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CN116800077B - A soft-start circuit for a switched-capacitor power converter and a soft-start operation method based thereon. - Google Patents

A soft-start circuit for a switched-capacitor power converter and a soft-start operation method based thereon.

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Publication number
CN116800077B
CN116800077B CN202310728499.7A CN202310728499A CN116800077B CN 116800077 B CN116800077 B CN 116800077B CN 202310728499 A CN202310728499 A CN 202310728499A CN 116800077 B CN116800077 B CN 116800077B
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China
Prior art keywords
vin
capacitor
power converter
switching transistor
formula
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Application number
CN202310728499.7A
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Chinese (zh)
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CN116800077A (en
Inventor
宋继斌
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Nanjing Nenglixin Technology Co ltd
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Nanjing Nenglixin Technology Co ltd
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Priority to CN202310728499.7A priority Critical patent/CN116800077B/en
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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/36—Means for starting or stopping converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H11/00—Emergency protective circuit arrangements for preventing the switching-on in case an undesired electric working condition might result
    • H02H11/002—Emergency protective circuit arrangements for preventing the switching-on in case an undesired electric working condition might result in case of inverted polarity or connection; with switching for obtaining correct connection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of DC power input into DC power output
    • H02M3/02—Conversion of DC power input into DC power output without intermediate conversion into AC
    • H02M3/04—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters
    • H02M3/06—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using resistors or capacitors, e.g. potential divider
    • H02M3/07—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using resistors or capacitors, e.g. potential divider using capacitors charged and discharged alternately by semiconductor devices with control electrode, e.g. charge pumps

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

本发明公开了一种开关电容电源变换器的缓启电路及其操作方法，缓启电路包括设置在开关电容电源变换器输入端与接地端之间的第一开关管和第二开关管、设置在开关电容电源变换器输入端与接地端之间的常通开关管、二极管、电阻、输出电容，二极管的负极位于靠近常通开关管的一侧，输出电感通过导线一端连接在第一开关管和第二开关管之间、另一端连接在电阻和输出电容之间；通过导线连接的自举电容、自举供电二极管、驱动供电电容；自举电容另一端通过导线连接在常通开关管与二极管之间；自举供电二极管的负极位于靠近常通开关管的一侧，驱动供电电容另一端通过导线连接在开关电容电源变换器的最高压侧开关管的源极上。

This invention discloses a soft-start circuit and its operation method for a switched-capacitor power converter. The soft-start circuit includes a first and second switching transistor disposed between the input terminal and the ground terminal of the switched-capacitor power converter, a normally-on switching transistor disposed between the input terminal and the ground terminal of the switched-capacitor power converter, a diode, a resistor, and an output capacitor. The cathode of the diode is located near the normally-on switching transistor. One end of the output inductor is connected between the first and second switching transistors via a wire, and the other end is connected between the resistor and the output capacitor. A bootstrap capacitor, a bootstrap power supply diode, and a drive power supply capacitor are connected via wires. The other end of the bootstrap capacitor is connected between the normally-on switching transistor and the diode via a wire. The cathode of the bootstrap power supply diode is located near the normally-on switching transistor. The other end of the drive power supply capacitor is connected to the source of the highest voltage-side switching transistor of the switched-capacitor power converter via a wire.

Description

Switch capacitor power supply converter slow start circuit and switch capacitor power supply converter slow start operation method based on same
Technical Field
The invention relates to the technical field of power supply conversion, in particular to a slow start or hot plug circuit of a switched capacitor power supply converter.
Background
The switch capacitor power supply converter has the advantages of less magnetic or non-magnetic devices, small volume, high power density, high efficiency, low EMI, low noise and the like. However, since the switched capacitor power converter has a large number of capacitors, at the moment of starting, the capacitors are approximately shorted, so that a large surge current is generated, and the risk of damaging the capacitors is greatly increased. Because the switched capacitor power converter uses a large number of low-voltage switching tubes at the same time, the impact current at the moment of starting can also increase the damage risk of the switching tubes. When the switching tube works in a switching state at the moment of starting, larger impulse voltage can be caused on the low-voltage switching tube by larger turn-off current, so that overvoltage breakdown damage of the low-voltage switching tube is easy to cause. The above problems also exist at the moment of circuit hot plug, resulting in damage to the switched capacitor power converter.
Disclosure of Invention
The invention aims to solve the technical problem of providing a slow starting circuit with simple structure, small volume and low cost, which can be applied to a switch capacitor power supply converter to reduce the voltage/current stress of the switch capacitor power supply converter at the starting moment and improve the reliability of the circuit.
