WO2017020189A1 - Switching mode power supply - Google Patents
- ️Thu Feb 09 2017
本申请涉及电力电子技术领域，更具体地，涉及一种开关电源。The present application relates to the field of power electronics technology, and more particularly to a switching power supply.
背景技术Background technique开关电源(Switching mode power supply)利用脉宽调制(Pulse width modulation)技术控制开关管开通和关断的时间比率来调节输出的电压或电流，用于给不同的负载供应电能。由于其效率高，体积小，控制灵活，在各个领域得到了广泛的应用。The switching mode power supply uses the pulse width modulation technique to control the ratio of the turn-on and turn-off times of the switch to regulate the output voltage or current for supplying power to different loads. Due to its high efficiency, small size and flexible control, it has been widely used in various fields.
在大部分应用场合，开关电源的输出是恒压特性，保持输出电压恒定，其输出电流由负载决定。而在一些领域，如LED照明领域，由于LED负载的光通输出和通过自身的电流成正比，为了维持稳定的光通输出，需要采用直流稳流输出的开关电源实现对于LED负载的驱动。In most applications, the output of the switching power supply is constant voltage, keeping the output voltage constant, and its output current is determined by the load. In some fields, such as LED lighting, since the luminous flux output of the LED load is proportional to the current through itself, in order to maintain a stable luminous flux output, a switching power supply with a DC steady current output is required to drive the LED load.
目前LED照明的趋势正朝着模组化的方向发展，一个开关电源通常能够实现对于多个模组的LED负载的驱动，这就要求所述开关电源能够提供多路的恒流输出以驱动多个模组。At present, the trend of LED lighting is moving toward modularization. A switching power supply can usually drive LED loads for multiple modules, which requires the switching power supply to provide multiple constant current outputs to drive multiple Modules.
现有技术中对于多路输出的设计中，由于要使得各路输出相互独立互不影响，都是采用AC-DC变换器获得直流电压，然后再通过多路DC-DC变换器独立恒流控制。这样使得整体的方案比较复杂，成本较高。In the prior art, for the design of multiple outputs, since the outputs of the respective channels are independent of each other, the AC voltage is obtained by using an AC-DC converter, and then the independent constant current control is performed by the multi-channel DC-DC converter. . This makes the overall solution more complicated and costly.
发明内容Summary of the invention
有鉴于此，本申请提供了一种开关电源，用以解决现有技术中方案复杂和成本高的问题。In view of this, the present application provides a switching power supply to solve the problem of complicated scheme and high cost in the prior art.
为实现所述目的，本申请提供的技术方案如下：To achieve the stated object, the technical solution provided by the present application is as follows:
一种开关电源，应用于多个负载的恒流驱动，所述开关电源包括：A switching power supply for constant current driving of a plurality of loads, the switching power supply comprising:
电压变换单元，用于接收交流输入电压，对所述交流输入电压进行滤波和变换，生成并输出高频交流电压；a voltage conversion unit, configured to receive an AC input voltage, filter and transform the AC input voltage, generate and output a high frequency AC voltage;
输入端均与所述电压变换单元的输出端相连的多个无源开关单元，一个所述无源开关单元的输出端与一个所述负载对应相连；a plurality of passive switching units each connected to an output end of the voltage converting unit, and an output end of one of the passive switching units is correspondingly connected to one of the loads;
所述无源开关单元包括：The passive switch unit includes:
一端为所述无源开关单元的一个输入端的限流电容，用于接收所述高频交 流电压，并对所述高频交流电压的输出电流进行限制；a current limiting capacitor at one end of the passive switching unit for receiving the high frequency Flowing a voltage and limiting an output current of the high frequency alternating voltage;
与所述限流电容的另一端相连的整流电路，用于对所述高频交流电压进行整流；a rectifying circuit connected to the other end of the current limiting capacitor for rectifying the high frequency alternating current voltage;
与所述整流电路并联的滤波电容，并联的两个连接点分别作为所述无源开关单元的输出端，所述滤波电容用于对所述高频交流电压进行滤波，生成并输出恒定的电流至相连接的所述负载。a filter capacitor connected in parallel with the rectifier circuit, two parallel connection points respectively serving as an output end of the passive switch unit, wherein the filter capacitor is used for filtering the high frequency alternating current voltage to generate and output a constant current To the load connected to the phase.
优选的，所述整流电路为全波整流，包括：第一二极管、第二二极管、第三二极管及第四二极管；所述无源开关单元中：Preferably, the rectifier circuit is full-wave rectified, comprising: a first diode, a second diode, a third diode, and a fourth diode; wherein the passive switch unit is:
所述限流电容的一端为所述无源开关单元的一个输入端；One end of the current limiting capacitor is an input end of the passive switching unit;
所述限流电容的另一端与所述第一二极管的阳极及所述第三二极管的阴极相连；The other end of the current limiting capacitor is connected to the anode of the first diode and the cathode of the third diode;
所述第一二极管的阴极与所述第二二极管的阴极相连，连接点与所述滤波电容的一端相连；a cathode of the first diode is connected to a cathode of the second diode, and a connection point is connected to one end of the filter capacitor;
所述第三二极管的阳极与所述第四二极管的阳极相连，连接点与所述滤波电容的另一端相连；An anode of the third diode is connected to an anode of the fourth diode, and a connection point is connected to the other end of the filter capacitor;
所述滤波电容的两端为所述无源开关单元的输出端；Both ends of the filter capacitor are outputs of the passive switch unit;
所述第二二极管的阳极与所述第四二极管的阴极相连，连接点为所述无源开关单元的另一个输入端。The anode of the second diode is connected to the cathode of the fourth diode, and the connection point is the other input terminal of the passive switching unit.
