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

Abstract

The present invention discloses a soft start device, method, switching power supply, controller and robot for a boost circuit, the device comprising: a comparison unit, comparing the current actual output voltage value of the boost circuit with the set intermediate target voltage value; and, if the current actual output voltage value is less than the set intermediate target voltage value, outputting a second control signal; if the current actual output voltage value is greater than or equal to the set intermediate target voltage value, outputting a first control signal; a first control unit, based on the first control signal, feeding back the first feedback voltage value of the current actual output voltage value to the boost circuit; a second control unit, based on the second control signal, feeding back the second feedback voltage value of the current actual output voltage value to the boost circuit. This solution, by making the feedback gain of the switching power chip adjustable, can avoid damaging components due to overshoot of the output voltage, thereby improving the safety of the switching power chip.

Description

Technical Field

[0001] The present invention belongs to the technical field of switching power supplies, and specifically relates to a soft starting device, method, switching power supply, controller and robot for a boost circuit, and more particularly to a boost topology hardware soft starting circuit, method, switching power supply, controller and robot. Background Art

[0002] With the continuous development of the science and technology industry, the reliability of power supply in electronic products has gradually attracted attention. In the boost topology circuit, a switching power supply chip is often used to control the duty cycle of the MOS tube to achieve boost. However, the feedback gain of the switching power supply chip is fixed, and there is a risk of output voltage overshoot and damage to components.

[0003] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0004] The purpose of the present invention is to provide a soft start device, method, switching power supply, controller and robot for a boost circuit to solve the problem that the fixed feedback gain of the switching power supply chip will cause the output voltage to overshoot and damage the components, so as to achieve the effect of making the feedback gain of the switching power supply chip adjustable to avoid the output voltage overshoot and damage to the components.

[0005] The present invention provides a soft start device for a boost circuit, comprising: 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; and if the current actual output voltage value is less than the set intermediate target voltage value, a second control signal is output; if the current actual output voltage value is greater than or equal to the set intermediate target voltage value, a first control signal is output; 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 of a switch power supply chip in the boost circuit, so as to perform a first adjustment on the feedback gain of the current actual output voltage value of the boost circuit; 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 of a switch power supply chip in the boost circuit, so as to perform a second adjustment on the feedback gain of the current actual output voltage value of the boost circuit.

[0006] In some embodiments, the boost circuit includes: a Boost boost circuit of a switching power supply chip; wherein the set intermediate target voltage value is a set coefficient times the steady-state voltage value of the boost circuit under normal operation after soft start.

[0007] In some embodiments, the comparison unit includes: a comparator module; the non-inverting input terminal of the comparator module can input the set intermediate target voltage value; the inverting input terminal of the comparator module can input the current actual output voltage value of the boost circuit; the output terminal of the comparator module outputs the second control signal when the current actual output voltage value is less than the set intermediate target voltage value; and outputs the first control signal when the current actual output voltage value is greater than or equal to the set intermediate target voltage value.

[0008] In some embodiments, the first control unit includes: a first gain adjustment module, a first switch module and a first control module; wherein the output end of the boost 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 switching 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.

[0009] In some embodiments, the first gain adjustment module includes: a first voltage divider module and a second voltage divider module arranged in series; the first connection end of the first switch module is connected to the common end of the first voltage divider module and the second voltage divider module; the first switch module includes: a first relay or a first MOS tube.

[0010] In some embodiments, the first control module includes: a unidirectional current limiting module and an interlocking control module; the unidirectional current limiting module includes: a diode module and a resistor module; the interlocking 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 is connected to the switch control end of the first switch module after passing through the first triode module and the second triode module in sequence; when the first triode module is turned on, the second triode module is turned off, and when the first triode module is turned off, the second triode module is turned on.

[0011] In some embodiments, the first control unit also includes: at least one of a first freewheeling module and a first unidirectional module; wherein 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 the gain feedback end of the switch power chip in the boost circuit, so as to enable unidirectional conduction between the second connection end of the first switch module and the gain feedback end of the switch power chip in the boost circuit.

[0012] In some embodiments, the second control unit includes: a second switch module, a second gain adjustment module and a second control module; wherein the output end of the boost circuit is connected to the first connection end of the second switch module; the second connection end of the second switch module is connected to the gain feedback end of the switching power supply chip in the boost circuit after passing through the second gain adjustment module; 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.

[0013] In some embodiments, the second switch module includes: a second relay or a second MOS tube; the second gain adjustment module includes: a third voltage divider module and a fourth voltage divider module arranged in series; the second connection end of the second switch module is connected to the gain feedback end of the switching power supply chip in the boost circuit after passing through the third voltage divider module, and is also connected to the fourth voltage divider module.

[0014] In some embodiments, the second control module includes: a current limiting module and a switch tube module; the current limiting module includes: a current limiting resistor module; the switch tube module includes: a third transistor module; wherein 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.

[0015] In some embodiments, the second control unit further includes: at least one of a second freewheeling module and a second unidirectional module; wherein the second freewheeling 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 chip in the boost circuit, so as to enable unidirectional conduction between the second connection end of the second switch module and the gain feedback end of the switch power chip in the boost circuit.

[0016] Matching the above device, the present invention further provides a switching power supply, including: the soft start device of the boost circuit described above.

[0017] Matching the above-mentioned switching power supply, the present invention further provides a controller on the other hand, including: the above-mentioned switching power supply.

[0018] Matching the above-mentioned controller, the present invention further provides a robot on the other hand, comprising: the above-mentioned controller.

