Low quiescent current and high detection accuracy requirements of DC/DC converters.
  • the technical problem to be solved by the present invention is to provide an output voltage detecting circuit of a DC/DC converting circuit, which has a small quiescent current and high detection precision.
  • the output voltage detecting circuit of the DC/DC converting circuit includes a first resistor, a second resistor, a fifth resistor, a sixth resistor, a Zener diode, a P-MOSFET, and a N-MOSFET;
  • the first resistor is connected in series with the second resistor at the drain of the P-MOSFET to The output voltage of the DC/DC converter circuit is negative, the connection point of the first resistor and the second resistor is used as a detection voltage sampling point, and the sampling point is used for connecting to the DC/DC conversion circuit. a detection voltage output terminal of the output voltage detecting circuit;
  • the fifth resistor is connected in series with the sixth resistor between the output voltage of the DC/DC converter circuit and the drain of the N-MOSFET;
  • a gate of the P-MOSFET is connected to a connection point of the fifth resistor and a sixth resistor, and a source is connected to an output voltage of the DC/DC converter circuit;
  • the negative terminal of the voltage regulator is connected to the output voltage of the DC/DC converter circuit, and the positive terminal is connected to the connection point of the fifth resistor and the sixth resistor;
  • the source of the N-MOSFET is connected to the output voltage of the DC/DC converter circuit, and the gate is connected to the DC/DC converter circuit operating state voltage;
  • the DC/DC conversion circuit operating state voltage is a high level when the DC/DC conversion circuit operates, and is a low level when the DC/DC conversion circuit stops operating.
  • the output voltage detecting circuit of the DC/DC converting circuit further includes a first capacitor
  • the first capacitor is connected between the gate and the source of the P-MOSFET.
  • the output voltage detecting circuit of the DC/DC converting circuit further includes a second capacitor and a seventh resistor;
  • the second capacitor is connected between a connection point of the first resistor and the second resistor to a negative output voltage of the DC/DC converter circuit;
  • the seventh resistor is connected to the connection point of the first resistor and the second resistor to the DC/DC conversion circuit
  • the output voltage detection circuit detects between the voltage output terminals.
  • the DC/DC conversion circuit is an analog type, and the analog DC/DC conversion circuit includes an operating voltage output terminal.
  • the DC/DC converter circuit When the DC/DC converter circuit is operating, the voltage at the output of the working voltage is at a high level. When the DC/DC converter circuit stops operating, the voltage at the output of the operating voltage is at a low level;
  • the output voltage detecting circuit of the DC/DC conversion circuit further includes a third resistor and a fourth resistor;
  • the third resistor is connected in series with the fourth resistor between the output voltage output terminal and the output voltage of the DC/DC converter circuit, and the connection point of the third resistor and the fourth resistor is connected to the gate of the N-MOSFET;
  • the operating voltage of the DC/DC converter circuit is the voltage of the connection point of the third resistor and the fourth resistor.
  • the DC/DC conversion circuit is a digital type, and the digital DC/DC conversion circuit includes an MCU, and the MCU includes an open signal output port when the DC/DC conversion circuit When working, the MCU's turn-on signal output port outputs a high level. When the DC/DC converter circuit stops working, the MCU's turn-on signal output port outputs a low level;
  • the output voltage detecting circuit of the DC/DC conversion circuit further includes an eighth resistor
  • the eighth resistor is connected to the open signal output port of the MCU to the DC/DC conversion circuit
  • the output signal of the MCU is connected to the gate of the N-MOSFET
  • the operating voltage of the DC/DC converter circuit is the voltage of the open signal output port of the MCU.
  • the output voltage detecting circuit realizes the opening and closing of the current path through the P-MOSFET at the front end of the voltage dividing resistor, and the P-MOSFET is turned on and off to control the gate-source voltage of the P-MOSFET through an N-MOSFET.
