CN103427643A - Control circuit of buck-boost drive circuit and control method thereof - Google Patents
Control circuit of buck-boost drive circuit and control method thereof Download PDFInfo
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- CN103427643A CN103427643A CN2013104023703A CN201310402370A CN103427643A CN 103427643 A CN103427643 A CN 103427643A CN 2013104023703 A CN2013104023703 A CN 2013104023703A CN 201310402370 A CN201310402370 A CN 201310402370A CN 103427643 A CN103427643 A CN 103427643A
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Abstract
The invention discloses a buck-boost drive circuit. The buck-boost drive circuit comprises an input voltage source providing input voltage, an energy transmission unit coupled with the input voltage source and providing electric power for a load circuit, a switching circuit coupled with the energy transmission unit, a fly-wheel diode providing follow current for the energy transmission unit and an output capacitor. The buck-boost drive circuit is characterized by further comprising a control circuit which is used for controlling the switching circuit coupled with the energy transmission unit and the input voltage source so that electricity passing through the load circuit can be controlled.
Description
Technical field
The present invention relates to the drive circuit field, relate in particular to a kind of control circuit and control method of buck-boost type drive circuit.
Background technology
Drive circuit commonly used comprises the constant-pressure type drive circuit, and the constant-current type drive circuit.The purpose of constant-pressure type drive circuit is to provide a constant voltage do not changed with input supply voltage and output load current to load circuit; The purpose of constant-current type drive circuit be to provide one not with the constant current of input supply voltage and output loading change in voltage to load circuit.Drive circuit commonly used, according to the different situations of the voltage of the voltage of input voltage source and output loading, can adopt booster type (Boost) circuit structure, voltage-dropping type (Buck) circuit structure, buck-boost type (Buck-boost) circuit structure.The booster type circuit structure is mainly used in, and in the scope of whole load voltage, output loading voltage is all higher than the situation of input supply voltage; The step-down circuit structure is mainly used in, and in the scope of whole load voltage, output loading voltage is all lower than the situation of input supply voltage; The buck-boost type circuit structure is mainly used in, and in the scope of whole load voltage, output loading voltage both can be lower than input supply voltage, also can be higher than the situation of input supply voltage.So the buck-boost type circuit structure is compared hoist die mould circuit structure and step-down circuit structure and is had range of application widely.But the control circuit more complicated due to the buck-boost type circuit structure, traditional buck-boost type circuit is difficult to meet load circuit to its output voltage precision or the requirement of output current precision, so, in the Practical Project circuit, the buck-boost type circuit structure does not obtain using comparatively widely.
The shortcoming of summing up existing buck drive circuit is: driving circuit structure complexity, output current precision or the output voltage precision is difficult to meet application requirements.
Summary of the invention
In order to solve the shortcoming of existing buck-boost type drive circuit, the present invention proposes a kind of buck-boost type driving circuit structure and control circuit, adopts output voltage or the output current of the drive circuit of this scheme can obtain controlling comparatively accurately.A kind of buck-boost type drive circuit according to one embodiment of the invention, comprise the input voltage source that input voltage is provided; The Energy Transfer unit coupled with input voltage source, for load circuit provides electric power; The switching circuit coupled with the Energy Transfer unit; For the Energy Transfer unit provides fly-wheel diode and the output capacitance of afterflow; It is characterized in that, described buck-boost type drive circuit also comprises a control circuit, for controlling the switching circuit coupled with Energy Transfer unit and input voltage source, thereby controls the electric power of the load circuit of flowing through.
Preferably, the control circuit of described buck-boost type drive circuit comprises: current detection circuit, and for when described switching circuit switches on and off, the electric current that all provides indication to flow through described switching circuit, and output electric current measure signal; Sample circuit, with described load circuit coupled in series, and the output sampled signal relevant to electric current on load circuit; Switch disconnects control circuit, couples with described current detection signal, sampled signal and the first reference voltage, and exports a reset signal; Zero current detecting circuit, the zero current moment point of detected energy transmission unit, and export an asserts signal; Pulse width modulation circuit, couple with described asserts signal and reset signal, and export a pulse width modulating signal control switch circuit and switch on and off, and the current constant maintained on load circuit of take is the desired value of setting; Wherein, the reference ground of the reference of buck-boost type drive circuit ground and control circuit is not same with reference to ground.
Preferably, the control circuit of described buck-boost type drive circuit comprises: current detection circuit, and for when described switching circuit switches on and off, the electric current that all provides indication to flow through described switching circuit, and output electric current measure signal; Sample circuit, with described load circuit coupled in parallel, and the output sampled signal relevant to voltage on load circuit; Switch disconnects control circuit, couples with described current detection signal, sampled signal and the first reference voltage, and exports a reset signal; Zero current detecting circuit, the zero current moment point of detected energy transmission unit, and export an asserts signal; Pulse width modulation circuit, couple with described asserts signal and reset signal, and export a pulse width modulating signal control switch circuit and switch on and off, and the voltage constant maintained on load circuit of take is the desired value of setting; Wherein, the reference ground of the reference of buck-boost type drive circuit ground and control circuit is not same with reference to ground.