[0019] Matching the above-mentioned switching power supply, the present invention provides a soft-start method for a boost circuit of a switching power supply on another aspect, comprising: comparing a current actual output voltage value of the boost circuit with a set intermediate target voltage value; and, if the current actual output voltage value is less than the set intermediate target voltage value, outputting a second control signal; if the current actual output voltage value is greater than or equal to the set intermediate target voltage value, outputting a first control signal; based on the first control signal, turning itself on to feed back a first feedback voltage value of the current actual output voltage value to a gain feedback end of a switching power chip in the boost circuit to perform a first adjustment on the feedback gain of the current actual output voltage value of the boost circuit; based on the second control signal, turning itself on to feed back a second feedback voltage value of the current actual output voltage value to a gain feedback end of a switching power chip in the boost circuit to perform a second adjustment on the feedback gain of the current actual output voltage value of the boost circuit.

[0020] Therefore, the solution of the present invention, by setting a soft start circuit on the basis of the boost circuit of the switching power supply chip, automatically switches the size of its target voltage value, thereby adjusting the feedback gain of the switching power supply chip to indirectly adjust the size of the control duty cycle, and realize soft start control of the boost circuit, which can avoid damaging components due to overshoot of the output voltage and improve the safety of the switching power supply chip.

[0021] Other features and advantages of the present 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 present invention.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of an embodiment of a soft start device of a boost circuit of the present invention;

[0024] Figure 2 It is a structural schematic diagram of an embodiment of a boost topology circuit;

[0025] Figure 3 It is a structural schematic diagram of an embodiment of a boost topology hardware soft start circuit;

[0026] Figure 4 A schematic diagram of a soft start control flow of an embodiment of a boost topology hardware soft start circuit;

[0027] Figure 5 This is a schematic diagram of the effect comparison curve with and without the soft start circuit;

[0028] Figure 6FIG. 4 is a flow chart of a soft-start method for a boost circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] According to an embodiment of the present invention, a soft start device for a boost circuit is provided. Figure 1 The schematic diagram of the structure of an embodiment of the device of the present invention is shown. The soft start device of the boost circuit can include: a comparison unit, a first control unit and a second control unit.

[0031] In some embodiments, the boost circuit includes: a Boost boost circuit of a switching power supply chip. For example, a switch chip IC1 (i.e., a Boost switching 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 can form a BOOST topology circuit for increasing the input voltage value. As a switch tube, the MOS tube Q1 can be controlled to be turned on and off using a PWM duty cycle. Capacitor C1 is an output capacitor.

[0032] The set intermediate target voltage value is a set coefficient times the steady-state voltage value of the boost circuit in normal operation after the soft start. For example, Vref is the target voltage value, that is, the expected steady-state voltage value in normal operation after the soft start. Vref1 is the intermediate target voltage value, and the intermediate target voltage value Vref1 = target voltage value Vref / 2 can be used, and the coefficients such as 1 / 3, 3 / 4 can be selected according to the circuit.

[0033] Therefore, by adding a hardware soft-start circuit without changing the original boost topology circuit, a boost circuit with soft start is formed. There is no need to calculate parameters or change the original switching power supply chip, which increases the circuit reliability without changing the difficulty of circuit design.

[0034] Specifically, the comparison unit is configured to compare the current actual output voltage value outputted from the output end of the boost circuit with the set intermediate target voltage value; and, if the current actual output voltage value is less than the set intermediate target voltage value, output a second control signal; if the current actual output voltage value is greater than or equal to the set intermediate target voltage value, output a first control signal.

[0035] Of course, in actual use, a 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 setting the sampling unit, the comparison unit is configured to compare the current actual output voltage value collected by the sampling unit with the set intermediate target voltage value.

[0036] In some embodiments, the comparison unit includes: a comparator module (such as comparator U1). The non-inverting input terminal of the comparator module can input the set intermediate target voltage value. The inverting input terminal of the comparator module can input the current actual output voltage value of the boost circuit. The output terminal of the comparator module outputs the second control signal to the first control unit and the second control unit when the current actual output voltage value is less than the set intermediate target voltage value; and outputs the first control signal to the first control unit and the second control unit when the current actual output voltage value is greater than or equal to the set intermediate target voltage value.

[0037] For example, 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 it outputs a low level. The high or low level signal output by comparator U1 is the key signal for controlling relays K1 and K2.

[0038] Therefore, the comparator module outputs the second control signal or the first control signal to control the operation of the first control unit and the second control unit, which has a simple structure and good control reliability.

[0039] Specifically, the first control unit is configured to turn itself on based on the first control signal to feed back the first feedback voltage value of the current actual output voltage value to the gain feedback end of the switching power supply chip in the boost circuit (such as the FB signal end of the Boost chip) to perform a first adjustment on the feedback gain of the current actual output voltage value of the boost circuit.

[0040] In some implementations, the first control unit includes: a first gain adjustment module, a first switch module and a first control module.

[0041] The current actual output voltage outputted from the output end of the boost 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 chip in the boost circuit (such as the FB signal end of the Boost chip). 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.

[0042] In some embodiments, the first gain adjustment module includes: a first voltage divider module and a second voltage divider module arranged in series. The first connection end of the first switch module is connected to a common end of the first voltage divider module and the second voltage divider module.

