Four-switch Buck-Boost converter state trajectory control and finite-state machine implementation method

Abstract

The invention provides a four-switch Buck-Boost converter state track control and finite-state machine implementation method, which is characterized in that a drain electrode of a first switch tube s1 is connected to an input voltage Vin positive electrode of a converter, a source electrode of the first switch tube s1 is connected to a drain electrode of a second switch tube s2 and one end of an energy storage inductor L respectively, and the other end of the energy storage inductor L is connected to the other end of the energy storage inductor L; the source electrode of the second switch tube s2 is connected to the negative electrode of the input voltage Vin, the source electrode of the fourth switch tube s4, the negative electrode of the output capacitor C and one end of the load R, the drain electrode of the third switch tube is connected to the other end of the output capacitor and the other end of the load R, and the source electrode of the third switch tube is connected to the drain electrode of the fourth switch tube s4 and the other end of the energy storage inductor L. According to the invention, the state plane of the four-switch Buck-Boost converter is established, the natural trajectory of the four-switch Buck-Boost converter is deduced, and the rapid dynamic response of the converter is optimized by using the state trajectory control method, so that the dynamic and steady-state performance of the output voltage is greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of automatic control, and in particular to a state trajectory control of a four-switch Buck-Boost converter and a finite state machine implementation method. Background Art

[0002] In various fields related to electric energy, it is necessary to convert the battery voltage to the DC voltage required by the load. In order to ensure that the battery voltage can still stably supply power to the electrical equipment when it changes in a wide range, and to extend the battery's power supply time and service life, the four-switch Buck-Boost converter has become a research hotspot in the fields of new energy power generation systems, new energy vehicles, distributed power generation systems, portable electronic devices, etc. At the same time, in order to meet the high performance requirements in practical applications, it is of great significance to conduct in-depth research on the control technology of the four-switch Buck-Boost converter (FSBB).

[0003] For the four-switch Buck-Boost converter, the current control strategies mainly include single-mode control strategy and multi-mode control strategy. However, both the single-mode control strategy and the multi-mode control strategy for the four-switch Buck-Boost converter have shortcomings:

[0004] (1) In the dynamic adjustment process of the single-mode control strategy, the switching cycle and duty cycle of the converter cannot be flexibly adjusted, which will result in a long dynamic adjustment time. In addition, the single-mode control strategy uses a time-triggered method to control the dynamic adjustment process, which has many switching actions and also leads to a long adjustment time for the converter.

[0005] (2) In the multi-mode control strategy, the dynamic performance of the four-switch Buck-Boost converter has rarely been studied, and the improvement of the converter's dynamic performance is limited. In addition, designing controllers for different modes in the multi-mode control strategy will greatly increase the design burden, and accurate mode detection is required to achieve switching between modes; if a unified controller is used for different modes, current research often uses model predictive control methods, which will lead to a heavy system calculation burden. Summary of the invention

[0006] The present invention aims to at least solve the technical problems existing in the prior art, and in particular innovatively proposes a state trajectory control and finite state machine implementation method for a four-switch Buck-Boost converter.

[0007] In order to achieve the above-mentioned object of the present invention, the present invention provides a four-switch Buck-Boost converter state trajectory control and finite state machine implementation method, wherein the four-switch Buck-Boost converter includes four switch tubes: the drain of the first switch tube s1 is connected to the converter input voltage V inThe positive electrode of the first switch tube s1 is connected to the drain of the second switch tube s2 and one end of the inductor L, and the source of the second switch tube s2 is connected to the input voltage V in The negative electrode of the output capacitor C, the source electrode of the fourth switch tube s4, one end of the capacitor C and one end of the load R, the drain electrode of the third switch tube s3 is connected to the other end of the output capacitor C and the other end of the load R, and the source electrode of the third switch tube s3 is connected to the drain electrode of the fourth switch tube s4 and the other end of the inductor L;

[0008] The four-switch Buck-Boost converter state trajectory control and finite state machine implementation method comprises the following steps:

[0009] When the input voltage V in , reference voltage v ref When one or any combination of the resistance of the load R changes, the four-switch Buck-Boost converter will first perform a dynamic adjustment process and then a steady-state adjustment process, and finally keep the four-switch Buck-Boost converter in a steady state;

[0010] In the dynamic and steady-state regulation process, eight state drives of the four-switch Buck-Boost converter are involved, including:

[0011] Initial State: indicates the initialization state;

[0012] D-left 1: Mode 1: indicates the left half plane dynamic adjustment state 1;

[0013] D-left 2: Mode 2: indicates the left half plane dynamic adjustment state 2;

[0014] D-left 3: Mode 3: indicates the left half plane dynamic adjustment state three;

[0015] D-right / Steady 1: Mode 3: Indicates steady-state regulation state 1 or right half-plane dynamic regulation state 1;

[0016] D-right / Steady 2:Mode 4: Indicates steady-state regulation state 2 or right half-plane dynamic regulation state 2;

[0017] D-right / Steady 3: Mode 1: Indicates steady-state regulation state 3 or right half-plane dynamic regulation state 3;

[0018] Steady 4:Mode 2: indicates steady-state regulation state 4;

[0019] The left half plane refers to the normalized state plane vout -i L * Left half plane, that is, the output voltage is less than the reference voltage v out <v ref The right half plane refers to the normalized state plane v out -i L *Right half plane, that is, the output voltage is greater than the reference voltage v out >v ref hour;

[0020] State 1 refers to the state of Mode 1, State 2 refers to the state of Mode 2, State 3 refers to the state of Mode 3, and State 4 refers to the state of Mode 4;

[0021] The suffixes Mode 1, Mode 2, Mode 3, and Mode 4 of the above eight state drives respectively represent the modes of the switch states of the four-switch Buck-Boost converter during each state drive process; the state trajectory design of the dynamic regulation process and the steady-state regulation process of the four-switch Buck-Boost converter is completed through the combination of the above eight state drives; in the state trajectory control process, the dynamic regulation process will be carried out first, and then the steady-state regulation process will be carried out, and finally the four-switch Buck-Boost converter will be kept in a steady state; when the input voltage V in Or reference voltage v ref Or when the resistance of the load R changes, the four-switch Buck-Boost converter will enter the dynamic regulation process again, and finally perform the steady-state regulation process to enter a new steady state.

[0022] Mode 1, Mode 2, Mode 3, Mode 4, the switching states of the four-switch Buck-Boost converter equivalent circuit corresponding to these four modes are:

[0023] In mode 1, switches s1 and s4 are turned on, and switches s2 and s3 are turned off.

[0024] In Mode 2, switch tubes s1 and s3 are turned on, and switch tubes s2 and s4 are turned off;

[0025] In Mode 3, switch tubes s2 and s3 are turned on, and switch tubes s1 and s4 are turned off;

[0026] In mode 4, switch tubes s2 and s4 are turned on, and switch tubes s1 and s3 are turned off;

[0027] The dynamic adjustment is left half plane dynamic adjustment or right half plane dynamic adjustment;

[0028] The state trajectory of the left half plane dynamic adjustment is: out <v ref In the dynamic adjustment process, the left half plane dynamic adjustment state D-left 1:Mode 1 is used as the first activated state after the initialization state Initial State, and then the state trajectory is first driven in the order of D-left 1:Mode 1→D-left 2:Mode 2→D-left 3:Mode 3, and then it is driven in a loop according to D-left 1:Mode 1→D-left 3:Mode 3 until it enters the steady-state adjustment process through D-left 3:Mode3→D-right / Steady 1:Mode 3;

[0029] The state trajectory of the right half plane dynamic adjustment is: out >v ref During the dynamic adjustment process, the right half-plane dynamic adjustment state D-right / Steady 1:Mode 3 is used as the first activated state after the initialization state Initial State, and then the state trajectory is driven in the order of D-right / Steady 1:Mode 3→D-right / Steady 2:Mode4→D-right / Steady 3:Mode 1 until it enters the steady-state adjustment process through D-right / Steady 3:Mode 1→Steady 4:Mode 2.