In order to solve the technical problems, the invention adopts the following technical scheme:
The slow start circuit structure of the switched capacitor power supply converter comprises a first switching tube Q1 and a second switching tube Q2 which are sequentially arranged between an input end and a grounding end of the switched capacitor power supply converter and connected through a wire, a normally-on switching tube Q3, a diode D1, a resistor R1 and an output capacitor Co which are sequentially arranged between the input end and the grounding end of the switched capacitor power supply converter and connected through a wire, wherein the cathode of the diode D1 is positioned at one side close to the normally-on switching tube Q3, an output inductor Lo is connected between the first switching tube Q1 and the second switching tube Q2 through one end of the wire, and the other end of the output inductor Lo is connected between the resistor R1 and the output capacitor Co;
The bootstrap capacitor Cbst2, the bootstrap power supply diode D2 and the driving power supply capacitor Cbst1 are sequentially connected through wires, the other end of the bootstrap capacitor Cbst2 is connected between the normally-on switching tube Q3 and the diode D1 through wires, the negative electrode of the bootstrap power supply diode D2 is located at one side close to the normally-on switching tube Q3, and the other end of the driving power supply capacitor Cbst1 is connected to a source electrode of a highest-voltage side switching tube of the switching capacitor power converter through wires.
As a preferable embodiment, the normally-on switching transistor Q3 is a switching transistor having a low on-resistance.
The technical problem to be solved by the invention is to provide a slow start operation method of a switched capacitor power supply converter, wherein the slow start circuit of the switched capacitor power supply converter is in an ideal state and has a transformation ratio of K.
In order to solve the technical problems, the technical scheme adopted by the invention is that the slow start operation method of the switched capacitor power supply converter with the transformation ratio of K in the ideal state comprises the slow start circuit of the switched capacitor power supply converter, and the method comprises the following steps of:
(1) t0 to t1:
starting at time t0, starting a slow start process of the power converter, enabling the duty ratio of the first switching tube Q1 to increase from 0%, enabling the duty ratio of the second switching tube Q2 to decrease from 100%, enabling the on time of the first switching tube Q1 and the on time of the second switching tube Q2 to be complementary, and continuously detecting Vin 'and Vout in the circuit slow start process to judge whether the rising amplitude value of Vin' meets the formula (A) or whether the rising amplitude value of Vout meets the formula (B):
Vin’>a*M*t*Vin-b(A)
Vout>K*(a*M*t*Vin-b)(B)
wherein, the transformation ratio is K, the duty ratio increasing rate is M, the input voltage is Vin, and the time is t;
wherein the values of the coefficients a and b are as follows:
1≥a>0 (C)
VBR>b≥0 (D)
v BR in the above is the allowable maximum voltage stress of a high-voltage side switching tube of the switch capacitor power supply converter;
If the formula (A) or the formula (B) is established, the duty ratio of the first switching tube Q1 is always increased to 100%, and the duty ratio of the second switching tube Q2 is reduced to 0%, namely to the moment t1, and in the process of t0 to t1, the voltage V Co at two ends of the output capacitor Co in the slow starting circuit is linearly increased from 0V to the power input voltage Vin;
If the formula (A) or the formula (B) is not satisfied, the first switching tube Q1 duty ratio D needs to be stopped to be increased, or the first switching tube Q1 duty ratio D needs to be restored to 0%, the next round of starting process is restarted, and the time t is increased again from 0, namely the hiccup type starting is realized;
If the formula (A) and the formula (B) cannot be established all the time, the slow start circuit enters a continuous hiccup mode, namely the Vin ' level can not be close to Vin forever, so that the normally-on switching tube Q3 does not meet the closing condition that Vin-Vin ' < V BR -Vin '. Times.K, and therefore the normally-on switching tube Q3 can not be closed, and the slow start circuit realizes self protection;
(2) t1 to t2:
at time t1, due to the effect of the current limiting resistor R1, the output voltage Vout of the switched capacitor power supply converter is smaller than K times of Vin, vout is continuously increased for a period of time, and when Vout is approximately equal to K times of Vin;
If Vin 'satisfies the formula (a) or Vout satisfies the formula (B), and the difference between Vin and Vin' does not exceed the voltage stress margin of the high-voltage side switching tube of the switched capacitor power converter, namely:
Vin-Vin’<VBR-Vin’*K;
V BR is the allowable maximum voltage stress of a high-voltage side switching tube of the switched-capacitor power supply converter, and K is the transformation ratio of the switched-capacitor power supply converter in an ideal state;
At the time t2, the normally-on switching tube Q3 is closed, the first switching tube Q1, the diode D1, the resistor R1 and the output inductor Lo are bypassed, the slow start process is finished, and the steady state operation stage is entered.
