Direct-current-direct-current converter

Abstract

The present application relates to a kind of direct current-direct current converters, comprising: first capacitor;First switch, second switch, third switch and fourth switch, which are connected in series between the first electrode and the second electrode of first capacitor;Second capacitor, which is connected to the connection node of first switch and second switch and the connection node of third switch and fourth switch;Inductance, which is connected to the connection node of second switch and third switch;And controller, which performs pulse width modulation control.In the event of a failure of second capacitor, based on the comparison result between the first detection voltage measured as output voltage and the target output voltage of direct current-direct current converter, the direct current-direct current converter performs pulse width modulation control, so that first switch and second switch enter the same state and third switch and fourth switch enter the same state.

Description

Technical Field

[0001] The present invention relates to a DC-DC converter, and more particularly, to a flyover DC-DC converter that can operate stably even if the voltage of the flyover capacitor cannot be controlled due to an open-circuit or short-circuit fault in the flyover capacitor. Background Technology

[0002] DC-DC converters, which convert direct current (DC) power from one voltage level to another, are widely used in a variety of electronic devices.

[0003] Regarding conventional DC-DC converters, a known technique involves converting a DC power supply voltage to another voltage by controlling the energy accumulation and release of an inductor through the on / off operation of a semiconductor switch. This type of DC-DC converter suffers from the disadvantages of large inductance and bulkiness.

[0004] To address this problem—that is, to reduce the size and weight of the inductor—it is necessary to reduce the inductance value. To this end, techniques have been developed to reduce the voltage applied to the inductor by charging and discharging the capacitor.

[0005] Among the various DC-DC converters utilizing this technology, there exists a DC-DC converter that includes a series of switches and a flying capacitor disposed between two adjacent switches in the series of switches.

[0006] This type of DC-DC converter with a flying capacitor has the following problem: it is difficult to control because the voltage of the flying capacitor needs to be kept at a predetermined level (half of the converter's output voltage).

[0007] When the flying capacitor experiences an open or short circuit fault, its voltage cannot be maintained. In this situation, there is a risk of applying excessively high voltage to the switch, which could cause the switch to burn out.

[0008] The above statements are merely intended to help understand the background technology of the present invention, and are not intended to imply that the present invention falls within the scope of related technologies known to those skilled in the art. Summary of the Invention

[0009] One object of the present invention is to provide a flyover DC-DC converter that can operate stably even when the voltage of the flyover capacitor cannot be controlled due to an open or short circuit fault in the flyover capacitor.

[0010] To achieve this objective, according to one aspect of the present invention, a DC-DC converter is provided, comprising: a first capacitor; a first switch, a second switch, a third switch, and a fourth switch connected in series between a first electrode and a second electrode of the first capacitor; a second capacitor, the first electrode of which is connected to a connection node of the first switch and the second switch, and the connection node of the third switch and the fourth switch, respectively; an inductor, the first terminal of which is connected to the connection node of the second switch and the third switch; and a controller, wherein, in the event of an open-circuit or short-circuit fault in the second capacitor, the controller performs pulse width modulation (PWM) control based on a comparison between a first detection voltage (as a measured output voltage) and an output voltage command value (as a target output voltage), such that the first switch and the second switch enter the same state, and the third switch and the fourth switch enter the same state. The output voltage is the voltage between the first electrode and the second electrode of the first capacitor or the voltage between the inductor and the connection node of the first capacitor and the fourth switch.

[0011] According to one embodiment of the present invention, in the event of an open-circuit or short-circuit fault in the second capacitor, the controller may: generate an inductor current command value as the target inductor current based on a comparison result between the first detected voltage and the output voltage command value; generate a first control voltage command value based on a comparison result between the inductor current command value and the actual detected current of the inductor; and execute PWM control based on a comparison result between the first control voltage command value and a triangular wave signal with a preset frequency, so that the first switch and the second switch enter the same state and the third switch and the fourth switch enter the same state.

[0012] According to one embodiment of the present invention, when PWM control is executed such that the first switch and the second switch enter the same state and the third switch and the fourth switch enter the same state, the controller can reduce the boost ratio of the DC-DC converter.

[0013] According to one embodiment of the present invention, the controller can send the control state of the DC-DC converter to an upper-level controller, which generates an output voltage command value to reduce the boost ratio of the DC-DC converter.