  • the output voltage detecting circuit of the DC/DC converting circuit of the present invention can cut off the current path of the voltage dividing resistor in the battery to the output voltage detecting circuit when the DC/DC converting circuit stops operating, ensuring that the quiescent current is sufficiently small while being in the DC /DC conversion circuit When working, can turn on the DC/DC converter circuit
  • the output voltage is to the current path of the voltage dividing resistor in the output voltage detecting circuit, and the resistance value of the voltage dividing resistor is not required to be large, which can ensure a sufficiently high detection precision, and can meet the low quiescent current and high of the vehicle DC/DC converter.
  • the detection accuracy is required, and the circuit is simple and the cost is low.
  • Figure 1 is a schematic diagram of a common switching DC/DC converter circuit
  • FIG. 2 is a schematic diagram of a common vehicle DC/DC conversion circuit
  • FIG. 3 is a circuit diagram showing an embodiment of an output voltage detecting circuit of a DC/DC converting circuit of the present invention
  • Fig. 4 is a circuit diagram showing another embodiment of an output voltage detecting circuit of the DC/DC converting circuit of the present invention.
  • the output voltage detecting circuit of the conversion circuit includes a first resistor R1, a second resistor R2, a fifth resistor R5, a sixth resistor R6, a Zener diode D1, and a P-MOSFET (P Channel power metal oxide semiconductor field effect transistor), an N-MOSFET (N-channel power metal oxide semiconductor field effect transistor);
  • the first resistor R1 is connected in series with the second resistor R2 at the drain of the P-MOSFET to DC/DC Between the negative output voltage of the conversion circuit, the connection point of the first resistor R1 and the second resistor R2 is used as a detection voltage sampling point, and the sampling point is used for connecting to the DC/DC conversion circuit. a detection voltage output terminal of the output voltage detecting circuit;
  • the fifth resistor R5 is connected in series with the sixth resistor R6 in the output voltage of the DC/DC converter circuit between the drain of the N-MOSFET;
  • the gate of the P-MOSFET is connected to the connection point of the fifth resistor R5 and the sixth resistor R6, and the source is connected to the output voltage of the DC/DC converter circuit;
  • the negative terminal of the Zener diode D1 is connected to the output voltage of the DC/DC converter circuit, and the positive terminal is connected to the connection point of the fifth resistor R5 and the sixth resistor R6;
  • the source of the N-MOSFET is connected to the DC/DC conversion circuit
  • the output voltage is negative, and the gate is connected to the operating voltage of the DC/DC converter circuit
  • the DC/DC conversion circuit operating state voltage is a high level when the DC/DC conversion circuit operates, and is a low level when the DC/DC conversion circuit stops operating.
  • the output voltage detecting circuit is connected between the positive and negative output voltages of the DC/DC converter circuit, and the P-MOSFET is used as the switching tube for cutting off the quiescent current, and the first resistor R1 and the second resistor R2 are used as the voltage dividing resistors. Detection of output voltage.
  • the fifth resistor R5 and the sixth resistor R6 divide the voltage to control the minimum gate voltage of the P-MOSFET, and the Zener diode D1 can control the maximum gate voltage of the P-MOSFET.
  • the voltage of the fifth resistor R5 and the sixth resistor R6 is smaller than the voltage regulator of the Zener diode D1.
  • the gate voltage of the P-MOSFET is divided by the voltage of the fifth resistor R5 and the sixth resistor R6. Determine; when DC/DC converter circuit When the output voltage is high, the voltage of the fifth resistor R5 and the sixth resistor R6 is greater than the voltage regulator of the Zener diode D1. At this time, the gate voltage of the P-MOSFET is determined by the voltage regulator of the regulator D1.
  • the turn-on and turn-off of the P-MOSFET is controlled by the N-MOSFET, while the turn-on and turn-off of the N-MOSFET is controlled by its gate voltage.
  • the N-MOSFET When the N-MOSFET is turned on, the gate-source voltage of the P-MOSFET is greater than the turn-on voltage, and the P-MOSFET is turned on; when the N-MOSFET is turned off, the current flowing through R5 is about 0, and the gate-source voltage of the P-MOSFET is 0. Less than its turn-on voltage, the P-MOSFET is turned off.