In the process from t0 to t1, when the duty ratio of the first switching tube Q1 in the slow start circuit is increased to not more than 10%, whether the voltage of the Vout is greater than 0V or not is detected, whether the circuit is in a load short circuit state or not can be judged, and when the voltage of the Vout is 0V, the slow start circuit is restarted, so that self protection is realized.
The beneficial effects of the invention are as follows:
(1) The slow start circuit has the function of pulling up the voltage V Co at two ends of the output capacitor Co in the slow start circuit to Vin with a certain slope in the slow start process. During the starting process, the duty ratio of the first switching tube Q1 in the slow starting circuit is increased from 0% to 100%, so that the voltage V Co of the output capacitor Co in the slow starting circuit is increased from 0V to Vin.
(2) The series resistor R1 and the diode D1 form a current limiting and backflow preventing circuit. The resistor R1 plays a role in limiting current, so as to limit the sudden short circuit of the switched capacitor converter during starting or the excessive impact current generated by the short circuit before starting, thereby burning out the slow start circuit. In addition, when the rear end of the switch capacitor converter is connected with a larger capacitive load, the resistor R1 can also play a role in current limiting protection.
The diode D1 functions to prevent current back flow during start-up of the switched capacitor converter. When the rear end of the switch capacitor converter is connected with a larger capacitive load, the slow start circuit adopts a hiccup type start mode. In the hiccup type starting process, the duty ratio of a first switching tube Q1 in a slow starting circuit is increased from 0% to a certain value, then the duty ratio is increased from 0% to a certain value again, the operation is repeated in a circulating mode until Vin' voltage approaches Vin, and then a normally-on switching tube Q3 is closed.
(3) The switching tube Q3 is normally on, and the bootstrap power supply capacitor Cbst2 and the bootstrap power supply diode D2 are booted. Q3 is closed after the slow start process is finished, so that the input current of the switched capacitor converter in normal load can not generate excessive loss in the slow start circuit. The supply of Q3 is provided by a bootstrap capacitor Cbst2, the energy of Cbst2 being supplemented by the drive supply capacitor Cbst1 and the bootstrap supply diode D2 of the highest voltage side switching tube of the switched capacitor converter. In each switching period of the switched capacitor converter, the switching tube at the highest voltage side of the switched capacitor converter is closed, the bootstrap power supply capacitor Cbst2 is connected with the driving power supply capacitor Cbst1 in parallel through the bootstrap power supply diode D2, and charges stored in the driving power supply capacitor Cbst1 are released to the bootstrap power supply capacitor Cbst2 through the bootstrap power supply diode D2, namely the driving power supply capacitor Cbst1 charges the bootstrap power supply capacitor Cbst 2. In addition, the driving of the normally-on switching transistor Q3 may be performed by a power source such as fly-buck, fly-back, etc., but the volume may be disadvantageous. The drive power supply capacitor of the high-voltage switch tube of the switch capacitor converter, the bootstrap power supply capacitor Cbst2 and the bootstrap power supply diode D2 are used for supplying power to the normally-on switch tube Q3, so that the number of devices can be reduced, and the characteristics of small volume and high power density of the switch capacitor converter are exerted.
Drawings
FIG. 1 is a block diagram of a switched capacitor power converter with a slow start circuit
FIG. 2 shows a slow start circuit and a 1/2 switched capacitor power converter according to a first embodiment
FIG. 3 shows a second embodiment of a slow start circuit and a 1/4 switched capacitor power converter
FIG. 4 is a voltage-current waveform diagram of a slow start process of a 1/4 switched capacitor power converter
Detailed Description
Specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.
As shown in fig. 1 and 2, the switch capacitor power converter is an ideal switch capacitor power converter with a 1/2 conversion ratio in a slow start circuit comprising the switch capacitor power converter.
