CN106452073A - A DC-DC power converter energy control circuit and control method thereof - Google Patents

Abstract

The invention belongs to the field of control of DC-DC power converters, and particularly relates to an energy control circuit for a DC-DC power converter and a control method for controlling the circuit by taking whether actual output energy of the circuit is equal to expected energy required by a circuit load or not as a criterion. The energy control circuit consists of a DC-DC converter main circuit, an input energy detection circuit, an output energy detection circuit, an energy analysis circuit, a pulse width modulation signal generation circuit and a logical driving circuit, wherein an input filter capacitor C1, a power electronic device K1, a flywheel diode D1, a filter inductor L1 and an output filter capacitor C2 form the DC-DC power converter main circuit. According to the energy control circuit and the control method thereof, the switching state of the power electronic device in the main circuit is further controlled by taking whether energy output by the DC-DC converter meets a requirement of a load or not as a criterion, so that the phenomenon of dynamic overshooting of output current can be effectively inhibited, and the phenomenon of dynamic overshooting of output voltage can be effectively inhibited.

Description

A DC-DC power converter energy control circuit and control method thereof

technical field

The invention belongs to the control field of DC-DC power converters, and specifically relates to a DC-DC power converter energy converter that controls the circuit based on whether the actual output energy of the circuit is equal to the expected energy required by the circuit load. Control circuit and its control method.

Background technique

In the controller design of the DC-DC converter (the DC-DC converter referred to in the following text refers to the DC-DC converter that uses the power electronic switching device to realize the power conversion), the hysteresis controller and the PID controllers are the most common. Hysteresis control is widely used because of its fast system response, good robustness, simple structure and easy implementation of the controller. However, when the voltage hysteresis controller is used to control the output voltage of the DC-DC converter, the output current fluctuates too much, and even the maximum value of the current exceeds the allowable value; while the current hysteresis controller is used to control the DC-DC converter. When the output current of the DC converter is controlled, the output voltage may not be controllable. In addition, when the hysteresis control is used, the switching frequency of the power electronic devices in the converter is always changing, which increases the complexity of the parameter design of the output filter circuit. However, the traditional PID controller has good steady-state performance, but there are phenomena such as overshoot and oscillation during the dynamic adjustment process, especially when the load changes, such problems are more prominent, resulting in poor output power quality.

Contents of the invention

The purpose of the present invention is to address the deficiencies of existing hysteresis controllers and PID controllers, to provide an energy controller with output energy as the control target and its control method, under the premise of realizing effective control of the DC-DC converter A DC-DC power converter energy control circuit that can solve the defects of existing hysteresis controllers and PID controllers.

The object of the present invention is also to provide a method for controlling the energy control circuit of the DC-DC power converter.

The purpose of the present invention is achieved like this:

An energy control circuit for a DC-DC power converter, which is composed of a DC-DC converter main circuit, an input energy detection circuit, an output energy detection circuit, an energy analysis circuit, a pulse width modulation signal generation circuit and a logic drive circuit, and an input filter capacitor C1, power electronic device K1, freewheeling diode D1, filter inductor L1, and output filter capacitor C2 form the main circuit of the DC-DC converter; the input terminal A and input terminal B of the input energy detection circuit are respectively connected to the positive and negative poles of the external power supply , the output terminal C and the output terminal D of the input energy detection circuit are respectively connected to the input positive and negative poles of the BUCK circuit, and the input energy detection circuit W1 is connected to the energy analysis circuit through the data bus; the input terminal E and the input terminal of the output energy detection circuit F is respectively connected to the output positive and negative poles of the BUCK circuit, the output terminal G and the output terminal H of the output energy detection circuit are respectively connected to the positive and negative poles of the load, and the output energy detection circuit is connected to the energy analysis circuit through the data bus at the same time; pulse width modulation The pulse width modulation signal output terminal of the signal generation circuit is connected to a digital signal input terminal of the logic driving circuit, and is also connected to the digital signal input terminal of the energy analysis circuit; it is connected to the other digital signal input terminal of the logic driving circuit Connect with the digital output signal terminal of the energy analysis circuit, connect with the drive signal output terminal of the logic drive circuit and the drive terminal of the power electronic device in the BUCK circuit;