Preferably, the input voltage that the input voltage source of described buck-boost type drive circuit provides comprises: the direct voltage of the direct voltage of AC-DC converter output, DC-to-DC converter output or alternating voltage be the direct voltage after rectifier bridge directly.
Preferably, the switch of the switching circuit of described buck-boost type drive circuit is comprised of field-effect transistor (FET) or bipolar transistor (BJT).
Preferably, the Energy Transfer unit of described buck-boost type drive circuit is an inductance or a transformer.
Preferably, switching circuit first end and the input voltage source of described buck-boost type drive circuit couple, and the second end and current detection circuit couple, and the pulse width modulating signal of the 3rd end and control circuit output couples; The common node of the other end of current detection circuit and Energy Transfer unit, output capacitance, sample circuit couples; Described common node is also the reference ground of control circuit; The other end and the fly-wheel diode of Energy Transfer unit couple, the reference ground that the common node of Energy Transfer unit and fly-wheel diode is described buck-boost type drive circuit; The common port of the other end of fly-wheel diode and output capacitance, load circuit couples; The other end and the sample circuit of load circuit couple.
Preferably, switching circuit first end and the input voltage source of described buck-boost type drive circuit couple, and the second end and current detection circuit couple, and the pulse width modulating signal of the 3rd end and control circuit output couples; The common node of the other end of current detection circuit and Energy Transfer unit, output capacitance, sample circuit, load circuit couples; Described common node is also the reference ground of control circuit; The other end and the fly-wheel diode of Energy Transfer unit couple, the reference ground that the common node of Energy Transfer unit and fly-wheel diode is described buck-boost type drive circuit; The common port of the other end of fly-wheel diode and output capacitance, load circuit, sample circuit couples.
Preferably, be the reference of described control circuit the common node of Energy Transfer unit and current detection circuit, or the common node of current detection circuit and switching circuit.
Preferably, the current detection circuit of described control circuit is coupled in series on the current path of switching circuit, and one end and switching circuit couple, and the other end and Energy Transfer unit couple, comprise,
One current sense resistor, the electric current that flows through switching circuit flows through described resistance, and exports the current detection signal of indicator cock circuit transient current on described current sense resistor.
Preferably, the sample circuit of described control circuit and load circuit coupled in series, comprise
The first sample resistance, the load current that flows through load circuit flows through described the first sample resistance, and exports the sampled signal of indication load circuit transient current and average current on described the first sample resistance.
Preferably, the sample circuit of described control circuit and load circuit coupled in parallel, comprise
The second sample resistance and the 3rd sample resistance, load voltage on the second sample resistance and the 3rd sample resistance proportional sampling load circuit, and on the common node of the second sample resistance and the 3rd sample resistance, the sampled signal of output indication load circuit instantaneous voltage and average voltage.
Preferably, the switch of described control circuit disconnects control circuit and comprises,
Averaging circuit, couple with described sampled signal and the first reference voltage, and the output average value signal;
Comparison circuit, couple with described current detection signal and average value signal, and the output reset signal.
Preferably, the averaging circuit that described switch disconnects control circuit comprises error amplifier, and the error intergal electric capacity of its output, and the in-phase input end of described error amplifier and the first reference voltage couple, inverting input and described sampled signal couple, and it is output as average value signal; The output of error intergal electric capacity one end and error amplifier couples, and couples to the reference of the other end and control circuit.
Preferably, the comparison circuit that described switch disconnects control circuit comprises the first comparator, the current detection signal of its in-phase input end and current detection circuit output couples, inverting input and described average value signal couple, output output reset signal, when described current detection signal is more than or equal to average value signal, reset signal is logic high, otherwise, be logic low.
Preferably, the switch of described control circuit disconnects control circuit and comprises,
Averaging circuit, couple with described sampled signal and the first reference voltage, and the output average value signal;
Sawtooth wave generating circuit, export the sawtooth signal of a fixed frequency;
Comparison circuit, couple with described sawtooth signal and average value signal, and export a pre-reset signal;
Current foldback circuit, couple with described current detection signal and the second reference voltage, and export an overcurrent protection signal;
One or the door, couple with described pre-reset signal and overcurrent protection signal, and export a reset signal.
Preferably, the averaging circuit that described switch disconnects control circuit comprises error amplifier, and the error intergal electric capacity of its output, and the in-phase input end of described error amplifier and the first reference voltage couple, inverting input and described sampled signal couple, and it is output as average value signal; The output of error intergal electric capacity one end and error amplifier couples, and couples to the reference of the other end and control circuit.
Preferably, the comparison circuit that described switch disconnects control circuit comprises the first comparator, its in-phase input end and sawtooth wave generating circuit output sawtooth signal couple, inverting input and described average value signal couple, output is exported pre-reset signal, and when described sawtooth signal is more than or equal to average value signal, pre-reset signal is logic high, otherwise, be logic low.
Preferably, the current foldback circuit that described switch disconnects control circuit comprises the second comparator, the current detection signal of its in-phase input end and current detection circuit output couples, and inverting input and the second reference voltage couple, and output is exported an overcurrent protection signal; When described current detection signal is more than or equal to the second reference voltage, the overcurrent protection signal is logic high, otherwise, be logic low.