[0014] According to one embodiment of the present invention, when PWM control is executed such that the first switch and the second switch enter the same state and the third switch and the fourth switch enter the same state, the controller can increase the switching frequency of each of the first to fourth switches.

[0015] According to one embodiment of the present invention, when PWM control is performed such that the first switch and the second switch enter the same state and the third switch and the fourth switch enter the same state, the controller can impose a limit on the current command value.

[0016] According to one embodiment of the present invention, the controller may include: a voltage controller that generates a current command value for the current flowing through the inductor based on the difference between a first detected voltage and an output voltage command value; a current controller that generates a first control voltage command value based on the difference between the current command value and a detected current; and a flying capacitor voltage controller that generates a second control voltage command value based on the difference between a second detected voltage and a second voltage command value and the reciprocal of the detected current. In the event of an open-circuit or short-circuit fault in the second capacitor, the operation of the flying capacitor voltage controller may be stopped, and PWM control may be performed based on a comparison between the first control voltage command value and a triangular wave signal having a preset frequency, such that the first switch and the second switch enter the same state, and the third switch and the fourth switch enter the same state.

[0017] According to the present invention, when the voltage of the flying capacitor in the flying DC-DC converter cannot be controlled, i.e., when the flying capacitor experiences an open-circuit or short-circuit fault, PWM control is executed to cause the switches on the upper side of the inductor to enter the same state, and the switches on the lower side of the inductor to enter the same state. Through this control, the flying DC-DC converter can operate stably as a two-stage converter without being affected by flying capacitor faults.

[0018] When the DC-DC converter operates as a two-stage converter, the boost ratio is reduced to prevent overvoltage from being applied to the switch, and the heat generation problem is solved by increasing the switching frequency or current derating.

[0019] The effects and advantages that can be achieved by the present invention are not limited to those described above, and those skilled in the art will clearly understand, through the following description, other effects and advantages that can be achieved by the present invention but not described above. Attached Figure Description

[0020] The above and other objects, features, and other advantages of the present invention will become more clearly understood from the following detailed description presented in conjunction with the accompanying drawings, in which:

[0021] Figure 1 A circuit diagram illustrating a DC-DC converter according to one embodiment of the present invention is provided.

[0022] Figure 2 A block diagram of the controller of a DC-DC converter according to one embodiment of the present invention is shown in more detail; and

[0023] Figures 3 to 6 This is a schematic diagram illustrating the flow of current in a DC-DC converter according to one embodiment of the present invention. Detailed Implementation

[0024] Hereinafter, DC-DC converters according to various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0025] Figure 1 This is a circuit diagram of a DC-DC converter according to one embodiment of the present invention.

[0026] refer to Figure 1 According to one embodiment of the present invention, the DC-DC converter converts the voltage applied between the first input / output (I / O) terminal T11 and the second I / O terminal T12 to a higher voltage, and provides the increased voltage between the third I / O terminal T21 and the fourth I / O terminal T22. Conversely, the DC-DC converter converts the voltage applied between the third I / O terminal T21 and the fourth I / O terminal T22 to a lower voltage, and provides the generated lower voltage between the first I / O terminal T11 and the second I / O terminal T12. Figure 1 An exemplary converter is shown, comprising a battery BAT disposed between a first I / O terminal T11 and a second I / O terminal T12. The converter boosts the voltage of the supply current of the battery BAT to a higher voltage and provides the generated higher voltage between a third I / O terminal T21 and a fourth I / O terminal T22. For example, a load is connected between the third I / O terminal T21 and the fourth I / O terminal T22.

[0027] The following description relates to an example of applying a voltage obtained by boosting the output voltage of the battery BAT between the third I / O terminal T21 and the fourth I / O terminal T22. However, those skilled in the art will understand that the reverse flow is also possible. That is, the voltage applied between the third I / O terminal T21 and the fourth I / O terminal T22 is stepped down, and the resulting reduced voltage is applied between the first I / O terminal T11 and the second I / O terminal T12.

