CN112234813A

CN112234813A - Soft start device and method, switching power supply, controller and robot

Info

Publication number: CN112234813A
Application number: CN202010995418.6A
Authority: CN
Inventors: 王长恺; 经琦; 黄勇宾; 区均灌; 丁雪健; 张晓瑞
Original assignee: Gree Electric Appliances Inc of Zhuhai
Current assignee: Gree Electric Appliances Inc of Zhuhai
Priority date: 2020-09-21
Filing date: 2020-09-21
Publication date: 2021-01-15
Anticipated expiration: 2040-09-21
Also published as: CN112234813B

Abstract

The invention discloses a soft start device, method, switching power supply, controller and robot of a booster circuit. The device comprises: a comparison unit, which compares the current actual output voltage value of the booster circuit and a set intermediate target voltage value. comparing; and, if the current actual output voltage value is less than the set intermediate target voltage value, then output the second control signal; if the current actual output voltage value is greater than or equal to the set intermediate target voltage value, then output the first control signal; The first control unit, based on the first control signal, feeds back the first feedback voltage value of the current actual output voltage value to the booster circuit; the second control unit, based on the second control signal, feeds back the second feedback voltage value of the current actual output voltage value The voltage value is fed back to the boost circuit. In this solution, by making the feedback gain of the switching power supply chip adjustable, it can avoid overshooting the output voltage and damage the components, and improve the safety of the switching power supply chip.

Description

Soft start device and method, switching power supply, controller and robot

Technical Field

The invention belongs to the technical field of switching power supplies, and particularly relates to a soft start device and method of a boost circuit, a switching power supply, a controller and a robot, in particular to a boost topology hardware soft start circuit and method, a switching power supply, a controller and a robot.

Background

With the continuous development of the science and technology industry, the problem of power reliability in electronic products is also gradually emphasized. In a boost topology circuit, a switching power supply chip is often adopted to control the duty ratio of a MOS transistor to realize boost. However, the feedback gain of the switching power supply chip is fixed, and the risk of damaging components due to output voltage overshoot exists.

The above is only for the purpose of assisting understanding of the technical aspects of the present invention, and does not represent an admission that the above is prior art.

Disclosure of Invention

The invention aims to provide a soft start device and method of a booster circuit, a switching power supply, a controller and a robot, so as to solve the problem that components are damaged due to overshoot of output voltage caused by fixed feedback gain of a switching power supply chip and achieve the effect that the components are damaged due to overshoot of the output voltage caused by adjustable feedback gain of the switching power supply chip.

The invention provides a soft start device of a booster circuit, comprising: the device comprises a comparison unit, a first control unit and a second control unit; wherein the comparing unit is configured to compare the current actual output voltage value of the boosting circuit with a set intermediate target voltage value; if the current actual output voltage value is smaller than the set intermediate target voltage value, outputting a second control signal; if the current actual output voltage value is larger than or equal to the set intermediate target voltage value, outputting a first control signal; the first control unit is configured to turn on itself based on the first control signal to feed back a first feedback voltage value of the current actual output voltage value to a gain feedback end of a switch power supply chip in the boost circuit, so as to perform first adjustment on a feedback gain of the current actual output voltage value of the boost circuit; the second control unit is configured to turn on itself based on the second control signal to feed back a second feedback voltage value of the current actual output voltage value to a gain feedback end of a switch power supply chip in the boost circuit, so as to perform a second adjustment on a feedback gain of the current actual output voltage value of the boost circuit.

In some embodiments, the boost circuit includes: a Boost circuit of the switching power supply chip; and the set intermediate target voltage value is a set coefficient multiple of the steady-state voltage value under the normal operation condition after the soft start of the booster circuit is finished.

In some embodiments, the comparison unit includes: a comparator module; the non-inverting input end of the comparator module can input the set intermediate target voltage value; the inverting input end of the comparator module can input the current actual output voltage value of the booster circuit; the output end of the comparator module outputs the second control signal under the condition that the current actual output voltage value is smaller than the set intermediate target voltage value; and outputting the first control signal when the current actual output voltage value is greater than or equal to the set intermediate target voltage value.

In some embodiments, the first control unit comprises: the device comprises a first gain adjusting module, a first switch module and a first control module; the output end of the booster circuit is connected to the first connection end of the first switch module after passing through the first gain adjustment module; the second connection end of the first switch module is connected to the gain feedback end of the switch power supply chip in the booster circuit; and the output end of the comparison unit is connected to the switch control end of the first switch module after passing through the first control module.

In some embodiments, the first gain adjustment module comprises: the first voltage division module and the second voltage division module are arranged in series; the first connecting end of the first switch module is connected to the common end of the first voltage division module and the second voltage division module; the first switch module includes: the first relay or the first MOS tube.

In some embodiments, the first control module comprises: the device comprises a one-way current limiting module and an interlocking control module; the unidirectional current limiting module comprises: a diode module and a resistance module; the interlock control module includes: a first triode module and a second triode module; wherein the anode of the diode module is connected to the output end of the comparison unit; the cathode of the diode module sequentially passes through the first triode module and the second triode module and then is connected to the switch control end of the first switch module; when the first triode module is switched on, the second triode module is switched off, and when the first triode module is switched off, the second triode module is switched on.

In some embodiments, the first control unit further comprises: at least one of a first freewheel module and a first unidirectional module; the first follow current module is connected to the switch control end of the first switch module; the first unidirectional module is connected between the second connecting end of the first switch module and the gain feedback end of the switch power supply chip in the booster circuit, so that the second connecting end of the first switch module and the gain feedback end of the switch power supply chip in the booster circuit are conducted in a unidirectional mode.

In some embodiments, the second control unit comprises: the second switch module, the second gain adjusting module and the second control module; the output end of the booster circuit is connected to the first connecting end of the second switch module; a second connection end of the second switch module is connected to a gain feedback end of a switch power supply chip in the booster circuit after passing through the second gain adjustment module; and the output end of the comparison unit is connected to the switch control end of the second switch module after passing through the second control module.

