阅读说明：本技术 一种供电电路的控制电路及供电电路 (Control circuit of power supply circuit and power supply circuit ) 是由 李雅静 于 2021-01-07 设计创作，主要内容包括：本申请公开了一种供电电路的控制电路,包括RC串联支路与控制支路；所述RC串联支路与供电电路中的滤波电感并联；所述控制支路,用于在每个开关周期对所述RC串联支路中的电容的电压进行积分,将积分值与参考值进行比较,当所述积分值达到所述参考值时,关断所述供电电路中的驱动开关管并导通所述供电电路中的续流开关管,以使所述供电电路中的所述滤波电感放电。该控制电路在能够使负载电流保持恒定的同时,可以减少功率损耗,提高转换效率,且响应速度快、鲁棒性好。本申请还公开了一种供电电路,同样具有上述技术效果。(The application discloses a control circuit of a power supply circuit, which comprises an RC series branch and a control branch; the RC series branch is connected with a filter inductor in the power supply circuit in parallel; and the control branch circuit is used for integrating the voltage of the capacitor in the RC series branch circuit in each switching period, comparing an integral value with a reference value, and turning off a driving switch tube in the power supply circuit and turning on a follow current switch tube in the power supply circuit when the integral value reaches the reference value so as to discharge the filter inductor in the power supply circuit. The control circuit can reduce power loss and improve conversion efficiency while keeping the load current constant, and has high response speed and good robustness. The application also discloses a power supply circuit, which has the technical effect.)

1. A control circuit for a power supply circuit, comprising:

the RC series branch and the control branch;

the RC series branch is connected with a filter inductor in the power supply circuit in parallel;

and the control branch circuit is used for integrating the voltage of the capacitor in the RC series branch circuit in each switching period, comparing an integral value with a reference value, and turning off a driving switch tube in the power supply circuit and turning on a follow current switch tube in the power supply circuit when the integral value reaches the reference value so as to discharge the filter inductor in the power supply circuit.

2. The control circuit of claim 1, wherein the control branch comprises:

an integrator, a comparator and an RS trigger;

the integrator is used for integrating the voltage of the filter inductor in the RC series circuit and outputting an integrated value to the comparator;

the comparator is used for comparing the integral value with the reference value and triggering the RS trigger to reset when the integral value reaches the reference value;

and the RS trigger is used for switching off the driving switch tube in the power supply circuit and switching on the follow current switch tube in the power supply circuit when the RS trigger is reset so as to discharge the filter inductor in the power supply circuit.

3. The control circuit of claim 2, wherein the integrator comprises:

an operational amplifier, an integrating capacitor and a switch;

the integrating capacitor is connected in parallel with the inverting input end and the output end of the operational amplifier; the switch is connected with the integrating capacitor in parallel and is connected with the RS trigger; when the RS trigger is reset, the switch is closed, and the integrating capacitor is discharged.

4. The control circuit according to claim 3, wherein the switch is any one of a MOS transistor, an IGBT and a relay.

5. The control circuit according to any one of claims 1 to 4, further comprising:

and the hysteresis comparator is used for comparing the output voltage of the power supply circuit with a reference voltage and outputting a comparison result serving as the reference value to the control branch circuit.

6. The control circuit of claim 1, wherein the RC series circuit is a primary RC series circuit.

7. A power supply circuit, characterized in that the power supply circuit comprises a power supply, a driving switch tube, a follow current switch tube, a filter inductor, an output capacitor and a control circuit according to any one of claims 1 to 6.

8. The power supply circuit of claim 7, wherein the driving switch and the freewheeling switch are both MOS transistors.

Technical Field

The present disclosure relates to the field of power supply circuits, and more particularly, to a control circuit of a power supply circuit; it also relates to a supply circuit.

Background

The load generally includes various types such as a constant current type load, a constant voltage type load, and a constant power load. The constant current type load needs stable current for stable operation, and the constant voltage type load needs stable voltage for stable operation. Among them, for a constant current type load, most current power supply circuits adopt a single closed loop control scheme, as shown in fig. 1, at a load end R_loadSeries connection precision resistor R_senCollecting voltage at two ends of the precision resistor to represent load current, comparing the load current with a target value, performing PID adjustment on the difference value of the load current and the target value, and outputting V by a comparator^*Further comparing with the sawtooth wave, the final output signal is used for controlling the upper and lower switch tubes (S1 and S2 shown in the figure); the driving waveforms of the upper and lower switching tubes are designed complementarily.