优选的，所述整流电路为半波整流，包括：第五二极管和第六二极管；所述无源开关单元中：Preferably, the rectifier circuit is half-wave rectified, comprising: a fifth diode and a sixth diode; and in the passive switch unit:
所述限流电容的一端为所述无源开关单元的第一输入端；One end of the current limiting capacitor is a first input end of the passive switching unit;
所述限流电容的另一端与所述第五二极管的阴极及所述第六二极管的阳极相连；The other end of the current limiting capacitor is connected to the cathode of the fifth diode and the anode of the sixth diode;
所述第六二极管的阴极与所述滤波电容的一端相连；a cathode of the sixth diode is connected to one end of the filter capacitor;
所述第五二极管的阳极与所述滤波电容的另一端相连；An anode of the fifth diode is connected to another end of the filter capacitor;
所述滤波电容的两端为所述无源开关单元的输出端；Both ends of the filter capacitor are outputs of the passive switch unit;
所述第五二极管的阳极与所述滤波电容的连接点为所述无源开关单元的第二输入端。A connection point of the anode of the fifth diode and the filter capacitor is a second input end of the passive switch unit.
优选的，所述多个无源开关单元两两对称连接于所述电压变换单元的输出 端；其中，每两个对称连接的所述无源开关单元的第一输入端分别与所述电压变换单元的两个输出端相连，每两个对称连接的所述无源开关单元的第二输入端相连。Preferably, the plurality of passive switch units are symmetrically connected to the output of the voltage conversion unit a first input end of each of the two symmetrically connected passive switching units is respectively connected to two output ends of the voltage conversion unit, and a second of each of the two symmetrically connected passive switching units The inputs are connected.
优选的，所述无源开关单元还包括：Preferably, the passive switch unit further includes:
与所述第二二极管及所述第四二极管的串联支路并联的第一开关管；a first switching transistor connected in parallel with the series branch of the second diode and the fourth diode;
阳极与所述第一开关管及所述第二二极管的阴极相连的第七二极管；所述第七二极管的阴极与所述滤波电容相连；a seventh diode connected to the cathode of the first switching transistor and the second diode; a cathode of the seventh diode is connected to the filter capacitor;
输出端与所述第一开关管的控制端相连的控制单元；所述控制单元的一个输入端接收基准信号；a control unit connected to the control end of the first switch tube; an input end of the control unit receives a reference signal;
对流经所述负载的电流进行检测并输出检测信号的电流检测装置，所述电流检测装置的输出端与所述控制单元的另一输入端相连。A current detecting device that detects a current flowing through the load and outputs a detection signal, and an output of the current detecting device is connected to another input terminal of the control unit.
优选的，所述无源开关单元还包括：Preferably, the passive switch unit further includes:
与所述第五二极管并联的第一开关管；a first switching transistor connected in parallel with the fifth diode;
输出端与所述第一开关管的控制端相连的控制单元；所述控制单元的一个输入端接收基准信号；a control unit connected to the control end of the first switch tube; an input end of the control unit receives a reference signal;
对流经所述负载的电流进行检测并输出检测信号的电流检测装置，所述电流检测装置的输出端与所述控制单元的另一输入端相连。A current detecting device that detects a current flowing through the load and outputs a detection signal, and an output of the current detecting device is connected to another input terminal of the control unit.
优选的，所述第一开关管为晶体管、金属-氧化物半导体场效应晶体管MOSFET或者绝缘三双极型功率管IGBT。Preferably, the first switching transistor is a transistor, a metal-oxide semiconductor field effect transistor MOSFET or an insulated three bipolar power transistor IGBT.
优选的，所述电流检测装置为：与所述负载串联连接的电阻；所述电阻与所述负载的连接点为所述电流检测装置的输出端；Preferably, the current detecting device is: a resistor connected in series with the load; a connection point of the resistor and the load is an output end of the current detecting device;
或者所述电流检测装置为：与所述负载串联连接的霍尔传感器；所述霍尔传感器的输出端为所述电流检测装置的输出端；Or the current detecting device is: a Hall sensor connected in series with the load; an output end of the Hall sensor is an output end of the current detecting device;
或者所述电流检测装置为：电流互感器与信号处理电路；所述电流互感器的一次绕组与所述负载串联，所述电流互感器的二次绕组与所述信号处理电路相连，所述信号处理电路的输出端为所述电流检测装置的输出端。Or the current detecting device is: a current transformer and a signal processing circuit; a primary winding of the current transformer is connected in series with the load, and a secondary winding of the current transformer is connected to the signal processing circuit, the signal The output of the processing circuit is the output of the current sensing device.
优选的，所述电压变换单元包括依次串联连接的低通滤波器、PFC稳压器及半桥谐振电路。Preferably, the voltage conversion unit includes a low pass filter, a PFC regulator, and a half bridge resonant circuit that are sequentially connected in series.
优选的，所述低通滤波器为EMI滤波器。 Preferably, the low pass filter is an EMI filter.
优选的，所述PFC稳压器包括：桥式整流桥、第一电感、第二开关管、第八二极管、第三电容及第四电容；其中：Preferably, the PFC regulator includes: a bridge rectifier bridge, a first inductor, a second switch transistor, an eighth diode, a third capacitor, and a fourth capacitor; wherein:
所述桥式整流桥的输入端为所述PFC稳压器的输入端；The input end of the bridge rectifier bridge is an input end of the PFC regulator;
所述第一电感的一端与所述桥式整流桥的输出端相连；所述第一电感的另一端与所述第二开关管的输入端及所述第八二极管的阳极相连；所述第二开关管的输出端接地；One end of the first inductor is connected to an output end of the bridge rectifier bridge; the other end of the first inductor is connected to an input end of the second switch tube and an anode of the eighth diode; The output end of the second switch tube is grounded;
所述第三电容及所述第四电容串联连接于所述第八二极管的阴极与地之间；所述第三电容及所述第四电容的串联支路的两端为所述PFC稳压器的输出端。The third capacitor and the fourth capacitor are connected in series between the cathode of the eighth diode and the ground; the two ends of the series branch of the third capacitor and the fourth capacitor are the PFC The output of the regulator.