In some embodiments, the second switch module comprises: a second relay or a second MOS tube; the second gain adjustment module comprises: the third voltage division module and the fourth voltage division module are arranged in series; and a second connecting end of the second switch module is connected to a gain feedback end of a switch power supply chip in the booster circuit after passing through the third voltage division module, and is also connected to the fourth voltage division module.

In some embodiments, the second control module comprises: the current limiting module and the switch tube module; the current limiting module includes: a current limiting resistance module; the switch tube module comprises: a third triode module; the output end of the comparison unit is connected to the switch control end of the second switch module after passing through the current limiting module and the switch tube module.

In some embodiments, the second control unit further comprises: at least one of a second freewheel module and a second unidirectional module; the second freewheeling module is connected to a switch control end of the second switch module; the second unidirectional module is connected between the second connection end of the second switch module and the gain feedback end of the switch power supply chip in the booster circuit, so that the second connection end of the second switch module and the gain feedback end of the switch power supply chip in the booster circuit are conducted in a unidirectional mode.

In accordance with another aspect of the present invention, there is provided a switching power supply, including: the soft start device of the boost circuit is described above.

In accordance with the above switching power supply, a further aspect of the present invention provides a controller, including: the switching power supply described above.

In accordance with the above controller, a further aspect of the present invention provides a robot comprising: the controller described above.

In another aspect, the present invention provides a soft start method for a boost circuit of a switching power supply, including: comparing the current actual output voltage value of the booster circuit with a set intermediate target voltage value; if the current actual output voltage value is smaller than the set intermediate target voltage value, outputting a second control signal; if the current actual output voltage value is larger than or equal to the set intermediate target voltage value, outputting a first control signal; based on the first control signal, the self is switched on to feed back a first feedback voltage value of the current actual output voltage value to a gain feedback end of a switch power supply chip in the booster circuit so as to perform first adjustment on the feedback gain of the current actual output voltage value of the booster circuit; and switching on the booster circuit based on the second control signal to feed back a second feedback voltage value of the current actual output voltage value to a gain feedback end of a switch power supply chip in the booster circuit so as to perform second adjustment on the feedback gain of the current actual output voltage value of the booster circuit.

Therefore, according to the scheme of the invention, the soft start circuit is arranged on the basis of the boost circuit of the switching power supply chip, and the target voltage value of the boost circuit is automatically switched, so that the feedback gain of the switching power supply chip is adjusted, the duty ratio is indirectly adjusted and controlled, the soft start control of the boost circuit is realized, the components can be prevented from being damaged due to overshoot of the output voltage, and the safety of the switching power supply chip is improved.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.

Drawings

FIG. 1 is a schematic structural diagram of a soft start apparatus of a boost circuit according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of an embodiment of a boost topology circuit;

FIG. 3 is a schematic diagram of an embodiment of a hardware soft start circuit of a boost topology;

FIG. 4 is a schematic diagram of a soft-start control flow of an embodiment of a boost topology hardware soft-start circuit;

FIG. 5 is a graph showing the effect comparison with the soft start circuit;

fig. 6 is a flowchart illustrating a soft-start method of the boost circuit according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the specific embodiments of the present invention and the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. 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 invention.

According to an embodiment of the present invention, there is provided a soft-start apparatus of a booster circuit. Referring to fig. 1, a schematic diagram of an embodiment of the apparatus of the present invention is shown. The soft start device of the booster circuit can include: the device comprises a comparison unit, a first control unit and a second control unit.

In some embodiments, the boost circuit includes: boost voltage Boost circuit of switching power supply chip. For example: the Boost topological circuit comprises a switch chip IC1 (namely a Boost switch power supply chip), a switch tube (such as a MOS tube Q1), a Boost inductor (such as an inductor L1), a diode D1, an output capacitor (such as a capacitor C1), a resistor R5 and a sampling resistor R10, and can form the Boost topological circuit for boosting an input voltage value. The MOS transistor Q1 is used as a switching transistor, and can be turned on and off by a PWM duty ratio. The capacitor C1 is an output capacitor.

And the set intermediate target voltage value is a set coefficient multiple of the steady-state voltage value under the normal operation condition after the soft start of the booster circuit is finished. For example: vref is a target voltage value, i.e., a steady-state voltage value expected during normal operation after the end of soft start. Vref1 is an intermediate target voltage value, and it is possible to use an intermediate target voltage value Vref1 equal to the target voltage value Vref/2, and coefficients such as 1/3 and 3/4 can be arbitrarily selected according to the circuit.

Therefore, on the basis of not changing the original boost topological circuit, a hardware soft start circuit is added to form the boost circuit with soft start, parameter calculation is not needed, the original switch power supply chip is not needed to be changed, the reliability of the circuit is improved, and the design difficulty of the circuit is not changed.

Specifically, the comparing unit is configured to compare a current actual output voltage value output by the output end of the voltage boosting circuit with a set intermediate target voltage value; if the current actual output voltage value is smaller than the set intermediate target voltage value, outputting a second control signal; and if the current actual output voltage value is greater than or equal to the set intermediate target voltage value, outputting a first control signal.

Of course, in actual use, the sampling unit can be set as needed. The sampling unit is configured to sample the output end of the boost circuit to obtain the current actual output voltage value of the boost circuit. In the case of providing a sampling unit, the comparing unit is configured to compare the current actual output voltage value collected by the sampling unit with a set intermediate target voltage value.

In some embodiments, the comparison unit includes: a comparator module (e.g., comparator U1). The non-inverting input end of the comparator module can input the set intermediate target voltage value. And the inverting input end of the comparator module can input the current actual output voltage value of the booster circuit. The output end of the comparator module outputs the second control signal to the first control unit and the second control unit under the condition that the current actual output voltage value is smaller than the set intermediate target voltage value; and under the condition that the current actual output voltage value is greater than or equal to the set intermediate target voltage value, outputting the first control signal to the first control unit and the second control unit.