The pulse width modulation signal generation circuit outputs a PWM signal with constant switching frequency and constant duty cycle. The duty cycle of the PWM signal ensures that when the PWM signal is used to control the BUCK circuit, its open-loop output voltage or current value must be greater than the load The required output voltage value or current value; the selection of the switching frequency of the PWM signal is determined based on the operating frequency of the power electronic device and the parameters of the output filter of the main circuit of the DC-DC converter;

The input energy detection circuit detects the energy provided by the external power supply to the BUCK circuit, and sends the detection result to the energy analysis circuit Y1 in real time through the data bus. The energy detection frequency of the input energy detection circuit W1 is equal to the data transmission frequency, and the energy detection frequency and the data transmission frequency are equal. The frequency of the PWM signal whose data transmission frequency is not less than 5 times;

The output energy detection circuit detects the output voltage, output current, and output energy of the BUCK circuit, and sends the detection results to the energy analysis circuit in real time through the data bus. The output energy detection circuit detects the output voltage, output current, and output energy. The data transmission frequency is equal, and equal to the energy detection frequency value of the input energy detection circuit W1;

The energy analysis circuit captures the PWM signal output by the pulse width modulation signal generation circuit, judges the moment of level change, that is, the moment when the rising edge and falling edge of the level occur, and defines the initial moment of the switching cycle; the input energy is received in real time The energy detection result sent by the detection circuit through the data bus calculates the energy W _inq provided by the external power supply to the BUCK circuit in the previous switching cycle, that is, in the time period from the initial moment of the previous switching cycle to the ending moment of the previous switching cycle; real-time Receive the energy detection result sent by the input energy detection circuit through the data bus, and calculate in real time the energy W _ind provided by the external power supply to the BUCK circuit in the current switching cycle, from the initial moment of the current switching cycle to the current moment; real-time reception The energy detection result sent by the output energy detection circuit through the data bus calculates the energy W _outq provided by the BUCK circuit to the load in the previous switching cycle, that is, in the time period from the initial moment of the previous switching cycle to the termination moment of the previous switching cycle; Calculate the efficiency η of the BUCK circuit in the previous switching cycle;

Receive the output voltage and output current detection results sent by the output energy detection circuit W2 through the data bus in real time. When the control target of the BUCK circuit is constant voltage output, the energy analysis circuit Y1 predicts that in the current complete switching cycle, that is, from During the period from the initial moment of the current switching cycle to the end of the current switching cycle, the BUCK circuit needs to provide energy W _outy to the load; when the control target of the BUCK circuit is constant current output, the energy analysis circuit predicts the size of W _outy ;

In the formula, U _ref is the given value of the output voltage of the BUCK circuit;

U _outd is the latest output voltage value detected by the energy detection circuit W2;

I _outd is the latest output current value detected by the energy detection circuit W2;

R _L =Uo _utd /I _outd is the load equivalent resistance value of the BUCK circuit;

T _S is the switching period of the PWM signal output by the pulse width modulation signal generating circuit P1;

In the formula

I _ref is the given value of the output current of the BUCK circuit;

Calculate the size of the energy criterion ΔW

ΔW＝W _ind η-W _outy

If ΔW<0, the energy analysis circuit Y1 sets the digital output signal EN to 1; if ΔW≥0, the energy analysis circuit Y1 sets the digital output signal EN to 0; at the initial moment of each PWM signal switching cycle, the digital Quantity output signal EN is set to 1;

The logic drive circuit performs AND logic operation on the input PWM signal and EN signal, and conducts electrical isolation and power amplification processing on the output signal after operation, so that it can meet the needs of driving power electronic devices.