Preferably, the zero current detecting circuit of described control circuit can be by the common node of inductance and current detection circuit, or the LC of the common node of switching circuit and current detection circuit vibration, detects inductive current and be zero moment point.
Preferably, the zero current detecting circuit of described control circuit can pass through the common node of transformer main winding and current detection circuit, or assists the LC vibration of winding one end by transformer, and detecting transformer current is zero moment point.
The Cgd electric capacity of the fet switch (FET) that preferably, the zero current detecting circuit of described control circuit can be by switching circuit or Cgs electric capacity discharge and recharge the moment point that detected energy transmission unit electric current is zero.
Preferably, the pulse width modulation circuit of described control circuit comprises a rest-set flip-flop, its reset terminal and described reset signal couple, set end and described asserts signal couple, the Q output is pulse width modulating signal, the switching circuit that the pulse width modulating signal of output is used for controlling and transformer couples switches on and off, and voltage or the current constant that maintains load circuit of take is the desired value of setting.
According to embodiments of the invention, a kind of control method of buck-boost type drive circuit is also proposed, adopt the buck-boost type drive circuit of described control method at least to comprise switching circuit and the inductance or the transformer that are coupled to described switching circuit, along with switching on and off of switching circuit, described inductance or transformer storage and output energy, described control method comprises the following steps:
A. switching current detecting step: during switching circuit is connected, detect the electric current that flows through described switching circuit, obtain a current detection signal;
B. load signal sampling procedure: the load signal of sampling load circuit obtains a sampled signal relevant to load circuit;
C. mean value calculation step: by sampled signal and the computing of the reference voltage value of averaging, obtain an average value signal;
D. switching circuit disconnects and controls step: compare with average value signal and current detection signal, when current detection signal is more than or equal to average value signal, switching circuit is disconnected;
E. switching circuit is connected and is controlled step, and zero current detecting circuit is exported an asserts signal after the zero current moment point of inductance or transformer being detected, and switching circuit is connected;
F. steps A-E forms the cycle of operation, and during described buck-boost type drive circuit works, steps A-E repetitive cycling operation, make the buck-boost type drive circuit be output as the desired value of setting.
Preferably, the load signal sampling procedure of described control method, sample circuit and load circuit coupled in series, the sampled signal that sample circuit output is relevant to the load current of load circuit.
Preferably, the load signal sampling procedure of described control method, sample circuit and load circuit coupled in parallel, the sampled signal that sample circuit output is relevant to the load voltage of load circuit.
According to embodiments of the invention, a kind of control method of buck-boost type drive circuit is also proposed, adopt the buck-boost type drive circuit of described control method at least to comprise switching circuit and the inductance or the transformer that are coupled to described switching circuit, along with switching on and off of switching circuit, described inductance or transformer storage and output energy, described control method comprises the following steps:
A. switching current detecting step: during switching circuit is connected, detect the electric current that flows through described switching circuit, obtain a current detection signal;
B. load signal sampling procedure: the load signal of sampling load circuit obtains a sampled signal relevant to load circuit;
C. mean value calculation step: by sampled signal and the computing of the reference voltage value of averaging, obtain an average value signal;
D. switching circuit disconnects and controls step: compare by average value signal and a fixed frequency sawtooth signal, when described sawtooth signal is more than or equal to average value signal, export a pre-reset signal, switching circuit is disconnected;
E. switching circuit is connected and is controlled step, and zero current detecting circuit is exported an asserts signal after the zero current moment point of inductance or transformer being detected, and switching circuit is connected;
F. steps A-E forms the cycle of operation, and during described buck-boost type drive circuit works, steps A-E repetitive cycling operation, make the buck-boost type drive circuit be output as the desired value of setting.
Preferably, the load signal sampling procedure of described control method, sample circuit and load circuit coupled in series, the sampled signal that sample circuit output is relevant to the load current of load circuit.
Preferably, the load signal sampling procedure of described control method, sample circuit and load circuit coupled in parallel, the sampled signal that sample circuit output is relevant to the load voltage of load circuit.
Preferably; the switching circuit of described control method disconnects controls step; also comprise the output of pre-reset signal and current foldback circuit overcurrent protection signal phase or sub-step; when described current detection signal is more than or equal to the second reference voltage; current foldback circuit output overcurrent guard signal, disconnect switching circuit.
Preferably, the buck-boost type drive circuit in described control method also comprises input voltage source, fly-wheel diode, output capacitance, load circuit, current detection circuit and sample circuit; Described switching circuit first end and input voltage source couple, and the second end and current detection circuit couple, and the pulse width modulating signal of the 3rd end and control circuit output couples; The common node of the main winding of the other end of current detection circuit and inductance or transformer, output capacitance, sample circuit couples; Described common node is also the reference ground of control circuit; The other end and the fly-wheel diode of inductance or transformer main winding couple, the reference ground that the common node of inductance or transformer main winding and fly-wheel diode is described buck-boost type drive circuit; The common port of the other end of fly-wheel diode and output capacitance, load circuit couples; The other end and the sample circuit of load circuit couple.