For example: the comparator U1 outputs a high level when the output voltage value of the BOOST topology circuit is less than the reference value (such as the intermediate target voltage value Vref1), otherwise outputs a low level. The high level or low level signal output from the comparator U1 is a key signal for controlling the relay K1 and the relay K2.

Therefore, the comparator module outputs the second control signal or the first control signal to control the work of the first control unit and the second control unit, the structure is simple, and the control reliability is good.

Specifically, the first control unit is configured to turn itself on based on the first control signal, so as to feed back a first feedback voltage value of the current actual output voltage value to a gain feedback end (such as an FB signal end of a Boost chip) of a switching power supply chip in the Boost circuit, so as to perform a first adjustment on a feedback gain of the current actual output voltage value of the Boost circuit.

In some embodiments, the first control unit comprises: the device comprises a first gain adjusting module, a first switch module and a first control module.

The current actual output voltage output by the output end of the booster circuit is connected to the first connection end of the first switch module after passing through the first gain adjustment module. The second connection end of the first switch module is connected to a gain feedback end (such as a FB signal end of a Boost chip) of a switch power supply chip in the Boost circuit. And the output end of the comparison unit is connected to the switch control end of the first switch module after passing through the first control module.

In some embodiments, the first gain adjustment module comprises: the first voltage division module and the second voltage division module are arranged in series. And the first connecting end of the first switch module is connected to the common end of the first voltage division module and the second voltage division module.

For example: the resistors R1 and R2 can divide the output voltage. Since the present actual output voltage Vout > the intermediate target voltage Vref1 and the input of the intermediate target voltage Vref1 is connected to the non-inverting input of the comparator U1, the output of the comparator U1 will be low. The current state is that the relay K2 is turned off and the relay K1 is closed, the gain of the output voltage feedback is determined by the resistor R1 and the resistor R2, the gain affects the feedback voltage value (namely the value of the feedback voltage FB), the feedback voltage value (namely the value of the feedback voltage FB) flows into the Boost switching power supply chip through the diode D4, and the diode D5 is turned off reversely. The feedback voltage value (i.e., the value of the feedback voltage FB) is input into the Boost switching power supply chip to perform error amplification calculation by using the feedback voltage value (i.e., the value of the feedback voltage FB).

In some embodiments, the first switch module comprises: a first relay (e.g., relay K1) or a first MOS transistor. The coil power obtaining end of the first relay is the switch control end of the first switch module, and the grid electrode of the first MOS tube is the switch control end of the first switch module.

For example: relay K1 can be replaced by a MOS transistor (preferably a MOS transistor with low on-resistance) and functions as a switch, and the effect is equivalent to relay K1.

In some embodiments, the first control module comprises: the device comprises a one-way current limiting module and an interlocking control module. The unidirectional current limiting module comprises: diode modules and resistor modules, such as diode D6 and resistor R8. The interlock control module includes: a first triode module and a second triode module, such as a switch tube Q3 and a switch tube Q4.

Wherein the anode of the diode module is connected to the output terminal of the comparison unit. And the cathode of the diode module sequentially passes through the first triode module and the second triode module and then is connected to the switch control end of the first switch module. When the first triode module is switched on, the second triode module is switched off, and when the first triode module is switched off, the second triode module is switched on.

For example: the resistor R8, the diode D6, the triode Q3, the triode Q4 and the resistor R9 form a peripheral circuit for controlling the relay K1, the relay K1 is attracted only when the comparator U1 outputs a low level, and otherwise, the relay K1 does not act. The voltage of the output capacitor (e.g., the capacitor C1) is rising all the time, when the current actual output voltage Vout rises to a level greater than the intermediate target voltage Vref1, it is at the time that the current actual output voltage Vout is greater than or equal to the intermediate target voltage Vref 1. The high output of the comparator U1 also turns on the transistor Q3, turns on the transistor Q3, turns off the transistor Q4, and turns off the relay K1 because the transistor Q4 is turned off (when the transistor Q4 is turned off, the coil of the relay K1 cannot form a loop). The output of the comparator U1 is low level, and it can be known that the normally open contact of the relay K2 is turned off when the transistor Q2 is turned off, and the normally open contact of the relay K1 is closed when the transistor Q3 is turned off and the transistor Q4 is turned on.

In some embodiments, the first control unit further comprises: at least one of the first freewheel module and the first unidirectional module. A first freewheel module, such as diode D2. A first unidirectional module, such as diode D4.

The first freewheeling module is connected to the switch control end of the first switch module. The first unidirectional module is connected between the second connection end of the first switch module and a gain feedback end (such as a FB signal end of a Boost chip) of a switch power supply chip in the Boost circuit, so that the second connection end of the first switch module and the gain feedback end (such as the FB signal end of the Boost chip) of the switch power supply chip in the Boost circuit are in unidirectional conduction.

For example: diode D2, can provide a return path to the relay for energy release. The diode D4 can prevent a signal from flowing back by utilizing the property of unidirectional conduction.

Specifically, the second control unit is configured to turn itself on based on the second control signal, so as to feed back a second feedback voltage value of the current actual output voltage value to a gain feedback end (such as an FB signal end of a Boost chip) of a switching power supply chip in the Boost circuit, so as to perform a second adjustment on a feedback gain of the current actual output voltage value of the Boost circuit.

Therefore, the gain fed back by the output voltage is adjusted by the sampling unit, the comparison unit, the first control unit and the second control unit in a switching mode of the first control unit and the second control unit, so that the size of a feedback voltage value FB signal is changed, the problem that the feedback gain of a switching power supply chip is fixed, the output voltage overshoots and a component is damaged can be solved, and the feedback gain of the switching power supply chip is adjustable through soft start so as to avoid the overshoot of the output voltage and the damage of the component.

In some embodiments, the second control unit comprises: the second switch module, the second gain adjustment module and the second control module.