A method for controlling an energy control circuit of a DC-DC power converter, comprising the steps of:

(1) After the control circuit and the main circuit are powered on successively, the BUCK circuit starts to work, and the pulse width modulation signal generating circuit outputs a PWM signal with constant frequency and constant duty ratio;

(2) The energy analysis circuit captures the PWM signal and defines the starting moment of the switching cycle;

(3) If the current moment is the start moment of the switching cycle, then set EN to 1, otherwise directly execute step (4);

(4) If EN=1, execute (5), otherwise execute (9);

(5) The input energy detection circuit detects the input energy, and the detection result is sent to the energy analysis circuit;

(6) The output energy detection circuit detects the output voltage, output current and output energy, and the detection results are sent to the energy analysis circuit;

(7) The energy analysis circuit receives the data sent by the input energy detection circuit and the output energy detection circuit, and calculates ΔW;

(8) If ΔW≥0, then set EN to 0; if ΔW<0, then EN remains unchanged;

(9) AND the logic driving circuit on the EN and the PWM signal output by the pulse width modulation signal generating circuit, and the operation result is used to drive the power electronic device after power amplification, thereby controlling the operation of the BUCK circuit;

(10) If stop, then execute (11), otherwise execute (3);

(11) Disconnect the main circuit power supply and the control circuit power supply successively, and the BUCK circuit stops working.

The beneficial effects of the present invention are:

Compared with the existing voltage or current hysteresis controller, the DC-DC converter energy control circuit and its control method proposed by the present invention have the following advantages: (1) The energy control circuit and its control method are based on DC-DC Whether the energy output by the converter meets the demand of the load is the criterion, and then the switching state of the power electronic devices in the main circuit is controlled. Therefore, in the control process with the output voltage as the control target, the dynamic overshoot of the output current can be effectively suppressed. phenomenon, but in the control process with the output current as the control target, it can effectively suppress the dynamic overshoot phenomenon of the output voltage. (2) The pulse width modulation signal generation circuit P1 outputs a PWM signal with constant switching frequency and constant duty ratio. The PWM signal and the digital output signal EN of the energy analysis circuit Y1 are processed together with the logic drive circuit A1 to generate The driving signal of the power electronic device, the digital output signal EN is 1 or 0 will only change the duty cycle of the driving signal in the current switching cycle, and the switching frequency of the driving signal (that is, the switching frequency of the power electronic device) is always consistent with the PWM The frequency of the signal is the same and is a fixed value, so the parameter design of the filter in the DC-DC converter can be greatly simplified.

Description of drawings

Figure 1 takes the BUCK circuit as an example to realize the structure diagram of the DC-DC converter energy control circuit;

Fig. 2 takes the BUCK circuit as an example to realize the control flow chart of the DC-DC converter energy control method.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings.

There are various topological forms of the main circuit of the DC-DC converter. For ease of understanding, the present invention takes the structure of the BUCK main circuit as an example for specific description and illustration.

The DC-DC converter energy control circuit proposed by the present invention, in addition to the main circuit of the DC-DC converter, is mainly composed of an input energy detection circuit W1, an output energy detection circuit W2, an energy analysis circuit Y1, and a pulse width modulation signal generation circuit P1 , and logic drive circuit A1 and other components.

Taking the BUCK type DC-DC converter as an example, when the energy control circuit proposed by the present invention is adopted, the circuit structure is shown in Figure 1, and the connection relationship of the circuit is: input filter capacitor C1, power electronic device K1, freewheeling diode D1, filter inductor L1, and output filter capacitor C2 constitute the main circuit of the BUCK type DC-DC converter. The connection relationship between these devices is the same as that of the existing BUCK type circuit; the input terminal A of the input energy detection circuit W1 and the input terminal B are respectively connected to the positive and negative poles of the external power supply, the output terminal C and the output terminal D of the input energy detection circuit W1 are respectively connected to the input positive and negative poles of the BUCK circuit, and the input energy detection circuit W1 is connected to the energy analysis through the data bus The circuit Y1 is connected; the input terminal E and the input terminal F of the output energy detection circuit W2 are respectively connected to the output positive and negative poles of the BUCK circuit, and the output terminal G and output terminal H of the output energy detection circuit W2 are respectively connected to the positive and negative poles of the load. At the same time, the output energy detection circuit W2 is connected with the energy analysis circuit Y1 through the data bus; the PWM (pulse width modulation) signal output terminal of the pulse width modulation signal generation circuit P1 is connected with a digital signal input terminal of the logic drive circuit A1, and also Connect with the digital signal input terminal of the energy analysis circuit Y1; connect with another digital signal input terminal of the logic drive circuit A1 and the digital output signal (EN) terminal of the energy analysis circuit Y1, and connect with the drive signal of the logic drive circuit A1 The output end is connected with the driving end of the power electronic device K1 in the BUCK circuit.