[0030] The state trajectory of the steady-state regulation process is:

[0031] When the state trajectory of the left half plane dynamic adjustment enters the steady-state adjustment process from the dynamic adjustment process, the state trajectory of the steady-state adjustment process is driven in a cycle of D-right / Steady 1: Mode 3 → D-right / Steady 2: Mode 4 → D-right / Steady 3: Mode 1 → Steady 4: Mode 2;

[0032] When the state trajectory of the right half-plane dynamic adjustment enters the steady-state adjustment process from the dynamic adjustment process, the state trajectory of the steady-state adjustment process is driven in a cycle of Steady 4: Mode 2 → D-right / Steady 1: Mode 3 → D-right / Steady2 → Mode 4D-right / Steady 3: Mode 1.

[0033] Preferably, the switching condition of the mode during the dynamic regulation of the four-switch Buck-Boost converter is:

[0034] The switching condition from the left half plane dynamic adjustment state 1 D-left 1: Mode 1 to the left half plane dynamic adjustment state 2 D-left2: Mode 2 is:

[0035] (v out -V in ) 2 +(i L *-i o *) 2 ≥r m2D 2 (18)

[0036] Among them, v out represents the output voltage of the four-switch Buck-Boost converter;

[0037] V in represents the input voltage of the four-switch Buck-Boost converter;

[0038] i L * represents the normalized inductor current of the four-switch Buck-Boost converter;

[0039] i o *Represents the normalized output current of a four-switch Buck-Boost converter;

[0040] r m2D Indicates the radius of the Mode 2 state trajectory during the mode switching process of the left half plane switch;

[0041] The switching condition from the left half plane dynamic adjustment state 2 D-left 2: Mode 2 to the left half plane dynamic adjustment state 3 D-left3: Mode 3 is:

[0042] v out 2 +(i L *-i o *) 2 ≥r m3ref 2 +β (21)

[0043] Among them, β represents the compensation parameter;

[0044] r m3ref is the reference point (v ref ,i Lref *) The radius of Mode 3 at the position;

[0045] The compensation parameter β is described as:

[0046] β=r m3ref 2 -r m1initial2 (19)

[0047] where r m3ref 2 and r m1initial 2 Respectively expressed as:

[0048]

[0049] Among them, v outm10 and i Lm10 * respectively represent the normalized state plane v out -i L * Output voltage and normalized inductor current when the left half plane state trajectory enters Mode 1;

[0050] v ref Indicates the reference voltage;

[0051] i Lref *Represents the standardized reference current value of the four-switch Buck-Boost converter;

[0052] The switching condition from the left half plane dynamic adjustment state 3 D-left 3: Mode 3 to the left half plane dynamic adjustment state 1 D-left1: Mode 1 is:

[0053] i L *≤i Lref * (twenty two)

[0054] Among them, i L * represents the normalized inductor current of the four-switch Buck-Boost converter;

[0055] i Lref *Represents the standardized reference current value of the four-switch Buck-Boost converter;

[0056] The switching condition from the left half plane dynamic adjustment state 1 D-left 1: Mode 1 to the left half plane dynamic adjustment state 3 D-left3: Mode 3 is the same as formula (21);

[0057] The switching conditions from the right half plane dynamic adjustment state 1 D-right / Steady 1: Mode 3 to the right half plane dynamic adjustment state 2 D-right / Steady 2: Mode 4 are as follows:

[0058] i L *≤i LK * (twenty four)

[0059] Among them, i L* represents the normalized inductor current of the four-switch Buck-Boost converter;

[0060] i LK * represents the normalized switching inductor current of the four-switch Buck-Boost converter;

[0061] The switching conditions from the right half plane dynamic adjustment state 2 D-right / Steady 2: Mode 4 to the right half plane dynamic adjustment state 3 D-right / Steady 3: Mode 1 are as follows:

[0062]

[0063] Among them, i Lref *Represents the normalized inductor current reference value of the four-switch Buck-Boost converter;

[0064] v ref represents the tracking reference voltage of the four-switch Buck-Boost converter;

[0065] v out represents the output voltage of the four-switch Buck-Boost converter;

[0066] v in represents the input voltage of the four-switch Buck-Boost converter;

[0067] i o *Denotes the normalized output current of a four-switch Buck-Boost converter.

[0068] Preferably, the switching condition of the mode during the steady-state regulation of the four-switch Buck-Boost converter is:

[0069] The switching condition from steady-state regulation state 1 D-right / Steady 1: Mode 3 to steady-state regulation state 2 D-right / Steady2: Mode 4 is:

[0070] i L *≤i LK * (twenty four)

[0071] Among them, i L * represents the normalized inductor current of the four-switch Buck-Boost converter;

[0072] i LK * represents the normalized switching inductor current of the four-switch Buck-Boost converter;

[0073] The switching condition from steady-state regulation state 2 D-right / Steady 2: Mode 4 to steady-state regulation state 3 D-right / Steady3: Mode 1 is:

[0074]

[0075] Among them, i Lref *Represents the normalized inductor current reference value of the four-switch Buck-Boost converter;

[0076] v ref represents the tracking reference voltage of the four-switch Buck-Boost converter;

[0077] v out represents the output voltage of the four-switch Buck-Boost converter;

[0078] v in represents the input voltage of the four-switch Buck-Boost converter;

[0079] i o *Represents the normalized output current of a four-switch Buck-Boost converter;

[0080] The state trajectory switching condition from steady-state regulation state three D-right / Steady 3: Mode 1 to steady-state regulation state four Steady 4: Mode 2 is expressed as:

[0081] (v out -V in ) 2 +(i L *-i o *) 2 ≥r m2ref 2 +δr 2 (28)

[0082] Among them, v out represents the output voltage of the four-switch Buck-Boost converter;

[0083] r m2ref Indicates the reference point (v ref ,i Lref *) The radius of Mode 2;

[0084] i L * represents the normalized inductor current of the four-switch Buck-Boost converter;

[0085] i o *Represents the normalized output current of a four-switch Buck-Boost converter;

[0086] δr 2 represents the hysteresis parameter, which is used to limit the switching frequency and form a steady-state limit cycle;

[0087] In the steady-state regulation process, the state trajectory switching condition from the steady-state regulation state 4 Steady 4: Mode 2 to the steady-state regulation state 1 D-right / Steady 1: Mode 3 is expressed as:

[0088] v out 2 +(i L *-i o *) 2 ≥r m3ref 2 +δr 2 (30)

[0089] Among them, r m3ref Denotes the reference point (v ref ,i Lref *) is the radius of Mode 3.

[0090] Preferably, the four-switch Buck-Boost converter state trajectory control and finite state machine implementation method further includes:

[0091] S1, establish a dynamic mathematical model of a four-switch Buck-Boost converter in four modes, wherein the four modes are Mode 1, Mode 2, Mode 3 and Mode 4; and use the output voltage v out The horizontal axis is the standardized inductor current i L * Establish a normalized state plane v for the ordinate out -i L *; The natural trajectory of the converter in the standardized state plane is derived based on the dynamic mathematical model of the four modes;

[0092] S2, analyzing the natural trajectory of the converter in the standardized state plane, designing the state trajectory of the dynamic and steady-state regulation process; and then deriving the switching conditions of the modes in the dynamic and steady-state regulation process of the four-switch Buck-Boost converter;

[0093] S3, these switching conditions are applied to the finite state machine controller of the four-switch Buck-Boost converter. The switching conditions can realize the mode conversion, that is, control the on and off of each switch tube, so as to realize the control of the four-switch Buck-Boost converter. The design of the switching conditions can realize the precise adjustment of the converter output voltage, so that its output voltage v out Closely tracks the reference voltage v ref, while achieving the purpose of reducing the steady-state output voltage ripple and inductor current ripple.