The current actual output voltage output by the output end of the booster circuit is connected to the first connection end of the second switch module. And a second connection end of the second switch module is connected to a gain feedback end (such as an FB signal end of a Boost chip) of a switch power supply chip in the Boost circuit after passing through the second gain adjustment module. And the output end of the comparison unit is connected to the switch control end of the second switch module after passing through the second control module.

In some embodiments, the second switch module comprises: a second relay (e.g., relay K2) or a second MOS transistor. And the coil power obtaining end of the second relay is the switch control end of the second switch module, and the grid electrode of the second MOS tube is the switch control end of the second switch module.

For example: relay K2 can be replaced by a MOS transistor (preferably a MOS transistor with low on-resistance) and functions as a switch, and the effect is equivalent to relay K2. The method utilizes the automatic switching mode of the relays (such as the relay K1 and the relay K2) to adjust the feedback gain of the output voltage so as to change the magnitude of a feedback voltage value FB signal, solves the problem of output voltage overshoot caused by fixed feedback gain in the original switch circuit, and achieves the purpose of soft start.

In some embodiments, the second gain adjustment module comprises: and the third voltage division module and the fourth voltage division module are arranged in series. And a second connection end of the second switch module is connected to a gain feedback end (such as a FB signal end of a Boost chip) of a switch power supply chip in the booster circuit after passing through the third voltage division module, and is also connected to the fourth voltage division module, namely is grounded after passing through the fourth voltage division module.

For example: the resistor R3 and the resistor R4 can divide the output voltage. During the initial power-on stage, the voltage across the output capacitor (e.g., the capacitor C1) is very low, i.e., the current actual output voltage Vout is small, and the current actual output voltage Vout is less than the intermediate target voltage Vref 1. The current state is that the normally open contact of the relay K1 is turned off, the normally open contact of the relay K2 is closed, the gain of the current actual output voltage value feedback is determined by the resistor R3 and the resistor R4, the gain influences the feedback voltage value (namely the value of the feedback voltage FB), the feedback voltage value (namely the value of the feedback voltage FB) flows into the Boost chip through the diode D5, and the diode D4 is cut off reversely at the moment. The relay K1 and the relay K2 are used for switching the gain of the output voltage value, and different gains generate different feedback voltage values (namely the value of the feedback voltage FB), so that the output duty ratio is indirectly changed.

In some embodiments, the second control module comprises: a current limiting module and a switch tube module. The current limiting module includes: and current limiting resistance modules such as a resistor R6 and a resistor R7. The switch tube module comprises: and a third transistor module, such as transistor Q2.

The output end of the comparison unit is connected to the switch control end of the second switch module after passing through the current limiting module and the switch tube module.

For example: since the current actual output voltage Vout < the intermediate target voltage Vref1 and the input of the intermediate target voltage Vref1 is connected to the non-inverting input of the comparator U1, the output of the comparator U1 will be high. The high level output by the comparator U1 can make the transistor Q2 conduct, the transistor Q2 conduct and make the coil of the relay K2 conduct (the 12V direct current power supply is connected to the ground through the coil of the relay K2 to form a loop), and therefore the switch of the relay K2 is closed.

In some embodiments, the second control unit further comprises: at least one of a second freewheel module and a second unidirectional module. A first freewheel module, such as diode D3. A first unidirectional module, such as diode D5.

And the second freewheeling module is connected to the switch control end of the second switch module. The second unidirectional module is connected between a second connection end of the second switch module and a gain feedback end (such as a FB signal end of a Boost chip) of a switch power supply chip in the Boost circuit, so that the second connection end of the second switch module and the gain feedback end (such as the FB signal end of the Boost chip) of the switch power supply chip in the Boost circuit are in unidirectional conduction.

For example: diode D3, can provide a return path to the relay for energy release. The diode D5 can prevent a signal from flowing back by utilizing the property of unidirectional conduction.

Through a large number of tests, the technical scheme of the invention is adopted, the soft start circuit is arranged on the basis of the booster circuit of the switching power supply chip, the soft start is realized by utilizing the automatic switching feedback gain of the relay according to the output voltage value, all the component parameters of the soft start circuit are fixed, the calculation of the component parameters is not needed, the use threshold of the circuit is reduced, and the reliability of the circuit is high.

According to an embodiment of the present invention, there is also provided a switching power supply corresponding to a soft start apparatus of a booster circuit. The switching power supply can include: the soft start device of the boost circuit is described above.

When the switching power supply chip is started, the output voltage of the switching power supply chip is too small, so that the output value of an error amplifier inside the switching power supply chip is always in a higher voltage, and the higher voltage can cause loop control to reach an upper limit, so that the maximum duty ratio is output, and overlarge surge current and overlarge overshoot voltage are generated. In this case, by increasing the pressure and flow resistance parameters of the element, damage to the element can be avoided, but the cost and volume of the element are increased.

In order to solve the above problem, a soft start control can be added and introduced when the switching power supply chip is powered on. The working mechanism of the soft start control is to make the output value of the error amplifier in the control loop as flat as possible, because the control duty ratio reaches the upper limit due to the overlarge output value of the error amplifier.

Some soft start control schemes use software control, which is complex and requires modification of the original circuit. For example: in the software control mode, a soft start timing sequence needs to be inserted into an original control timing sequence, timing sequence problems often easily generate BUG (i.e. some undetected defects or problems), and the BUG may cause damage to components in a circuit. If the scheme adopted by the original power supply circuit is controlled by an integrated switch chip, the soft start cannot be completed by adopting a software control mode, and the realization of the soft start circuit by utilizing software control consumes great time cost unless the circuit deletion of a control loop in the original circuit is realized by software control, so that the mode also greatly limits the application range of the soft start circuit.

In some schemes, the method of exponentially attenuating the feedback gain coefficient is adopted for soft start, the circuit element is strictly selected, the parasitic parameter of the element is uncontrollable, the reliability is weak, and the output voltage is slower to reach a stable state.

In some schemes, a method of changing reference voltage is adopted for soft start, specific circuits or algorithms are not explicitly indicated, and the original switch chip is required to be changed for changing the reference voltage theoretically, so that the limitation is large.