The function of the pulse width modulation signal generating circuit P1 is to output a PWM signal with a constant switching frequency and a constant duty cycle. The duty cycle of the PWM signal should ensure that when the PWM signal is used to control the BUCK circuit, the open-loop output voltage value (or current value) must be greater than the output voltage value (or current value) required by the load. The selection of the switching frequency of the PWM signal should be determined based on the operating frequency of the power electronic device K1 and the parameter design of the output filter of the main circuit of the DC-DC converter (such as the filter inductor L1 and output filter capacitor C2 in the BUCK circuit).

The function of the input energy detection circuit W1 is to detect the energy provided by the external power supply to the BUCK circuit, and send the detection result to the energy analysis circuit Y1 in real time through the data bus. In order to improve the control effect of the energy control circuit, the input energy detection circuit W1 is required The energy detection frequency is equal to the data transmission frequency, and the higher the frequency, the better. Considering the limitations of practical applications, the energy detection frequency and data transmission frequency should not be less than 5 times the PWM signal (that is, the output of the pulse width modulation signal generation circuit P1 )Frequency of. Under the premise of ignoring the energy loss generated by the detection circuit itself, the input energy detection circuit W1 does not change parameters such as the amplitude and waveform of the voltage and current supplied to the BUCK circuit by the external power supply.

The function of the output energy detection circuit W2 is to detect the output voltage, output current and output energy of the BUCK circuit, and send the detection results to the energy analysis circuit Y1 in real time through the data bus, requiring the output energy detection circuit W2 to check the output voltage, output current . The detection frequency of the output energy is equal to the data transmission frequency, and is equal to the energy detection frequency value of the input energy detection circuit W1. On the premise of ignoring the energy loss generated by the detection circuit itself, the output energy detection circuit W2 does not change parameters such as the amplitude and waveform of the output voltage and output current of the BUCK circuit.

The functions of the energy analysis circuit Y1 mainly include the following points:

Function 1: Capture the PWM signal output by the pulse width modulation signal generation circuit P1, determine the moment of level change, that is, the moment when the rising edge and falling edge of the level occur, and define the initial moment of the switching cycle, for example, you can define The rising edge (or falling edge) of each level is the initial moment corresponding to a switching cycle, and the time interval between two adjacent rising edges (or falling edges) is a switching cycle;

Function 2: Receive the energy detection result sent by the input energy detection circuit W1 through the data bus in real time, and calculate the external power supplied to The energy W _inq of the BUCK circuit;

Function 3: Receive the energy detection result sent by the input energy detection circuit W1 through the data bus in real time, and calculate in real time the energy provided by the external power supply to the BUCK circuit in the current switching cycle, from the initial moment of the current switching cycle to the current moment _Wind ;

Function 4: Receive the energy detection result sent by the output energy detection circuit W2 through the data bus in real time, and calculate the time period from the initial moment of the previous switching cycle to the end of the previous switching cycle, the BUCK circuit provides to The energy W _outq of the load;

Function 5: Use formula (1) to calculate the efficiency η of the BUCK circuit in the previous switching cycle;

Function 6: Receive the output voltage and output current detection results sent by the output energy detection circuit W2 through the data bus in real time. When the control target of the BUCK circuit is constant voltage output, the energy analysis circuit Y1 uses the formula (2) to predict the current one In a complete switching period, that is, within the time period from the initial moment of the current switching period to the termination moment of the current switching period, the BUCK circuit needs to provide energy W _outy to the load. When the control target of the BUCK circuit is constant current output, the energy analysis circuit Y1 uses the formula (3) to predict the size of W _outy ;