  • the N-MOSFET is turned on and off by DC/DC Transform circuit operating state voltage control.
  • the DC/DC conversion circuit operating state voltage is high when the DC/DC conversion circuit operates, and the N-MOSFET is controlled to be turned on.
  • the DC/DC conversion circuit stops operating it is low, and the N-MOSFET is controlled to be turned off.
  • the output voltage detecting circuit of the DC/DC converter circuit further includes a first capacitor C1;
  • the first capacitor C1 is connected between the gate and the source of the P-MOSFET to prevent the output voltage of the DC/DC converter circuit from overshooting, and the gate-source voltage of the P-MOSFET is abruptly changed to damage the P-MOSFET.
  • the output voltage detecting circuit of the DC/DC converting circuit further includes a second capacitor C2 and a seventh resistor R7;
  • the second capacitor C2 is connected between the connection point of the first resistor R1 and the second resistor R2 to the output voltage of the DC/DC converter circuit for filtering interference noise;
  • the seventh resistor R7 is connected between the connection point of the first resistor R1 and the second resistor R2 to the detection voltage output end of the output voltage detecting circuit of the DC/DC converter circuit for current limiting.
  • the DC/DC conversion circuit is an analog type, and the analog DC/DC conversion circuit includes an operating voltage Ucc output terminal.
  • the working voltage output terminal is powered on.
  • the voltage at the output of the working voltage is high (for example, 5V).
  • the DC/DC converter circuit stops working the output of the working voltage is not powered, and the voltage at the output of the working voltage is low (for example, 0V);
  • the output voltage detecting circuit of the DC/DC conversion circuit further includes a third resistor R3 and a fourth resistor R4;
  • the third resistor R3 is connected in series with the fourth resistor R4 between the output voltage Ucc output terminal and the output voltage of the DC/DC converter circuit, and the connection point of the third resistor and the fourth resistor is connected to the gate of the N-MOSFET.
  • a voltage, a voltage of a connection point of the third resistor R3 and the fourth resistor R4 is used as the operating voltage of the DC/DC converter circuit, and is output to a gate of the N-MOSFET to control turn-on and turn-off of the N-MOSFET .
  • the voltage at the output of the working voltage is high (for example, 5V)
  • the gate-source voltage of the N-MOSFET is greater than the turn-on voltage, and the N-MOSFET is turned on;
  • the voltage at the output of the operating voltage is low (for example, 0V)
  • the gate voltage of the N-MOSFET is low (for example, 0V)
  • the gate-source voltage of the N-MOSFET is less than its turn-on voltage, and the N-MOSFET is turned off.
  • the DC/DC conversion circuit is digital, and the digital DC/DC conversion circuit includes an MCU. (Microprocessor), the MCU includes an open signal output port. When the DC/DC converter circuit is working, the MCU is powered on, and the MCU open signal output port outputs a high level 1 when the DC/DC conversion circuit stops. During operation, the MCU does not power on, and the MCU's turn-on signal output port outputs a low level of 0;
  • MCU Microprocessor
  • the output voltage detecting circuit of the DC/DC conversion circuit further includes an eighth resistor R8;
  • the eighth resistor R8 is connected to the open signal output port of the MCU to the DC/DC conversion circuit
  • the output signal of the MCU is connected to the gate of the N-MOSFET, and the voltage of the open signal output port of the MCU is the operating voltage of the DC/DC converter circuit. Controlling the turn-on and turn-off of the N-MOSFET;
  • the MCU When the DC/DC conversion circuit is working, the MCU is powered on, the voltage of the open signal output port of the MCU is high level 1, the gate-source voltage of the N-MOSFET is greater than the turn-on voltage thereof, and the N-MOSFET is turned on, thereby turning the P-MOSFET Open
  • the output voltage detecting circuit of the DC/DC converter circuit of the present invention turns on and off the current path through the P-MOSFET at the front end of the voltage dividing resistor, and the P-MOSFET is turned on and off to control the P-MOSFET through an N-MOSFET.