[0094] Preferably, the S1 comprises the following steps:

[0095] S1-1, according to Kirchhoff's law, the dynamic mathematical models of the equivalent circuits of the four-switch Buck-Boost converter in Mode 1, Mode 2, Mode 3, and Mode 4 are as follows:

[0096] Mode 1:

[0097]

[0098] Mode 2:

[0099]

[0100] Mode 3:

[0101]

[0102] Mode 4:

[0103]

[0104] Wherein, L represents the inductance of the inductor L;

[0105] i L represents the inductor current;

[0106] represents the first-order derivative of the inductance of the inductor L with respect to time, and “·” represents the first-order derivative with respect to time;

[0107] V in represents the input voltage of the four-switch Buck-Boost converter;

[0108] C represents the capacitance of capacitor C;

[0109] represents the first-order derivative of the output voltage of the four-switch Buck-Boost converter with respect to time;

[0110] v out represents the output voltage of the four-switch Buck-Boost converter;

[0111] R represents the resistance value of resistor R;

[0112] S1-2, with output voltage v out is the horizontal coordinate axis, the standardized inductor current i L* Establish a standardized state plane v for the vertical axis out -i L *, where the normalized inductor current i L * means:

[0113]

[0114] S1-3, based on the dynamic mathematical model of the equivalent circuit of the four-switch Buck-Boost converter Mode 1 Mode 2 Mode 3 Mode 4, derive Mode 1 Mode 1, Mode 2 Mode 2, Mode 3 Mode 3, Mode 4 Mode 4 on the standardized state plane v out -i L *Natural trajectory on the

[0115] Mode 1 is in the normalized state plane v out -i L The process of obtaining the natural trajectory on * is:

[0116] According to the mathematical model (1), the normalized inductor current i L * and output voltage v out The relationship is expressed as:

[0117]

[0118] At each step, the inductor current i L and the output voltage v out During sampling, considering the fast sampling rate, the inductor current i L and the output voltage v out They all change within a very small range, so formula (6) can be expressed as:

[0119]

[0120] Among them, Δi L * represents the change of the standardized inductor current iL* in each sampling interval;

[0121] Δv out Indicates the change in output voltage vout at each sampling interval;

[0122] Therefore, Mode 1 is in the normalized state plane v out -i L The natural trajectory on * is expressed as:

[0123]

[0124] Among them, i L0 * represents the initial value of the normalized inductor current;

[0125] v out0 Indicates the initial value of the output voltage;

[0126] i o0 *Indicates the initial value of the standardized output current;

[0127] From formula (8), we know that in the standardized state plane v out -i L *, the natural trajectory of the four-switch Buck-Boost converter mode 1 is represented by a straight line with a negative slope, and the slope of the straight line is determined by the converter input voltage V in and the initial value i of the standardized output current when entering Mode 1 o0 * Joint decision making;

[0128] Mode 2 Mode 2 in the normalized state plane v out -i L The process of obtaining the natural trajectory on * is:

[0129] According to the mathematical model (2), the inductor current i can be obtained L The second-order derivative of is:

[0130]

[0131] Where, “··” represents the second-order derivative with respect to time;

[0132] By transforming equation (9) and combining it with mathematical model (2), we get the following dynamic equations:

[0133]

[0134] Equivalent transformation is performed on equation (10) and the inductor current i L Integrate to get Mode 2 on the normalized state plane v out -i L The natural trajectory on * is:

[0135] (v out -V in ) 2 +(i L *-i o *) 2 =r m2 2 (11)

[0136] Among them, i o * indicates the standardized output current, r m2 is in the normalized state plane v out -i L* The initial position of the four-switch Buck-Boost converter when entering Mode 2 is at the reference point (v ref ,i Lref *) distance;

[0137] From formula (11), we know that in the standardized state plane v out -i L *, the natural trajectory of the four-switch Buck-Boost converter mode 2 Mode2 is (V in ,i o *) is the cluster of circular trajectories with the center of the circle;

[0138] Mode 3 Mode 3 in the normalized state plane v out -i L The process of obtaining the natural trajectory on * is:

[0139] According to mathematical model (3), equation (9) is transformed to obtain the following dynamic equations:

[0140]

[0141] in, Inductor current i L The second derivative with respect to time;

[0142] Indicates the inductor current i L First derivative with respect to time;

[0143] Perform an equivalent transformation on equation (12) and calculate the inductor current i L Integrate to get Mode 3 on the normalized state plane v out -i L The natural trajectory on * is:

[0144]

[0145] Among them, r m3 is in the normalized state plane v out -i L * The initial position of the four-switch Buck-Boost converter when entering Mode 2 Mode 3 is at the reference point (v ref ,i Lref *) distance;

[0146] From formula (13), we know that in the standardized state plane v out -i L *, the natural trajectory of Mode 3 is (0,i o *) is the cluster of circular trajectories with the center of the circle;

[0147] Mode 4 Mode 4 in the normalized state plane v out -i L The process of obtaining the natural trajectory on * is:

[0148] According to mathematical model (4), the time domain model of inductor current and output voltage is obtained:

[0149]

[0150] Wherein, c represents a constant, i.e., the inductor current iL of the four-switch Buck-Boost converter in Mode 4;

[0151] v out0 Indicates the initial value of the output voltage;

[0152] e is a natural constant;

[0153] t represents time;

[0154] From formula (14), we can get mode 4 on the standardized state plane v out -i L The natural trajectory on * is:

[0155]

[0156] From formula (15), we know that in the standardized state plane v out -i L *, the natural trajectory of Mode 4 is parallel to the normalized state plane v out -i L * Cluster of lines on the horizontal axis.

[0157] The above equations (8), (11), (13), and (15) are respectively the four-switch Buck-Boost converter mode 1 Mode 1, mode 2 Mode 2, mode 3 Mode 3, and mode 4 Mode 4 on the standardized state plane v out -i L *Natural trajectory on the skin.

[0158] Preferably, by analyzing the natural trajectory of the converter in the standardized state plane, it is known that the state trajectory control process of the four-switch Buck-Boost converter will go through dynamic and steady-state adjustment processes, in which eight state drives of the four-switch Buck-Boost converter are involved.

[0159] Preferably, the switching condition of the mode during the dynamic regulation of the four-switch Buck-Boost converter is obtained by:

[0160] First, solve the dynamic mathematical equations of Mode 1 in Equation (1) and Mode 3 in Equation (3) respectively, and set the standardized reference inductor current i Lref *for:

[0161]

[0162] Among them, v ref represents the tracking reference voltage of the four-switch Buck-Boost converter;

[0163] i o *Represents the normalized output current of a four-switch Buck-Boost converter;

[0164] v in represents the input voltage of the four-switch Buck-Boost converter;

[0165] The normalized state plane v out -i L *The reference point is expressed as (v ref ,i Lref *), the reference point is the target point that needs to be finally reached by the state trajectory control method;

[0166] The dynamic regulation process is divided into a standardized state plane v out -i L * Left half plane (i.e. output voltage is less than reference voltage v out <v ref The switching condition of the switching mode when out -i L *Right half plane (i.e. output voltage is greater than reference voltage v out >v ref There are two situations:

[0167] Normalized state plane v out -i L *The switching conditions of the left half plane switching mode are derived as follows:

[0168] Set the radius r of Mode 2 during the left half plane switch mode switching process m2D for:

[0169] r m2D =r m2min +m(r m2max -r m2min ) (17)

[0170] in, m is a constant between 0 and 1, and the constant m is used to represent the mode 2 Mode 2 in the normalized state plane v out-i L * The degree of participation in the left half plane switch mode switching process. The closer m is to 0, the greater the degree of participation of Mode 2. The closer m is to 1, the smaller the degree of participation of Mode 2.