优选的，所述半桥谐振电路包括：第三开关管、第四开关管、第二电感、第五电容及变压器；其中：Preferably, the half bridge resonant circuit comprises: a third switch tube, a fourth switch tube, a second inductor, a fifth capacitor and a transformer; wherein:
所述第三开关管的输入端为所述半桥谐振电路的一个输入端；The input end of the third switch tube is an input end of the half bridge resonant circuit;
所述第二电感连接于所述第三开关管的输出端与所述第四开关管的输入端之间；所述第四开关管的输出端接地；The second inductor is connected between the output end of the third switch tube and the input end of the fourth switch tube; the output end of the fourth switch tube is grounded;
所述第五电容的一端与所述第二电感的中点及所述变压器原边绕组的异名端相连；所述第五电容的另一端与所述第三电容和所述第四电容的串联连接点及所述变压器原边绕组的同名端相连；One end of the fifth capacitor is connected to a midpoint of the second inductor and a different end of the transformer primary winding; the other end of the fifth capacitor is opposite to the third capacitor and the fourth capacitor The series connection point is connected to the same name end of the primary winding of the transformer;
所述变压器副边绕组的两端分别为所述半桥谐振电路的输出端。The two ends of the secondary winding of the transformer are respectively the output ends of the half bridge resonant circuit.
优选的，所述半桥谐振电路包括：第三开关管、第四开关管、第三电感、第五电容及变压器；其中：Preferably, the half bridge resonant circuit comprises: a third switch tube, a fourth switch tube, a third inductor, a fifth capacitor and a transformer; wherein:
所述第三电感的第一线圈的同名端为所述半桥谐振电路的一个输入端；The same name end of the first coil of the third inductor is an input end of the half bridge resonant circuit;
所述第三开关管的输入端与所述第三电感的第一线圈的异名端相连；An input end of the third switch tube is connected to a different end of the first coil of the third inductor;
所述第三开关管的输出端与所述第四开关管的输入端相连；An output end of the third switch tube is connected to an input end of the fourth switch tube;
所述第四开关管的输出端与所述第三电感的第二线圈的同名端相连；所述第三电感的第二线圈的异名端接地；An output end of the fourth switch tube is connected to a same end of the second coil of the third inductor; a different end of the second coil of the third inductor is grounded;
所述第五电容的一端与所述第三开关管的输出端、所述第四开关管的输入端及所述变压器原边绕组的异名端相连；所述第五电容的另一端与所述第三电容和所述第四电容的串联连接点及所述变压器原边绕组的同名端相连；One end of the fifth capacitor is connected to an output end of the third switch tube, an input end of the fourth switch tube, and a different name end of the primary winding of the transformer; the other end of the fifth capacitor is Connecting a series connection point of the third capacitor and the fourth capacitor to a terminal of the same name of the primary winding of the transformer;
所述变压器副边绕组的两端分别为所述半桥谐振电路的输出端。 The two ends of the secondary winding of the transformer are respectively the output ends of the half bridge resonant circuit.
由以上可知，本申请提供的开关电源，通过电压变换单元接收交流输入电压，对所述交流输入电压进行滤波和变换，生成并输出高频交流电压；再通过多个无源开关单元接收所述高频交流电压，并对所述高频交流电压进行整流滤波后，生成恒定的电流并分别输出至多个负载；其中，所述无源开关单元中仅通过限流电容、整流电路及滤波电容这些无源器件即可实现对多个所述负载的独立恒流驱动，较通过AC-DC变换器与多路DC-DC变换器实现多路恒流驱动的现有技术而言，系统简单且成本低。It can be seen from the above that the switching power supply provided by the present application receives the AC input voltage through the voltage conversion unit, filters and transforms the AC input voltage, generates and outputs a high frequency AC voltage, and receives the above through a plurality of passive switch units. a high-frequency alternating voltage, and rectifying and filtering the high-frequency alternating current voltage to generate a constant current and outputting to a plurality of loads respectively; wherein the passive switching unit only passes through a current limiting capacitor, a rectifier circuit, and a filter capacitor The passive device can realize independent constant current driving for a plurality of the loads, and the system is simple and cost-effective compared to the prior art that realizes multi-channel constant current driving through an AC-DC converter and a multi-channel DC-DC converter. low.
附图说明DRAWINGS图1为本申请提供的开关电源的结构示意图；1 is a schematic structural view of a switching power supply provided by the present application;
图2为本申请提供的另一开关电源的结构示意图；2 is a schematic structural diagram of another switching power supply provided by the present application;
图3为本申请提供的另一开关电源的结构示意图；3 is a schematic structural diagram of another switching power supply provided by the present application;
图4为本申请提供的开关电源的结构连接示意图；4 is a schematic structural connection diagram of a switching power supply provided by the present application;
图5为本申请提供的开关电源的供电示意图；FIG. 5 is a schematic diagram of power supply of a switching power supply provided by the present application; FIG.
图6为本申请提供的另一开关电源的供电示意图；6 is a schematic diagram of power supply of another switching power supply provided by the present application;
图7为本申请提供的无源开关单元的电路图；7 is a circuit diagram of a passive switch unit provided by the present application;
图8为本申请提供的另一无源开关单元的电路图；FIG. 8 is a circuit diagram of another passive switch unit provided by the present application; FIG.
图9为本申请提供的电压变换单元的结构示意图；9 is a schematic structural diagram of a voltage conversion unit provided by the present application;
图10为本申请提供的电压变换单元的结构示意图。FIG. 10 is a schematic structural diagram of a voltage conversion unit provided by the present application.