[0028] A DC-DC converter according to one embodiment of the present invention includes: a first capacitor C DC The first to fourth switches S1, S2, S3 and S4, and the second capacitor C FC Inductor L and controller 10; the first capacitor C DC The first and second electrodes are respectively connected to the third I / O terminal T21 and the fourth I / O terminal T22; the first to fourth switches S1, S2, S3 and S4 are connected in series to the first capacitor C. DC Between the first electrode and the second electrode; the second capacitor C FCThe first and second electrodes are respectively connected to the connection node between the first switch S1 and the second switch S2 and the connection node between the third switch S3 and the fourth switch S4; the first terminal of the inductor L is connected to the connection node between the second switch S2 and the third switch S3; the controller 10 controls the on / off state of each of the first switch S1 to the fourth switch S4. In one example, the outputs S1 to S4 of the controller 10 can be connected to the gates of the first switch S1 to the fourth switch S4 respectively.

[0029] First capacitor C DC It is a smoothing capacitor connected between the third I / O terminal T21 and the fourth I / O terminal T22. Although Figure 1 It is not shown in the figure, but an additional smoothing capacitor can be connected between the first I / O terminal T11 and the second I / O terminal T12.

[0030] The first switch S1 to the fourth switch S4 are connected to the first capacitor C. DC The first electrode side is connected in series with the second electrode side. Each of the first switches S1 to the fourth switches S4 is implemented by an insulated gate bipolar transistor (IGBT). Each switch is turned on or off according to an on / off control signal input from the controller 10 to its gate. Alternatively, each of the first switches S1 to the fourth switches S4 can be implemented using any switching element known in the art instead of an IGBT.

[0031] Second capacitor C FC It is a flying capacitor, whose first electrode and second electrode are respectively connected to the connection node between the first switch S1 and the second switch S2 and the connection node between the third switch S3 and the fourth switch S4.

[0032] Although not shown in the accompanying drawings, a DC-DC converter according to one embodiment of the present invention may include multiple sensors for detecting internal circuitry information used by a controller 10 to generate an on / off control signal for each of the first switch S1 to the fourth switch S4. The multiple sensors may include: sensors for measuring the voltage V between the first I / O terminal T11 and the second I / O terminal T12 or the voltage V between the third I / O terminal T21 and the fourth I / O terminal T22. DC A voltage sensor is used to measure the second capacitor C. FC voltage V FC A voltage sensor, and a current I used to measure the current flowing through inductor L. L The current sensor. The voltage and current values ​​measured by the voltage and current sensors are input to the controller 10.

[0033] Controller 10 receives a first detection voltage, the first detection voltage being in the first capacitor CDC Between the first electrode and the second electrode, or at the second terminal of the inductor L and the first capacitor C DC The actual measured voltage between the connection node of the first I / O terminal and the fourth I / O terminal S4. The first detected voltage corresponds to the output voltage obtained by boost operation of the DC-DC converter or by buck operation. In the case of boost operation, the first detected voltage corresponds to the voltage between the third I / O terminal T21 and the fourth I / O terminal T22 (i.e., the voltage between the first capacitor C and the fourth I / O terminal T22). DC (The voltage). In the case of buck operation, the first detection voltage corresponds to the voltage between the first I / O terminal T11 and the second I / O terminal T12.

[0034] Controller 10 compares the first detected voltage with a first voltage command value and calculates the difference between them. The first voltage command value represents the target voltage set for output from the DC-DC converter. The first voltage command value is set by a higher-level controller. In one example, the set value or preset value may be stored in a storage device and can be read by controller 10, or it may be sent to controller 10 from a higher-level controller.

[0035] When the second capacitor C is the flying capacitor FC During normal operation, the controller receives the second detection voltage V. FC The second detection voltage V FC It is applied to the second capacitor C FC The controller will detect the second voltage V. FC The voltage is compared with a preset second voltage command value, and the difference between them is calculated. The second voltage command value is preset by the upper-level controller and is approximately equal to the first capacitor C. DC Half of the voltage. According to one embodiment of the invention, the controller 10 is based on the actual measured current of the inductor L and the voltage applied to the second capacitor C. FC Detection voltage V FC The PWM control is performed by multiplying the difference between the second voltage command value and the second voltage value to determine the on / off state of each of the switches S1 to S4.