[0043] For example: resistors R1 and R2 can divide the output voltage. Since the current actual output voltage value Vout> the intermediate target voltage value Vref1, and the input terminal of the intermediate target voltage value Vref1 is connected to the non-inverting input terminal of the comparator U1, the output of the comparator U1 will be a low level at this time. The current state is that relay K2 is off and relay K1 is energized. At this time, the gain of the output voltage feedback is determined by resistors R1 and R2. This gain affects the feedback voltage value (i.e., the value of the feedback voltage FB). The feedback voltage value (i.e., the value of the feedback voltage FB) flows into the Boost switching power supply chip through diode D4, and diode D5 is reversely cut off at this time. The feedback voltage value (i.e., the value of the feedback voltage FB) is input into the Boost switching power supply chip to use the feedback voltage value (i.e., the value of the feedback voltage FB) for error amplification calculation.

[0044] In some embodiments, the first switch module includes: a first relay (such as relay K1) or a first MOS tube. The power supply end of the coil of the first relay is the switch control end of the first switch module, and the gate of the first MOS tube is the switch control end of the first switch module.

[0045] For example, the relay K1 can be replaced by a MOS tube (preferably a MOS tube with low on-resistance) to play a switch role, and the effect produced is equivalent to that of the relay K1.

[0046] In some embodiments, the first control module includes: a unidirectional current limiting module and an interlocking control module. The unidirectional current limiting module includes: a diode module and a resistor module, such as a diode D6 and a resistor R8. The interlocking control module includes: a first triode module and a second triode module, such as a switch tube Q3 and a switch tube Q4.

[0047] The anode of the diode module is connected to the output end of the comparison unit. The cathode of the diode module is connected to the switch control end of the first switch module after passing through the first triode module and the second triode module in sequence. When the first triode module is turned on, the second triode module is turned off, and when the first triode module is turned off, the second triode module is turned on.

[0048] For example, resistor R8, diode D6, transistor Q3, transistor Q4 and resistor R9 form the peripheral circuit of the control relay K1. Relay K1 is only energized when the comparator U1 outputs a low level, otherwise it does not work. The voltage of the output capacitor (such as capacitor C1) keeps rising. When the current actual output voltage value Vout rises to a stage greater than the intermediate target voltage value Vref1, it is in the stage where the current actual output voltage value Vout ≥ the intermediate target voltage value Vref1. The high level output of comparator U1 will also turn on transistor Q3, and the conduction of transistor Q3 will turn off transistor Q4. Therefore, relay K1 is turned off due to the turn-off of transistor Q4 (if transistor Q4 is turned off, the coil of relay K1 cannot form a loop). The output of comparator U1 is a low level. It can be seen that at this time, transistor Q2 is turned off, causing the normally open contact of relay K2 to be turned off, and transistor Q3 is turned off, causing transistor Q4 to be turned on, causing the normally open contact of relay K1 to be energized.

[0049] In some embodiments, the first control unit further includes: at least one of a first freewheeling module and a first unidirectional module. The first freewheeling module is such as a diode D2. The first unidirectional module is such as a diode D4.

[0050] The first freewheeling module is connected to the switch control terminal of the first switch module. The first unidirectional module is connected between the second connection terminal of the first switch module and the gain feedback terminal of the switch power chip in the boost circuit (such as the FB signal terminal of the Boost chip), so that the second connection terminal of the first switch module and the gain feedback terminal of the switch power chip in the boost circuit (such as the FB signal terminal of the Boost chip) are unidirectionally connected.

[0051] For example, diode D2 can provide a loop for the relay to release energy, and diode D4 can prevent signal backflow by using its unidirectional conduction property.

[0052] Specifically, the second control unit is configured to turn itself on based on the second control signal to feed back the second feedback voltage value of the current actual output voltage value to the gain feedback end of the switching power supply chip in the boost circuit (such as the FB signal end of the Boost chip) to perform a second adjustment on the feedback gain of the current actual output voltage value of the boost circuit.

[0053] Therefore, by using the sampling unit, the comparison unit, the first control unit and the second control unit, the gain of the output voltage feedback is adjusted by switching the first control unit and the second control unit, thereby changing the size of the feedback voltage value FB signal. This can solve the problem that the fixed feedback gain of the switching power supply chip will cause the output voltage to overshoot and damage components. The feedback gain of the switching power supply chip is made adjustable through soft start to avoid overshoot of the output voltage and damage to components.

[0054] In some implementations, the second control unit includes: a second switch module, a second gain adjustment module and a second control module.

[0055] The current actual output voltage outputted from the output end of the boost circuit is connected to the first connection end of the second switch module. The second connection end of the second switch module is connected to the gain feedback end of the switch power chip in the boost circuit (such as the FB signal end of the Boost chip) after passing through the second gain adjustment module. 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.

[0056] In some embodiments, the second switch module includes: a second relay (such as relay K2) or a second MOS tube. The power supply end of the coil of the second relay is the switch control end of the second switch module, and the gate of the second MOS tube is the switch control end of the second switch module.

[0057] For example, relay K2 can be replaced by a MOS tube (preferably a MOS tube with low on-resistance) to play a switch role, and the effect produced is equivalent to that of relay K2. By using the automatic switching method of relays (such as relay K1 and relay K2) to adjust the gain of the output voltage feedback, the magnitude of the feedback voltage value FB signal is changed. This method solves the problem of output voltage overshoot caused by fixed feedback gain in the original switch circuit, and achieves the purpose of soft start.

[0058] In some embodiments, the second gain adjustment module includes: a third voltage divider module and a fourth voltage divider module arranged in series. The second connection end of the second switch module is connected to the gain feedback end of the switch power chip in the boost circuit (such as the FB signal end of the Boost chip) after passing through the third voltage divider module, and is also connected to the fourth voltage divider module, that is, grounded after passing through the fourth voltage divider module.