具体实施方式detailed description为了进一步了解本发明，下面结合实施例对本发明优选实施方案进行描述，但是应当理解，这些描述只是为进一步说明本发明的特征和优点，而不是对本发明权利要求的限制。In order to further understand the present invention, the preferred embodiments of the present invention are described in the accompanying drawings.
本申请提供了一种开关电源，应用于多个负载的恒流驱动，用以解决现有技术中方案复杂和成本高的问题。The present application provides a switching power supply that is applied to constant current driving of a plurality of loads to solve the problems of the complicated scheme and high cost in the prior art.
具体的，如图1所示，所述开关电源包括：Specifically, as shown in FIG. 1, the switching power supply includes:
电压变换单元101； Voltage conversion unit 101;
输入端均与电压变换单元101的输出端相连的多个无源开关单元102，一个无源开关单元102的输出端与一个所述负载对应相连；a plurality of passive switching units 102 each connected to an output end of the voltage converting unit 101, and an output end of a passive switching unit 102 is correspondingly connected to one of the loads;
无源开关单元102包括： The passive switch unit 102 includes:
一端为无源开关单元102的一个输入端的限流电容；One end is a current limiting capacitor of one input end of the passive switching unit 102;
与所述限流电容的另一端相连的整流电路；a rectifier circuit connected to the other end of the current limiting capacitor;
与所述整流电路并联的滤波电容，并联的两个连接点分别作为所述无源开关单元的输出端。A filter capacitor connected in parallel with the rectifier circuit has two connection points connected in parallel as an output end of the passive switch unit.
具体的工作原理为：The specific working principle is:
电压变换单元101接收交流输入电压，对所述交流输入电压进行滤波和变换，生成并输出高频交流电压；The voltage conversion unit 101 receives an AC input voltage, filters and transforms the AC input voltage, generates and outputs a high frequency AC voltage;
无源开关单元102中，所述限流电容用于接收所述高频交流电压，并对所述高频交流电压的输出电流进行限制；所述整流电路用于对所述高频交流电压进行整流；所述滤波电容用于对所述高频交流电压进行滤波，生成并输出恒定的电流至相连接的所述负载。多个无源开关单元102分别接收所述高频交流电压，并对所述高频交流电压进行整流滤波后，生成并输出恒定的电流至相连接的所述负载。In the passive switch unit 102, the current limiting capacitor is configured to receive the high frequency alternating current voltage and limit an output current of the high frequency alternating current voltage; the rectifier circuit is configured to perform the high frequency alternating current voltage The rectifying capacitor is configured to filter the high frequency alternating current voltage to generate and output a constant current to the connected load. The plurality of passive switching units 102 respectively receive the high-frequency alternating voltage, and after rectifying and filtering the high-frequency alternating voltage, generate and output a constant current to the connected load.
无源开关单元102中包括的所述限流电容、所述整流电路及所述滤波电容均为无源器件。The current limiting capacitor, the rectifier circuit and the filter capacitor included in the passive switch unit 102 are passive devices.
本实施例所述的开关电源通过电压变换单元101获得高频交流电压；然后多个无源开关单元102中仅通过所述限流电容、所述整流电路及所述滤波电容这些无源器件即可实现对多个所述负载的独立恒流驱动，较通过AC-DC变换器与多路DC-DC变换器实现多路恒流驱动的现有技术而言，系统简单且成本低。The switching power supply of the embodiment obtains a high-frequency AC voltage through the voltage conversion unit 101; then, the passive components of the plurality of passive switching units 102 pass only the current limiting capacitor, the rectifier circuit, and the filter capacitor. Independent constant current driving for a plurality of said loads can be realized, and the system is simple and low in cost compared to the prior art in which multi-channel constant current driving is realized by an AC-DC converter and a multi-channel DC-DC converter.
值得说明的是，在具体的实际应用中，当所述开关电源需要驱动的所述负载为一个时，无源开关单元102也可以为一个；通过所述限流电容、所述整流电路及所述滤波电容，同样可以实现对所述负载的恒流驱动；无源开关单元102的个数视需要驱动的所述负载的个数而定，此处不做具体限定，均在本申请的保护范围内。It should be noted that, in a specific practical application, when the load required to be driven by the switching power supply is one, the passive switch unit 102 may also be one; through the current limiting capacitor, the rectifier circuit, and the The filter capacitor can also implement constant current driving for the load; the number of the passive switch units 102 depends on the number of the loads to be driven, and is not specifically limited herein, and is protected in the present application. Within the scope.
优选的，如图2所示，无源开关单元102中的所述整流电路为全波整流，包括：第一二极管D1、第二二极管D2、第三二极管D3及第四二极管D4；无源开关单元102中： Preferably, as shown in FIG. 2, the rectifier circuit in the passive switch unit 102 is full-wave rectified, including: a first diode D1, a second diode D2, a third diode D3, and a fourth Diode D4; in the passive switch unit 102:
限流电容C1的一端为无源开关单元102的一个输入端；One end of the current limiting capacitor C1 is an input end of the passive switching unit 102;
限流电容C1的另一端与第一二极管D1的阳极及第三二极管D3的阴极相连；The other end of the current limiting capacitor C1 is connected to the anode of the first diode D1 and the cathode of the third diode D3;
第一二极管D1的阴极与第二二极管D2的阴极相连，连接点与滤波电容C2的一端相连；The cathode of the first diode D1 is connected to the cathode of the second diode D2, and the connection point is connected to one end of the filter capacitor C2;
第三二极管D3的阳极与第四二极管D4的阳极相连，连接点与滤波电容C2的另一端相连；The anode of the third diode D3 is connected to the anode of the fourth diode D4, and the connection point is connected to the other end of the filter capacitor C2;
滤波电容C2的两端为无源开关单元102的输出端；Both ends of the filter capacitor C2 are the output ends of the passive switch unit 102;
第二二极管D2的阳极与第四二极管D4的阴极相连，连接点为无源开关单元102的另一个输入端。The anode of the second diode D2 is connected to the cathode of the fourth diode D4, and the connection point is the other input terminal of the passive switching unit 102.