[0036] Second capacitor C FC An open circuit or short circuit fault occurs, thereby causing the second capacitor C to... FC If the voltage cannot be controlled, the controller 10 does not perform the operation of generating a second voltage command value, but instead performs PWM control to adjust the voltage based on the first voltage command value and the first detected voltage V. DC The difference between them determines the on / off state of each of switches S1 to S4.

[0037] Although not shown, an open-circuit or short-circuit fault in the second capacitor can be determined by checking the sensing value of a voltage sensor installed in the second capacitor. This technique for determining faults in the second capacitor will be readily apparent to those skilled in the art.

[0038] Figure 2 A block diagram of the controller of a DC-DC converter according to one embodiment of the present invention is shown in more detail.

[0039] refer to Figure 2 According to one embodiment of the present invention, the controller 10 of the DC-DC converter includes a voltage controller 11, a current controller 12, and a flying capacitor voltage controller 13.

[0040] The voltage controller 11 includes a subtractor 111 and a PI controller 112. The subtractor 111 converts the detected voltage V between the first I / O terminal T11 and the second I / O terminal T12 into a subtractor. DC Or the measured voltage V between the third I / O terminal T21 and the fourth I / O terminal T22 DC With the first voltage command value V DC * Compare and calculate the measured voltage V DC With the first voltage command value V DC The difference between * is calculated by the subtractor 111. The PI controller 112 performs proportional-integral control to reduce the difference calculated by the subtractor 111. By performing proportional-integral control, the PI controller 112 outputs an inductor current command value I representing the target current of the inductor L. L * This reduces the difference calculated by subtractor 111.

[0041] The current controller 12 includes a subtractor 121 and a PI controller 122. The subtractor 121 calculates the inductor current command value I provided by the voltage controller 11. L *The difference between the actual detected current flowing through inductor L and the current measured by the PI controller 122. The PI controller 122 performs proportional-integral control to generate a first control voltage command value V that reduces the output value of the subtractor 121. DM *. First control voltage command value V DM *Used to determine the on-off duty cycle of switches S1 to S4.

[0042] Figure 2 An example of voltage controller 11 and current controller 12 performing proportional-integral control is shown. However, the control technique is not limited to this. Various techniques known in the art can be utilized.

[0043] The flying capacitor voltage controller 13 includes a subtractor 131, a proportional controller 132, a reciprocal calculator 133, and a multiplier 134. The subtractor 131 receives the voltage applied to the second capacitor C.FC Detection voltage V FC The detection voltage V FC With the preset second voltage command value V FC The subtractor 131 compares the values ​​and calculates the difference. The proportional controller 132 performs proportional control and outputs a control command value to decrease the output value of the subtractor 131. The reciprocal calculator 133 calculates the measured inductor current I. L The multiplier 134 multiplies the output value of the proportional controller 132 with the reciprocal output from the reciprocal calculator 133, and uses the calculated product as the second control voltage command value V. CM * Output.

[0044] In one embodiment of the invention, the flying capacitor voltage controller 13 only applies to the second capacitor C. FC It operates under a voltage controllable condition. For example, when due to the second capacitor C FC The second capacitor C cannot be controlled due to a short circuit or open circuit fault. FC When the voltage reaches a certain value, the operation of the flyback capacitor voltage controller 13 stops, and only the first voltage command value V generated by the voltage controller 11 and the current controller 12 remains. DC *Used to perform PWM control on the first switch S1 to the fourth switch S4.

[0045] Additionally, the controller 10 may further include: an adder 141, a subtractor 142, a second adder 143, a first switch controller 144, and a second switch controller 145; the adder 141 converts the first control voltage command value V output by the current controller 12 into a single value. DM *The second control voltage command value V output by the flying capacitor voltage controller 13 CM *Add them together to generate a first duty cycle command value V1*; the subtractor 142 detects the detection voltage V between the I / O terminals. DC Subtract the first control voltage command value V from the middle DM *; The second adder 143 adds the result value output by the subtractor 142 to the second control voltage command value V. CM *Add together; the first switch controller 144 determines the on / off state of the first switch S1 and the fourth switch S4 based on the comparison result between the first duty cycle command value V1* and the triangular wave signal with a preset frequency generated by the triangular wave generator 146; the second switch controller 145 determines the on / off state of the second switch S2 and the third switch S3 based on the comparison result between the second duty cycle command value V2* and the triangular wave signal with a preset frequency output by the triangular wave generator 146.