[0059] For example, resistors R3 and R4 can divide the output voltage. In the initial power-on stage, the voltage across the output capacitor (such as capacitor C1) is very low, that is, the current actual output voltage value Vout is small, and the current actual output voltage value Vout < intermediate target voltage value Vref1 is in the stage. The current state is that the normally open contact of relay K1 is closed and the normally open contact of relay K2 is closed. At this time, the gain of the current actual output voltage value feedback is determined by resistors R3 and R4. This gain affects the feedback voltage value (that is, the value of the feedback voltage FB), and the feedback voltage value (that is, the value of the feedback voltage FB) flows into the Boost chip through diode D5. At this time, diode D4 is reversely cut off. Relays K1 and K2 are used to switch the gain of the output voltage value. Different gains produce different feedback voltage values ​​(that is, the value of the feedback voltage FB), thereby indirectly changing the output duty cycle.

[0060] In some embodiments, the second control module includes: a current limiting module and a switch module. The current limiting module includes: a current limiting resistor module, such as resistor R6 and resistor R7. The switch module includes: a third transistor module, such as transistor Q2.

[0061] Wherein, 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.

[0062] For example: since the current actual output voltage value Vout < the intermediate target voltage value Vref1, and the input terminal of the intermediate target voltage value Vref1 is connected to the non-inverting input terminal of the comparator U1, the output of the comparator U1 will be high level. The high level output of the comparator U1 will turn on the transistor Q2, and the conduction of the transistor Q2 will turn on the coil of the relay K2 (the 12V DC power supply is connected to the ground through the coil of the relay K2 to form a loop), so the switch of the relay K2 is closed.

[0063] In some embodiments, the second control unit further includes: at least one of a second freewheeling module and a second unidirectional module. A first freewheeling module, such as a diode D3. A first unidirectional module, such as a diode D5.

[0064] The second freewheeling module is connected to the switch control terminal of the second switch module. The second unidirectional module is connected between the second connection terminal of the second switch module and the gain feedback terminal of the switch power chip in the boost circuit (such as the FB signal terminal of the Boost chip), so that the second connection terminal of the second switch module and the gain feedback terminal of the switch power chip in the boost circuit (such as the FB signal terminal of the Boost chip) are unidirectionally connected.

[0065] For example, diode D3 can provide a loop for the relay to release energy, and diode D5 can prevent signal backflow by using its unidirectional conduction property.

[0066] After a large number of experimental verifications, the technical solution of the present invention is adopted. By setting a soft start circuit on the basis of the boost circuit of the switching power supply chip, the feedback gain is automatically switched by a relay according to the output voltage value to achieve soft start. The parameters of all components of the soft start circuit are fixed, and there is no need to calculate the device parameters, which reduces the use threshold of this circuit and has high circuit reliability.

[0067] According to an embodiment of the present invention, a switching power supply corresponding to a soft start device of a voltage boost circuit is also provided. The switching power supply can include: the soft start device of the voltage boost circuit described above.

[0068] When the switching power supply chip is started, the output voltage of the switching power supply chip is too small, which will cause the output value of the error amplifier inside the switching power supply chip to be always at a higher voltage. The higher voltage will cause the loop control to reach the upper limit and output the maximum duty cycle, resulting in excessive surge current and excessive overshoot voltage. In this case, by increasing the withstand voltage and current parameters of the component, damage to the component can be avoided, but the cost and volume of the component will be increased.

[0069] In order to solve the above problems, a soft start control can be 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 smooth as possible, because if the output value of the error amplifier is too large, the control duty cycle will reach the upper limit.

[0070] Some soft start control schemes use software control, which is complex and requires changes to the original circuit. For example, in the software control method, it is necessary to insert a soft start sequence into the original control sequence. Timing problems often easily cause bugs (that is, some undiscovered defects or problems), which can damage components in the circuit. If the original power supply circuit uses an integrated switch chip control scheme, it is impossible to use software control to complete the soft start, unless the control loop circuit in the original circuit is deleted and replaced by software control. In this case, it will take a lot of time to implement a soft start circuit using software control, and this method also greatly limits the scope of use of the soft start circuit.

[0071] In some schemes, an exponential decay feedback gain coefficient method is used for soft start, which has strict requirements on the selection of circuit components and uncontrollable component parasitic parameters, resulting in poor reliability and a slow output voltage reaching a stable state.

[0072] In some solutions, a variable reference voltage method is used for soft start, but no specific circuit or algorithm is clearly specified. In theory, changing the reference voltage requires modifying the original switch chip, which has great limitations.

[0073] In addition, there are still many switching power supply chips on the market that do not have a built-in soft-start function. Switching power supply circuits without soft-start may damage key components such as switching tubes and capacitors at the moment of power-on, causing the power supply to fail to work properly.

[0074] In some embodiments, the solution of the present invention provides a boost topology hardware soft-start circuit to achieve soft start by utilizing a hardware circuit. Without changing the original boost topology circuit, a soft-start circuit can be built by only using discrete components and connected to the original boost topology circuit. Soft start can be achieved without replacing the switching power supply chip or software control, thereby effectively avoiding damage to the switching tube due to overcurrent and effectively suppressing overshoot voltage.