当无源开关单元102接收的所述高频交流电压为信号正半周时，电流流经限流电容C1和第一二极管D1，为所述负载供电，再通过第四二极管D4流出。当无源开关单元102接收的所述高频开关电源为信号负半周时，电流流经第二二极管D2为所述负载供电，再通过第三二极管D3和限流电容C1流出。滤波电容C2用于滤除所述高频交流电压的高频成分，使所述负载得到平滑的直流。When the high frequency alternating current voltage received by the passive switching unit 102 is a positive half cycle of the signal, the current flows through the current limiting capacitor C1 and the first diode D1 to supply power to the load, and then flows out through the fourth diode D4. . When the high frequency switching power supply received by the passive switching unit 102 is a signal negative half cycle, current flows through the second diode D2 to supply power to the load, and then flows out through the third diode D3 and the current limiting capacitor C1. The filter capacitor C2 is used to filter out high frequency components of the high frequency alternating voltage, so that the load obtains a smooth direct current.
如图2所示，无源开关单元102接收的所述高频交流电压为UTS，流经所述负载的恒定电流为IL，所述负载电压为UL+△UL，其中△UL为不同的负载造成的电压变化，忽略二极管的导通压降，限流电容C1的容抗为ZC1，可以得到下面的关系：As shown in FIG. 2, the high frequency alternating current voltage received by the passive switching unit 102 is U TS , the constant current flowing through the load is I L , and the load voltage is U L +ΔU L , where ΔU L is the voltage change caused by different loads, ignoring the conduction voltage drop of the diode. The capacitive reactance of the current limiting capacitor C1 is Z C1 , and the following relationship can be obtained:
如果不同的负载造成的电压变化△UL在相对高频交流电压UTS比较小的范围，流经所述负载的恒定电流为IL就可以保持基本恒定。If the voltage change ΔU L caused by the different loads is relatively small in the relatively high-frequency AC voltage U TS , the constant current flowing through the load is I L and can be kept substantially constant.
或者，如图3所示，所述整流电路为半波整流，包括：第五二极管D5和第六二极管D6；无源开关单元102中：Alternatively, as shown in FIG. 3, the rectifier circuit is half-wave rectified, comprising: a fifth diode D5 and a sixth diode D6; and in the passive switch unit 102:
限流电容C1的一端为无源开关单元102的第一输入端；One end of the current limiting capacitor C1 is a first input end of the passive switching unit 102;
限流电容C1的另一端与第五二极管D5的阴极及第六二极管D6的阳极相连； The other end of the current limiting capacitor C1 is connected to the cathode of the fifth diode D5 and the anode of the sixth diode D6;
第六二极管D6的阴极与滤波电容C2的一端相连；a cathode of the sixth diode D6 is connected to one end of the filter capacitor C2;
第五二极管D5的阳极与滤波电容C2的另一端相连；The anode of the fifth diode D5 is connected to the other end of the filter capacitor C2;
滤波电容C2的两端为无源开关单元102的输出端；Both ends of the filter capacitor C2 are the output ends of the passive switch unit 102;
第五二极管D5的阳极与滤波电容C2的连接点为无源开关单元102的第二输入端。The junction of the anode of the fifth diode D5 and the filter capacitor C2 is the second input of the passive switch unit 102.
当无源开关单元102接收的所述高频交流电压为信号正半周时，电流流经限流电容C1和第六二极管D6，为所述负载供电。当无源开关单元102接收的所述高频开关电源为信号负半周时，电流流经第五二极管D5和限流电容C1，并不通过所述负载，为无功电流。所述负载由滤波电容C2供电。滤波电容C2用于滤除所述高频交流电压的高频成分，使所述负载得到平滑的直流。When the high frequency alternating current voltage received by the passive switching unit 102 is a positive half cycle of the signal, current flows through the current limiting capacitor C1 and the sixth diode D6 to supply power to the load. When the high frequency switching power supply received by the passive switching unit 102 is a signal negative half cycle, the current flows through the fifth diode D5 and the current limiting capacitor C1, and does not pass the load, and is a reactive current. The load is powered by a filter capacitor C2. The filter capacitor C2 is used to filter out high frequency components of the high frequency alternating voltage, so that the load obtains a smooth direct current.
如图3所示，无源开关单元102接收的所述高频交流电压为UTS，流经所述负载的恒定电流为IL，所述负载电压为UL+△UL，其中△UL为不同的负载造成的电压变化，忽略二极管的导通压降，限流电容C1的容抗为ZC1，可以得到下面的关系：3, the high-frequency AC voltage is received by a passive switching unit 102 is U TS, the constant current flowing through the load is I L, the load voltage U L + △ U L, where △ U L is the voltage change caused by different loads, ignoring the conduction voltage drop of the diode. The capacitive reactance of the current limiting capacitor C1 is Z C1 , and the following relationship can be obtained:
公式中分母部分的2是由于在半波整流的模式下只有正半周的电流供应到了负载端。The 2 of the denominator part of the formula is due to the fact that only a positive half cycle of current is supplied to the load terminal in the half wave rectification mode.
如果不同的负载造成的电压变化△UL在相对高频交流电压UTS比较小的范围，流经所述负载的恒定电流为IL就可以保持基本恒定。If the voltage change ΔU L caused by the different loads is relatively small in the relatively high-frequency AC voltage U TS , the constant current flowing through the load is I L and can be kept substantially constant.