Preferably, the buck-boost type drive circuit in described control method also comprises input voltage source, fly-wheel diode, output capacitance, load circuit, current detection circuit and sample circuit; Described switching circuit first end and input voltage source couple, and the second end and current detection circuit couple, and the pulse width modulating signal of the 3rd end and control circuit output couples; The common node of the other end of current detection circuit and inductance or transformer main winding, output capacitance, sample circuit, load circuit couples; Described common node is also the reference ground of control circuit; The other end and the fly-wheel diode of inductance or transformer main winding couple, the reference ground that the common node of inductance or transformer main winding and fly-wheel diode is described buck-boost type drive circuit; The common port of the other end of fly-wheel diode and output capacitance, load circuit, sample circuit couples.
Compared with prior art, the helpfulness effect of technology provided by the present invention is: the average current of LED will be more accurate, and can not be subject to inputting the impact of pressure, inductance value and LED forward drop.
The accompanying drawing explanation
Figure 1 shows that the schematic diagram according to the first embodiment of buck-boost type drive circuit of the present invention.
Figure 2 shows that the part control circuit schematic diagram according to buck-boost type drive circuit of the present invention.
Figure 3 shows that the part control circuit schematic diagram according to buck-boost type drive circuit of the present invention.
Figure 4 shows that the schematic diagram according to the second embodiment of buck-boost type drive circuit of the present invention.
Drawing reference numeral
100 drive circuit the first embodiment; 101 control circuit the first embodiment; 110 input voltage sources; 111 output capacitances; 112 fly-wheel diodes; 113 load circuits; 120 switching circuits; 121 switches; 130 sample circuits; 131 first sample resistances; 140 Energy Transfer unit; 141 inductance; 150 current detection circuits; 151 current sense resistors; 160 zero current detecting circuits; 170 switches disconnect control circuit; 180 pulse width modulation circuits; 200 control circuit the second embodiment; 220 averaging circuits; 221 error intergal electric capacity; 222 error amplifiers; 230 comparison circuits; 231 first comparators; 250 pulse width modulation circuits; 300 control circuit the second embodiment; 310 sawtooth wave generating circuits; 350 current foldback circuits; 351 second comparators; 360 or the door; 400 drive circuit the second embodiment; 401 control circuits the 3rd embodiment; 432 second sample resistances; 433 the 3rd sample resistances
Embodiment
Below will describe specific embodiments of the invention in detail, it should be noted that the embodiments described herein, only for illustrating, is not limited to the present invention.In the following description, in order to provide thorough understanding of the present invention, a large amount of specific detail have been set forth.Yet, for those of ordinary skills, it is evident that: needn't adopt these specific detail to carry out the present invention.In other embodiments, for fear of obscuring the present invention, do not specifically describe known circuit, material or method.
In whole specification, " embodiment ", " embodiment ", " example " or mentioning of " example " are meaned: special characteristic, structure or characteristic in conjunction with this embodiment or example description are comprised at least one embodiment of the present invention.Therefore, phrase " in one embodiment ", " in an embodiment ", " example " or " example " occurred in each place of whole specification differs to establish a capital and refers to same embodiment or example.In addition, can, with any suitable combination and/or sub-portfolio by specific feature, structure or characteristic, be combined in one or more embodiment or example.In addition, it should be understood by one skilled in the art that the accompanying drawing provided at this is all for illustrative purposes, and accompanying drawing is not necessarily drawn in proportion.Should be appreciated that it can be directly connected or coupled to another element or can have intermediary element when claiming element " connection ", " being connected to " or " coupling ", " being couple to " another element.On the contrary, when claiming element " to be directly connected to " or during " being directly coupled to " another element, not having intermediary element.Identical Reference numeral is indicated identical element.Term used herein " and/or " comprise any and all combinations of one or more relevant projects of listing.
With reference to figure 1, be depicted as a kind of buck-boost type drive circuit 100 according to one embodiment of the invention, comprise the input voltage source 110 that input voltage VIN is provided; The Energy Transfer unit 140 coupled with input voltage source VIN, for load circuit 113 provides electric power; The switching circuit 120 coupled with Energy Transfer unit 140; For Energy Transfer unit 140 provides fly-wheel diode 112 and the output capacitance 111 of afterflow.In one embodiment, described buck-boost type drive circuit 100 also comprises a control circuit 101, for controlling the switching circuit 120 coupled with Energy Transfer unit 140 and input voltage source 110, thereby controls the electric power of the load circuit 113 of flowing through.
In one embodiment, the control circuit 101 of described buck-boost type drive circuit 100 comprises: current detection circuit 150, for when described switching circuit 120 switches on and off, the electric current that all provides indication to flow through described switching circuit 120, and output electric current measure signal Vcs; Sample circuit 130, with described load circuit 113 coupled in series, and the output sampled signal VFB relevant to electric current on load circuit 113; Switch disconnects control circuit 170, couples with described current detection signal Vcs, sampled signal VFB and the first reference voltage VR1, and exports a reset signal Rst; Zero current detecting circuit 160, the zero current moment point of detected energy transmission unit 140, and export an asserts signal Set; Pulse width modulation circuit 180, couple with described asserts signal Set and reset signal Rst, and export a pulse width modulating signal PWM control switch circuit 120 and switch on and off, and the current constant maintained on load circuit 113 of take is the desired value of setting; Wherein, the reference ground of the reference of buck-boost type drive circuit 100 ground and control circuit 101 is not same with reference to ground.