However, the series connection of the precision resistors not only increases the loop loss and reduces the efficiency, but also is easily affected by temperature drift, and when the operation is performed for a long time or the load current changes greatly, the temperature change is also large, and the sampling precision is affected. In addition, the existing single closed loop control method does not consider the change of the output voltage, the voltage stress on the switching tube and the load is increased due to overlarge voltage fluctuation, the voltage stress may exceed the bearable range of the load, and a device with a larger voltage margin needs to be selected.

In view of the above, how to solve the above technical defects has become an urgent technical problem to be solved by those skilled in the art.

Disclosure of Invention

The purpose of the present application is to provide a control circuit for a power supply circuit, which can reduce power loss and improve conversion efficiency while keeping a load current constant. Another object of the present application is to provide a power supply circuit, which also has the above technical effects.

In order to solve the above technical problem, the present application provides a control circuit of a power supply circuit, including:

the RC series branch and the control branch;

the RC series branch is connected with a filter inductor in the power supply circuit in parallel;

and the control branch circuit is used for integrating the voltage of the capacitor in the RC series branch circuit in each switching period, comparing an integral value with a reference value, and turning off a driving switch tube in the power supply circuit and turning on a follow current switch tube in the power supply circuit when the integral value reaches the reference value so as to discharge the filter inductor in the power supply circuit.

Optionally, the control branch includes:

an integrator, a comparator and an RS trigger;

the integrator is used for integrating the voltage of the filter inductor in the RC series circuit and outputting an integrated value to the comparator;

the comparator is used for comparing the integral value with the reference value and triggering the RS trigger to reset when the integral value reaches the reference value;

and the RS trigger is used for switching off the driving switch tube in the power supply circuit and switching on the follow current switch tube in the power supply circuit when the RS trigger is reset so as to discharge the filter inductor in the power supply circuit.

Optionally, the integrator includes:

an operational amplifier, an integrating capacitor and a switch;

the integrating capacitor is connected in parallel with the inverting input end and the output end of the operational amplifier; the switch is connected with the integrating capacitor in parallel and is connected with the RS trigger; when the RS trigger is reset, the switch is closed, and the integrating capacitor is discharged.

Optionally, the switch is any one of an MOS transistor, an IGBT, and a relay.

Optionally, the method further includes:

and the hysteresis comparator is used for comparing the output voltage of the power supply circuit with a reference voltage and outputting a comparison result serving as the reference value to the control branch circuit.

Optionally, the RC series circuit is a primary RC series circuit.

In order to solve the above technical problem, the present application further provides a power supply circuit, where the power supply circuit includes a power supply, a driving switch tube, a freewheeling switch tube, a filter inductor, an output capacitor, and the control circuit as described in any one of the above.

Optionally, the driving switch tube and the follow current switch tube are both MOS tubes.

The application provides a power supply circuit's control circuit includes: the RC series branch and the control branch;

the RC series branch is connected with a filter inductor in the power supply circuit in parallel; and the control branch circuit is used for integrating the voltage of the capacitor in the RC series branch circuit in each switching period, comparing an integral value with a reference value, and turning off a driving switch tube in the power supply circuit and turning on a follow current switch tube in the power supply circuit when the integral value reaches the reference value so as to discharge the filter inductor in the power supply circuit.

Therefore, the control circuit provided by the application has the advantages that the RC series circuit is connected in parallel with the two ends of the filter inductor in the power supply circuit, the voltage of the capacitor in the RC series circuit is used for representing the current of the filter inductor in the power supply circuit, and then the driving switch tube and the follow current switch tube in the power supply circuit are controlled by integrating the voltage of the capacitor and comparing the integral value with the reference value in each switching period, so that the load current is kept constant. Compared with the traditional technical scheme of serially connecting the precision resistor at the load end, the power loss can be effectively reduced, and the conversion efficiency is improved. Compared with the traditional scheme of using the output current as the state variable, the current of the filter inductor is used as the state variable, and the response speed is higher. In addition, because of the adoption of the single-period control mode, the load current can be kept constant by taking the switching period as a unit, and the robustness is better.