优选的，如图4、图5和图6所示，多个无源开关单元102两两对称连接于电压变换单元101的输出端；其中，每两个对称连接的无源开关单元102的第一输入端分别与电压变换单元101的两个输出端相连，每两个对称连接的无源开关单元102的第二输入端相连。Preferably, as shown in FIG. 4, FIG. 5 and FIG. 6, a plurality of passive switch units 102 are symmetrically connected to the output end of the voltage conversion unit 101; wherein, each of the two symmetrically connected passive switch units 102 An input terminal is connected to the two output terminals of the voltage conversion unit 101, and the second input terminals of each of the two symmetrically connected passive switch units 102 are connected.
如图4所示，负载1和负载2以一种对称的结构和电压变换单元101的输出端连接。当所述高频交流电压为正半周时，电流通过如图5所示的回路，流经与所述负载1相连的无源开关单元102中的限流电容C1和第六二极管D6为所述负载1供电.当所述高频交流电压为负半周时，电流通过如图6所示的 回路，流经与所述负载2相连的无源开关单元102中的限流电容C1和第六二极管D6为所述负载2供电。通过这样的对称结构，可以大大的降低无功电流，在所述负载1和所述负载2相等的情况下，回路里没有无功电流。As shown in FIG. 4, the load 1 and the load 2 are connected in a symmetrical structure to the output of the voltage conversion unit 101. When the high frequency alternating current voltage is a positive half cycle, the current flows through the loop as shown in FIG. 5, and the current limiting capacitor C1 and the sixth diode D6 in the passive switching unit 102 connected to the load 1 are The load 1 is powered. When the high frequency alternating current voltage is negative half cycle, the current passes through as shown in FIG. A loop through which the current limiting capacitor C1 and the sixth diode D6 in the passive switching unit 102 connected to the load 2 supplies power to the load 2. With such a symmetrical structure, the reactive current can be greatly reduced, and in the case where the load 1 and the load 2 are equal, there is no reactive current in the loop.
优选的，无源开关单元102中的所述整流电路为全波整流时，在图2的基础上，无源开关单元102如图7所示，还包括：Preferably, when the rectifying circuit in the passive switching unit 102 is full-wave rectification, on the basis of FIG. 2, the passive switching unit 102, as shown in FIG. 7, further includes:
与第二二极管D2及第四二极管D4的串联支路并联的第一开关管S1；a first switching transistor S1 connected in parallel with the series branch of the second diode D2 and the fourth diode D4;
阳极与第一开关管S1及第二二极管D2的阴极相连的第七二极管D7；第七二极管D7的阴极与滤波电容C2相连；a seventh diode D7 whose anode is connected to the cathodes of the first switching transistor S1 and the second diode D2; a cathode of the seventh diode D7 is connected to the filter capacitor C2;
输出端与第一开关管S1的控制端相连的控制单元200；控制单元200的一个输入端接收基准信号；a control unit 200 whose output is connected to the control end of the first switch S1; an input of the control unit 200 receives a reference signal;
对流经所述负载的电流进行检测并输出检测信号的电流检测装置300，电流检测装置300的输出端与控制单元200的另一输入端相连。A current detecting device 300 that detects a current flowing through the load and outputs a detection signal, and an output of the current detecting device 300 is connected to another input terminal of the control unit 200.
优选的，无源开关单元102中的所述整流电路为半波整流时，在图3的基础上，无源开关单元102如图8所示，还包括：Preferably, when the rectifying circuit in the passive switching unit 102 is half-wave rectified, on the basis of FIG. 3, the passive switching unit 102 is as shown in FIG.
与第五二极管D5并联的第一开关管S1；a first switch tube S1 connected in parallel with the fifth diode D5;
输出端与第一开关管S1的控制端相连的控制单元200；控制单元200的一个输入端接收基准信号；a control unit 200 whose output is connected to the control end of the first switch S1; an input of the control unit 200 receives a reference signal;
对流经所述负载的电流进行检测并输出检测信号的电流检测装置300，电流检测装置300的输出端与控制单元200的另一输入端相连。A current detecting device 300 that detects a current flowing through the load and outputs a detection signal, and an output of the current detecting device 300 is connected to another input terminal of the control unit 200.
其中，第一开关管S1可以为晶体管、MOSFET或者IGBT。The first switch S1 may be a transistor, a MOSFET or an IGBT.
从上面的公式(2)可以看到，当不同的负载造成的电压变化△UL比较小时，流经所述负载的恒定电流为就可以保持基本恒定。但是如果需要在不同的负载造成的电压变化△UL较大的情况下保持恒定电流输出的话，可以进一步在每一个无源开关单元102内加入一个主动开关来调节电流，如图7或图8所示，一个主动开关器件(第一开关管S1)并联在限流电容C1之后，当第一开关管S1关断时，电流正常流入所述负载。当第一开关管S1闭合时，电流通过第一开关管S1直接回到电压变换单元101的输出端，成为了无功电流。所以通过调节第一开关管S1开通与关断的比例可以控制从电压变换单元101的输出端流 入的电流的有功和无功的比例。It can be seen from the above formula (2) that when the voltage change ΔU L caused by the different loads is relatively small, the constant current flowing through the load can be kept substantially constant. However, if it is required to maintain a constant current output under a large voltage change ΔU L caused by different loads, an active switch can be further added to each of the passive switching units 102 to adjust the current, as shown in FIG. 7 or FIG. As shown, an active switching device (first switching transistor S1) is connected in parallel after the current limiting capacitor C1, and when the first switching transistor S1 is turned off, current flows into the load normally. When the first switch S1 is closed, the current directly returns to the output end of the voltage conversion unit 101 through the first switch S1, and becomes a reactive current. Therefore, the ratio of the active and reactive power of the current flowing from the output terminal of the voltage converting unit 101 can be controlled by adjusting the ratio of the opening and closing of the first switching transistor S1.