  • the gate-source voltage is achieved.
  • DC/DC conversion circuit of the present invention The output voltage detecting circuit can cut off the current path of the voltage dividing resistor in the battery to the output voltage detecting circuit when the DC/DC converting circuit stops working, ensuring that the quiescent current is sufficiently small, and at the same time, when the DC/DC converting circuit is working, Turn on the output voltage of the DC/DC converter circuit to the current path of the voltage divider resistor in the output voltage detection circuit.
  • the resistance of the voltage divider resistor is not required to be large, and the detection accuracy can be sufficiently high to meet the on-board DC/DC conversion.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)
  • Measurement Of Current Or Voltage (AREA)
  • Control Of Voltage And Current In General (AREA)

Abstract

本发明公开了一种DC/DC变换电路的输出电压检测电路，其包括第一电阻、第二电阻、第五电阻、第六电阻、稳压管、P-MOSFET、N-MOSFET；第一电阻同第二电阻串接在P-MOSFET的漏极到DC/DC变换电路的输出电压负之间，第一电阻同第二电阻的连接点作为检测电压采样点；第五电阻同第六电阻串接在DC/DC变换电路的输出电压正到N-MOSFET的漏极之间；P-MOSFET的栅极接所述连接点，源极接DC/DC变换电路的输出电压正；稳压管的负端接DC/DC变换电路的输出电压正，正端接所述连接点；N-MOSFET的源极接DC/DC变换电路的输出电压负，栅极接DC/DC变换电路工作状态电压；DC/DC变换电路工作状态电压。本发明的DC/DC变换电路的输出电压检测电路，保证静态电流足够小，并能保证足够高的检测精度。

Description

DC/DC变换电路的输出电压检测电路 技术领域
本发明涉及电源电路，特别涉及一种DC/DC变换电路的输出电压检测电路。
背景技术
将一个不受控制的输入直流电压变换成为另一个受控的输出直流电压称之为 DC/DC 变换。在电动汽车驱动及再生制动系统 中，DC/DC变换器和电机驱动器是系统能量流动的重要环节,DC/DC变换器是将电池、直流电机等直流电压源固定的直流电压变换成受控制的直流电压输出 。
开关型DC/DC变换电路是通过周期性的控制开关器件（功率半导体器件）的通断时间或通断频率来调整输出电压或维持输出电压恒定，将固定的直流电压变换成受控制的直流电压输出。常见的开关型DC/DC（直流到直流）变换电路如图1所示，包括电压变换电路、逆变电路、整流输出电路；电压变换电路输入端接直流电压源Ud，用于通过控制其中的开关器件导通与关断来控制输出到逆变电路的直流电压Ui的大小，从而控制 开关型 直流变换（DC/DC）电路的输出直流电压Uo的大小；逆变电路的输入端接电压变换电路的输出直流电压Ui，用于将电压变换电路的输出直流电压Ui变为高频交流电压输出到整流输出电路；整流输出电路用于将逆变电路输出的高频交流电压整流，输出直流电压Uo；电压变换电路通常有升压变换电路（Boost）、降压变换电路(Buck)、升降压变换电路（Buck-Boost）、库克变换电路（Cuk）等；常用的逆变电路有全桥式、半桥式、推挽式。