The power supply circuit provided by the application also has the technical effects.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the prior art and the embodiments are briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a schematic diagram of a conventional control circuit;

fig. 2 is a schematic diagram of a power supply circuit and a control circuit thereof according to an embodiment of the present disclosure;

fig. 3 is a schematic diagram of another power supply circuit and a control circuit thereof according to an embodiment of the present disclosure.

Detailed Description

The core of the application is to provide a control circuit of a power supply circuit, which can reduce power loss and improve conversion efficiency while keeping load current constant. Another core of the present application is to provide a power supply circuit, which also has the above technical effects.

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Referring to fig. 2, fig. 2 is a schematic diagram of a power supply circuit and a control circuit thereof according to an embodiment of the present disclosure, and referring to fig. 2, the control circuit mainly includes:

the RC series branch 10 and the control branch 20;

the RC series branch 10 is connected with a filter inductor L in the power supply circuit in parallel; a control branch 20 for integrating the voltage of the capacitor in the RC series branch 10 in each switching cycle, comparing the integral value with a reference value, and switching off the driving switch tube S in the power supply circuit when the integral value reaches the reference value₁And a follow current switch tube S in the power supply circuit is conducted₂So as to discharge the filter inductor L in the power supply circuit.

Specifically, the power supply circuit mainly comprises a power supply V_IDriving switch tube S₁Freewheeling switch tube S₂A filter inductor L and an output capacitor C. Drive switch tube S₁Is connected with a power supply V_IPositive electrode of (2), driving switch tube S₁The second end of the driving switch tube S is connected with the first end of the filter inductor L₁A third terminal (control terminal) of the filter inductor L is connected to a first output terminal of a control branch 20 of the control circuit, a second terminal of the filter inductor L is connected to one terminal of an output capacitor C, and the other terminal of the output capacitor C is connected to a power supply V_INegative pole of (1), follow current switch tube S₂Is connected with the first end of the filter inductor L, and is provided with a follow current switchPipe S₂Is connected with a power supply V_INegative pole of (1), follow current switch tube S₂Is connected to the second output terminal of the control branch 20 in the control circuit.

The RC series branch 10 in the control circuit is connected in parallel with the filter inductance L in the supply circuit. The RC series branch 10 may be a primary RC series branch 10, that is, an RC circuit with a resistor and a capacitor connected in series, as shown in fig. 3, the resistor R is₁And a capacitor C₁And the two ends of the filter inductor L are connected in parallel after being connected in series. Thereby passing through the capacitor C in the RC circuit₁The voltage across represents the current of the filter inductor L in the supply circuit.

The control branch 20 connects the RC series branch 10 and two switching tubes (driving switching tube S1 and freewheeling switching tube S2) in the power supply circuit, and is configured to integrate the voltage of the capacitor in the RC series branch 10 in each switching cycle, i.e. integrate the current of the filter inductor in the power supply circuit, compare the integrated value with a reference value, and turn off the driving switching tube S in the power supply circuit when the integrated value reaches the reference value₁And a follow current switch tube S in the power supply circuit is conducted₂So as to discharge the filter inductor L in the power supply circuit and discharge the output capacitor C in the power supply circuit, so that the current of the filter inductor L in the power supply circuit tracks the reference value. Therefore, when the current of the filter inductor L in the power supply circuit is disturbed, the current can be recovered to a stable state in a switching period, and constant current control is realized.

In one specific embodiment, the control branch 20 includes: an integrator, a comparator and an RS trigger; the integrator is used for integrating the voltage of the filter inductor L in the RC series circuit and outputting an integral value to the comparator; the comparator is used for comparing the integral value with the reference value and triggering the RS trigger to reset when the integral value reaches the reference value; RS trigger for turning off the driving switch tube S in the power supply circuit when resetting₁And a follow current switch tube S in the power supply circuit is conducted₂So as to discharge the filter inductor L in the power supply circuit.