电流检测装置300可以为：与所述负载串联连接的电阻；所述电阻与所述负载的连接点为电流检测装置300的输出端；The current detecting device 300 may be: a resistor connected in series with the load; a connection point of the resistor and the load is an output end of the current detecting device 300;
或者为：与所述负载串联连接的霍尔传感器；所述霍尔传感器的输出端为电流检测装置300的输出端；Or a Hall sensor connected in series with the load; an output end of the Hall sensor is an output end of the current detecting device 300;
或者为：电流互感器与信号处理电路；所述电流互感器的一次绕组与所述负载串联，所述电流互感器的二次绕组与所述信号处理电路相连，所述信号处理电路的输出端为电流检测装置300的输出端。Or a current transformer and a signal processing circuit; a primary winding of the current transformer is connected in series with the load, a secondary winding of the current transformer is connected to the signal processing circuit, and an output end of the signal processing circuit It is the output of the current detecting device 300.
电流检测装置300与所述负载串联，用于对流经所述负载的电流进行检测并输出检测信号；但是电流检测装置300的位置并不限于所述负载所在的回路，也可以是和第六二极管D6或者第七二极管D7串联，只要能检测出流经所述负载的电流信号，并转换为控制单元200可以接收的信号即可。The current detecting device 300 is connected in series with the load for detecting a current flowing through the load and outputting a detection signal; however, the position of the current detecting device 300 is not limited to the circuit in which the load is located, and may be the sixth and second The pole tube D6 or the seventh diode D7 are connected in series as long as the current signal flowing through the load can be detected and converted into a signal that the control unit 200 can receive.
再由控制单元200通过负反馈控制，采用脉宽调制(PWM)控制第一开关管S1的开通占空比，可以使所述负载上的电流达到预设的数值，进而在不同的负载造成的电压变化△UL较大的情况下实现对流经所述负载的电流的精确控制，保持恒定电流输出。Then, the control unit 200 controls the turn-on duty ratio of the first switch S1 by pulse width modulation (PWM) through the negative feedback control, so that the current on the load can reach a preset value, and thus is caused by different loads. Accurate control of the current flowing through the load is achieved with a large voltage change ΔU L , maintaining a constant current output.
本发明另一实施例还提供了另外一种开关电源，如图1所示，包括：Another embodiment of the present invention further provides another switching power supply, as shown in FIG. 1, comprising:
电压变换单元101； Voltage conversion unit 101;
多个无源开关单元102，多个无源开关单元102的输入端均与电压变换单元101的输出端相连，一个无源开关单元102的输出端与一个所述负载对应相连；a plurality of passive switching units 102, the input ends of the plurality of passive switching units 102 are connected to the output end of the voltage converting unit 101, and the output end of a passive switching unit 102 is connected to one of the loads;
无源开关单元102包括限流电容、整流电路及滤波电容；其具体的实现形式可以参见上述任一实施例。The passive switch unit 102 includes a current limiting capacitor, a rectifier circuit, and a filter capacitor. For a specific implementation, refer to any of the above embodiments.
优选的，电压变换单元101如图9所示，包括：依次串联连接的低通滤波器111、PFC稳压器112及半桥谐振电路113。Preferably, as shown in FIG. 9, the voltage conversion unit 101 includes a low pass filter 111, a PFC regulator 112, and a half bridge resonance circuit 113 which are sequentially connected in series.
其中，低通滤波器111为EMI滤波器。Among them, the low pass filter 111 is an EMI filter.
PFC稳压器112包括：桥式整流桥、第一电感L1、第二开关管Q2、第七二极管D7、第三电容C3及第四电容C4；其中： The PFC regulator 112 includes: a bridge rectifier bridge, a first inductor L1, a second switch transistor Q2, a seventh diode D7, a third capacitor C3, and a fourth capacitor C4; wherein:
所述桥式整流桥的输入端为PFC稳压器112的输入端；The input end of the bridge rectifier bridge is an input end of the PFC regulator 112;
第一电感L1的一端与所述桥式整流桥的输出端相连；第一电感L1的另一端与第二开关管Q2的输入端及第七二极管D7的阳极相连；第二开关管Q2的输出端接地；One end of the first inductor L1 is connected to the output end of the bridge rectifier bridge; the other end of the first inductor L1 is connected to the input end of the second switch tube Q2 and the anode of the seventh diode D7; the second switch tube Q2 The output is grounded;
第三电容C3及第四电容C4串联连接于第七二极管D7的阴极与地之间；第三电容C3及第四电容C4的串联支路的两端为PFC稳压器112的输出端。The third capacitor C3 and the fourth capacitor C4 are connected in series between the cathode of the seventh diode D7 and the ground; the two ends of the series branch of the third capacitor C3 and the fourth capacitor C4 are the output ends of the PFC regulator 112. .
半桥谐振电路113包括：第三开关管Q3、第四开关管Q4、第二电感L2、第五电容C5及变压器T；其中：The half bridge resonant circuit 113 includes: a third switching transistor Q3, a fourth switching transistor Q4, a second inductor L2, a fifth capacitor C5, and a transformer T; wherein:
第三开关管Q3的输入端为半桥谐振电路113的一个输入端；The input end of the third switching transistor Q3 is an input end of the half bridge resonant circuit 113;
第二电感L2连接于第三开关管Q3的输出端与第四开关管Q4的输入端之间；第四开关管Q4的输出端接地；The second inductor L2 is connected between the output end of the third switch tube Q3 and the input end of the fourth switch tube Q4; the output end of the fourth switch tube Q4 is grounded;
第五电容C5的一端与第二电感L2的中点及变压器T原边绕组的异名端相连；第五电容C5的另一端与第三电容C3和第四电容C4的串联连接点及变压器T原边绕组的同名端相连；One end of the fifth capacitor C5 is connected to the midpoint of the second inductor L2 and the different end of the transformer T primary winding; the other end of the fifth capacitor C5 is connected to the series connection point of the third capacitor C3 and the fourth capacitor C4 and the transformer T The same name end of the primary winding is connected;
变压器T副边绕组的两端分别为半桥谐振电路113的输出端。Both ends of the secondary winding of the transformer T are respectively the output ends of the half bridge resonant circuit 113.