In one embodiment, the control circuit 401 of described buck-boost type drive circuit 400 comprises: current detection circuit 150, for when described switching circuit 120 switches on and off, the electric current that all provides indication to flow through described switching circuit 120, and output electric current measure signal Vcs; Sample circuit 130, with described load circuit 113 coupled in parallel, and the output sampled signal relevant to voltage on load circuit 113; Switch disconnects control circuit 170, couples with described current detection signal Vcs, sampled signal VFB and the first reference voltage VR1, and exports a reset signal Rst; Zero current detecting circuit 160, the zero current moment point of detected energy transmission unit 140, and export an asserts signal Set; Pulse width modulation circuit 180, couple with described asserts signal Set and reset signal Rst, and export a pulse width modulating signal PWM control switch circuit 120 and switch on and off, and the voltage constant maintained on load circuit 113 of take is the desired value of setting; Wherein, the reference ground of the reference of buck-boost type drive circuit 400 ground and control circuit 401 is not same with reference to ground.
In one embodiment, the input voltage VIN that described input voltage source 110 provides comprises: the direct voltage of the direct voltage of AC-DC converter output, DC-to-DC converter output or alternating voltage be the direct voltage after rectifier bridge directly.In one embodiment, the switch 121 of described switching circuit 120 is comprised of field-effect transistor (FET) or bipolar transistor (BJT).Total at an embodiment, the Energy Transfer unit 140 of described buck-boost type drive circuit 100 is an inductance 141 or a transformer.In one embodiment, be the reference of described control circuit 101 common node of Energy Transfer unit 140 and current detection circuit 150, or the common node of current detection circuit 150 and switching circuit 120.
In one embodiment, switching circuit 120 first ends and the input voltage source 110 of buck-boost type drive circuit 100 as shown in Figure 1 couple, the second end and current detection circuit 150 couple, and the pulse width modulating signal PWM of the 3rd end and control circuit 101 outputs couples; The common node of the other end of current detection circuit 150 and Energy Transfer unit 140, output capacitance 111, sample circuit 130 couples; Described common node is also the reference ground of control circuit 101; The other end of Energy Transfer unit 140 and fly-wheel diode 112 couple, the reference ground that the common node of Energy Transfer unit 140 and fly-wheel diode 112 is described buck-boost type drive circuit 100; The common port of the other end of fly-wheel diode 112 and output capacitance 111, load circuit 113 couples; The other end of load circuit 113 and sample circuit 130 couple.
In one embodiment, switching circuit 120 first ends and the input voltage source 110 of buck-boost type drive circuit 400 as shown in Figure 4 couple, the second end and current detection circuit 150 couple, and the pulse width modulating signal PWM of the 3rd end and control circuit 401 outputs couples; The common node of the other end of current detection circuit 150 and Energy Transfer unit 140, output capacitance 111, sample circuit 130, load circuit 113 couples; Described common node is also the reference ground of control circuit 401; The other end of Energy Transfer unit 140 and fly-wheel diode 112 couple, the reference ground that the common node of Energy Transfer unit 140 and fly-wheel diode 112 is described buck-boost type drive circuit 400; The common port of the other end of fly-wheel diode 112 and output capacitance 111, load circuit 113, sample circuit 130 couples.
In one embodiment, the current detection circuit 150 of control circuit 101 is coupled in series on the current path of switching circuit 120 as shown in Figure 1, one end and switching circuit 120 couple, the other end and Energy Transfer unit 140 couple, comprise, one current sense resistor 151, the electric current that flows through switching circuit 120 flows through described resistance, and exports the current detection signal Vcs of indicator cock circuit 120 transient currents on described current sense resistor 151.
In one embodiment, the sample circuit 130 of control circuit 101 and load circuit 113 coupled in series as shown in Figure 1, comprise the first sample resistance 131, the load current that flows through load circuit 113 flows through described the first sample resistance 131, and the sampled signal VFB of load circuit 113 transient currents and average current is indicated in output on described the first sample resistance 131.
In one embodiment, the sample circuit 130 of control circuit 401 and load circuit 113 coupled in parallel as shown in Figure 4, comprise the second sample resistance 432 and the 3rd sample resistance 433, load voltage on the second sample resistance 432 and the 3rd sample resistance 433 proportional sampling load circuits 113, and on the common node of the second sample resistance 432 and the 3rd sample resistance 433, the sampled signal VFB of output indication load circuit 113 instantaneous voltages and average voltage.
In one embodiment, the switch of part control circuit 200 disconnection control circuit 170 comprises as shown in Figure 2, and averaging circuit 220, couple with described sampled signal VFB and the first reference voltage VR1, and output average value signal Veao; Comparison circuit 230, couple with described current detection signal Vcs and average value signal Veao, and output reset signal Rst; In one embodiment, the averaging circuit 220 that described switch disconnects control circuit 170 comprises error amplifier 222, error intergal electric capacity 221 with its output, the in-phase input end of described error amplifier 222 and the first reference voltage VR1 couple, inverting input and described sampled signal VFB couple, and it is output as average value signal Veao; The output of error intergal electric capacity 221 1 ends and error amplifier 222 couples, and couples to the reference of the other end and control circuit 101.In one embodiment, the comparison circuit 230 that described switch disconnects control circuit 170 comprises the first comparator 231, the current detection signal Vcs of its in-phase input end and current detection circuit 150 outputs couples, inverting input and described average value signal Veao couple, output output reset signal Rst, when described current detection signal Vcs is more than or equal to average value signal Veao, reset signal Rst is logic high, otherwise, be logic low.