[0171] The switching condition from the left half plane dynamic adjustment state 1 D-left 1: Mode 1 to the left half plane dynamic adjustment state 2 D-left2: Mode 2 is:

[0172] (v out -V in ) 2 +(i L *-i o *) 2 ≥r m2D 2 (18)

[0173] Among them, v out represents the output voltage of the four-switch Buck-Boost converter;

[0174] V in represents the input voltage of the four-switch Buck-Boost converter;

[0175] i L represents the inductor current of the four-switch Buck-Boost converter;

[0176] i o *Represents the normalized output current of a four-switch Buck-Boost converter;

[0177] r m2D Indicates the radius of the Mode 2 state trajectory during the mode switching process of the left half plane switch;

[0178] Considering the power loss in the four-switch Buck-Boost converter, which is mainly due to the existence of parasitic parameters such as capacitor equivalent series resistance, inductor DC resistance and switch on-resistance, when the converter works in Mode 2 and Mode 3, the natural trajectory decreases faster than in the ideal state, resulting in the normalized state plane v out -i L *The state trajectory in the dynamic adjustment process of the left half plane cannot directly reach the reference point through Mode 3; therefore, in the standardized state plane v out -i L * The compensation parameter β is introduced in the left half plane, thereby delaying the switching of other modes to Mode 3, and the compensation parameter β is updated in Mode 3; the compensation parameter β updated when the state trajectory is in the left plane is described as:

[0179] β=r m3ref 2 -r m1initial 2 (19)

[0180] where r m3ref is the reference point (v ref ,i Lref *) The radius of Mode 3, r m3ref 2 and r m1initial 2 Respectively expressed as:

[0181]

[0182] Among them, v outm10 and i Lm10 * respectively represent the normalized state plane v out -i L * Output voltage and normalized inductor current when the left half plane state trajectory enters Mode 1;

[0183] The switching condition from the left half plane dynamic adjustment state 2 D-left 2: Mode 2 to the left half plane dynamic adjustment state 3 D-left3: Mode 3 is:

[0184] v out 2 +(i L *-i o *) 2 ≥r m3ref 2 +β (21)

[0185] The existence of parasitic parameters makes the state trajectory unable to reach the reference point (v) in one go after the sequential driving of D-left 1: Mode 1 → D-left 2: Mode 2 → D-left3: Mode 3. ref ,i Lref *); when moving along the state trajectory of Mode 3, the output voltage v out <v ref , and the standardized inductor current i L *=i Lref *, the four-switch Buck-Boost converter needs to work in mode 1 again, and then it is driven in a cycle from D-left 1: Mode 1 → D-left 3: Mode 3. The switching condition from the left half plane dynamic adjustment state 3 D-left 3: Mode 3 to the left half plane dynamic adjustment state 1 D-left1: Mode 1 is:

[0186] iL *≤i Lref * (twenty two)

[0187] Among them, i L * represents the normalized inductor current of the four-switch Buck-Boost converter;

[0188] i Lref *Represents the standardized reference current value of the four-switch Buck-Boost converter;

[0189] The switching condition from the left half plane dynamic adjustment state 1 D-left 1: Mode 1 to the left half plane dynamic adjustment state 3 D-left3: Mode 3 is the same as formula (21);

[0190] S2-2, normalized state plane v out -i L *The switching conditions of the right half plane switching mode are derived as follows:

[0191] Set the normalized switching inductor current i LK *for:

[0192] i LK *=i Lref * / K (23)

[0193] Where K is a gain parameter greater than 1, which is used to set the modal four trajectories and i L *=i Lref * The distance between the horizontal lines, the larger the K, the closer the modal four trajectories are to i L *=i Lref *The larger the distance between the horizontal lines, the smaller K is. The modal four trajectories and i L *=i Lref *The smaller the distance between the horizontal lines;

[0194] The switching conditions from the right half plane dynamic adjustment state 1 D-right / Steady 1: Mode 3 to the right half plane dynamic adjustment state 2 D-right / Steady 2: Mode 4 are as follows:

[0195] i L *≤i LK * (twenty four)

[0196] Among them, i L * represents the normalized inductor current of the four-switch Buck-Boost converter;

[0197] i LK * represents the normalized switching inductor current of the four-switch Buck-Boost converter;

[0198] The switching conditions from the right half plane dynamic adjustment state 2 D-right / Steady 2: Mode 4 to the right half plane dynamic adjustment state 3 D-right / Steady 3: Mode 1 are as follows:

[0199]

[0200] Among them, i Lref *Represents the normalized inductor current reference value of the four-switch Buck-Boost converter;

[0201] v ref represents the tracking reference voltage of the four-switch Buck-Boost converter;

[0202] v out represents the output voltage of the four-switch Buck-Boost converter;

[0203] v in represents the input voltage of the four-switch Buck-Boost converter;

[0204] i o *Denotes the normalized output current of a four-switch Buck-Boost converter.

[0205] In summary, due to the adoption of the above technical solutions, the state trajectory control method of the four-switch Buck-Boost converter designed in the present invention plans the motion trajectory of the converter in the state plane and adopts an event-triggered control method, so that the output voltage and inductor current in the dynamic process change according to the designed state trajectory, thereby achieving rapid dynamic response, ensuring rapid start-up of the output voltage without overshoot, eliminating the inductor current impact when the reference voltage drops in step, and ensuring that the output voltage has a shorter adjustment time when the load changes in step; achieving lower steady-state output voltage ripple and inductor current ripple. At the same time, the output voltage is kept stable when the input voltage changes rapidly, so that the converter has stronger adaptability. The specific advantages are as follows:

[0206] 1. Compared with the model predictive control method, the present invention plans the motion trajectory of the converter in the state plane and adopts an event-triggered control method, so that the output voltage and inductor current in the dynamic process change according to the designed state trajectory, thereby reducing the design burden;

[0207] 2. Compared with the traditional control strategy, the present invention can achieve a fast dynamic response of the output voltage of the four-switch Buck-Boost converter, ensure a fast start-up of the output voltage without overshoot, eliminate the inductor current impact when the reference voltage drops in step, and ensure that the output voltage has a shorter adjustment time when the load changes in step;

[0208] 3. Multi-mode (modal) control If multiple controllers are designed for multiple modes, accurate mode detection is required to determine which controller to use, while the state trajectory control of the present invention only requires one controller, so there is no need to switch controllers. In addition, compared with the model predictive control method that uses the same controller for multiple modes (modalities), the control algorithm that needs to be designed is more complex than the algorithm of the state trajectory control of the present invention.

[0209] 4. Achieve lower steady-state output voltage ripple and inductor current ripple through steady-state process control strategy design;

[0210] 5. The present invention can achieve that the output voltage remains stable when the input voltage changes rapidly, making the converter more adaptable.

[0211] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned through time of the present invention.

[0212] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0213] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0214] Figure 1 Schematic diagram of a four-switch Buck-Boost converter according to the present invention.

[0215] Figure 2 It is a circuit diagram of four modes of the four-switch Buck-Boost converter of the present invention.

[0216] Figure 3 It is a finite state machine controller of the novel state trajectory control method of the present invention.

[0217] Figure 4 is the converter in the invention in the standardized state plane v out -i L *The state trajectory of the dynamic regulation process.

[0218] Figure 5 is the converter in the invention in the standardized state plane v out -i L *State trajectory of the steady-state regulation process.

[0219] Figure 6 is the converter in the invention in the standardized state plane v out -i L * Up v out <vref State trajectory motion diagram when .

[0220] Figure 7 is the converter in the invention in the standardized state plane v out -i L * Up v out >v ref State trajectory motion diagram when .

[0221] Figure 8 are the standardized inductor current ripple and output voltage ripple of the converter in the present invention. DETAILED DESCRIPTION

[0222] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0223] Figure 1 The circuit structure of the four-switch Buck-Boost converter of the present invention includes four switch tubes, the drain of the first switch tube s1 is connected to the converter input voltage V in The positive electrode of the first switch tube s1 is connected to the drain of the second switch tube s2 and one end of the inductor L, and the source of the second switch tube s2 is connected to the input voltage V in The negative electrode of the fourth switch tube s4, the source of the fourth switch tube s4, one end of the capacitor C and one end of the load R, the drain of the third switch tube s3 is connected to the other end of the output capacitor C and the other end of the load R, and the source of the third switch tube s3 is connected to the drain of the fourth switch tube s4 and the other end of the inductor L. Figure 1 The positive direction of the inductor current is specified in , and the value is positive if it is in the same direction as the specified current, and negative if it is opposite to the specified current direction.