[0075] The scheme of the present invention is to add a hardware soft start circuit to the original boost topology circuit, automatically switch the size of its target voltage value through hardware control, thereby indirectly adjusting the size of the control duty cycle to achieve soft start control of the boost circuit; the target voltage value can be automatically switched to achieve the soft start function, and the timely switching of the target voltage value effectively suppresses the size of the duty cycle of the MOS tube. In other words, the soft start circuit adopted by the scheme of the present invention will not change the loop parameters of the original switching power supply circuit, and the parameters of each component of the soft start circuit do not need to be calculated. According to the size of the output voltage value, the relay is used to automatically switch the feedback gain to achieve soft start.

[0076] Among them, in the scheme of the present invention, the soft start circuit does not make much change to the original switching power supply circuit and can be implemented without software control. In other words, the soft start function can achieve soft start control only through hardware circuits without software programming.

[0077] In the solution of the present invention, all component parameters of the soft start circuit are fixed, and there is no need to calculate the component parameters, which lowers the use threshold of the circuit and increases the circuit reliability.

[0078] In the solution of the present invention, the soft start circuit can automatically determine whether the current switching power supply needs to perform a soft start function. The addition of the soft start circuit can suppress surge current and overshoot voltage, and protect the switch tube and output capacitor.

[0079] Among them, the soft start circuit relies on the size of the output voltage to achieve control switching. If the output voltage is already at the target voltage value at the moment of power-on, then soft start will not be performed at this time, because the comparator output is always at a low level, so it is equivalent to judging whether the soft start function is needed by itself.

[0080] At the same time, the scheme of the present invention turns off the soft start circuit after the boost circuit startup process is completed. After the soft start process is completed, the circuit will no longer operate, thereby avoiding the continuous power loss of the startup circuit and improving efficiency. Moreover, after the soft start is completed, the soft start circuit will no longer interfere with the normal operation of the switching power supply circuit, so there is no need to change the component parameters of the original switching power supply circuit, and the soft start circuit parameters are fixed and no circuit parameter calculation is required.

[0081] Combine the following Figures 2 to 5 The examples shown are used to illustrate the specific implementation process of the solution of the present invention.

[0082] Figure 2 FIG. 1 is a schematic diagram of a structure of an embodiment of a boost topology circuit. Figure 2 The boost topology circuit shown includes: a switch chip (such as a Boost chip), a MOS tube Q1, a capacitor C1, an inductor L1, a diode D1, a resistor R1, a resistor R2, a resistor Rs, and a resistor R5. The positive electrode of the power supply is connected to the anode of the diode D1 through the inductor L1.

[0083] Among them, the anode of the diode D1 is connected to the drain of the MOS tube Q1. The cathode of the diode D1 is connected to the positive electrode of the capacitor C1, and is grounded to GND after passing through the resistors R1 and R2, and is also connected to the voltage output terminal Vout. The gate of the MOS tube Q1 is connected to the first connection terminal of the switch chip, and is also grounded to GND after passing through the resistor R5. The source of the MOS tube Q1 is grounded to GND. The common end of the resistor R1 and the resistor R2 is connected to the second connection terminal of the switch chip (i.e., the feedback voltage value FB gain feedback terminal). The negative electrode of the power supply is grounded to GND after passing through the resistor Rs.

[0084] The present invention proposes a boost topology hardware soft start circuit, which mainly achieves the effect of not changing the original boost topology circuit (such as Figure 2 The boost topology circuit shown in the figure is added with a hardware soft start circuit to form a boost circuit with soft start. The boost circuit with soft start shown in the solution of the present invention does not require parameter calculation and does not require modification of the original switching power supply chip, thereby increasing circuit reliability without changing the difficulty of circuit design.

[0085] Figure 3 FIG. 1 is a schematic diagram of a structure of an embodiment of a boost topology hardware soft start circuit. Figure 3 In the example shown, Figure 2 The resistor Rs in the example shown is a resistor R10. Figure 3The boost topology hardware soft start circuit shown includes: resistor R1, resistor R2, resistor R3, resistor R4, resistor R6, resistor R7, resistor R8, resistor R9, diode D2, diode D3, diode D4, diode D5, diode D6, transistor Q2, transistor Q3, transistor Q4, transistor Q5, comparator U1, relay K1 and relay K2.

[0086] in, Figure 3 The voltage output terminal Vout shown (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 (such as the Boost chip). The diode D3 is connected in parallel to the two ends of the coil of the relay K2, the cathode of the diode D3 is connected to the 12V DC power supply, and the anode of the diode D3 is connected to the collector of the transistor Q2. The base of the transistor Q2 is connected to the output terminal of the comparator U1 through the resistor R6, and is also connected to the emitter of the transistor Q2 through the resistor R7. The emitter of the transistor Q2 and the negative end of the power supply of the comparator U1 are both connected to the analog ground. The positive end of the power supply of the comparator is connected to the 12V power supply. The non-inverting input terminal of the comparator U1 is the reference value input terminal, which can input the intermediate target voltage value Vref1. The output end 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. The voltage output end Vout can output the current actual output voltage value Vout.

[0087] The FB gain feedback terminal of the switch chip IC1 (such as the Boost chip) is also connected to the cathode of the diode D4. 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 to the two ends of the coil of the relay K1, the cathode of the diode D2 is connected to the 12V DC power supply, and the anode of the diode D2 is connected to the collector of the transistor Q4. The emitter of the transistor Q4 is connected to the emitter of the transistor Q3. The base of the transistor Q2 is connected to the 12V DC power supply after the resistor R9, and is also connected to the collector of the transistor Q3.