The slow start circuit of the switched capacitor power supply converter comprises a first switching tube Q1 and a second switching tube Q2 which are sequentially arranged between an input end of the switched capacitor power supply converter and a grounding end and connected through a wire, a normally-on switching tube Q3, a diode D1, a resistor R1 and an output capacitor Co which are sequentially arranged between the input end of the switched capacitor power supply converter and the grounding end and connected through a wire, and the normally-on switching tube Q3 is a switching tube with low on resistance. The cathode of the diode D1 is positioned at one side close to the normally-on switching tube Q3, one end of an output inductor Lo is connected between the first switching tube Q1 and the second switching tube Q2 through a lead, and the other end of the output inductor Lo is connected between the resistor R1 and the output capacitor Co;
The bootstrap capacitor Cbst2, the bootstrap power supply diode D2 and the driving power supply capacitor Cbst1 are sequentially connected through wires, the other end of the bootstrap capacitor Cbst2 is connected between the normally-on switching tube Q3 and the diode D1 through wires, the negative electrode of the bootstrap power supply diode D2 is located at one side close to the normally-on switching tube Q3, and the other end of the driving power supply capacitor Cbst1 is connected to a source electrode of a highest-voltage side switching tube S4 of the switching capacitor power converter through wires.
The switching tube Q2 can be replaced by a diode, and the connection direction is consistent with the direction of the Q2 body diode.
As shown in fig. 3, the ideal state of the slow start circuit comprising the switched capacitor power converter is a switched capacitor power converter with a transformation ratio of 1/4.
A slow start operation method of a switched capacitor power supply converter with a transformation ratio K in an ideal state of a slow start circuit of the switched capacitor power supply converter comprises the following steps:
(1) t0 to t1:
Starting at time t0, starting a slow start process of the power converter, enabling the duty ratio of the first switching tube Q1 to increase from 0%, enabling the duty ratio of the second switching tube Q2 to decrease from 100%, and enabling the on time of the first switching tube Q1 and the on time of the second switching tube Q2 to be complementary;
When the duty ratio of the switching tube of the first switching tube Q1 in the slow starting circuit is increased to not more than 10%, detecting whether the voltage of the Vout is greater than 0V or not, and judging whether the circuit is in a load short-circuit state or not;
when the voltage of Vout is greater than 0V, the circuit is started slowly and normally;
in the slow start process of the circuit, vin 'and Vout are continuously detected to judge whether the rising amplitude value of Vin' meets the formula (A) or whether the rising amplitude value of Vout meets the formula (B):
Vin’>a*M*t*Vin-b(A)
Vout>K*(a*M*t*Vin-b)(B)
wherein, the transformation ratio is K, the duty ratio increasing rate is M, the input voltage is Vin, and the time is t;
wherein the values of the coefficients a and b are as follows:
1≥a>0 (C)
VBR>b≥0 (D)
v BR in the above is the allowable maximum voltage stress of a high-voltage side switching tube of the switch capacitor power supply converter;
If the formula (A) or the formula (B) is established, the duty ratio of the first switching tube Q1 is always increased to 100%, and the duty ratio of the second switching tube Q2 is reduced to 0%, namely to the moment t1, and in the process of t0 to t1, the voltage V Co at two ends of the output capacitor Co in the slow starting circuit is linearly increased from 0V to the power input voltage Vin;
If the formula (A) or the formula (B) is not satisfied, the first switching tube Q1 duty ratio D needs to be stopped to be increased, or the first switching tube Q1 duty ratio D needs to be restored to 0%, the next round of starting process is restarted, and the time t is increased again from 0, namely the hiccup type starting is realized;
If the formula (A) and the formula (B) cannot be established all the time, the slow start circuit enters a continuous hiccup mode, namely the Vin ' level can not be close to Vin forever, so that the normally-on switching tube Q3 does not meet the closing condition that Vin-Vin ' < V BR -Vin '. Times.K, and therefore the normally-on switching tube Q3 can not be closed, and the slow start circuit realizes self protection;
(2) t1 to t2:
at time t1, due to the effect of the current limiting resistor R1, the output voltage Vout of the switched capacitor power supply converter is smaller than K times of Vin, vout is continuously increased for a period of time, and when Vout is approximately equal to K times of Vin;
If Vin 'satisfies the formula (a) or Vout satisfies the formula (B), and the difference between Vin and Vin' does not exceed the voltage stress margin of the high-voltage side switching tube of the switched capacitor power converter, namely:
Vin-Vin’<VBR-Vin’*K;
V BR is the allowable maximum voltage stress of a high-voltage side switching tube of the switched-capacitor power supply converter, and K is the transformation ratio of the switched-capacitor power supply converter in an ideal state;
At the time t2, the normally-on switching tube Q3 is closed, the first switching tube Q1, the diode D1, the resistor R1 and the output inductor Lo are bypassed, the slow start process is finished, and the steady state operation stage is entered.