In the formula

U _ref ——The given value of the output voltage of the BUCK circuit (expected constant voltage value);

U _outd - the latest output voltage value detected by the energy detection circuit W2;

I _outd - the latest output current value detected by the energy detection circuit W2;

R _L ＝U _outd /I _{outd ——load} equivalent resistance value of BUCK circuit;

T _S ——the switching period of the PWM signal output by the pulse width modulation signal generating circuit P1.

In the formula

I _ref ——The given value of the output current of the BUCK circuit (expected constant current value).

Function 7: Calculate the size of the energy criterion ΔW according to the formula (4)

ΔW＝W _ind η-W _outy (4)

If ΔW<0, the energy analysis circuit Y1 sets the digital output signal EN to 1 (in the patent of the present invention, it is assumed that the PWM signal is active at a high level, and for the case that the PWM signal is active at a low level, according to existing knowledge, it can be Just add a logic negation circuit in the actualized circuit). If ΔW≥0, the energy analysis circuit Y1 sets the digital output signal EN to 0;

Function 8: Set the digital output signal EN to 1 at the initial moment of each PWM signal switching cycle.

The function of AND logic drive circuit A1 is to perform AND logic operation on the input PWM signal and EN signal, and conduct electrical isolation and power amplification processing on the output signal after operation, so that it can meet the requirements of driving the power electronic device K1.

Adopt the BUCK circuit of the energy control circuit and control method proposed by the present invention, its working principle is as follows:

After the BUCK circuit and the control circuit are powered on, the pulse width modulation signal generation circuit P1 outputs a PWM signal with a constant switching frequency and a constant duty cycle; the energy analysis circuit Y1 captures the PWM signal output by the pulse width modulation signal generation circuit P1, And define the initial moment of the switching cycle. At the initial moment of each PWM signal switching cycle, the digital output signal EN is set to 1; when the digital output signal EN is 1, the PWM signal can pass through the logic drive circuit A1. Realize the driving of the power electronic device K1, and then make the BUCK circuit in the working state; the input energy detection circuit W1 detects the energy provided by the external power supply to the BUCK circuit, and sends the detection result to the energy analysis circuit Y1 in real time through the data bus; output The energy detection circuit W2 detects the output voltage, output current and output energy of the BUCK circuit, and sends the detection results to the energy analysis circuit Y1 in real time through the data bus; the energy analysis circuit Y1 receives the input energy detection circuit W1 in real time and outputs The detection data sent by the energy detection circuit W2 through the data bus, comprehensively utilize the formulas (1), (2), and (4) (for the case when the control target of the DC-DC converter is constant voltage output), or comprehensively utilize the formula (1), (3), (4) (when the control target of the DC-DC converter is constant current output) calculate the size of the energy criterion ΔW, if ΔW<0, it means that the external power supply is in the current switching cycle The energy provided is less than the energy required by the load, the energy analysis circuit Y1 will maintain the digital output signal EN as 1, then the PWM signal can still drive the power electronic device K1 through the logic drive circuit A1, and the external power supply continues to supply the BUCK circuit Input energy, and the energy analysis circuit Y1 continues to use the latest received detection data to calculate the size of the energy criterion ΔW. If ΔW≥0, it means that the energy provided by the external power supply can meet the energy demand of the load in the current switching cycle. Energy analysis The circuit Y1 sets the digital output signal EN to 0, that is, the PWM signal is blocked by the logic drive circuit A1, so that the power electronic device K1 is in the cut-off state, and then the energy analysis circuit Y1 no longer calculates the size of the energy criterion ΔW, and will always Maintain the state of the digital output signal EN as 0 until the arrival of the initial moment of the next PWM signal switching cycle. The above process is repeated, which can realize the control of the BUCK circuit, so that the output voltage value or current value in the steady state operation is equal to the given value.