In particular, referring to fig. 3, the input of the integrator is connected to the RC series branch 10 and to the input of the integratorSmall current reference value V_IminCapacitance C in the RC series branch 10₁Voltage V of_IramAnd a minimum current reference value V_IminThe output of the integrator is connected to the inverting input of the comparator, and the non-inverting input of the comparator is connected to the reference value V_IrefThe output end of the comparator is connected with the reset end of the RS trigger, and the two output ends of the RS trigger are respectively and correspondingly connected with a driving switch tube S in the power supply circuit₁And a follow current switch tube S₂. When the integral value V output by the integrator^*Up to the reference value V_IrefWhen the power supply circuit is started, the comparator triggers the RS trigger to reset, and the driving switch tube S in the power supply circuit is switched off₁And simultaneously conducting a follow current switch tube S in the power supply circuit₂The filter inductor L and the output capacitor C in the power supply circuit are discharged, and the current of the filter inductor L in the power supply circuit and the output voltage of the power supply circuit are gradually reduced.

Further, in a specific embodiment, the integrator includes: operational amplifier and integrating capacitor C₂And a switch K; integrating capacitor C₂The inverting input end and the output end of the operational amplifier are connected in parallel; switch K and integrating capacitor C₂The parallel connection is connected with an RS trigger; when the RS trigger is reset, the switch K is closed to enable the integrating capacitor C₂And (4) discharging.

Referring to FIG. 3, the inverting input terminal of the operational amplifier is connected with a resistor R in series₂Resistor R connected in RC series circuit₁And a capacitor C₁The non-inverting input end of the operational amplifier is connected with the minimum current reference value V_Imin. Integrating capacitor C₂The inverting input end and the output end of the operational amplifier are connected in parallel; switch K and integrating capacitor C₂And (4) connecting in parallel. When the trigger is reset, the integrating capacitor C₂The switch K with two parallel ends is conducted, and the integral capacitor C₂And (4) discharging. The switch may be any one of a MOS transistor, an IGBT, and a relay, or may be another type of switch.

Based on the above circuit structure, the working principle of the control branch 20 is as follows:

filter inductor L route for practical application in power supply circuitAn inductance LL and an equivalent resistance DCR, wherein an RC series branch 10 (a resistance R) is connected in parallel at two ends of a filter inductance L₁And a capacitor C₁In series). Can use a capacitor C₁Voltage V across_IramRepresenting the filter inductor L current. Let the current flowing through the filter inductor L be i_L，

According to the frequency domain analysis, the voltage at the two ends of the filter inductor L is:

u_L＝(sLL+DCR)i_L

where s ═ j ω is a complex parametric variable, called the complex frequency.

Capacitor C₁The voltages at both ends are:

selecting circuit parameters satisfying conditionsCommander variable V_IramAnd i_LIs proportional, i.e.

V_Iram＝DCR*i_L。

At the beginning of the switching period, the SET signal SETs the RS trigger to turn on the driving switch tube S₁Input power supply V_ICharging the filter inductor L and the output capacitor C, and the current i of the filter inductor_LAnd the output voltage V of the power supply circuit_OStepwise increase of V_IramBut also increases synchronously.

t₀<t<t₁(ii) a Wherein, t₀As the start of the switching cycle, t₁Is the end time of charging.

Integrating capacitor C in integrator₂Voltage V on by V_IminStart to taper:

t₀<t<t₁(ii) a Wherein, V_Imin＝DCR*I_min，I_minTo the minimum allowable operating current.

Namely, it is

When the integral value V output by the integrator^*Up to a reference voltage V_refAfter that, the comparator is operated and the trigger is reset.

At this time

Wherein, I_peakThe peak current of the filter inductor L.

Trigger reset in turn-off driving switch tube S₁While the follow current switch tube S is conducted₂Follow current, filter inductance L and output capacitance C discharge, i_LAnd V_OStepwise decrease of V_IramAlso gradually decreases until it decreases to V_IminAnd the current reset of the filter inductor is completed, so that the SET signal is SET high, and a new period is started.

At this timet₁<t<T；

Wherein T is a switching period. Off time

Further, on the basis of the above embodiment, as a preferred implementation, the control circuit further includes: and a hysteresis comparator for comparing the output voltage of the power supply circuit with a reference voltage and outputting the comparison result as a reference value to the control branch 20.