交流输入电压经过所述EMI滤波器、所述桥式整流桥之后，再经过第一电感L1、第七二极管D7和第二开关管Q2组成的boost电路，在第三电容C3及第四电容C4(两个电解电容)上产生400V左右的直流电压。After the AC input voltage passes through the EMI filter and the bridge rectifier bridge, the boost circuit consists of the first inductor L1, the seventh diode D7 and the second switch transistor Q2, and the third capacitor C3 and the fourth capacitor A DC voltage of about 400V is generated across the capacitor C4 (two electrolytic capacitors).
第三开关管Q3和第四开关管Q4组成了半桥电路，第五电容C5及变压器T构成了LC谐振网络，并在变压器T的副边隔离输出高频交流电压。由于第二电感L2的存在，使得半桥电路的输出特性接近于电流源。变压器T输出的高频交流电压的频率由第三开关管Q3和第四开关管Q4的开关频率决定。The third switch tube Q3 and the fourth switch tube Q4 form a half bridge circuit, and the fifth capacitor C5 and the transformer T constitute an LC resonance network, and the high frequency AC voltage is isolated and output on the secondary side of the transformer T. Due to the presence of the second inductance L2, the output characteristics of the half bridge circuit are close to the current source. The frequency of the high-frequency AC voltage output by the transformer T is determined by the switching frequency of the third switching transistor Q3 and the fourth switching transistor Q4.
在具体的实际应用中，第二开关管Q2的控制信号可以来自于如图9所示的L6562，即PFC稳压器112的内部信号；第三开关管Q3和第四开关管Q4的控制信号可以来自第二电感L2的辅助绕组，具体的实现形式此处不做具体限定，视其应用环境而定即可，均在本申请的保护范围内。In a specific practical application, the control signal of the second switching transistor Q2 may be from L6562 as shown in FIG. 9, that is, the internal signal of the PFC regulator 112; the control signals of the third switching transistor Q3 and the fourth switching transistor Q4. The auxiliary winding may be from the second inductor L2. The specific implementation is not limited herein, and may be within the scope of protection of the present application.
或者，如图10所示，半桥谐振电路113包括：第三开关管Q3、第四开关管Q4、第三电感、第五电容C5及变压器T；其中：Alternatively, as shown in FIG. 10, the half bridge resonant circuit 113 includes: a third switching transistor Q3, a fourth switching transistor Q4, a third inductor, a fifth capacitor C5, and a transformer T; wherein:
第三电感的第一线圈L3-1的同名端为半桥谐振电路113的一个输入端； The same name end of the first coil L3-1 of the third inductor is an input end of the half bridge resonant circuit 113;
第三开关管Q3的输入端与第三电感的第一线圈L3-1的异名端相连；The input end of the third switch tube Q3 is connected to the different end of the first coil L3-1 of the third inductor;
第三开关管Q3的输出端与第四开关管Q4的输入端相连；The output end of the third switch tube Q3 is connected to the input end of the fourth switch tube Q4;
第四开关管Q4的输出端与第三电感的第二线圈L3-2的同名端相连；第三电感的第二线圈L3-2的异名端接地；The output end of the fourth switch tube Q4 is connected to the same end of the second coil L3-2 of the third inductor; the second end of the second inductor L3-2 of the third inductor is grounded;
第五电容C5的一端与第三开关管Q3的输出端、第四开关管Q4的输入端及变压器T原边绕组的异名端相连；第五电容C5的另一端与第三电容C3和第四电容C4的串联连接点及变压器T原边绕组的同名端相连；One end of the fifth capacitor C5 is connected to the output end of the third switch tube Q3, the input end of the fourth switch tube Q4, and the different end of the transformer T primary winding; the other end of the fifth capacitor C5 and the third capacitor C3 and the The series connection point of the four capacitor C4 is connected to the same name end of the primary winding of the transformer T;
变压器T副边绕组的两端分别为半桥谐振电路113的输出端。Both ends of the secondary winding of the transformer T are respectively the output ends of the half bridge resonant circuit 113.
电压变换单元101的具体实现形式也不做具体限定，只要能够接收并对所述交流输入电压进行滤波和变换，生成并输出所述高频交流电压即可，可以视其应用环境而定，均在本申请的保护范围内。The specific implementation form of the voltage conversion unit 101 is not specifically limited, as long as it can receive and filter and convert the AC input voltage, and generate and output the high-frequency AC voltage, which may be determined according to the application environment. Within the scope of protection of this application.
本说明书中各个实施例采用递进的方式描述，每个实施例重点说明的都是与其他实施例的不同之处，各个实施例之间相同相似部分互相参见即可。The various embodiments in the present specification are described in a progressive manner, and each embodiment focuses on differences from other embodiments, and the same similar parts between the various embodiments may be referred to each other.
对所公开的实施例的上述说明，使本领域专业技术人员能够实现或使用本发明。对这些实施例的多种修改对本领域的专业技术人员来说将是显而易见的，本文中所定义的一般原理可以在不脱离本发明的精神或范围的情况下，在其它实施例中实现。因此，本发明将不会被限制于本文所示的这些实施例，而是要符合与本文所公开的原理和新颖特点相一致的最宽的范围。 The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments are obvious to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but the scope of the invention is to be accorded