[0088] exist Figure 3In the example shown, the switch chip IC1 is a Boost switch power supply chip. The inductor L1 is a boost inductor. The MOS tube Q1 is used as a switch tube, and its conduction and shutdown can be controlled by using the PWM duty cycle. The capacitor C1 is the output capacitor. The resistors R1 to R10 are current limiting or pull-up and pull-down resistors, and the selection is based on experience without calculation. Relay K1 and relay K2 are both normally open relays. When the intermediate target voltage value Vref1 input to the non-inverting input terminal of the comparator U1 is greater than the input voltage value of the inverting input terminal, the comparator U1 outputs a high level. Transistors Q2 to Q4 can all be NPN transistors, which act as switches.

[0089] exist Figure 3 In the example shown, the switch chip IC1 (i.e., the Boost switching power supply chip), the switch tube (such as the MOS tube Q1), the boost inductor (such as the inductor L1), the diode D1, the output capacitor (such as the capacitor C1), the resistor R5, and the sampling resistor R10 can form a BOOST topology circuit for increasing the input voltage value.

[0090] exist Figure 3 In the example shown, resistors R1, R2, R3 and R4 can divide the output voltage, and diodes D2 and D3 can provide a loop for the relay to release energy.

[0091] exist Figure 3 In the example shown, the diode D4 and the diode D5 can prevent the signal from flowing back by utilizing the unidirectional conductive property.

[0092] exist Figure 3 In the example shown, 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 it outputs a low level. The high level or low level signal output by the comparator U1 is the key signal for controlling the relay K1 and the relay K2.

[0093] exist Figure 3 In the example shown, resistor R8, diode D6, transistor Q3, transistor Q4 and resistor R9 constitute a peripheral circuit for controlling relay K1. Relay K1 is only energized when comparator U1 outputs a low level, otherwise it will not operate.

[0094] exist Figure 3 In the example shown, transistor Q2, resistor R6 and resistor R7 form a peripheral circuit for controlling relay K2. Relay K1 is only energized when comparator U1 outputs a high level, otherwise it will not operate.

[0095] exist Figure 3In the example shown, relay K1 and relay K2 can be replaced by MOS tubes (preferably MOS tubes with low on-resistance) to play a switch role, and the effect produced is equivalent to that of relay K1 and relay K2. Specifically, PMOS tubes can be used instead, and the connection method is to remove relays K1, K2, D2, and D3, connect the control signal to the gate of PMOS, and connect a pull-up resistor to the gate; connect the feedback signal between the source and drain, which is actually to connect the three wires connected to the relay to the PMOS tube for replacement.

[0096] Figure 3 The example shown can automatically switch relay K1 and relay K2. Circuit parameters do not need to be calculated. It can be used in a wide range of scenarios, such as PFC (power factor correction), boost, buck, buck-boost and other topology circuits. For example, the soft start circuit can be used in PFC and DC-DC topology circuits.

[0097] Figure 4 The present invention is a soft start control process of an embodiment of a boost topology hardware soft start circuit.

[0098] The implementation scheme of the present invention is to use the automatic switching of relays (such as relay K1 and relay K2) to adjust the gain of the output voltage feedback, thereby changing the magnitude of the feedback voltage value FB signal. This method solves the problem of output voltage overshoot caused by fixed feedback gain in the original switch circuit, and achieves the purpose of soft start. Figure 4 As shown in the figure, the soft start process of the boost topology hardware soft start circuit is as follows:

[0099] Step 1, initial power-on stage, at this time, the voltage across the output capacitor (such as capacitor C1) is very low, that is, the current actual output voltage value Vout is small, and at this time it is in the stage where the current actual output voltage value Vout < the intermediate target voltage value Vref1.

[0100] Wherein, Vref is the target voltage value, i.e., the steady-state voltage value expected during normal operation after the soft start is completed. Vref1 is the intermediate target voltage value. The solution of the present invention adopts the intermediate target voltage value Vref1 = target voltage value Vref / 2 as an example, and the coefficients such as 1 / 3, 3 / 4 can be selected arbitrarily according to the circuit.

[0101] Since the current actual output voltage value Vout<the intermediate target voltage value Vref1, and the input terminal of the intermediate target voltage value Vref1 is connected to the non-inverting input terminal of the comparator U1, the output of the comparator U1 will be a high level at this time.

[0102] The high level output of the comparator U1 will turn on the transistor Q2, and the turning on of the transistor Q2 will turn on the coil of the relay K2 (the 12V DC power supply is connected to the ground through the coil of the relay K2 to form a loop), so the switch of the relay K2 is energized.

[0103] The high level output of comparator U1 will also turn on transistor Q3, which turns on transistor Q3 and turns off transistor Q4. Therefore, relay K1 is turned off due to transistor Q4 being turned off (if transistor Q4 is turned off, the coil of relay K1 cannot form a loop).

[0104] The current state is that the normally open contact of relay K1 is closed and the normally open contact of relay K2 is closed. At this time, the gain of the current actual output voltage value feedback is determined by resistors R3 and R4. This gain affects the feedback voltage value (that is, the value of feedback voltage FB), and the feedback voltage value (that is, the value of feedback voltage FB) flows into the Boost chip through diode D5. At this time, diode D4 is reversely cut off.

[0105] Step 2, the voltage of the output capacitor (such as capacitor C1) keeps rising. When the current actual output voltage value Vout rises to a stage greater than the intermediate target voltage value Vref1, it is at the stage where the current actual output voltage value Vout ≥ the intermediate target voltage value Vref1.