[0224] Figure 2 It is a circuit diagram of the four modes of the four-switch Buck-Boost converter of the present invention, in which the solid line indicates conduction and the dotted line indicates shutdown. The four-switch Buck-Boost converter has four modes: Mode 1, Mode 2, Mode 3, and Mode 4. In Mode 1, switch tubes s1 and s4 are turned on, and switch tubes s2 and s3 are turned off; in Mode 2, switch tubes s1 and s3 are turned on, and switch tubes s2 and s4 are turned off; in Mode 3, switch tubes s2 and s3 are turned on, and switch tubes s1 and s4 are turned off; in Mode 4, switch tubes s2 and s4 are turned on, and switch tubes s1 and s3 are turned off.

[0225] According to Kirchhoff's law, the dynamic mathematical models of the equivalent circuits of the four-switch Buck-Boost converter in Mode 1, Mode 2, Mode 3, and Mode 4 are as follows:

[0226] Mode 1:

[0227]

[0228] Mode 2:

[0229]

[0230] Mode 3:

[0231]

[0232] Mode 4:

[0233]

[0234] With output voltage v out is the horizontal coordinate axis, the standardized inductor current i L * Establish a standardized state plane v for the vertical axis out -i L *, where the normalized inductor current i L * means:

[0235]

[0236] According to equations (1), (2), (3) and (4), we can deduce Mode 1, Mode 2, Mode 3 and Mode 4 on the standardized state plane v out -i L *, we get the natural trajectories of four modes:

[0237] Mode 1 is in the normalized state plane v out -i L The natural trajectory on * is expressed as:

[0238]

[0239] From formula (8), we know that in the standardized state plane v out -i L *, the natural trajectory of the four-switch Buck-Boost converter mode 1 is represented by a straight line with a negative slope, and the slope of the straight line is determined by the converter input voltage V in and the initial value i of the standardized output current when entering Mode 1o0 * Joint decision making;

[0240] Mode 2 Mode 2 in the normalized state plane v out -i L *Natural trajectory on:

[0241] (v out -V in ) 2 +(i L *-i o *) 2 =r m2 2 (11)

[0242] From formula (11), we know that in the standardized state plane v out -i L *, the natural trajectory of the four-switch Buck-Boost converter mode 2 Mode2 is (V in ,i o *) is the cluster of circular trajectories with the center of the circle;

[0243] Mode 3 Mode 3 in the normalized state plane v out -i L *Natural trajectory on:

[0244] v out 2 +(i L *-i o *) 2 =r m3 2 (13)

[0245] From formula (13), we know that in the standardized state plane v out -i L *, the natural trajectory of Mode 3 is (0,i o *) is the cluster of circular trajectories with the center of the circle;

[0246] Mode 4 Mode 4 in the normalized state plane v out -i L *Natural trajectory on:

[0247]

[0248] From formula (15), we know that in the standardized state plane v out -i L *, the natural trajectory of Mode 4 is parallel to the normalized state plane v out -i L * Cluster of lines on the horizontal axis;

[0249] Figure 3 It is a finite state machine controller of the novel state trajectory control method of the present invention: the state trajectory control process of the four-switch Buck-Boost converter includes eight state drives, namely, initialization state Initial State, left half-plane dynamic adjustment state one D-left 1: Mode 1, left half-plane dynamic adjustment state two D-left 2: Mode 2, left half-plane dynamic adjustment state three D-left 3: Mode 3, steady-state adjustment and right half-plane dynamic adjustment state one D-right / Steady1: Mode 3, steady-state adjustment and right half-plane dynamic adjustment state two D-right / Steady 2: Mode 4, steady-state adjustment and right half-plane dynamic adjustment state three D-right / Steady 3: Mode 1, steady-state adjustment state four Steady 4: Mode 2.

[0250] During the dynamic adjustment process, according to the converter output voltage v out and reference voltage v ref The size relationship of the state trajectory control is divided into v out <v ref and v out >v ref Two control processes. out <v ref During the control process, the left half plane dynamic adjustment state D-left 1: Mode 1 is used as the first activated state after the initialization state Initial State, and then the state trajectory is first driven in the order of D-left 1: Mode 1 → D-left 2: Mode 2 → D-left 3: Mode 3, and then it is driven in a loop according to D-left 1: Mode 1 → D-left 3: Mode 3. out >v ref During the control process, the right half-plane dynamic adjustment state D-right / Steady 1:Mode 3 is used as the first activated state after the initialization state Initial State, and then the state trajectory is driven in the order of D-right / Steady 1:Mode 3→D-right / Steady 2:Mode4→D-right / Steady3:Mode 1.

[0251] The natural trajectory of the four modes of the converter is analyzed by equations (8), (11), (13), and (15). By designing the state trajectory of the dynamic and steady-state regulation processes, the switching conditions of the switching modes in the dynamic regulation process of the four-switch Buck-Boost converter and the switching conditions of the switching modes in the steady-state regulation process of the four-switch Buck-Boost converter are derived:

[0252] The switching conditions of the switching mode during the dynamic regulation of the four-switch Buck-Boost converter include:

[0253] Normalized state plane v out -i L * Left half plane, that is, the output voltage is less than the reference voltage v out <v ref The switching conditions and the standardized state plane v of the switching mode out -i L *Right half plane, that is, the output voltage is greater than the reference voltage v out >v ref The switching condition of the switch mode.

[0254] Solve the dynamic mathematical equations of Mode 1 in Equation (1) and Mode 3 in Equation (3) respectively, and set the standardized reference inductor current i Lref *for:

[0255]

[0256] The normalized state plane v out -i L *The reference point is expressed as (v ref ,i Lref *), the reference point is the target point that needs to be finally reached by the state trajectory control method.

[0257] Normalized state plane v out -i L *The switching conditions of the left half plane switching mode are as follows:

[0258] The switching condition from the left half plane dynamic adjustment state 1 D-left 1: Mode 1 to the left half plane dynamic adjustment state 2 D-left2: Mode 2 is:

[0259] (v out -V in ) 2 +(i L *-i o *) 2 ≥r m2D 2 (18)

[0260] Considering the power loss in the four-switch Buck-Boost converter, which is mainly due to the existence of parasitic parameters such as capacitor equivalent series resistance, inductor DC resistance and switch on-resistance, when the converter works in Mode 2 and Mode 3, the natural trajectory decreases faster than in the ideal state, resulting in the normalized state plane v out -i L *The state trajectory in the dynamic adjustment process of the left half plane cannot directly reach the reference point through Mode 3; therefore, in the standardized state plane v out -i L * The compensation parameter β is introduced in the left half plane, thereby delaying the switching of other modes to Mode 3, and the compensation parameter β is updated in Mode 3; the compensation parameter β updated when the state trajectory is in the left plane is described as:

[0261] β=r m3ref 2 -r m1initial 2 (19)

[0262] The switching condition from the left half plane dynamic adjustment state 2 D-left 2: Mode 2 to the left half plane dynamic adjustment state 3 D-left3: Mode 3 is:

[0263] v out 2 +(i L *-i o *) 2 ≥r m3ref 2 +β (21)

[0264] The existence of parasitic parameters makes the state trajectory unable to reach the reference point (v) in one go after the sequential driving of D-left 1: Mode 1 → D-left 2: Mode 2 → D-left3: Mode 3. ref ,i Lref *); when moving along the state trajectory of Mode 3, the output voltage v out <v ref , and the standardized inductor current i L *=i Lref *, the four-switch Buck-Boost converter needs to work in mode 1 again, and then it is driven in a cycle from D-left 1: Mode 1 → D-left 3: Mode 3. The switching condition from the left half plane dynamic adjustment state 3 D-left 3: Mode 3 to the left half plane dynamic adjustment state 1 D-left1: Mode 1 is:

[0265] iL *≤i Lref * (twenty two)

[0266] The switching condition from the left half plane dynamic adjustment state 1 D-left 1: Mode 1 to the left half plane dynamic adjustment state 3 D-left3: Mode 3 is the same as formula (21);

[0267] Normalized state plane v out -i L *The switching conditions of the right half plane switching mode are as follows:

[0268] Set the normalized switching inductor current i LK *for:

[0269] i LK *=i Lref * / K (23)

[0270] The switching conditions from the right half plane dynamic adjustment state 1 D-right / Steady 1: Mode 3 to the right half plane dynamic adjustment state 2 D-right / Steady 2: Mode 4 are as follows:

[0271] i L *≤i LK * (twenty four)

[0272] The switching conditions from the right half plane dynamic adjustment state 2 D-right / Steady 2: Mode 4 to the right half plane dynamic adjustment state 3 D-right / Steady 3: Mode 1 are as follows:

[0273]

[0274] The switching conditions of the switching mode during the steady-state regulation of the four-switch Buck-Boost converter include:

[0275] In the steady-state regulation process, the switching condition from the steady-state regulation state 1 D-right / Steady 1: Mode 3 to the steady-state regulation state 2 D-right / Steady 2: Mode 4 is the same as formula (24);

[0276] In the steady-state regulation process, the switching condition from the steady-state regulation state 2 D-right / Steady 2: Mode 4 to the steady-state regulation state 3 D-right / Steady 3: Mode 1 is the same as formula (25);

[0277] The hysteresis parameter δr is introduced in Mode 2 and Mode 3 of the steady-state regulation process. 2 , to limit the switching frequency and form a steady-state limit cycle;

[0278] The natural trajectory of Mode 2 during steady-state regulation is defined as:

[0279] (v out -V in ) 2 +(i L *-i o *) 2 =r m2ref 2 +δr 2 (26)

[0280] In the steady-state regulation process, the state trajectory switching condition from the steady-state regulation state three D-right / Steady 3: Mode 1 to the steady-state regulation state four Steady 4: Mode 2 is expressed as:

[0281] (v out -V in ) 2 +(i L *-i o *) 2 ≥r m2ref 2 +δr 2 (28)

[0282] The natural trajectory of Mode 3 during steady-state regulation is defined as:

[0283] v out 2 +(i L *-i o *) 2 =r m3ref 2 +δr 2 (29)

[0284] In the steady-state regulation process, the state trajectory switching condition from the steady-state regulation state 4 Steady 4: Mode 2 to the steady-state regulation state 1 D-right / Steady 1: Mode 3 is expressed as:

[0285] v out 2 +(i L *-i o *) 2 ≥r m3ref 2 +δr 2 (30)

[0286] Combining the above switching conditional equations (18), (21), (22), (24), (25), (28), and (30) with the eight states of the finite state machine controller of the four-switch Buck-Boost converter: initialization state Initial State, left half-plane dynamic adjustment state one D-left 1: Mode 1, left half-plane dynamic adjustment state two D-left 2: Mode 2, left half-plane dynamic adjustment state three D-left 3: Mode 3, steady-state adjustment and right half-plane dynamic adjustment state one D-right / Steady 1: Mode 3, steady-state adjustment and right half-plane dynamic adjustment state two D-right / Steady 2: Mode 4, steady-state adjustment and right half-plane dynamic adjustment state three D-right / Steady 3: Mode 1, steady-state adjustment state four Steady 4: Mode 2, the following is constructed. Figure 3 The finite state machine controller of the state trajectory control method is shown.

[0287] Combining the above switching conditions (18), (21), (22), (24), (25), (28), (30) and the four modes of the four-switch Buck-Boost converter on the standardized state plane v out -i L The natural trajectory formulas (8), (11), (13), and (15) on * are as follows: Figure 4 The converter shown is in the normalized state plane v out -i L *The state trajectory of the dynamic regulation process.

[0288] Combining the above switching conditions (24), (25), (28), (30) and the four modes of the four-switch Buck-Boost converter on the standardized state plane v out -i L The natural trajectory formulas (8), (11), (13), and (15) on * are as follows: Figure 5 The converter shown is in the normalized state plane v out -i L * The state trajectory of the steady-state regulation process. It should be noted that the natural trajectory shape of Mode 2 is similar to the input voltage V in related, Figure 5 (a) indicates v ref <V in situation; Figure 5 (b) indicates v ref =V in situation; Figure 5 (c) indicates v ref >V in situation.

[0289] The four-switch Buck-Boost converter circuit parameters involved are set at the input voltage V in =9V, reference voltage v ref =15V, output capacitor C = 100μF, negative electrode energy storage inductor L = 100μH, load R = 10Ω, hysteresis parameter δr 2 =0.04, gain parameter K = 1.05, m = 0.1, we get Figure 6 The normalized state plane v is shown out -i L * Up v out <v ref The state trajectory of the output voltage and inductor current during the converter startup process. The output voltage v of the four-switch Buck-Boost converter out After stabilizing at 15V, reduce the reference voltage v ref to 9V to get Figure 7 The normalized state plane v is shown out -i L * Up v out >v ref The state trajectory of the converter's output voltage and inductor current. Figure 7 The steady-state limit cycle formed in the converter is also the normalized state plane v out -i L *State trajectory of the steady-state regulation process. Figure 8 It is the standardized inductor current ripple and output voltage ripple formed by state trajectory control in the four-switch Buck-Boost converter circuit. Figure 8 (a) indicates v ref <V in situation; Figure 8 (b) indicates v ref =V in situation; Figure 8 (c) indicates v ref >V in situation.

[0290] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A four-switch Buck-Boost converter state trajectory control and finite state machine implementation method, the four-switch Buck-Boost converter includes four switch tubes: the drain of the first switch tube s1 is connected to the converter input voltage V in The positive electrode of the first switch tube s1 is connected to the drain of the second switch tube s2 and one end of the inductor L, and the source of the second switch tube s2 is connected to the input voltage V in The negative electrode of the output capacitor C, the source electrode of the fourth switch tube s4, one end of the capacitor C and one end of the load R, the drain electrode of the third switch tube s3 is connected to the other end of the output capacitor C and the other end of the load R, and the source electrode of the third switch tube s3 is connected to the drain electrode of the fourth switch tube s4 and the other end of the inductor L; It is characterized in that The four-switch Buck-Boost converter state trajectory control and finite state machine implementation method comprises the following steps: When the input voltage V in , reference voltage v ref When one or any combination of the resistance of the load R changes, the four-switch Buck-Boost converter will first perform a dynamic adjustment process and then a steady-state adjustment process, and finally keep the four-switch Buck-Boost converter in a steady state; In the dynamic and steady-state regulation process, eight state drives of the four-switch Buck-Boost converter are involved, including: Initial State: indicates the initialization state; D-left 1: Mode 1: indicates the left half plane dynamic adjustment state 1; D-left 2: Mode 2: indicates the left half plane dynamic adjustment state 2; D-left 3: Mode 3: indicates the left half plane dynamic adjustment state three; D-right / Steady 1: Mode 3: Indicates steady-state regulation state 1 or right half-plane dynamic regulation state 1; D-right / Steady 2:Mode 4: Indicates steady-state regulation state 2 or right half-plane dynamic regulation state 2; D-right / Steady 3: Mode 1: Indicates steady-state regulation state 3 or right half-plane dynamic regulation state 3; Steady 4:Mode 2: indicates steady-state regulation state 4; The left half plane refers to the output voltage being less than the reference voltage v out <v ref The right half plane refers to the output voltage being greater than the reference voltage v out >v ref hour; State 1 refers to the state of Mode 1, State 2 refers to the state of Mode 2, State 3 refers to the state of Mode 3, and State 4 refers to the state of Mode 4; Mode 1, Mode 2, Mode 3, Mode 4, the switching states of the four-switch Buck-Boost converter equivalent circuit corresponding to these four modes are: In mode 1, switches s1 and s4 are turned on, and switches s2 and s3 are turned off. In Mode 2, switch tubes s1 and s3 are turned on, and switch tubes s2 and s4 are turned off; In Mode 3, switch tubes s2 and s3 are turned on, and switch tubes s1 and s4 are turned off; In mode 4, switch tubes s2 and s4 are turned on, and switch tubes s1 and s3 are turned off; The dynamic adjustment is left half plane dynamic adjustment or right half plane dynamic adjustment; The state trajectory of the left half plane dynamic adjustment is: out <v ref During the dynamic adjustment process, the left half plane dynamic adjustment state D-left 1: Mode 1 is used as the first activated state after the initialization state Initial State, and then the state trajectory is first driven in the order of D-left 1: Mode 1 → D-left 2: Mode 2 → D-left 3: Mode 3, and then it is driven in a loop according to D-left 1: Mode 1 → D-left 3: Mode 3; The state trajectory of the right half plane dynamic adjustment is: out >v ref During the dynamic adjustment process, the right half plane dynamic adjustment state D-right / Steady 1:Mode 3 is used as the first activated state after the initialization state Initial State, and then the state trajectory is driven in the order of D-right / Steady 1:Mode 3→D-right / Steady 2:Mode4→D-right / Steady3:Mode 1; The state trajectory of the steady-state regulation process is: When the state trajectory of the left half plane dynamic adjustment enters the steady-state adjustment process from the dynamic adjustment process, the state trajectory of the steady-state adjustment process is driven in a cycle of D-right / Steady 1:Mode 3→D-right / Steady 2:Mode4→D-right / Steady3:Mode 1→Steady 4:Mode 2; When the state trajectory of the right half-plane dynamic adjustment enters the steady-state adjustment process from the dynamic adjustment process, the state trajectory of the steady-state adjustment process is driven cyclically according to Steady 4: Mode 2 → D-right / Steady 1: Mode 3 → D-right / Steady 2: Mode 4 → D-right / Steady 3: Mode 1.