The slow start operation method can be suitable for the slow start operation of the switched capacitor power supply converter in different situations.
As shown in fig. 4, the voltage and current waveforms of the 1/4 switched capacitor power converter change during the normal slow start process, specifically as follows:
(1) t0 to t1:
Starting at time t0, starting a slow start process of the power converter, wherein the duty ratio of the first switching tube Q1 is increased from 0%, the duty ratio of the second switching tube Q2 is reduced from 100%, and the conduction time of the first switching tube Q1 and the conduction time of the second switching tube Q2 are complementary;
detecting the voltage of Vout when the duty ratio of a switching tube Q1 of a first switching tube in the slow start circuit is increased to be not more than 10 percent, wherein the voltage of Vout is more than 0V, and the slow start of the circuit is normally carried out;
in the slow start process of the circuit, vin 'and Vout are continuously detected to judge whether the rising amplitude value of Vin' meets the formula (A) or whether the rising amplitude value of Vout meets the formula (B);
In the process from t0 to t1, the voltage V Co at two ends of an output capacitor Co in a slow start circuit is linearly increased from 0V to a power input voltage Vin;
(2) t1 to t2:
at time t1, due to the effect of the current limiting resistor R1, the output voltage Vout of the switched capacitor power supply converter is smaller than 1/4 times V Co, vout is continuously increased for a period of time, when Vout is approximately equal to 1/4 times V Co, if Vin 'satisfies formula (A) or Vout satisfies formula (B), and the difference value between Vin and Vin' does not exceed the voltage stress allowance of a high-voltage side switching tube of the switched capacitor power supply converter, namely:
Vin-Vin’<VBR-Vin’*K;
V BR is the allowable maximum voltage stress of a high-voltage side switching tube of the switch capacitor power supply converter, K is the transformation ratio of the switch capacitor power supply converter under ideal state, and the value is 1/4;
at the time of t2, the normally-on switching tube Q3 is closed, the first switching tube Q1, the diode D1, the resistor R1 and the output inductor Lo are bypassed, the slow start process is finished, and the steady state operation stage is entered
The load short circuit and the capacitive load starting situation can be met by the switched capacitor power supply converter, and the following description will be given of the slow start state of the slow start operation method under the load short circuit or capacitive load situation respectively:
When the load is in a short circuit state, the voltage of Vout is kept at 0V and vin' is approximately 0V in the time range of t0-t1 in the slow start process. When the duty ratio of the switching tube of the first switching tube Q1 in the slow start circuit is increased to be not more than 10%, the voltage of Vout is detected to be 0V. Due to the protection function of the current limiting resistor R1, excessive short-circuit current is not generated in the slow start circuit, so that the slow start circuit can be protected from being burnt. The slow start circuit is restarted at intervals, if the short circuit problem is not solved, the circuit cannot enter a normal working state, and therefore self-protection is achieved.
When the load is a capacitive load and the capacitance value is smaller, the slow start process adopting the slow start operation method comprises the following steps:
(1) t0 to t1:
Starting at time t0, starting a slow start process of the power converter, enabling the duty ratio of the first switching tube Q1 to increase from 0%, enabling the duty ratio of the second switching tube Q2 to decrease from 100%, and enabling the on time of the first switching tube Q1 and the on time of the second switching tube Q2 to be complementary;
When the duty ratio of the switching tube of the first switching tube Q1 in the slow starting circuit is increased to be not more than 10%, whether the Vout voltage is larger than 0V or not is detected, whether the circuit is in a load short-circuit state or not can be judged, and when the Vout voltage is not larger than 0V and the load short-circuit state is judged, the slow starting circuit is restarted at intervals, so that self-protection is realized.