DC/DC变换电路 通常在电压输出端接有输出电压检测电路及电池，一种常见的车载DC/DC变换电路 如图2所示，其输出电压检测电路包括第一电阻R1、第二电阻R2，第一电阻R1、第二电阻R2串接在DC/DC变换电路 的电压输出正、负两端（车载低压电池两端），以第一电阻R1、第二电阻R2连接点与DC/DC变换电路 的电压输出负的电压作为检测电压Uc。
该种输出电压检测电路，当第一电阻R1、第二电阻R2取值较小时，由于一般来说 DC/DC变换电路不工作时，低压电池和DC/DC变换电路的输出电压是不断开的，低压电池会通过第一电阻R1、第二电阻R2产生较大静态电流。当第一电阻R1、第二电阻R2取值较大时，虽然能减小静态电流，但过大是采样电阻会降低检测电压的精度。该种输出电压检测电路，无法满足车载 DC/DC变换器的低静态电流、高检测精度的要求。
 技术问题
本发明要解决的技术问题是提供一种DC/DC变换电路的输出电压检测电路，静态电流小，并且检测精度高。
技术解决方案
为解决上述技术问题，本发明提供的DC/DC变换电路的输出电压检测电路，其包括第一电阻、第二电阻、第五电阻、第六电阻、一稳压管、一P-MOSFET、一N-MOSFET；
所述第一电阻同第二电阻串接在所述P-MOSFET的漏极到 DC/DC变换电路的输出电压负之间，第一电阻同第二电阻的连接点作为检测电压采样点，所述采样点用于连接到DC/DC变换电路 的输出电压检测电路的检测电压输出端；
所述第五电阻同第六电阻串接在DC/DC变换电路的输出电压正到所述N-MOSFET的漏极之间；
所述P-MOSFET的栅极接所述第五电阻同第六电阻的连接点，源极接所述DC/DC变换电路的输出电压正；
所述稳压管的负端接所述DC/DC变换电路的输出电压正，正端接所述第五电阻同第六电阻的连接点；
所述N-MOSFET的源极接所述DC/DC变换电路的输出电压负，栅极接DC/DC变换电路工作状态电压；
所述DC/DC变换电路工作状态电压，在DC/DC变换电路工作时为高电平，在DC/DC变换电路停止工作时为低电平。
较佳的，DC/DC变换电路的输出电压检测电路还包括第一电容；
所述第一电容，接在所述P-MOSFET的栅极、源极之间。
较佳的，DC/DC变换电路的输出电压检测电路还包括第二电容、第七电阻；
所述第二电容，接在所述第一电阻同第二电阻的连接点到DC/DC变换电路 的输出电压负之间；
所述第七电阻，接在所述第一电阻同第二电阻的连接点到DC/DC变换电路 的输出电压检测电路的检测电压输出端之间。
较佳的， 所述DC/DC变换电路为模拟式，模拟式的DC/DC变换电路包括一工作电压输出端， 当DC/DC变换电路 工作时， 工作电压输出端的电压为高电平 ，当DC/DC变换电路停止 工作时， 工作电压输出端的电压为低电平；
DC/DC变换电路 的输出电压检测电路还包括第三电阻和第四电阻；
第三电阻同第四电阻串接在所述工作电压输出端到DC/DC变换电路的输出电压负之间，第三电阻同第四电阻的连接点接所述N-MOSFET的栅极；
所述DC/DC变换电路工作状态电压，为第三电阻同第四电阻的连接点的电压。
较佳的， 所述DC/DC变换电路为数字式，数字式的DC/DC变换电路包括一MCU，MCU包括一开通信号输出口，当DC/DC变换电路 工作时，MCU的开通信号输出口输出高电平，当 DC/DC变换电路停止 工作时，MCU的开通信号输出口输出低电平；
DC/DC变换电路 的输出电压检测电路还包括第八电阻；
所述第八电阻，接在MCU的开通信号输出口到DC/DC变换电路 的输出电压负之间，所述MCU的开通信号输出口并同所述N-MOSFET的栅极相接；