Can enter step operation principle clearly of the present invention in conjunction with Fig. 1 and Fig. 2, during switching circuit 120 is connected, input voltage source 110 is by 140 chargings of 120 pairs of Energy Transfer unit of switching circuit.During this period, output capacitance 111 provides load circuit 113 required electric current; At switching circuit 120 off periods, 140 pairs of Energy Transfer unit output capacitance 111 and load circuit 113 chargings; In whole switch periods, the current signal that sample circuit 130 sampling load circuits 113 flow through, and output sampled signal VFB; Error amplifier in averaging circuit 220 222 couples with described sampled signal VFB and the first reference voltage VR1, and by the mean value error accumulation of sampled signal VFB and the first reference voltage VR1 in error intergal electric capacity 221, output average value signal Veao; When the mean value of sampled signal VFB is less than the mean value of the first reference voltage VR1, the level of average value signal Veao will increase, the reset signal Rst of comparison circuit 230 outputs will postpone, the pulse width modulating signal PWM duty ratio of pulse width modulation circuit 180 outputs will increase, the time that switching circuit 120 is connected can synchronously increase, therefore, the electric current that passes to load circuit 113 also can increase, the mean value of sampled signal VFB also will increase, finally equal the mean value of the first reference voltage VR1, vice versa.
In one embodiment, the switch of control circuit 300 disconnection control circuit 170 comprises as shown in Figure 3, and averaging circuit 220, couple with described sampled signal VFB and the first reference voltage VR1, and output average value signal Veao; Sawtooth wave generating circuit 310, export the sawtooth signal Vsaw of a fixed frequency; Comparison circuit 230, couple with described sawtooth signal Vsaw and average value signal Veao, and export a pre-reset signal Prst; Current foldback circuit 350, couple with described current detection signal Vcs and the second reference voltage VR2, and export an overcurrent protection signal OCP; One or the door 360, couple with described pre-reset signal Prst and overcurrent protection signal OCP, and export a reset signal Rst.In one embodiment, the averaging circuit 220 that described switch disconnects control circuit 170 comprises error amplifier 222, error intergal electric capacity 221 with its output, the in-phase input end of described error amplifier 222 and the first reference voltage VR1 couple, inverting input and described sampled signal VFB couple, and it is output as average value signal Veao; The output of error intergal electric capacity 221 1 ends and error amplifier 222 couples, and couples to the reference of the other end and control circuit 101.In one embodiment, the comparison circuit 230 that described switch disconnects control circuit 170 comprises the first comparator 231, its in-phase input end and sawtooth wave generating circuit 310 output sawtooth signal Vsaw couple, inverting input and described average value signal Veao couple, output is exported pre-reset signal Prst, and when described sawtooth signal Vsaw is more than or equal to average value signal Veao, pre-reset signal Prst is logic high, otherwise, be logic low.In one embodiment, the current foldback circuit 350 that described switch disconnects control circuit 170 comprises the second comparator 351, the current detection signal Vcs of its in-phase input end and current detection circuit 150 outputs couples, inverting input and the second reference voltage VR2 couple, and output is exported an overcurrent protection signal OCP; When described current detection signal Vcs is more than or equal to the second reference voltage VR2, overcurrent protection signal OCP is logic high, otherwise, be logic low.
In one embodiment, described zero current detecting circuit 160 can pass through the common node of inductance 141 and current detection circuit 150, or switching circuit 120 vibrates with the LC of the common node of current detection circuit 150, and detecting inductance 141 electric currents is zero moment point.In one embodiment, described zero current detecting circuit 160 can pass through the common node of transformer main winding and current detection circuit 150, or assists the LC vibration of winding one end by transformer, and detecting transformer current is zero moment point.In one embodiment, described zero current detecting circuit 160 can be by the Cgd electric capacity of fet switch (FET) or the discharging and recharging of Cgs electric capacity of switching circuit 120, the moment point that detected energy transmission unit 140 electric currents are zero.
In one embodiment, described pulse width modulation circuit 180 comprises a rest-set flip-flop 250, its reset terminal and described reset signal Rst couple, set end and described asserts signal Set couple, the Q output is pulse width modulating signal PWM, the switching circuit 120 that the pulse width modulating signal PWM of output is used for controlling and transformer couples switches on and off, and voltage or the current constant that maintains load circuit 113 of take is the desired value of setting.