The energy control circuit and its control method proposed by the present invention are not only applicable to DC-DC converters with BUCK circuit and its topological structure as the main circuit, but also applicable to other common forms of DC-DC converters. For some DC-DC converters with special structures, it is necessary to modify the calculation methods of energy variables such as _{Wind and W outy involved} in formula (1) to formula (4) according to the specific working principle of the circuit , but the control circuit and control principle do not need to be changed.

control flow

The control flow chart when the energy control method proposed by the present invention is applied to the BUCK circuit is shown in Figure 2, and the control flow is as follows:

(1) After the control circuit and the main circuit are powered on successively, the BUCK circuit starts to work, and the pulse width modulation signal generation circuit P1 outputs a PWM signal with constant frequency and constant duty ratio.

(2) The energy analysis circuit Y1 captures the PWM signal and defines the starting moment of the switching cycle (it can be defined according to the actual working conditions).

(3) If the current moment is the start moment of the switching cycle, then set EN to 1, otherwise directly execute (4).

(4) If EN=1, execute (5), otherwise execute (9).

(5) The input energy detection circuit W1 detects the input energy, and the detection result is sent to the energy analysis circuit Y1.

(6) The output energy detection circuit W2 detects the output voltage, output current and output energy, and the detection results are sent to the energy analysis circuit Y1.

(7) The energy analysis circuit Y1 receives the data sent by the input energy detection circuit W1 and the output energy detection circuit W2, and calculates ΔW.

(8) If ΔW≥0, then set EN to 0; if ΔW<0, then EN remains unchanged.

(9) AND logic drive circuit A1 performs AND operation on EN and the PWM signal output by pulse width modulation signal generation circuit P1, and the operation result is used to drive the power electronic device K1 after power amplification, thereby controlling the operation of the BUCK circuit.

(10) If stop, then execute (11), otherwise execute (3).

(11) Disconnect the main circuit power supply and the control circuit power supply successively, and the BUCK circuit stops working.

Implementation method one

Input filter capacitor C1, power electronic device K1, freewheeling diode D1, filter inductor L1, and output filter capacitor C2 constitute the main circuit of the BUCK type DC-DC converter. The selection and parameter calculation of these devices are similar to those of the existing BUCK type The device selection and parameter calculation of the circuit are exactly the same. If it is a DC-DC converter of other forms, its main circuit component selection and parameter calculation are also completely consistent with the existing DC-DC converter main circuit component selection and parameter calculation methods.

The input energy detection circuit W1 can be realized by using an existing circuit capable of real-time detection of energy and real-time data communication functions, for example, the input voltage and The current is collected, and by integrating the product of the collected voltage value and current value with respect to time, the input energy of the DC-DC converter within a certain period of time can be calculated, and the calculation result can be transmitted through parallel bus and other communication methods sent to other circuits.

The output energy detection circuit W2 can be realized by using an existing circuit capable of real-time detection and real-time data communication of voltage, current and energy. Collect the output voltage and current of the DC-DC converter within a certain period of time, and calculate the output energy of the DC-DC converter within a certain period of time by integrating the product of the collected voltage value and current value with respect to time, and the collected voltage Value, current value and calculated output energy value are sent to other circuits through communication methods such as parallel bus.

The energy analysis circuit Y1 can be realized by existing circuits with functions of data communication, data calculation and analysis, digital input and output, for example, a digital signal processor (DSP) or a single-chip microcomputer supplemented by corresponding peripheral circuits.

The pulse width modulation signal generation circuit P1 can adopt various existing pulse width modulation signal generation circuits, and can also be realized by a digital signal processor (DSP) or a single-chip microcomputer with PWM output function.

The AND logic driving circuit A1 can be implemented by combining various existing circuits (or chips) capable of implementing AND logic operations and driving circuits of power electronic devices.

The data bus between the input energy detection circuit W1 and the energy analysis circuit Y1 can use various existing data buses, such as parallel data bus, serial data bus or CAN bus.

The data bus between the output energy detection circuit W2 and the energy analysis circuit Y1 can use various existing data buses, such as parallel data bus, serial data bus or CAN bus.