Specifically, referring to FIG. 3, the output voltage of the power supply circuitV_OAnd a reference voltage V_refThe difference e is used as the input of a hysteresis comparator, and the output of the hysteresis comparator is used as a reference value and is connected with the non-inverting input end of the comparator. When V is_OGradually decreases, e is gradually larger than 0, when e is larger than a threshold value e_maxThen, the hysteresis comparator outputs a larger voltage reference value V_refmaxThe output of the integrator is more easily decreased to the reference value; when the output voltage V of the power supply circuit_OGradually increasing, e is less than 0, when e is less than a threshold value e_minThen, the hysteresis comparator outputs a smaller reference voltage value V_refminThe time for the output of the integrator to fall to the reference value is prolonged, giving the load R_loadAnd charging and boosting are carried out, so that overlarge fluctuation of load voltage is avoided.

Namely:wherein e ═ V_ref-V_O。

Therefore, the output voltage of the power supply circuit can be kept within an allowable range by controlling the hysteresis of the output voltage of the power supply circuit, the stress environment of components can be effectively improved, and the working stability of a system is improved.

In summary, the control circuit provided by the present application connects the RC series circuit in parallel to the filter inductor in the power supply circuit, and uses the voltage of the capacitor in the RC series circuit to represent the current of the filter inductor in the power supply circuit, so as to control the driving switch tube and the freewheeling switch tube in the power supply circuit by integrating the voltage of the capacitor and comparing the integrated value with the reference value in each switching period, so as to keep the load current constant. Compared with the traditional technical scheme of serially connecting the precision resistor at the load end, the power loss can be effectively reduced, and the conversion efficiency is improved. Compared with the traditional scheme of using the output current as the state variable, the current of the filter inductor is used as the state variable, and the response speed is higher. In addition, because of the adoption of the single-period control mode, the load current can be kept constant by taking the switching period as a unit, and the robustness is better.

The present application also provides a power supply circuit, shown with reference to figure 1,the power supply circuit comprises a power supply V_IDriving switch tube S₁Freewheeling switch tube S₂A filter inductor L, an output capacitor C and a control circuit as described in the above embodiments.

Drive switch tube S₁Is connected with a power supply V_IPositive electrode of (2), driving switch tube S₁The second end of the driving switch tube S is connected with the first end of the filter inductor L₁The third end (control end) of the filter inductor L is connected with the first output end of a control branch circuit in the control circuit, the second end of the filter inductor L is connected with one end of an output capacitor C, and the other end of the output capacitor C is connected with a power supply V_INegative pole of (1), follow current switch tube S₂The first end of the fly-wheel switch tube S is connected with the first end of the filter inductor L₂Is connected with a power supply V_INegative pole of (1), follow current switch tube S₂The third end (control end) of the filter is connected with the second output end of a control branch circuit in the control circuit, and an RC series branch circuit in the control branch circuit is connected in parallel with the two ends of the filter inductor L.

Wherein, in a specific embodiment, the switch tube S is driven₁And a follow current switch tube S₂Are all MOS tubes. At this time, the switching tube S is driven₁And a follow current switch tube S₂The first end of the MOS tube is a drain electrode of the MOS tube, the second end of the MOS tube is a source electrode of the MOS tube, and the third end of the MOS tube is a grid electrode of the MOS tube.

It will be understood that the switching tube S is driven₁And a follow current switch tube S₂Other types of switching tubes are also possible, allowing for differential settings.

For the introduction of the power supply circuit provided in the present application, please refer to the embodiments of the control circuit described above, which are not described herein again.

Because the situation is complicated and cannot be illustrated by a list, those skilled in the art can appreciate that there can be many examples in combination with the actual situation under the basic principle of the embodiments provided in the present application and that it is within the scope of the present application without sufficient inventive effort.

The embodiments are described in a progressive manner in the specification, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The control circuit and the power supply circuit of the power supply circuit provided by the present application are described in detail above. The principles and embodiments of the present application are explained herein using specific examples, which are provided only to help understand the method and the core idea of the present application. It should be noted that, for those skilled in the art, it is possible to make several improvements and modifications to the present application without departing from the principle of the present application, and such improvements and modifications also fall within the scope of the claims of the present application.

It is further noted that, in the present specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.