[0046] When due to the second capacitor C FCThe second capacitor C cannot be controlled due to a short circuit or open circuit fault. FC When the voltage is [value], the second control voltage command value V is not output from the cross capacitor voltage controller 13. CM Therefore, adder 141 only processes the first voltage command value V. DC * Provided to the first switch controller 144, enabling PWM control of the first switch S1 and the fourth switch S4. The controller 10 includes a first switch unit 151 and a second switch unit 152. When the second capacitor C... FC During normal operation, the first switching unit 151 is open and the switching unit 152 is closed. Conversely, when the second capacitor C... FC In case of an abnormality, the first switching unit 151 is turned on and the switching unit 152 is turned off. In this situation, the first control voltage command value V... DC *Provided to the second switch controller 145, thereby performing PWM control on the second switch S2 and the third switch S3.

[0047] When the second capacitor C FC When the voltage cannot be controlled, the first control voltage command value V is used. DM The outputs of the first switch controller 144 and the second switch controller 145 are adjusted using a triangular wave signal, so that the first switch S1 and the second switch S2 enter the same state, and the third switch S3 and the fourth switch S4 enter the same state.

[0048] When the second capacitor C FC During normal operation, the first control voltage command value V is used. DM * and second control voltage command value V CM * Equation 1 represents the first duty cycle command value V1* and the second duty cycle command value V2*.

[0049] [Equation 1]

[0050] V1*=V CM *+V DM *

[0051] V2*=V CM *+(V DC -V DM *).

[0052] Here, the first control voltage command value V DM *Based on the output voltage V of the DC-DC converter DC The generated value affects the output, and the second control voltage command value V CM *Based on the voltage V of the flying capacitor FC The generated value, and the voltage V across the flying capacitor. FC Or output voltage V DCWith the voltage V across the capacitor FC The difference V between DC -V FC Yes, it has an impact. Specifically, it affects the first control voltage command value V. DM * Used to control the output voltage of the DC-DC converter, and the second control voltage command value V CM * Used to control the voltage across the flying capacitor.

[0053] Figures 3 to 6 This is a schematic diagram illustrating the flow of current in a DC-DC converter according to one embodiment of the present invention.

[0054] Figure 3 The first state is shown, in which the first switch S1 and the second switch S2 are turned on, and the third switch S3 and the fourth switch S4 are turned off. When capacitor C DC voltage V DC When applied to the connection point between inductor L and switch S2 or S3, the first state is established.

[0055] Figure 4 The second state is shown, in which the first switch S1 and the third switch S3 are turned on, and the second switch S2 and the fourth switch S4 are turned off. This corresponds to the capacitor C. DC voltage V DC With flying capacitor C FC voltage V FC When the voltage difference between the two is applied to the connection node between inductor L and switch S2 or S3, the second state is established.

[0056] Figure 5 The third state is shown, in which the second switch S2 and the fourth switch S4 are turned on, and the first switch S1 and the third switch S3 are turned off. When the flying capacitor C... FC voltage V FC When applied to the connection point between inductor L and switch S2 or S3, a third state is established.

[0057] Figure 6 The fourth state is shown, in which the first switch S1 and the second switch S2 are open, and the third switch S3 and the fourth switch S4 are closed. The fourth state is established when no voltage is applied to the connection point between the inductor L and the switch S2 or S3.

[0058] exist Figures 3 to 6 In the state shown, current flows through what is called the flying capacitor C. FC The second capacitor C FC In the second and third states, the flying capacitor C FC The voltage change. During the total duration of the second and third states, the flying capacitor C is charged. FC In or from the flying capacitor CFC The electrical energy released depends on the current flowing through the inductor L and the ratio of the second state to the third state.

[0059] This can be represented by Equation 2.

[0060] [Equation 2]

[0061] I FC =sC FC V FC

[0062] I FC =D CM ·I L

[0063]

[0064] Among them, “D” CM "This indicates that current flows through the flying capacitor C" FC The duty cycle, which is determined by the proportional control of the flying capacitor voltage controller 13, and is expressed by the third line of Equation 2. The third line of Equation 2 indicates that when no inductor current I is applied... L The duty cycle in the case of the reciprocal of K. In Equation 2, "K P "" indicates the gain of the proportional controller 132.