In addition, many switch power supply chips are still available in the market without a built-in soft start function, and a switch power supply circuit without the soft start may damage key devices such as a switch tube and a capacitor at the moment of power-on, so that the power supply cannot work normally.

In some embodiments, the present invention provides a boost topology hardware soft start circuit, so as to implement soft start by using a hardware circuit, and can implement soft start only by building a soft start circuit externally connected to the original boost topology circuit through discrete components without changing the original boost topology circuit, without replacing a switching power supply chip or software control, thereby effectively avoiding damage of a switching tube due to overcurrent, and simultaneously effectively suppressing overshoot voltage.

According to the scheme, a hardware soft start circuit is added on an original boost topological circuit, and the size of a target voltage value is automatically switched through hardware control, so that the size of a control duty ratio is indirectly adjusted and controlled, and the soft start control of the boost circuit is realized; the target voltage value can be automatically switched to realize the soft start function, and the target voltage value is timely switched to effectively inhibit the duty ratio of the MOS tube. That is to say, the soft start circuit adopted in the scheme of the invention does not change the loop parameters of the original switching power supply circuit, and simultaneously, the parameters of each element of the soft start circuit do not need to be calculated, and the soft start is realized by utilizing the automatic switching feedback gain of the relay according to the magnitude of the output voltage value.

In the scheme of the invention, the soft start circuit does not change the original switching power supply circuit greatly, and can realize the soft start without software control, namely, the soft start function can realize the soft start control only through a hardware circuit without software programming.

In the scheme of the invention, all the component parameters of the soft start circuit are fixed, the component parameters do not need to be calculated, the use threshold of the circuit is reduced, and the reliability of the circuit is high.

In the scheme of the invention, the soft start circuit can automatically judge whether the current switching power supply needs to perform the soft start function. The soft start circuit can inhibit surge current and overshoot voltage, and protect the switch tube and the output capacitor.

The soft start circuit realizes control switching by depending on the magnitude of the output voltage, if the output voltage is in a target voltage value at the moment of electrifying, the soft start cannot be carried out at the moment, and the output of the comparator is always in a low level, so that the function of judging whether the soft start is needed or not is equivalent to self.

Meanwhile, according to the scheme of the invention, the soft start circuit is turned off after the starting process of the booster circuit is finished. The soft start process finishes the circuit and can not act any more, thereby avoiding the continuous electric energy loss generated by the start circuit and improving the efficiency. Moreover, after the soft start is finished, the soft start circuit can not intervene in the normal operation of the switching power supply circuit, so that the element parameters of the original switching power supply circuit do not need to be changed, and the parameters of the soft start circuit are fixed without circuit parameter calculation.

The following describes an exemplary implementation process of the scheme of the present invention with reference to the examples shown in fig. 2 to 5.

Fig. 2 is a schematic structural diagram of an embodiment of a boost topology circuit. The boost topology circuit shown in fig. 2 includes: the circuit comprises a switch chip (such as a Boost chip), a MOS transistor Q1, a capacitor C1, an inductor L1, a diode D1, a resistor R1, a resistor R2, a resistor Rs and a resistor R5. The anode of the power supply is connected to the anode of the diode D1 through the inductor L1.

The anode of the diode D1 is connected to the drain of the MOS transistor Q1. The cathode of the diode D1 is connected to the anode of the capacitor C1, grounded GND through the resistor R1 and the resistor R2, and further connected to the voltage output terminal Vout. The gate of the MOS transistor Q1 is connected to the first connection terminal of the switch chip, and is grounded to GND through the resistor R5. The source of the MOS transistor Q1 is grounded GND. The common terminal of the resistor R1 and the resistor R2 is connected to the second connection terminal (i.e., the feedback voltage FB gain feedback terminal) of the switch chip. The negative pole of the power supply is grounded GND through a resistor Rs.

The boost topology hardware soft start circuit provided by the scheme of the invention has the main effect of adding a hardware soft start circuit on the basis of not changing the original boost topology circuit (such as the boost topology circuit shown in fig. 2) to form a boost circuit with soft start. The booster circuit with the soft start does not need parameter calculation, does not need to change an original switch power supply chip, and not only increases the reliability of the circuit but also does not change the design difficulty of the circuit.

Fig. 3 is a schematic structural diagram of an embodiment of a boost topology hardware soft start circuit. In the example shown in fig. 3, the resistance Rs in the example shown in fig. 2 is the resistance R10. The boost topology hardware soft start circuit shown in fig. 3 comprises: the circuit comprises a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a diode D2, a diode D3, a diode D4, a diode D5, a diode D6, a triode Q2, a triode Q3, a triode Q4, a triode Q5, a comparator U1, a relay K1 and a relay K2.

The voltage output terminal Vout shown in fig. 3 (i.e., the end of the resistor R1 away from the resistor R2) is connected to the first end of the normally open contact of the relay K2, and is also connected to the inverting input terminal of the comparator U1. The second end of the normally open contact of the relay K2 is connected to the anode of the diode D5 through the resistor R3 and is also connected to the analog ground through the resistor R4. The cathode of the diode D5 is connected to the FB gain feedback terminal of the switch chip IC1 (e.g., Boost chip). The diode D3 is connected in parallel at two ends of the coil of the relay K2, the cathode of the diode D3 is connected with a 12V direct current power supply, and the anode of the diode D3 is connected with the collector of the triode Q2. The base of the triode Q2 is connected to the output terminal of the comparator U1 through the resistor R6, and is also connected to the emitter of the triode Q2 through the resistor R7. The emitter of the transistor Q2 and the negative power supply terminal of the comparator U1 are both connected to analog ground. The positive power supply end of the comparator is connected with a 12V power supply. The non-inverting input terminal of the comparator U1 is a reference value input terminal, and the intermediate target voltage value Vref1 can be input. The output of the comparator U1 is also connected to the anode of the diode D6. The cathode of the diode D6 is connected to the base of the transistor Q3 through the resistor R8. And a voltage output terminal Vout capable of outputting the current actual output voltage value Vout.