所述DC/DC变换电路工作状态电压，为 所述MCU的开通信号输出口的电压 。
有益效果
本发明的DC/DC变换电路 的输出电压检测电路，在分压电阻前端通过P-MOSFET实现电流路径的开通与关闭，而P-MOSFET的开通与关闭通过一N-MOSFET控制该P-MOSFET的栅源电压实现。 本发明的DC/DC变换电路的输出电压检测电路，在DC/DC变换电路停止工作时，能切断电池到输出电压检测电路中的分压电阻的电流路径，保证静态电流足够小，同时在DC/DC变换电路 工作时，能接通DC/DC变换电路 的输出电压到输出电压检测电路中的分压电阻的电流路径，分压电阻的阻值不要求很大，能保证足够高的检测精度，可以满足车载DC/DC变换器的低静态电流、高检测精度的要求，并且电路简单，成本低。
附图说明
为了更清楚地说明本发明的技术方案，下面对本发明所需要使用的附图作简单的介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是 常见的开关型DC/DC变换电路示意图；
图2是一种常见的车载DC/DC变换电路示意图;
图3是本发明的DC/DC变换电路的输出电压检测电路一实施例电路图；
图4是本发明的DC/DC变换电路的输出电压检测电路另一实施例电路图。
 本发明的最佳实施方式
下面将结合附图，对本发明中的技术方案进行清楚、完整的描述，显然，所描述的实施例是本发明的一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动的前提下所获得的所有其它实施例，都属于本发明保护的范围。
实施例一
DC/DC 变换电路的输出电压检测电路，如图3所示，其包括第一电阻R1、第二电阻R2、第五电阻R5、第六电阻R6、一稳压管D1、一P-MOSFET( P 沟道功率金属氧化半导体场效应晶体管 ) 、一N-MOSFET(N- 沟道功率金属氧化半导体场效应晶体管 ) ；
所述第一电阻R1同第二电阻R2串接在所述P-MOSFET的漏极到 DC/DC 变换电路的输出电压负之间，第一电阻R1同第二电阻R2的连接点作为检测电压采样点，所述采样点用于连接到DC/DC变换电路 的输出电压检测电路的检测电压输出端；
所述第五电阻R5同第六电阻R6串接在DC/DC变换电路的输出电压正到所述N-MOSFET的漏极之间；
所述P-MOSFET的栅极接所述第五电阻R5同第六电阻R6的连接点，源极接所述DC/DC变换电路的输出电压正；
所述稳压管D1的负端接所述DC/DC变换电路的输出电压正，正端接所述第五电阻R5、第六电阻R6的连接点；
所述N-MOSFET的源极接所述DC/DC变换电路 的输出电压负，栅极接DC/DC变换电路工作状态电压；
所述DC/DC变换电路工作状态电压，在DC/DC变换电路工作时为高电平，在DC/DC变换电路停止工作时为低电平。
实施例一的DC/DC变换电路 的输出电压检测电路，接在DC/DC变换电路的输出电压正、负之间，以P-MOSFET作为切断静态电流的开关管，以第一电阻R1、第二电阻R2为分压电阻，实现输出电压的检测。
第五电阻R5和第六电阻R6分压能控制P-MOSFET的最小栅极电压，稳压管D1能控制P-MOSFET的最大栅极电压。当DC/DC变换电路 输出电压较低时，第五电阻R5和第六电阻R6分压小于稳压管D1的稳压值，此时P-MOSFET的栅极电压由第五电阻R5、第六电阻R6的分压来确定；当DC/DC变换电路 输出电压较高时，第五电阻R5、第六电阻R6分压大于稳压管D1的稳压值，此时P-MOSFET的栅极电压由稳压管D1的稳压值来确定。
P-MOSFET的开通与关闭由N-MOSFET控制，而N-MOSFET的开通与关闭由其栅极电压控制。当N-MOSFET开通时，P-MOSFET的栅源电压大于开启电压，P-MOSFET开通；当N-MOSFET的关闭时，R5流过的电流约为0，P-MOSFET的栅源电压为0，小于其开启电压，P-MOSFET关闭。