In the slow start process of the circuit, vin 'and Vout are continuously detected to judge whether the rising amplitude value of Vin' meets the formula (A) or whether the rising amplitude value of Vout meets the formula (B):
If the formula (A) or the formula (B) is established, the duty ratio of the first switching tube Q1 is always increased to 100%, and the duty ratio of the second switching tube Q2 is reduced to 0%, namely to the moment t1, and in the process of t0 to t1, the voltage at two ends of the output capacitor Co in the slow starting circuit is linearly increased from 0V to the power input voltage Vin;
If the formula (A) or the formula (B) is not satisfied, the first switching tube Q1 duty ratio D needs to be stopped to be increased, or the first switching tube Q1 duty ratio D needs to be restored to 0%, the next round of starting process is restarted, and the time t is increased again from 0, namely the hiccup type starting is realized;
(2) t1 to t2:
At time t1, due to the effect of the current limiting resistor R1, the output voltage Vout of the switched capacitor power supply converter is smaller than K times V Co, vout is continuously increased for a period of time, when Vout is approximately equal to K times V Co, if Vin 'satisfies formula (A) or Vout satisfies formula (B), and the difference value between Vin and Vin' does not exceed the voltage stress allowance of a high-voltage side switching tube of the switched capacitor power supply converter, namely:
Vin-Vin’<VBR-Vin’*K;
V BR is the allowable maximum voltage stress of a high-voltage side switching tube of the switched-capacitor power supply converter, and K is the transformation ratio of the switched-capacitor power supply converter in an ideal state;
At the time t2, the normally-on switching tube Q3 is closed, the first switching tube Q1, the diode D1, the resistor R1 and the output inductor Lo are bypassed, the slow start process is finished, and the steady state operation stage is entered.
When the switch capacitor power supply converter is connected to a larger capacitor load, in the slow start process of the circuit, vin 'and Vout are continuously detected to judge whether the rising amplitude value of Vin' meets the formula (A) or whether the rising amplitude value of Vout meets the formula (B), and if the formula (A) or the formula (B) is constantly met in the time range of t0-t1 in the slow start process, the slow start process is successful once.
If the formula (a) or the formula (B) is not satisfied in the slow start process, the first switching tube Q1 duty cycle D needs to be stopped to be increased, or the first switching tube Q1 duty cycle D is restored to 0%, the next start process is restarted, and the time t is increased from 0 again.
After hiccup is carried out for a plurality of times, the duty ratio D of the first switching tube Q1 reaches 100%, if Vin 'satisfies the formula (A) or Vout satisfies the formula (B), and the difference value between Vin and Vin' does not exceed the voltage stress allowance of the switching tube at the high voltage side of the switched capacitor power supply converter, namely:
Vin-Vin’<VBR-Vin’*K;
V BR is the allowable maximum voltage stress of a high-voltage side switching tube of the switched-capacitor power supply converter, and K is the transformation ratio of the switched-capacitor power supply converter in an ideal state;
Then normally-on switch Q3 is closed so that the circuit enters steady state operation.
When the capacitive load of the switch capacitor power supply converter is excessively large, the formula (A) or the formula (B) cannot be met, the slow start circuit can enter a continuous hiccup mode, namely the Vin ' level can not be close to Vin forever, so that the normally-on switch tube Q3 cannot meet the closing condition that Vin-Vin ' < V BR -Vin '. Times.K, and therefore the normally-on switch tube Q3 cannot be closed, and the slow start circuit realizes self protection.
When the switch-in load of the switched capacitor power supply converter is a resistive load and the resistance value is large, the formula (A) or the formula (B) can be met, and the slow start circuit can be started normally.
When the switch-in load of the switched capacitor power supply converter is a resistive load and the resistance value is smaller, neither the formula (A) nor the formula (B) is satisfied, the increase of the duty ratio D of the first switching tube Q1 is required to be stopped, or the duty ratio D of the first switching tube Q1 is restored to 0%, the next starting process is restarted, and the time t is increased again from 0.
If the formula (A) and the formula (B) cannot be established all the time, the slow start circuit can enter a continuous hiccup mode, namely the Vin ' level can not be close to Vin forever, so that the normally-on switching tube Q3 cannot meet the closing condition that Vin-Vin ' < V BR -Vin '. Times.K, the normally-on switching tube Q3 cannot be closed, the slow start circuit realizes self protection, and the switching tube and other components are prevented from being burnt out due to overlarge current stress.
The foregoing embodiments are merely illustrative of the principles of the invention and its effectiveness, and some of the practical examples, not intended to limit the invention, and it should be noted that modifications and improvements could be made by those skilled in the art without departing from the inventive concept.