The FB gain feedback terminal of the switch chip IC1 (e.g., Boost chip) is also connected to the cathode of the diode D4. And the anode of the diode D4 is connected to the second end of the normally open contact of the relay K1. The first end of the normally open contact of the relay K1 is connected to the common end of the resistor R1 and the resistor R2. The diode D2 is connected in parallel at two ends of the coil of the relay K1, the cathode of the diode D2 is connected with a 12V direct current power supply, and the anode of the diode D2 is connected with the collector of the triode Q4. The emitter of transistor Q4 is connected to the emitter of transistor Q3. The base of the triode Q2 is connected with a 12V direct current power supply through a resistor R9 and is also connected with the collector of the triode Q3.

In the example shown in fig. 3, the switch chip IC1 is a Boost switching power supply chip. Inductor L1 is a boost inductor. The MOS transistor Q1 is used as a switching transistor, and can be turned on and off by a PWM duty ratio. The capacitor C1 is an output capacitor. The resistor R1-resistor R10 are current limiting or pull-up and pull-down resistors, and the selection type is selected according to experience without calculation. Relay K1 and relay K2 are normally open relays. When the intermediate target voltage value Vref1 input to the non-inverting input terminal of the comparator U1 is larger than the input voltage value to the inverting input terminal, the comparator U1 outputs a high level. The transistors Q2-Q4 can be NPN transistors and have the switching function.

In the example shown in fig. 3, a switch chip IC1 (i.e., a Boost switch power supply chip), a switch tube (e.g., a MOS transistor Q1), a Boost inductor (e.g., an inductor L1), a diode D1, an output capacitor (e.g., a capacitor C1), a resistor R5, and a sampling resistor R10 can form a Boost topology circuit for boosting the input voltage value.

In the example shown in fig. 3, the resistor R1, the resistor R2, the resistor R3, and the resistor R4 can divide the output voltage. Diode D2 and diode D3 provide a circuit to release energy to the relay.

In the example shown in fig. 3, the diode D4 and the diode D5 can prevent signal backflow by utilizing the property of unidirectional conduction.

In the example shown in fig. 3, the comparator U1 outputs a high level when the output voltage value of the BOOST topology circuit is less than the reference value (e.g., the intermediate target voltage value Vref1), and otherwise outputs a low level. The high level or low level signal output from the comparator U1 is a key signal for controlling the relay K1 and the relay K2.

In the example shown in fig. 3, the resistor R8, the diode D6, the transistor Q3, the transistor Q4 and the resistor R9 form a peripheral circuit for controlling the relay K1, and the relay K1 is pulled in only when the comparator U1 outputs a low level, otherwise, the relay K1 is not operated.

In the example shown in fig. 3, the transistor Q2, the resistor R6 and the resistor R7 form a peripheral circuit for controlling the relay K2, and the relay K1 is pulled in only when the comparator U1 outputs a high level, otherwise, the relay K1 is not operated.

In the example shown in fig. 3, the relay K1 and the relay K2 can be replaced by MOS transistors (preferably MOS transistors with low on-resistance) to perform a switching function, and the effect is equivalent to that of the relay K1 and the relay K2. Specifically, a PMOS tube can be used for replacement, the connection mode is that the relays K1, K2, D2 and D3 are removed, a control signal is connected to the grid electrode of the PMOS, and the grid electrode is connected with a pull-up resistor; feedback signals are connected between the source electrode and the drain electrode, and actually, three wires connected into the relay are respectively connected onto the PMOS tube for replacement.

The example shown in fig. 3 can automatically switch the relay K1 and the relay K2, circuit parameters do not need to be calculated, and the applicable scenarios are wide, for example, topology circuits such as PFC (power factor correction), boost, buck-boost, etc., for example, a soft start circuit can be applied to the PFC and DC-DC topology circuits.

FIG. 4 is a soft-start control flow of an embodiment of a boost topology hardware soft-start circuit.

The implementation scheme of the invention is to utilize the automatic switching mode of the relay (such as the relay K1 and the relay K2) to adjust the feedback gain of the output voltage so as to change the magnitude of the feedback voltage value FB signal, and the mode solves the problem of overshoot of the output voltage caused by fixed feedback gain in the original switch circuit and achieves the purpose of soft start. As shown in fig. 4, the process of soft start of the boost topology hardware soft start circuit is as follows:

step 1, in an initial power-on stage, at this time, the voltage across the output capacitor (such as the capacitor C1) is very low, that is, the current actual output voltage value Vout is small, and at this time, the current actual output voltage value Vout is in a stage of being smaller than the intermediate target voltage value Vref 1.

Wherein Vref is a target voltage value, i.e., a steady-state voltage value expected during normal operation after the end of soft start. Vref1 is the intermediate target voltage value, and the intermediate target voltage value Vref1 is equal to the target voltage value Vref/2, and coefficients such as 1/3 and 3/4 can be arbitrarily selected according to the circuit in the present invention.

Since the current actual output voltage Vout < the intermediate target voltage Vref1 and the input of the intermediate target voltage Vref1 is connected to the non-inverting input of the comparator U1, the output of the comparator U1 will be high.

The high level output by the comparator U1 can make the transistor Q2 conduct, the transistor Q2 conduct and make the coil of the relay K2 conduct (the 12V direct current power supply is connected to the ground through the coil of the relay K2 to form a loop), and therefore the switch of the relay K2 is closed.

The high output of the comparator U1 also turns on the transistor Q3, turns on the transistor Q3, turns off the transistor Q4, and turns off the relay K1 because the transistor Q4 is turned off (when the transistor Q4 is turned off, the coil of the relay K1 cannot form a loop).