[0065] Equation 2 can be reduced to Equation 3, and Equation 4 can be obtained by calculating the transfer function based on Equation 3.

[0066] [Equation 3]

[0067]

[0068] [Equation 4]

[0069]

[0070] In order to control the transfer function of Equation 4 in the closed-loop form of a first-order low-pass filter, the relationship in Equation 5 must be established.

[0071] [Equation 5]

[0072]

[0073] Equation 5 shows that linear control characteristics can only be obtained when the gain of the proportional control is inversely proportional to the inductor current.

[0074] Therefore, the flying capacitor voltage controller 13 includes a method for obtaining the inductor current I. L The configuration of the reciprocal calculator 133 enables stable control characteristics of the overall current.

[0075] Here, the controller in the flying capacitor voltage controller 13 can be implemented using a proportional-integral (PI) controller instead of the proportional controller 132. However, when using a PI controller, the accumulated value in the integrator may generate a large duty cycle pulsation depending on the direction of the current. This means that in the inductor current I... L Controllability deteriorates significantly when the value approaches zero. Therefore, it is best to use a proportional controller.

[0076] Current flows through the second capacitor (i.e., the flying capacitor) C FC The output voltages in the second and third states are respectively "V DC -V FC " and "V FC Under normal conditions, the intermediate voltage in the output of the three-stage converter is 0.5V. DC .

[0077] Therefore, the output voltage of the flyback converter is close to 0.5V. DC At that time, the utilization frequency of the second and third states increases, and the output voltage of the flyback converter is 0.5*V. DC When the difference is greater, the utilization frequency of the first or third state increases. Additionally, when the flying capacitor C is stably controlled... FC With an output of 0.5*V DC When the voltage is such that the ratio of the second state to the third state is 1:1 (i.e., V...), the ratio of the second state to the third state is 1:1. CM * = 0).

[0078] However, when the second capacitor C FC In the event of a short circuit or open circuit fault, the second capacitor C cannot be used. FC The voltage control is insufficient, and the three-level operation described above cannot be performed.

[0079] In one embodiment of the present invention, when the second capacitor C FC A short circuit or open circuit fault occurs and the second capacitor C cannot be used. FC When the voltage is controlled, control switches S1 to S4 to enable two-stage operation.

[0080] Therefore, in one embodiment of the present invention, the first switch S1 and the second switch S2, which are disposed on the upper side of the inductor L, are controlled to enter the same state, and the third switch S3 and the fourth switch S4, which are disposed on the lower side of the inductor L, are controlled to enter the same state.

[0081] When the second capacitor C FC A malfunction occurred, preventing the second capacitor C from being used. FC When under control, execute in Figure 3 The first state shown and in Figure 6The two-level control switches between the fourth states shown.

[0082] In a two-stage control configuration, when the DC-DC converter operates as a boost converter, a portion of the entire DC power supply voltage may be applied to switches S1 through S4. This overvoltage can cause the switches to burn out. Therefore, when the second capacitor C cannot be activated... FC When performing two-stage control for voltage control, preferably, controller 10 reduces or limits the boost ratio of the converter. This can be achieved by controller 10 indicating that the second capacitor C cannot be used. FC The voltage control flag is sent to the upper-level controller.

[0083] When performing two-stage control, the inductance loss increases with the increase of ripple in inductor L. This leads to increased heat generation. To solve the heat generation problem, it is preferable to reduce inductance loss by increasing the switching frequency. The target switching frequency can be preset, which can be achieved by increasing the frequency of the triangular wave output from the triangular wave generator 146.

[0084] Another method to regulate heat generation is to dredge the current. Derating can be achieved by adding a limiter (not shown) before the current controller 12 and activating the limiter during two-stage control. This limiter will reduce the current command I output by the voltage controller 12. L The value of * is limited to a preset value.

[0085] The aforementioned operations / functions performed by the controller can be implemented as computer-readable code / algorithms / software stored on a computer-readable recording medium. A computer-readable recording medium is any data storage device capable of storing data that can subsequently be read by a computer or processor / microprocessor. Examples of computer-readable recording media include hard disk drives (HDDs), solid-state drives (SSDs), silicon disk drives (SDDs), read-only memory (ROM), random access memory (RAM), CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, etc.