2. The four-switch Buck-Boost converter state trajectory control and finite state machine implementation method according to claim 1, characterized in that: The switching conditions of the modes during the dynamic regulation of the four-switch Buck-Boost converter are: The switching condition from the left half plane dynamic adjustment state 1 D-left 1: Mode 1 to the left half plane dynamic adjustment state 2 D-left 2: Mode 2 is: (v out -V in ) 2 +(i L *-i o *) 2 ≥r m2D 2 (18) Where v out represents the output voltage of the four-switch Buck-Boost converter; V in represents the input voltage of the four-switch Buck-Boost converter; i L * represents the normalized inductor current of the four-switch Buck-Boost converter; i o *Represents the normalized output current of a four-switch Buck-Boost converter; r m2D Indicates the radius of the Mode 2 state trajectory during the mode switching process of the left half plane switch; The switching condition from the left half plane dynamic adjustment state 2 D-left 2: Mode 2 to the left half plane dynamic adjustment state 3 D-left 3: Mode 3 is: v out 2 +(i L *-i o *) 2 ≥r m3ref 2 +β (21) Among them, β represents the compensation parameter; r m3ref is the reference point (v ref ,i Lref *) The radius of Mode 3 at the position; The compensation parameter β is described as: β＝r m3ref 2 -r m1initial 2 (19) where r m3ref 2 and r m1initial 2 Respectively expressed as: Among them, v outm10 and i Lm10 * respectively represent the normalized state plane v out -i L * Output voltage and normalized inductor current when the left half plane state trajectory enters Mode 1; v ref Indicates the reference voltage; i Lref *Represents the standardized reference current value of the four-switch Buck-Boost converter; The switching condition from the left half plane dynamic adjustment state 3 D-left 3: Mode 3 to the left half plane dynamic adjustment state 1 D-left 1: Mode 1 is: i L *≤i Lref * (22) Among them, i L * represents the normalized inductor current of the four-switch Buck-Boost converter; i Lref *Represents the standardized reference current value of the four-switch Buck-Boost converter; The switching condition from the left half plane dynamic adjustment state 1 D-left 1: Mode 1 to the left half plane dynamic adjustment state 3 D-left 3: Mode 3 is the same as formula (21); The switching conditions from the right half plane dynamic adjustment state 1 D-right / Steady 1: Mode 3 to the right half plane dynamic adjustment state 2 D-right / Steady 2: Mode 4 are as follows: i L *≤i LK * (24) Among them, i L * represents the normalized inductor current of the four-switch Buck-Boost converter; i LK * represents the normalized switching inductor current of the four-switch Buck-Boost converter; The switching conditions from the right half plane dynamic adjustment state 2 D-right / Steady 2: Mode 4 to the right half plane dynamic adjustment state 3 D-right / Steady 3: Mode 1 are as follows: Among them, i Lref *Represents the normalized inductor current reference value of the four-switch Buck-Boost converter; v ref represents the tracking reference voltage of the four-switch Buck-Boost converter; v out represents the output voltage of the four-switch Buck-Boost converter; v in represents the input voltage of the four-switch Buck-Boost converter; i o *Denotes the normalized output current of a four-switch Buck-Boost converter.

3. The state trajectory control and finite state machine implementation method of a four-switch Buck-Boost converter according to claim 1, characterized in that: The switching conditions of the modes during the steady-state regulation of the four-switch Buck-Boost converter are: The switching condition from steady-state regulation state 1 D-right / Steady 1: Mode 3 to steady-state regulation state 2 D-right / Steady 2: Mode 4 is: i L *≤i LK * (24) Among them, i L * represents the normalized inductor current of the four-switch Buck-Boost converter; i LK * represents the normalized switching inductor current of the four-switch Buck-Boost converter; The switching conditions from steady-state regulation state 2 D-right / Steady 2: Mode 4 to steady-state regulation state 3 D-right / Steady 3: Mode 1 are: Among them, i Lref *Represents the normalized inductor current reference value of the four-switch Buck-Boost converter; v ref represents the tracking reference voltage of the four-switch Buck-Boost converter; v out represents the output voltage of the four-switch Buck-Boost converter; v in represents the input voltage of the four-switch Buck-Boost converter; i o *Represents the normalized output current of a four-switch Buck-Boost converter; The state trajectory switching condition from steady-state regulation state three D-right / Steady 3: Mode 1 to steady-state regulation state four Steady 4: Mode 2 is expressed as: (v out -V in ) 2 +(i L *-i o *) 2 ≥r m2ref 2 +δr 2 (28) Among them, v out represents the output voltage of the four-switch Buck-Boost converter; r m2ref Indicates the reference point (v ref ,i Lref *) The radius of Mode 2; i L * represents the normalized inductor current of the four-switch Buck-Boost converter; i o *Represents the normalized output current of a four-switch Buck-Boost converter; δr 2 represents the hysteresis parameter; In the steady-state regulation process, the state trajectory switching condition from the steady-state regulation state 4 Steady 4: Mode 2 to the steady-state regulation state 1 D-right / Steady 1: Mode 3 is expressed as: in out 2 +(i L *-and o *) 2 ≥r m3ref 2 +δr 2 (30) Among them, r m3ref Denotes the reference point (v ref ,i Lref *) is the radius of Mode 3.

4. The four-switch Buck-Boost converter state trajectory control and finite state machine implementation method according to claim 1, characterized in that: The state trajectory control and finite state machine implementation method of the four-switch Buck-Boost converter also includes: S1, establish a dynamic mathematical model of a four-switch Buck-Boost converter in four modes, wherein the four modes are Mode 1, Mode 2, Mode 3 and Mode 4; and use the output voltage v out The horizontal axis is the standardized inductor current i L * Establish a normalized state plane v for the ordinate out -i L *; The natural trajectory of the converter in the standardized state plane is derived based on the dynamic mathematical model of the four modes; S2, analyzing the natural trajectory of the converter in the standardized state plane, designing the state trajectory of the dynamic and steady-state regulation process; and then deriving the switching conditions of the modes in the dynamic and steady-state regulation process of the four-switch Buck-Boost converter; S3, these switching conditions are applied to the finite state machine controller of the four-switch Buck-Boost converter. The mode conversion can be realized through the switching conditions, that is, the on and off of each switch tube can be controlled, thereby realizing the control of the four-switch Buck-Boost converter.