The current state is that the normally open contact of the relay K1 is turned off, the normally open contact of the relay K2 is closed, the gain of the current actual output voltage value feedback is determined by the resistor R3 and the resistor R4, the gain influences the feedback voltage value (namely the value of the feedback voltage FB), the feedback voltage value (namely the value of the feedback voltage FB) flows into the Boost chip through the diode D5, and the diode D4 is cut off reversely at the moment.

And step 2, the voltage of the output capacitor (such as the capacitor C1) is increased all the time, and when the current actual output voltage value Vout is increased to be larger than the intermediate target voltage value Vref1, the current actual output voltage value Vout is equal to or larger than the intermediate target voltage value Vref 1.

Since the present actual output voltage Vout > the intermediate target voltage Vref1 and the input of the intermediate target voltage Vref1 is connected to the non-inverting input of the comparator U1, the output of the comparator U1 will be low.

The output of the comparator U1 is low level, and it can be known that the normally open contact of the relay K2 is turned off when the transistor Q2 is turned off, and the normally open contact of the relay K1 is closed when the transistor Q3 is turned off and the transistor Q4 is turned on. The interlocking of the two NPN triodes has the meaning that the relay can be disconnected by default when no control signal exists, and the relay can be attracted when the control signal is input into a high level, which cannot be realized by only adopting one NPN or one PNP.

The current state is that the relay K2 is turned off and the relay K1 is closed, the gain of the output voltage feedback is determined by the resistor R1 and the resistor R2, the gain affects the feedback voltage value (namely the value of the feedback voltage FB), the feedback voltage value (namely the value of the feedback voltage FB) flows into the Boost switching power supply chip through the diode D4, and the diode D5 is turned off reversely. The feedback voltage value (i.e., the value of the feedback voltage FB) is input into the Boost switching power supply chip to perform error amplification calculation by using the feedback voltage value (i.e., the value of the feedback voltage FB).

After the soft start is finished, the soft start circuit does not interfere the normal work of the original boost topology circuit.

In the example shown in fig. 4, relay K1 and relay K2 can be used to switch the gain of the output voltage value, and different gains produce different feedback voltage values (i.e., the value of feedback voltage FB), thereby indirectly changing the output duty cycle.

Therefore, according to the scheme of the invention, the soft start circuit does not change the loop characteristics, the reliability is higher, and the rise time of the output voltage is fast; a discrete element circuit is adopted to build the soft start circuit, a user can realize soft start without software programming, and an original switch chip is not required to be replaced, so that the application range of the circuit is wide. Moreover, the circuit does not need to be subjected to parameter design, the use threshold is low, and the reliability is stable; the gain of the output voltage is designed in two stages, and the output voltage is switched to the next stage only when reaching a target value; the control logic is switched to the next stage when the output voltage reaches the target value, the duty ratio is effectively limited, the reliability of the original switching power supply is enhanced, the current and the voltage at the moment of electrifying are reduced, a soft start circuit can be introduced on the basis of the original switching power supply circuit, and the circuit applying the scheme is wider.

Since the processes and functions implemented by the switching power supply of this embodiment substantially correspond to the embodiments, principles and examples of the apparatus shown in fig. 1, the descriptions of the embodiment are not detailed herein, and refer to the related descriptions in the embodiments, which are not described herein again.

Through a large number of tests, the technical scheme of the invention is adopted, and under the condition of not changing the original boost topological circuit, only a soft start circuit is built through discrete components and is externally connected with the original boost topological circuit, so that the target voltage value can be automatically switched to realize the soft start function, the target voltage value is timely switched to effectively inhibit the duty ratio of an MOS (metal oxide semiconductor) tube, the switch tube is prevented from being damaged due to overcurrent, and meanwhile, the overshoot voltage can be effectively inhibited.

According to an embodiment of the present invention, there is also provided a controller corresponding to the switching power supply. The controller can include: the switching power supply described above.

According to an embodiment of the present invention, there is also provided a robot corresponding to the controller. The robot can include: the controller described above.

According to an embodiment of the present invention, there is also provided a soft start method of a boost circuit of a switching power supply corresponding to the switching power supply, as shown in fig. 6, which is a schematic flow chart of an embodiment of the method of the present invention. The soft start method of the boost circuit of the switching power supply can comprise the following steps: step S110 to step S130.

At step S110, the present actual output voltage value output by the output terminal of the boosting circuit is compared with the set intermediate target voltage value. And if the current actual output voltage value is smaller than the set intermediate target voltage value, outputting a second control signal. And if the current actual output voltage value is greater than or equal to the set intermediate target voltage value, outputting a first control signal.

At step S120, based on the first control signal, the self is turned on to feed back a first feedback voltage value of the current actual output voltage value to a gain feedback terminal of a switching power chip (e.g., an FB signal terminal of a Boost chip) in the Boost circuit, so as to perform a first adjustment on a feedback gain of the current actual output voltage value of the Boost circuit.

In step S130, based on the second control signal, the self is turned on to feed back a second feedback voltage value of the current actual output voltage value to a gain feedback terminal (e.g., an FB signal terminal of a Boost chip) of a switching power chip in the Boost circuit, so as to perform a second adjustment on a feedback gain of the current actual output voltage value of the Boost circuit.

Since the processing and functions implemented by the method of this embodiment substantially correspond to the embodiments, principles, and examples of the switching power supply, reference can be made to the related descriptions in the foregoing embodiments without being detailed in the description of this embodiment.

Through a large amount of tests verification, adopt the technical scheme of this embodiment, through on the basis of the boost circuit at switching power supply chip, set up soft start circuit, need not change switching power supply chip, also need not software control, just can realize soft start to effectively avoid the switch tube to damage because of overflowing, can also effectively restrain overshoot voltage simultaneously.

In summary, it is readily understood by those skilled in the art that the advantageous modes described above can be freely combined and superimposed without conflict.