[0106] Since the current actual output voltage value Vout> the intermediate target voltage value Vref1, and the input terminal of the intermediate target voltage value Vref1 is connected to the non-inverting input terminal of the comparator U1, the output of the comparator U1 will be a low level at this time.

[0107] The output of comparator U1 is low level, which means transistor Q2 is cut off, causing the normally open contact of relay K2 to be closed, and transistor Q3 is cut off, causing transistor Q4 to be turned on, causing the normally open contact of relay K1 to be closed. The meaning of the interlocking of two NPN transistors is that when there is no control signal, the relay can be disconnected by default, and the relay can be closed when the control signal input is high level, which cannot be achieved by using only one NPN or one PNP.

[0108] The current state is that relay K2 is off and relay K1 is on. At this time, the gain of the output voltage feedback is determined by resistors R1 and R2. This gain affects the feedback voltage value (i.e., the value of the feedback voltage FB). The feedback voltage value (i.e., the value of the feedback voltage FB) flows into the Boost switching power supply chip through diode D4. At this time, diode D5 is reversely cut off. The feedback voltage value (i.e., the value of the feedback voltage FB) is input into the Boost switching power supply chip to use the feedback voltage value (i.e., the value of the feedback voltage FB) for error amplification calculation.

[0109] After the soft start is completed, the soft start circuit no longer interferes with the normal operation of the original boost topology circuit.

[0110] exist Figure 4In the example shown, relays K1 and K2 can be used to switch the gain of the output voltage value. Different gains produce different feedback voltage values ​​(ie, the value of feedback voltage FB), thereby indirectly changing the output duty cycle.

[0111] It can be seen that the scheme of the present invention, the soft start circuit does not change the loop characteristics, the reliability is high, and the output voltage rise time is fast; the soft start circuit is built with discrete component circuits, and the user can achieve soft start without software programming, and there is no need to replace the original switch chip, so the circuit has a wide range of applications. Moreover, there is no need to design parameters for the circuit, the use threshold is low and the reliability is stable; the gain of the output voltage is designed in two levels, and it will only switch to the next level when the output voltage reaches the target value; the control logic is that it will switch to the next level when the output voltage reaches the target value, and the duty cycle is effectively limited, which enhances the reliability of the original switching power supply, reduces the current and voltage at the moment of power-on, and can introduce a soft start circuit on the basis of the original switching power supply circuit, and the circuit that can apply this scheme is more extensive.

[0112] Since the processing and functions implemented by the switching power supply of this embodiment are basically corresponding to the aforementioned Figure 1 The embodiments, principles and examples of the device shown are as follows. Therefore, for matters not fully described in the description of this embodiment, reference can be made to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0113] A large number of experiments have verified that the technical solution of the present invention can be used to automatically switch the target voltage value to achieve the soft start function by building a soft start circuit externally connected to the original boost topology circuit only through discrete components without changing the original boost topology circuit. The timely switching of the target voltage value effectively suppresses the duty cycle of the MOS tube, avoids damage to the switch tube due to overcurrent, and can also effectively suppress overshoot voltage.

[0114] According to an embodiment of the present invention, a controller corresponding to a switching power supply is also provided. The controller can include: the switching power supply described above.

[0115] According to an embodiment of the present invention, a robot corresponding to the controller is also provided. The robot can include: the controller described above.

[0116] According to an embodiment of the present invention, a soft starting method for a boost circuit of a switching power supply corresponding to the switching power supply is also provided. Figure 6 The flowchart of an embodiment of the method of the present invention is shown in FIG. The soft start method of the boost circuit of the switching power supply can include: step S110 to step S130.

[0117] At step S110, the current actual output voltage value outputted from the output terminal of the boost circuit is compared with the set intermediate target voltage value. If the current actual output voltage value is less than the set intermediate target voltage value, a second control signal is outputted. If the current actual output voltage value is greater than or equal to the set intermediate target voltage value, a first control signal is outputted.

[0118] Of course, in actual use, a 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 setting the sampling unit, the comparison unit is configured to compare the current actual output voltage value collected by the sampling unit with the set intermediate target voltage value.

[0119] At step S120, based on the first control signal, it turns itself on to feed back the first feedback voltage value of the current actual output voltage value to the gain feedback end of the switching power supply chip in the boost circuit (such as the FB signal end of the Boost chip) to perform a first adjustment on the feedback gain of the current actual output voltage value of the boost circuit.

[0120] At step S130, based on the second control signal, it turns itself on to feed back the second feedback voltage value of the current actual output voltage value to the gain feedback end of the switching power supply chip in the boost circuit (such as the FB signal end of the Boost chip) to perform a second adjustment on the feedback gain of the current actual output voltage value of the boost circuit.

[0121] Therefore, by using the sampling unit, the comparison unit, the first control unit and the second control unit, the gain of the output voltage feedback is adjusted by switching the first control unit and the second control unit, thereby changing the size of the feedback voltage value FB signal. This can solve the problem that the fixed feedback gain of the switching power supply chip will cause the output voltage to overshoot and damage components. The feedback gain of the switching power supply chip is made adjustable through soft start to avoid overshoot of the output voltage and damage to components.

[0122] Since the processing and functions implemented by the method of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned switching power supply, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0123] After a large number of tests and verifications, the technical solution of this embodiment is adopted. By setting a soft start circuit on the basis of the boost circuit of the switching power supply chip, soft start can be achieved without replacing the switching power supply chip or software control, thereby effectively avoiding damage to the switching tube due to overcurrent and effectively suppressing overshoot voltage.