所述N-MOSFET的开通与关闭由 DC/DC 变换电路工作状态电压控制。DC/DC变换电路工作状态电压，在DC/DC变换电路工作时为高电平，控制所述N-MOSFET开通， 在DC/DC变换电路停止工作时为低电平，控制所述N-MOSFET关闭 。
实施例二
基于实施例一，DC/DC变换电路 的输出电压检测电路还包括第一电容C1；
所述第一电容C1接在所述P-MOSFET的栅极、源极之间，以防止DC/DC变换电路输出电压过冲时，P-MOSFET的栅源电压出现突变而损坏P-MOSFET。
实施例三
基于实施例二，DC/DC变换电路的输出电压检测电路还包括第二电容C2、第七电阻R7；
所述第二电容C2，接在所述第一电阻R1同第二电阻R2的连接点到DC/DC变换电路的输出电压负之间，用于滤除干扰噪声；
所述第七电阻R7，接在所述第一电阻R1同第二电阻R2的连接点到DC/DC变换电路的输出电压检测电路的检测电压输出端之间，用于限流。
实施例四
基于实施例三，如图3所示， 所述DC/DC变换电路为模拟式，模拟式的DC/DC变换电路包括一工作电压Ucc输出端， 当DC/DC变换电路 工作时， 工作电压输出端上电， 工作电压输出端的电压为高电平（例如5V），当DC/DC变换电路停止工作时，工作电压输出端不上电，工作电压输出端的电压为低电平（例如0V）；
DC/DC变换电路的输出电压检测电路还包括第三电阻R3和第四电阻R4；
第三电阻R3同第四电阻R4串接在所述工作电压Ucc输出端到DC/DC变换电路的输出电压负之间，第三电阻同第四电阻的连接点接所述N-MOSFET的栅极，以第三电阻R3同第四电阻R4的连接点的电压作为所述DC/DC变换电路工作状态电压，输出到所述N-MOSFET的栅极，控制所述N-MOSFET的开通与关闭。
DC/DC变换电路工作时，工作电压输出端的电压为高电平（例如5V），N-MOSFET的栅源电压大于其开启电压，N-MOSFET开通；
当DC/DC变换电路停止工作时， 工作电压输出端的电压为低电平（例如0V），N-MOSFET的栅极电压为低电平（例如0V），N-MOSFET的栅源电压小于其开启电压，N-MOSFET关闭。
实施例五
基于实施例三，如图4所示， 所述DC/DC变换电路为数字式，数字式的DC/DC变换电路包括一 MCU （微处理器），MCU包括一开通信号输出口，当DC/DC变换电路 工作时，MCU上电，MCU的开通信号输出口输出高电平1，当DC/DC变换电路停止 工作时，MCU不上电，MCU的开通信号输出口输出低电平0；
DC/DC变换电路 的输出电压检测电路还包括第八电阻R8；
所述第八电阻R8，接在MCU的开通信号输出口到DC/DC变换电路 的输出电压负之间，所述MCU的开通信号输出口并同所述N-MOSFET的栅极相接，以所述MCU的开通信号输出口的电压为所述DC/DC变换电路工作状态电压，控制所述N-MOSFET的开通与关闭；
DC/DC变换电路工作时，所述MCU上电，MCU的开通信号输出口的电压为高电平1，N-MOSFET的栅源电压大于其开启电压，N-MOSFET开通，从而将P-MOSFET开通；
当 DC/DC 变换电路停止工作时，MCU的开通信号输出口的电压为低电平0，N-MOSFET的栅极电压通过第八电阻R8下拉到地（DC/DC变换电路的输出电压负），栅源电压小于其开启电压，N-MOSFET关闭，从而将P-MOSFET关断。
本发明的DC/DC变换电路的输出电压检测电路，在分压电阻前端通过P-MOSFET实现电流路径的开通与关闭，而P-MOSFET的开通与关闭通过一N-MOSFET控制该P-MOSFET的栅源电压实现。 本发明的DC/DC变换电路 的输出电压检测电路，在DC/DC变换电路停止工作时，能切断电池到输出电压检测电路中的分压电阻的电流路径，保证静态电流足够小，同时在DC/DC变换电路工作时，能接通DC/DC变换电路的输出电压到输出电压检测电路中的分压电阻的电流路径，分压电阻的阻值不要求很大，能保证足够高的检测精度，可以满足车载DC/DC变换器的低静态电流、高检测精度的要求，并且电路简单，成本低。