According to embodiments of the invention, a kind of control method of buck-boost type drive circuit is also proposed, adopt the buck-boost type drive circuit of described control method at least to comprise switching circuit and the inductance or the transformer that are coupled to described switching circuit, along with switching on and off of switching circuit, described inductance or transformer storage and output energy, described control method comprises the following steps:
A. switching current detecting step: during switching circuit is connected, detect the electric current that flows through described switching circuit, obtain a current detection signal;
B. load signal sampling procedure: the load signal of sampling load circuit obtains a sampled signal relevant to load circuit;
C. mean value calculation step: by sampled signal and the computing of the reference voltage value of averaging, obtain an average value signal;
D. switching circuit disconnects and controls step: compare with average value signal and current detection signal, when current detection signal is more than or equal to average value signal, switching circuit is disconnected;
E. switching circuit is connected and is controlled step, and zero current detecting circuit is exported an asserts signal after the zero current moment point of inductance or transformer being detected, and switching circuit is connected;
F. steps A-E forms the cycle of operation, and during described buck-boost type drive circuit works, steps A-E repetitive cycling operation, make the buck-boost type drive circuit be output as the desired value of setting.
In one embodiment, the load signal sampling procedure of described control method, sample circuit and load circuit coupled in series, the sampled signal that sample circuit output is relevant to the load current of load circuit.
In one embodiment, the load signal sampling procedure of described control method, sample circuit and load circuit coupled in parallel, the sampled signal that sample circuit output is relevant to the load voltage of load circuit.
According to embodiments of the invention, a kind of control method of buck-boost type drive circuit is also proposed, adopt the buck-boost type drive circuit of described control method at least to comprise switching circuit and the inductance or the transformer that are coupled to described switching circuit, along with switching on and off of switching circuit, described inductance or transformer storage and output energy, described control method comprises the following steps:
A. switching current detecting step: during switching circuit is connected, detect the electric current that flows through described switching circuit, obtain a current detection signal;
B. load signal sampling procedure: the load signal of sampling load circuit obtains a sampled signal relevant to load circuit;
C. mean value calculation step: by sampled signal and the computing of the reference voltage value of averaging, obtain an average value signal;
D. switching circuit disconnects and controls step: compare by average value signal and a fixed frequency sawtooth signal, when described sawtooth signal is more than or equal to average value signal, export a pre-reset signal, switching circuit is disconnected;
E. switching circuit is connected and is controlled step, and zero current detecting circuit is exported an asserts signal after the zero current moment point of inductance or transformer being detected, and switching circuit is connected;
F. steps A-E forms the cycle of operation, and during described buck-boost type drive circuit works, steps A-E repetitive cycling operation, make the buck-boost type drive circuit be output as the desired value of setting.
In one embodiment, the load signal sampling procedure of described control method, sample circuit and load circuit coupled in series, the sampled signal that sample circuit output is relevant to the load current of load circuit.
In one embodiment, the load signal sampling procedure of described control method, sample circuit and load circuit coupled in parallel, the sampled signal that sample circuit output is relevant to the load voltage of load circuit.
In one embodiment; the switching circuit of described control method disconnects controls step; also comprise the output of pre-reset signal and current foldback circuit overcurrent protection signal phase or sub-step; when described current detection signal is more than or equal to the second reference voltage; current foldback circuit output overcurrent guard signal, disconnect switching circuit.
In one embodiment, the buck-boost type drive circuit in described control method also comprises input voltage source, fly-wheel diode, output capacitance, load circuit, current detection circuit and sample circuit; Described switching circuit first end and input voltage source couple, and the second end and current detection circuit couple, and the pulse width modulating signal of the 3rd end and control circuit output couples; The common node of the main winding of the other end of current detection circuit and inductance or transformer, output capacitance, sample circuit couples; Described common node is also the reference ground of control circuit; The other end and the fly-wheel diode of inductance or transformer main winding couple, the reference ground that the common node of inductance or transformer main winding and fly-wheel diode is described buck-boost type drive circuit; The common port of the other end of fly-wheel diode and output capacitance, load circuit couples; The other end and the sample circuit of load circuit couple.
In one embodiment, the buck-boost type drive circuit in described control method also comprises input voltage source, fly-wheel diode, output capacitance, load circuit, current detection circuit and sample circuit; Described switching circuit first end and input voltage source couple, and the second end and current detection circuit couple, and the pulse width modulating signal of the 3rd end and control circuit output couples; The common node of the other end of current detection circuit and inductance or transformer main winding, output capacitance, sample circuit, load circuit couples; Described common node is also the reference ground of control circuit; The other end and the fly-wheel diode of inductance or transformer main winding couple, the reference ground that the common node of inductance or transformer main winding and fly-wheel diode is described buck-boost type drive circuit; The common port of the other end of fly-wheel diode and output capacitance, load circuit, sample circuit couples.
Although with reference to several exemplary embodiments, described the present invention, should be appreciated that term used is explanation and exemplary, nonrestrictive term.The spirit or the essence that do not break away from invention because the present invention can specifically implement in a variety of forms, so be to be understood that, above-described embodiment is not limited to any aforesaid details, and explain widely in the spirit and scope that should limit in the claim of enclosing, therefore fall into whole variations in claim or its equivalent scope and remodeling and all should be the claim of enclosing and cover.