[0124] In summary, it is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0125] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can be modified and varied in various ways. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A soft start device for a boost circuit, characterized in that: include: 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 the set intermediate target voltage value; and output a second control signal if the current actual output voltage value is less than the set intermediate target voltage value; and output a first control signal if the current actual output voltage value is greater than or equal to the set intermediate target voltage value; The first control unit is configured to turn on the first control unit itself based on the first control signal, so as to feed back the first feedback voltage value of the current actual output voltage value to the gain feedback end of the switch power chip in the boost circuit, so as to perform a first adjustment on the feedback gain of the current actual output voltage value of the boost circuit; the first control unit includes: a first gain adjustment module, a first switch module and a first control module; wherein the output end of the boost 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 chip in the boost circuit; 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; The second control unit is configured to turn on the second control unit itself based on the second control signal, so as to feed back the second feedback voltage value of the current actual output voltage value to the gain feedback end of the switching power supply chip in the boost circuit, so as to perform a second adjustment on the feedback gain of the current actual output voltage value of the boost circuit; the second control unit includes: a second switch module, a second gain adjustment module and a second control module; wherein the output end of the boost circuit is connected to the first connection end of the second switch module; the second connection end of the second switch module is connected to the gain feedback end of the switching power supply chip in the boost circuit after passing through the second gain adjustment module; 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.

2. The soft start device of the boost circuit according to claim 1, characterized in that: The boost circuit comprises: a Boost boost circuit of a switching power supply chip; The set intermediate target voltage value is a set coefficient times the steady-state voltage value of the boost circuit under normal operation after the soft start is completed.

3. The soft start device of the boost circuit according to claim 1 or 2, characterized in that: The comparison unit comprises: a comparator module; The non-inverting input terminal of the comparator module can input the set intermediate target voltage value; The inverting input terminal of the comparator module can input the current actual output voltage value of the boost circuit; The output end of the comparator module outputs the second control signal when the current actual output voltage value is less than the set intermediate target voltage value; and outputs 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 device of the boost circuit according to claim 1, characterized in that: The first gain adjustment module includes: a first voltage dividing module and a second voltage dividing module arranged in series; a first connection end of the first switch module is connected to a common end of the first voltage dividing module and the second voltage dividing module; The first switch module includes: a first relay or a first MOS tube.

5. The soft start device of the boost circuit according to claim 1, characterized in that: The first control module includes: a unidirectional current limiting module and an interlocking control module; the unidirectional current limiting module includes: a diode module and a resistor module; the interlocking 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 is connected to the switch control end of the first switch module after passing through the first transistor module and the second transistor module in sequence; when the first transistor module is turned on, the second transistor module is turned off, and when the first transistor module is turned off, the second transistor module is turned on.

6. The soft start device of the boost circuit according to any one of claims 1, 4 to 5, characterized in that: The first control unit further includes: at least one of a first freewheeling module and a first unidirectional module; wherein, The first freewheeling module is connected to the switch control terminal of the first switch module; The first unidirectional module is connected between the second connection end of the first switch module and the gain feedback end of the switch power chip in the boost circuit, so that the second connection end of the first switch module and the gain feedback end of the switch power chip in the boost circuit are unidirectionally conductive.

7. The soft start device of the boost circuit according to claim 1, characterized in that: The second switch module includes: a second relay or a second MOS tube; The second gain adjustment module includes: a third voltage divider module and a fourth voltage divider module arranged in series; the second connection end of the second switch module is connected to the gain feedback end of the switching power supply chip in the boost circuit after passing through the third voltage divider module, and is also connected to the fourth voltage divider module.

8. The soft start device of the boost circuit according to claim 1, characterized in that: The second control module includes: a current limiting module and a switch tube module; the current limiting module includes: a current limiting resistor module; the switch tube module includes: a third triode module; Wherein, 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.

9. The soft start device of the boost circuit according to any one of claims 1, 7 to 8, characterized in that: The second control unit further includes: at least one of a second freewheeling module and a second unidirectional module; wherein, The second freewheeling module is connected to the switch control terminal 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 chip in the boost circuit, so that the second connection end of the second switch module and the gain feedback end of the switch power chip in the boost circuit are unidirectionally conductive.

10. A switching power supply, characterized in that: include: A soft starting device for a boost circuit as claimed in any one of claims 1 to 9.

11. A controller, characterized in that: include: The switching power supply as claimed in claim 10.

12. A robot, characterized in that: include: A controller as claimed in claim 11.

13. A soft-start method for a boost circuit of a switching power supply as claimed in claim 10, characterized in that: include: By means of the comparison unit, the current actual output voltage value of the boost circuit is compared with the set intermediate target voltage value; and, if the current actual output voltage value is less than the set intermediate target voltage value, outputting a second control signal; If the current actual output voltage value is greater than or equal to the set intermediate target voltage value, outputting a first control signal; By means of the first control unit, based on the first control signal, the first control unit itself is turned on to feed back the first feedback voltage value of the current actual output voltage value to the gain feedback terminal of the switching power supply chip in the boost circuit to perform a first adjustment on the feedback gain of the current actual output voltage value of the boost circuit; Through the second control unit, based on the second control signal, the second control unit itself is turned on to feed back the second feedback voltage value of the current actual output voltage value to the gain feedback end of the switching power supply chip in the boost circuit to perform a second adjustment on the feedback gain of the current actual output voltage value of the boost circuit.

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