Claims (4)

1.一种开关电容电源变换器的缓启电路，其特征在于：包括依次设置在开关电容电源变换器输入端与接地端之间通过导线相连接的第一开关管Q1和第二开关管Q2、依次设置在开关电容电源变换器输入端与接地端之间通过导线相连接的常通开关管Q3、二极管D1、电阻R1、输出电容Co，二极管D1的负极位于靠近常通开关管Q3的一侧，输出电感Lo通过导线一端连接在第一开关管Q1和第二开关管Q2之间、另一端连接在电阻R1和输出电容Co之间；还包括通过导线依次连接的自举电容Cbst2、自举供电二极管D2、驱动供电电容Cbst1；自举电容Cbst2另一端通过导线连接在常通开关管Q3与二极管D1之间；自举供电二极管D2的负极位于靠近常通开关管Q3的一侧，驱动供电电容Cbst1另一端通过导线连接在开关电容电源变换器的最高压侧开关管的源极上。1. A soft-start circuit for a switched-capacitor power converter, characterized in that: it includes a first switching transistor Q1 and a second switching transistor Q2 connected by a wire between the input terminal and the ground terminal of the switched-capacitor power converter; a normally-on switching transistor Q3 connected by a wire between the input terminal and the ground terminal of the switched-capacitor power converter; a diode D1; a resistor R1; and an output capacitor Co, wherein the cathode of the diode D1 is located near the normally-on switching transistor Q3; and an output inductor Lo is connected by a wire, one end of which is connected between the first switching transistor Q1 and the second switching transistor Q2, and the other end of which is connected between the resistor R1 and the output capacitor Co; it also includes a bootstrap capacitor Cbst2, a bootstrap power supply diode D2, and a drive power supply capacitor Cbst1 connected by a wire in sequence; the other end of the bootstrap capacitor Cbst2 is connected by a wire between the normally-on switching transistor Q3 and the diode D1; the cathode of the bootstrap power supply diode D2 is located near the normally-on switching transistor Q3; and the other end of the drive power supply capacitor Cbst1 is connected by a wire to the source of the highest voltage-side switching transistor of the switched-capacitor power converter. 2.如权利要求1所述的一种开关电容电源变换器的缓启电路，其特征在于：所述常通开关管Q3为低导通电阻的开关管。2. The soft-start circuit of a switched capacitor power converter as described in claim 1, characterized in that: the normally-on switching transistor Q3 is a switching transistor with low on-resistance. 3.一种包括如上1或2所述的开关电容电源变换器的缓启电路的理想状态下变比为K的开关电容电源变换器缓启操作方法，具体如下：3. A soft-start operation method for a switched capacitor power converter with an ideal turns ratio of K, including the soft-start circuit of the switched capacitor power converter as described in 1 or 2 above, is as follows: (1)t0至t1：(1) From t0 to t1: t0时刻开始，电源变换器开始缓启过程，使第一开关管Q1占空比从0％开始增加，第二开关管Q2占空比从100％开始减少，第一开关管Q1与第二开关管Q2导通时间互补；在电路缓启过程中，持续对Vin’和Vout进行检测，来判断Vin’的上升幅值是否满足公式(A)或者Vout的上升幅值是否满足公式(B)：Vin’>a*M*t*Vin-b(A)Starting at time t0, the power converter begins its slow-start process, increasing the duty cycle of the first switch Q1 from 0% and decreasing the duty cycle of the second switch Q2 from 100%. The conduction times of the first switch Q1 and the second switch Q2 are complementary. During the circuit's slow-start process, Vin' and Vout are continuously monitored to determine whether the rise amplitude of Vin' satisfies formula (A) or the rise amplitude of Vout satisfies formula (B): Vin'>a*M*t*Vin-b (A) Vout>K*(a*M*t*Vin-b)(B)Vout>K*(a*M*t*Vin-b)(B) 式中，变比为K，占空比增加速率为M，输入电压为Vin，时间为t；In the formula, the turns ratio is K, the duty cycle increase rate is M, the input voltage is Vin, and the time is t; 式中，系数a、b的取值范围为：In the formula, the range of values for coefficients a and b is: 1≥a＞0(C)1 ≥ a > 0 (C) VBR＞b≥0(D)V BR > b≥0(D) 上式中VBR为开关电容电源变换器高压侧开关管允许最大电压应力；In the above formula, VBR represents the maximum allowable voltage stress of the high-voltage side switching transistor in the switched capacitor power converter. 