Claims (10)
1. a buck-boost type drive circuit, comprise the input voltage source that input voltage is provided; The Energy Transfer unit coupled with input voltage source, for load circuit provides electric power; The switching circuit coupled with the Energy Transfer unit; For the Energy Transfer unit provides fly-wheel diode and the output capacitance of afterflow; It is characterized in that, described buck-boost type drive circuit also comprises a control circuit, for controlling the switching circuit coupled with Energy Transfer unit and input voltage source, thereby controls the electric power of the load circuit of flowing through.
2. buck-boost type drive circuit according to claim 1, is characterized in that, the control circuit of described buck-boost type drive circuit comprises:
Current detection circuit, for when described switching circuit switches on and off, the electric current that all provides indication to flow through described switching circuit, and output electric current measure signal;
Sample circuit, with described load circuit coupled in series, and the output sampled signal relevant to electric current on load circuit;
Switch disconnects control circuit, couples with described current detection signal, sampled signal and the first reference voltage, and exports a reset signal;
Zero current detecting circuit, the zero current moment point of detected energy transmission unit, and export an asserts signal;
Pulse width modulation circuit, couple with described asserts signal and reset signal, and export a pulse width modulating signal control switch circuit and switch on and off, and the current constant maintained on load circuit of take is the desired value of setting;
Wherein, the reference ground of the reference of buck-boost type drive circuit ground and control circuit is not same with reference to ground.
3. buck-boost type drive circuit according to claim 1, is characterized in that, the control circuit of described buck-boost type drive circuit comprises:
Current detection circuit, for when described switching circuit switches on and off, the electric current that all provides indication to flow through described switching circuit, and output electric current measure signal;
Sample circuit, with described load circuit coupled in parallel, and the output sampled signal relevant to voltage on load circuit;
Switch disconnects control circuit, couples with described current detection signal, sampled signal and the first reference voltage, and exports a reset signal;
Zero current detecting circuit, the zero current moment point of detected energy transmission unit, and export an asserts signal;
Pulse width modulation circuit, couple with described asserts signal and reset signal, and export a pulse width modulating signal control switch circuit and switch on and off, and the voltage constant maintained on load circuit of take is the desired value of setting;
Wherein, the reference ground of the reference of buck-boost type drive circuit ground and control circuit is not same with reference to ground.
4. buck-boost type drive circuit according to claim 1, it is characterized in that, the input voltage that the input voltage source of described buck-boost type drive circuit provides comprises: the direct voltage of the direct voltage of AC-DC converter output, DC-to-DC converter output or alternating voltage be the direct voltage after rectifier bridge directly.
5. buck-boost type drive circuit according to claim 1, is characterized in that, the switch of the switching circuit of described buck-boost type drive circuit is comprised of field-effect transistor (FET) or bipolar transistor (BJT).
6. buck-boost type drive circuit according to claim 1, is characterized in that, the Energy Transfer unit of described buck-boost type drive circuit is an inductance or a transformer.
7. buck-boost type drive circuit according to claim 1, it is characterized in that, switching circuit first end and the input voltage source of described buck-boost type drive circuit couple, and the second end and current detection circuit couple, and the pulse width modulating signal of the 3rd end and control circuit output couples; The common node of the other end of current detection circuit and Energy Transfer unit, output capacitance, sample circuit couples; Described common node is also the reference ground of control circuit; The other end and the fly-wheel diode of Energy Transfer unit couple, the reference ground that the common node of Energy Transfer unit and fly-wheel diode is described buck-boost type drive circuit; The common port of the other end of fly-wheel diode and output capacitance, load circuit couples; The other end and the sample circuit of load circuit couple.
8. buck-boost type drive circuit according to claim 1, it is characterized in that, switching circuit first end and the input voltage source of described buck-boost type drive circuit couple, and the second end and current detection circuit couple, and the pulse width modulating signal of the 3rd end and control circuit output couples; The common node of the other end of current detection circuit and Energy Transfer unit, output capacitance, sample circuit, load circuit couples; Described common node is also the reference ground of control circuit; The other end and the fly-wheel diode of Energy Transfer unit couple, the reference ground that the common node of Energy Transfer unit and fly-wheel diode is described buck-boost type drive circuit; The common port of the other end of fly-wheel diode and output capacitance, load circuit, sample circuit couples.
9. according to the described buck-boost type drive circuit of claim 2 or 3, it is characterized in that, the reference ground of described control circuit is the common node of Energy Transfer unit and current detection circuit, or the common node of current detection circuit and switching circuit.
10. according to the described buck-boost type drive circuit of claim 2 or 3, it is characterized in that, the current detection circuit of described control circuit is coupled in series on the current path of switching circuit, one end and switching circuit couple, the other end and Energy Transfer unit couple, and comprise
One current sense resistor, the electric current that flows through switching circuit flows through described resistance, and exports the current detection signal of indicator cock circuit transient current on described current sense resistor.
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| CN2013104023703A CN103427643A (en) | 2013-09-07 | 2013-09-07 | Control circuit of buck-boost drive circuit and control method thereof |
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| CN2013104023703A CN103427643A (en) | 2013-09-07 | 2013-09-07 | Control circuit of buck-boost drive circuit and control method thereof |
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| CN113381626A (en) * | 2021-05-08 | 2021-09-10 | 深圳市必易微电子股份有限公司 | Load power supply system suitable for dimming driving and power supply method |
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