The above description is only an example of the present invention, and is not intended to limit the present invention, and it is obvious to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A soft start apparatus of a booster circuit, comprising: the device comprises a comparison unit, a first control unit and a second control unit; wherein,

the comparison unit is configured to compare the current actual output voltage value of the boost circuit with a set intermediate target voltage value; if the current actual output voltage value is smaller than the set intermediate target voltage value, outputting a second control signal; if the current actual output voltage value is larger than or equal to the set intermediate target voltage value, outputting a first control signal;

the first control unit is configured to turn on itself based on the first control signal to feed back a first feedback voltage value of the current actual output voltage value to a gain feedback end of a switch power supply chip in the boost circuit, so as to perform first adjustment on a feedback gain of the current actual output voltage value of the boost circuit;

the second control unit is configured to turn on itself based on the second control signal to feed back a second feedback voltage value of the current actual output voltage value to a gain feedback end of a switch power supply chip in the boost circuit, so as to perform a second adjustment on a feedback gain of the current actual output voltage value of the boost circuit.

2. The soft-start apparatus of a boost circuit according to claim 1, wherein said boost circuit comprises: a Boost circuit of the switching power supply chip;

and the set intermediate target voltage value is a set coefficient multiple of the steady-state voltage value under the normal operation condition after the soft start of the booster circuit is finished.

3. The soft-start apparatus of a boost circuit according to claim 1 or 2, wherein said comparison unit comprises: a comparator module;

the non-inverting input end of the comparator module can input the set intermediate target voltage value;

the inverting input end of the comparator module can input the current actual output voltage value of the booster circuit;

the output end of the comparator module outputs the second control signal under the condition that the current actual output voltage value is smaller than the set intermediate target voltage value; and outputting the first control signal when the current actual output voltage value is greater than or equal to the set intermediate target voltage value.

4. The soft-start apparatus of a booster circuit according to claim 1, wherein the first control unit includes: the device comprises a first gain adjusting module, a first switch module and a first control module; wherein,

the output end of the booster circuit is connected to the first connection end of the first switch module after passing through the first gain adjustment module; the second connection end of the first switch module is connected to the gain feedback end of the switch power supply chip in the booster circuit;

and the output end of the comparison unit is connected to the switch control end of the first switch module after passing through the first control module.

5. The soft-start apparatus of a boost circuit as claimed in claim 4, wherein said first gain adjustment module comprises: the first voltage division module and the second voltage division module are arranged in series; the first connecting end of the first switch module is connected to the common end of the first voltage division module and the second voltage division module;

the first switch module includes: the first relay or the first MOS tube.

6. The soft-start apparatus of a boost circuit according to claim 4, wherein said first control module comprises: the device comprises a one-way current limiting module and an interlocking control module; the unidirectional current limiting module comprises: a diode module and a resistance module; the interlock control module includes: a first triode module and a second triode module; wherein,

the anode of the diode module is connected to the output end of the comparison unit; the cathode of the diode module sequentially passes through the first triode module and the second triode module and then is connected to the switch control end of the first switch module; when the first triode module is switched on, the second triode module is switched off, and when the first triode module is switched off, the second triode module is switched on.

7. The soft-start apparatus of a booster circuit according to any one of claims 4 to 6, wherein the first control unit further includes: at least one of a first freewheel module and a first unidirectional module; wherein,

the first follow current module is connected to the switch control end of the first switch module;

the first unidirectional module is connected between the second connecting end of the first switch module and the gain feedback end of the switch power supply chip in the booster circuit, so that the second connecting end of the first switch module and the gain feedback end of the switch power supply chip in the booster circuit are conducted in a unidirectional mode.

8. The soft-start apparatus of a booster circuit according to claim 1, wherein the second control unit includes: the second switch module, the second gain adjusting module and the second control module; wherein,

the output end of the booster circuit is connected to the first connecting end of the second switch module; a second connection end of the second switch module is connected to a gain feedback end of a switch power supply chip in the booster circuit after passing through the second gain adjustment module;

and the output end of the comparison unit is connected to the switch control end of the second switch module after passing through the second control module.

9. The soft-start apparatus of a boost circuit as set forth in claim 8, wherein said second switching module comprises: a second relay or a second MOS tube;

the second gain adjustment module comprises: the third voltage division module and the fourth voltage division module are arranged in series; and a second connecting end of the second switch module is connected to a gain feedback end of a switch power supply chip in the booster circuit after passing through the third voltage division module, and is also connected to the fourth voltage division module.

10. The soft-start apparatus of a boost circuit as set forth in claim 8, wherein said second control module comprises: the current limiting module and the switch tube module; the current limiting module includes: a current limiting resistance module; the switch tube module comprises: a third triode module;

11. The soft-start apparatus of a booster circuit according to any one of claims 8 to 10, wherein the second control unit further includes: at least one of a second freewheel module and a second unidirectional module; wherein,

the second follow current module is connected to the switch control end of the second switch module;

the second unidirectional module is connected between the second connection end of the second switch module and the gain feedback end of the switch power supply chip in the booster circuit, so that the second connection end of the second switch module and the gain feedback end of the switch power supply chip in the booster circuit are conducted in a unidirectional mode.

12. A switching power supply, comprising: a soft start apparatus of a booster circuit as claimed in any one of claims 1 to 11.

13. A controller, comprising: the switching power supply of claim 12.

14. A robot, comprising: the controller of claim 13.

15. A soft start method of a boost circuit of a switching power supply, comprising:

comparing the current actual output voltage value of the booster circuit with a set intermediate target voltage value; if the current actual output voltage value is smaller than the set intermediate target voltage value, outputting a second control signal; if the current actual output voltage value is larger than or equal to the set intermediate target voltage value, outputting a first control signal;

based on the first control signal, the self is switched on to feed back a first feedback voltage value of the current actual output voltage value to a gain feedback end of a switch power supply chip in the booster circuit so as to perform first adjustment on the feedback gain of the current actual output voltage value of the booster circuit;

and switching on the booster circuit based on the second control signal to feed back a second feedback voltage value of the current actual output voltage value to a gain feedback end of a switch power supply chip in the booster circuit so as to perform second adjustment on the feedback gain of the current actual output voltage value of the booster circuit.