如果公式(A)或者公式(B)成立，第一开关管Q1占空比一直增加至100％，第二开关管Q2占空比减少至0％，即至t1时刻；t0至t1过程中，缓启电路中输出电容Co的两端电压VCo从0V线性增加至电源输入电压Vin；If formula (A) or formula (B) holds true, the duty cycle of the first switch Q1 increases to 100%, and the duty cycle of the second switch Q2 decreases to 0%, i.e., until time t1; during the process from t0 to t1, the voltage VCo across the output capacitor Co in the soft-start circuit increases linearly from 0V to the power input voltage Vin. 如果公式(A)或公式(B)都不成立，需要停止增加第一开关管Q1占空比D，或者将第一开关管Q1占空比D恢复至0％，重新开启下一轮启动过程，时间t重新从0开始增加，即实现打嗝式启动；打嗝若干次后，第一开关管Q1占空比D达到100％，第二开关管Q2占空比减少至0％，即至t1时刻；If neither formula (A) nor formula (B) holds true, it is necessary to stop increasing the duty cycle D of the first switch Q1, or restore the duty cycle D of the first switch Q1 to 0%, restart the next round of the start-up process, and the time t starts increasing again from 0, thus achieving hiccup-style start-up; after hiccuping several times, the duty cycle D of the first switch Q1 reaches 100%, and the duty cycle of the second switch Q2 decreases to 0%, that is, at time t1; 如果公式(A)和公式(B)都一直不能成立，缓启电路会进入持续打嗝模式，即Vin’电平永远无法接近Vin，使得常通开关管Q3不满足闭合条件：Vin-Vin’<VBR-Vin’*K；从而常通开关管Q3无法闭合，缓启电路实现自我保护；If neither formula (A) nor formula (B) can be valid, the soft-start circuit will enter a continuous hiccup mode, meaning that the Vin' level can never approach Vin, causing the normally-on switch Q3 to fail to meet the closing condition: Vin - Vin'< V BR - Vin'*K; thus, the normally-on switch Q3 cannot close, and the soft-start circuit achieves self-protection. (2)t1至t2：(2) t1 to t2: t1时刻，由于限流电阻R1的作用，开关电容电源变换器的输出电压Vout小于K倍Vin，Vout继续增加一段时间，当Vout近似等于K倍Vin；At time t1, due to the effect of the current-limiting resistor R1, the output voltage Vout of the switched capacitor power converter is less than K times Vin. Vout continues to increase for a period of time until Vout is approximately equal to K times Vin. 若Vin’满足公式(A)或者Vout满足公式(B)，且Vin与Vin’的差值不超过开关电容电源变换器高压侧开关管的电压应力余量，即：If Vin’ satisfies formula (A) or Vout satisfies formula (B), and the difference between Vin and Vin’ does not exceed the voltage stress margin of the high-voltage side switching transistor of the switched capacitor power converter, that is: Vin-Vin’<VBR-Vin’*K；Vin-Vin'<V BR -Vin'*K; 上式中VBR为开关电容电源变换器高压侧开关管允许最大电压应力，K为理想状态下开关电容电源变换器的变比；In the above formula, VBR is the maximum allowable voltage stress of the high-voltage side switching transistor of the switched capacitor power converter, and K is the turns ratio of the switched capacitor power converter under ideal conditions. 此时记为t2时刻，将常通开关管Q3闭合，将第一开关管Q1、二极管D1、电阻R1、输出电感Lo旁路掉，缓启过程结束，进入稳态运行阶段。This moment is recorded as time t2. The normally open switch Q3 is closed, and the first switch Q1, diode D1, resistor R1, and output inductor Lo are bypassed. The slow start process ends, and the system enters the steady-state operation stage. 4.如权利要求3所述的包括开关电容电源变换器的缓启电路的理想状态下变比为K的开关电容电源变换器缓启操作方法，其特征在于：所述t0至t1过程中，在缓启电路中第一开关管Q1开关管占空比增加到不超过10％的时候，对Vout电压进行检测是否大于0V，即可判断电路是否处于负载短路状态；当Vout电压为0V判断为负载短路状态时，缓启电路进行重新启动，从而实现自我保护。4. The soft-start operation method of a switched capacitor power converter with a turns ratio of K under ideal conditions, as described in claim 3, comprising a soft-start circuit of a switched capacitor power converter, is characterized in that: during the process from t0 to t1, when the duty cycle of the first switching transistor Q1 in the soft-start circuit increases to no more than 10%, the Vout voltage is detected to determine whether it is greater than 0V, thereby determining whether the circuit is in a load short-circuit state; when the Vout voltage is 0V and it is determined to be in a load short-circuit state, the soft-start circuit restarts, thereby achieving self-protection.
CN202310728499.7A 2023-06-19 2023-06-19 A soft-start circuit for a switched-capacitor power converter and a soft-start operation method based thereon. Active CN116800077B (en)

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