[0086] The aforementioned controller may include one or more processors / microprocessors. The controller may be implemented using circuitry. The controller may perform the aforementioned operations / functions by executing computer-readable code / algorithms / software stored on a computer-readable recording medium.

[0087] Although the invention has been described with reference to preferred embodiments, these preferred embodiments are presented for illustrative purposes only to describe the technical spirit of the invention, and those skilled in the art will understand that various modifications and changes can be made without departing from the scope and spirit of the invention. Therefore, it should be understood that the scope of protection of the invention is defined by the appended claims rather than the foregoing description.

Claims

1. A DC-DC converter, comprising: First capacitor; The first switch, the second switch, the third switch, and the fourth switch are connected in series between the first electrode and the second electrode of the first capacitor; The second capacitor has its first electrode connected to the connection node between the first switch and the second switch, and its second electrode connected to the connection node between the third switch and the fourth switch. An inductor, the first terminal of which is connected to the connection node between the second and third switches; as well as In the event of an open-circuit or short-circuit fault in the second capacitor, the controller performs pulse width modulation control based on a comparison between a first detection voltage, which is the measured output voltage, and an output voltage command value, which is the target voltage to be output, such that the first switch and the second switch enter the same state, and the third switch and the fourth switch enter the same state. The output voltage is either the voltage between the first electrode and the second electrode of the first capacitor or the voltage between the second terminal of the inductor and the connection node of the first capacitor and the fourth switch. The controller includes: A voltage controller configured to generate a current command value for the current flowing through the inductor based on the difference between a first detected voltage and an output voltage command value; A current controller configured to generate a first control voltage command value based on the difference between a current command value and a detected current; and A flying capacitor voltage controller is configured to generate a second control voltage command value based on the difference between a second detected voltage and a second voltage command value and the reciprocal of the detected current.

2. The DC-DC converter according to claim 1, wherein, In the event of an open or short circuit fault in the second capacitor, the controller generates an inductor current command value as the target inductor current based on the comparison result between the first detected voltage and the output voltage command value. Based on the comparison result between the inductor current command value and the actual detected current of the inductor, the controller generates a first control voltage command value. Based on the comparison result between the first control voltage command value and a triangular wave signal with a preset frequency, the controller performs pulse width modulation control, so that the first switch and the second switch enter the same state, and the third switch and the fourth switch enter the same state.

3. The DC-DC converter according to claim 2, further comprising a current sensor for obtaining the actual detected current of the inductor.

4. The DC-DC converter according to claim 2, further comprising a triangular wave generator that generates a triangular wave signal having a preset frequency.

5. The DC-DC converter according to claim 1, wherein, When pulse width modulation control is executed to make the first switch and the second switch enter the same state, and when pulse width modulation control is executed to make the third switch and the fourth switch enter the same state, the controller reduces the boost ratio of the DC-DC converter.

6. The DC-DC converter according to claim 5, wherein, The controller sends the control status of the DC-DC converter to the upper-level controller, which generates an output voltage command value to reduce the boost ratio of the DC-DC converter.

7. The DC-DC converter according to claim 1, wherein, When pulse width modulation control is executed to make the first switch and the second switch enter the same state, and when pulse width modulation control is executed to make the third switch and the fourth switch enter the same state, the controller increases the switching frequency of each of the first to fourth switches.

8. The DC-DC converter according to claim 2, wherein, When pulse width modulation control is executed such that the first and second switches enter the same state, and the third and fourth switches enter the same state, the controller imposes a limit on the current command value.

9. The DC-DC converter according to claim 1, wherein, In the event of an open-circuit or short-circuit fault in the second capacitor, the operation of the flying capacitor voltage controller stops, and pulse width modulation control is performed based on the comparison result between the first control voltage command value and the triangular wave signal with a preset frequency, so that the first switch and the second switch enter the same state, and the third switch and the fourth switch enter the same state.

10. The DC-DC converter according to claim 9, wherein, The controller further includes a triangular wave generator that generates a triangular wave signal with a preset frequency.

11. The DC-DC converter of claim 1, further comprising a voltage sensor for obtaining the measured output voltage.

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