5. The method for state trajectory control and finite state machine implementation of a four-switch Buck-Boost converter according to claim 4, characterized in that: The S1 comprises the following steps: S1-1, according to Kirchhoff's law, the dynamic mathematical models of the equivalent circuits of the four-switch Buck-Boost converter in Mode 1, Mode 2, Mode 3, and Mode 4 are as follows: Mode 1: Mode 2: Mode 3: Mode 4: Wherein, L represents the inductance of the inductor L; i L represents the inductor current; i L It represents the first-order derivative of the inductance of the inductor L with respect to time; V in represents the input voltage of the four-switch Buck-Boost converter; C represents the capacitance of capacitor C; represents the first-order derivative of the output voltage of the four-switch Buck-Boost converter with respect to time; v out represents the output voltage of the four-switch Buck-Boost converter; R represents the resistance value of resistor R; S1-2, with output voltage v out is the horizontal coordinate axis, the standardized inductor current i L * Establish a standardized state plane v for the vertical axis out -i L *, where the normalized inductor current i L * means: S1-3, based on the dynamic mathematical model of the equivalent circuit of the four-switch Buck-Boost converter Mode 1 Mode 1, Mode 2 Mode 2, Mode 3 Mode 3, Mode 4 Mode 4, derive Mode 1 Mode 1, Mode 2 Mode 2, Mode 3 Mode 3, Mode 4 Mode 4 on the standardized state plane v out -i L *Natural trajectory on the Mode 1 is in the normalized state plane v out -i L The natural trajectory on * is expressed as: Among them, i L0 * represents the initial value of the normalized inductor current; v out0 Indicates the initial value of the output voltage; i o0 *Indicates the initial value of the standardized output current; Mode 2 Mode 2 in the normalized state plane v out -i L The natural trajectory on * is: (v out -V in ) 2 +(i L *-i o *) 2 =r m2 2 (11) Where i o * indicates the standardized output current, r m2 is in the normalized state plane v out -i L * The initial position of the four-switch Buck-Boost converter when entering Mode 2 is at the reference point (v ref ,i Lref *) distance; From formula (11), we know that in the standardized state plane v out -i L *, the natural trajectory of the four-switch Buck-Boost converter mode 2 Mode2 is (V in ,i o *) is the cluster of circular trajectories with the center of the circle; Mode 3 Mode 3 in the normalized state plane v out -i L The natural trajectory on * is: v out 2 +(i L *-i o *) 2 =r m3 2 (13) Among them, r m3 is in the normalized state plane v out -i L * The initial position of the four-switch Buck-Boost converter when entering Mode 2 Mode 3 is at the reference point (v ref ,i Lref *) distance; Mode 4 Mode 4 in the normalized state plane v out -i L The natural trajectory on * is: From formula (15), we know that in the standardized state plane v out -i L *, the natural trajectory of Mode 4 is parallel to the normalized state plane v out -i L * Cluster of lines on the horizontal axis.

6. The method for state trajectory control and finite state machine implementation of a four-switch Buck-Boost converter according to claim 4, characterized in that: By analyzing the natural trajectory of the converter in the standardized state plane, it is found that the state trajectory control process of the four-switch Buck-Boost converter will go through dynamic and steady-state adjustment processes, in which eight state drives of the four-switch Buck-Boost converter are involved.

7. The method for state trajectory control and finite state machine implementation of a four-switch Buck-Boost converter according to claim 4, characterized in that: The switching conditions of the modes during the dynamic regulation of the four-switch Buck-Boost converter are obtained as follows: First, solve the dynamic mathematical equations of Mode 1 and Mode 3 respectively, and set the standardized reference inductor current i Lref *for: Among them, v ref represents the tracking reference voltage of the four-switch Buck-Boost converter; i o *Represents the normalized output current of a four-switch Buck-Boost converter; v in represents the input voltage of the four-switch Buck-Boost converter; The normalized state plane v out -i L *The reference point is expressed as (v ref ,i Lref *), the reference point is the target point that needs to be finally reached by the state trajectory control method; The dynamic regulation process is divided into a standardized state plane v out -i L * Left half plane and normalized state plane v out -i L *Two cases in the right half plane; Normalized state plane v out -i L *The switching conditions of the left half plane switching mode are derived as follows: Set the radius r of Mode 2 during the left half plane switch mode switching process m2D for: r m2D ＝r m2min +m(r m2max -r m2min ) (17) in, m is a constant between 0 and 1, and the constant m is used to represent the mode 2 Mode 2 in the normalized state plane v out -i L * The degree of participation in the left half plane switching mode switching process; The switching condition from the left half plane dynamic adjustment state 1 D-left 1: Mode 1 to the left half plane dynamic adjustment state 2 D-left 2: Mode 2 is: (v out -V in ) 2 +(i L *-i o *) 2 ≥r m2D 2 (18) Where v out represents the output voltage of the four-switch Buck-Boost converter; V in represents the input voltage of the four-switch Buck-Boost converter; i L represents the inductor current of the four-switch Buck-Boost converter; i o *Represents the normalized output current of a four-switch Buck-Boost converter; r m2D Indicates the radius of the Mode 2 state trajectory during the mode switching process of the left half plane switch; When the converter works in Mode 2 and Mode 3, the normalized state plane v out -i L *The state trajectory in the dynamic adjustment process of the left half plane cannot directly reach the reference point through Mode 3; therefore, in the standardized state plane v out -i L * The compensation parameter β is introduced in the left half plane, thereby delaying the switching of other modes to Mode 3, and the compensation parameter β is updated in Mode 3; the compensation parameter β updated when the state trajectory is in the left plane is described as: β＝r m3ref 2 -r m1initial 2 (19) where r m3ref is the reference point (v ref ,i Lref *) The radius of Mode 3, r m3ref 2 and r m1initial 2 Respectively expressed as: Among them, v outm10 and i Lm10 * respectively represent the normalized state plane v out -i L * Output voltage and normalized inductor current when the left half plane state trajectory enters Mode 1; The switching condition from the left half plane dynamic adjustment state 2 D-left 2: Mode 2 to the left half plane dynamic adjustment state 3 D-left 3: Mode 3 is: v out 2 +(i L *-i o *) 2 ≥r m3ref 2 +β (21) The existence of parasitic parameters makes the state trajectory unable to reach the reference point (v) in one go after the sequential driving of D-left 1: Mode 1 → D-left 2: Mode 2 → D-left 3: Mode 3. ref ,i Lref *); when moving along the state trajectory of Mode 3, the output voltage v out <v ref , and the standardized inductor current i L *=i Lref *, the four-switch Buck-Boost converter needs to work in mode 1 again, and then it is driven in a cycle from D-left 1: Mode 1 → D-left 3: Mode 3. The switching condition from the left half plane dynamic adjustment state 3 D-left 3: Mode 3 to the left half plane dynamic adjustment state 1 D-left1: Mode 1 is: i L *≤i Lref * (22) Among them, i L * represents the normalized inductor current of the four-switch Buck-Boost converter; i Lref *Represents the standardized reference current value of the four-switch Buck-Boost converter; The switching condition from the left half plane dynamic adjustment state 1 D-left 1: Mode 1 to the left half plane dynamic adjustment state 3 D-left 3: Mode 3 is the same as formula (21); S2-2, normalized state plane v out -i L *The switching conditions of the right half plane switching mode are derived as follows: Set the normalized switching inductor current i LK *for: i LK *=i Lref * / K (23) Where K is a gain parameter greater than 1, which is used to set the modal four trajectories and i L *=i Lref * The distance between the horizontal lines, the larger the K, the closer the modal four trajectories are to i L *=i Lref *The larger the distance between the horizontal lines, the smaller K is. The modal four trajectories and i L *=i Lref *The smaller the distance between the horizontal lines; The switching conditions from the right half plane dynamic adjustment state 1 D-right / Steady 1: Mode 3 to the right half plane dynamic adjustment state 2 D-right / Steady 2: Mode 4 are as follows: i L *≤i LK * (24) Among them, i L * represents the normalized inductor current of the four-switch Buck-Boost converter; i LK * represents the normalized switching inductor current of the four-switch Buck-Boost converter; The switching conditions from the right half plane dynamic adjustment state 2 D-right / Steady 2: Mode 4 to the right half plane dynamic adjustment state 3 D-right / Steady 3: Mode 1 are as follows: Among them, i Lref *Represents the normalized inductor current reference value of the four-switch Buck-Boost converter; v ref represents the tracking reference voltage of the four-switch Buck-Boost converter; v out represents the output voltage of the four-switch Buck-Boost converter; v in represents the input voltage of the four-switch Buck-Boost converter; i o *Denotes the normalized output current of a four-switch Buck-Boost converter.

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