以上所述仅为本发明的较佳实施例而已，并不用以限制本发明，凡在本发明的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本发明保护的范围之内。

Claims (6)

  1. 一种DC/DC变换电路的输出电压检测电路，其特征在于，输出电压检测电路包括第一电阻、第二电阻、第五电阻、第六电阻、一稳压管、一P-MOSFET、一N-MOSFET；
    所述第一电阻同第二电阻串接在所述P-MOSFET的漏极到DC/DC变换电路的输出电压负之间，第一电阻同第二电阻的连接点作为检测电压采样点，所述采样点用于连接到DC/DC变换电路的输出电压检测电路的检测电压输出端；
    所述第五电阻同第六电阻串接在 DC/DC 变换电路的输出电压正到所述N-MOSFET的漏极之间；
    所述P-MOSFET的栅极接所述第五电阻同第六电阻的连接点，源极接所述DC/DC变换电路的输出电压正；
    所述稳压管的负端接所述DC/DC变换电路 的输出电压正，正端接所述第五电阻同第六电阻的连接点；
    所述N-MOSFET的源极接所述 DC/DC 变换电路的输出电压负，栅极接DC/DC变换电路工作状态电压。
  2. 根据权利要求1所述的DC/DC变换电路的输出电压检测电路，其特征在于，
    所述DC/DC变换电路工作状态电压，在DC/DC变换电路工作时为高电平，在DC/DC变换电路停止工作时为低电平。
  3. 根据权利要求1所述的DC/DC变换电路的输出电压检测电路，其特征在于，
    DC/DC变换电路的输出电压检测电路还包括第一电容；
    所述第一电容，接在所述P-MOSFET的栅极、源极之间。
  4. 根据权利要求3所述的DC/DC变换电路的输出电压检测电路，其特征在于，
    DC/DC变换电路的输出电压检测电路还包括第二电容、第七电阻；
    所述第二电容，接在所述第一电阻同第二电阻的连接点到DC/DC变换电路的输出电压负之间；
    所述第七电阻，接在所述第一电阻同第二电阻的连接点到DC/DC变换电路的输出电压检测电路的检测电压输出端之间。
  5. 根据权利要求3所述的DC/DC变换电路的输出电压检测电路，其特征在于，
    所述DC/DC变换电路为模拟式，模拟式的DC/DC变换电路包括一工作电压输出端， 当DC/DC变换电路 工作时， 工作电压输出端的电压为高电平 ，当DC/DC变换电路停止 工作时， 工作电压输出端的电压为低电平；
    DC/DC变换电路的输出电压检测电路还包括第三电阻和第四电阻；
    第三电阻同第四电阻串接在所述 工作电压输出端到DC/DC变换电路的输出电压负之间，第三电阻同第四电阻的连接点接所述N-MOSFET的栅极；
    所述DC/DC变换电路工作状态电压，为第三电阻同第四电阻的连接点的电压 。
  6. 根据权利要求3所述的DC/DC变换电路的输出电压检测电路，其特征在于，
    所述DC/DC变换电路为数字式，数字式的DC/DC变换电路包括一MCU ，MCU包括一开通信号输出口，当DC/DC变换电路 工作时，MCU的开通信号输出口输出高电平，当DC/DC变换电路停止工作时，MCU的开通信号输出口输出低电平；
    DC/DC变换电路的输出电压检测电路还包括第八电阻；
    所述第八电阻，接在MCU的开通信号输出口到DC/DC变换电路的输出电压负之间，所述MCU的开通信号输出口并同所述N-MOSFET的栅极相接；
    所述DC/DC变换电路工作状态电压，为所述MCU的开通信号输出口的电压 。
PCT/CN2012/087798 2012-10-19 2012-12-28 Dc/dc变换电路的输出电压检测电路 WO2014059736A1 (zh)

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