Claims (2)

1. A DC-DC power converter energy control circuit is composed of a DC-DC converter main circuit, an input energy detection circuit, an output energy detection circuit, an energy analysis circuit, a pulse width modulation signal generation circuit and a logic drive circuit, and its It is characterized in that: the input filter capacitor (C1), power electronic device (K1), freewheeling diode (D1), filter inductor (L1), and output filter capacitor (C2) constitute the main circuit of the DC-DC converter; the input energy detection circuit The input terminal A and the input terminal B are respectively connected to the positive and negative poles of the external power supply, the output terminal C and the output terminal D of the input energy detection circuit are respectively connected to the positive and negative poles of the input of the BUCK circuit, and the input energy detection circuit W1 is connected to the positive and negative poles of the BUCK circuit through the data bus. The energy analysis circuit is connected; the input terminal E and the input terminal F of the output energy detection circuit are respectively connected to the output positive and negative poles of the BUCK circuit, and the output terminal G and the output terminal H of the output energy detection circuit are respectively connected to the positive and negative poles of the load. The output energy detection circuit is connected to the energy analysis circuit through the data bus; the pulse width modulation signal output terminal of the pulse width modulation signal generation circuit is connected to a digital signal input terminal of the logic drive circuit, and is also connected to the digital signal input terminal of the energy analysis circuit Connected to the input terminal; connected to another digital signal input terminal of the logic driving circuit and the digital output signal terminal of the energy analysis circuit, connected to the driving signal output terminal of the logic driving circuit and the driving terminal of the power electronic device in the BUCK circuit; The pulse width modulation signal generation circuit outputs a PWM signal with constant switching frequency and constant duty cycle. The duty cycle of the PWM signal ensures that when the PWM signal is used to control the BUCK circuit, its open-loop output voltage or current value must be greater than the load The required output voltage value or current value; the selection of the switching frequency of the PWM signal is determined based on the operating frequency of the power electronic device and the parameters of the output filter of the main circuit of the DC-DC converter; The input energy detection circuit detects the energy provided by the external power supply to the BUCK circuit, and sends the detection result to the energy analysis circuit Y1 in real time through the data bus. The energy detection frequency of the input energy detection circuit W1 is equal to the data transmission frequency, and the energy detection frequency and the data transmission frequency are equal. The frequency of the PWM signal whose data transmission frequency is not less than 5 times; The output energy detection circuit detects the output voltage, output current, and output energy of the BUCK circuit, and sends the detection results to the energy analysis circuit in real time through the data bus. The output energy detection circuit detects the output voltage, output current, and output energy. The data transmission frequency is equal, and equal to the energy detection frequency value of the input energy detection circuit W1; The energy analysis circuit captures the PWM signal output by the pulse width modulation signal generation circuit, judges the moment of level change, that is, the moment when the rising edge and falling edge of the level occur, and defines the initial moment of the switching cycle; the input energy is received in real time The energy detection result sent by the detection circuit through the data bus calculates the energy W _inq provided by the external power supply to the BUCK circuit in the previous switching cycle, that is, in the time period from the initial moment of the previous switching cycle to the ending moment of the previous switching cycle; real-time Receive the energy detection result sent by the input energy detection circuit through the data bus, calculate in real time the energy W _ind provided by the external power supply to the BUCK circuit in the current switching cycle, from the initial moment of the current switching cycle to the current moment; receive in real time The energy detection result sent by the output energy detection circuit through the data bus calculates the energy W _outq provided by the BUCK circuit to the load in the previous switching cycle, that is, in the time period from the initial moment of the previous switching cycle to the termination moment of the previous switching cycle; Calculate the efficiency η of the BUCK circuit in the previous switching cycle; $\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; q</span>}}}{{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; q</span>}}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}\mathrm{<span\; class="notranslate">\; \%</span>}$ Receive the output voltage and output current detection results sent by the output energy detection circuit W2 through the data bus in real time. When the control target of the BUCK circuit is constant voltage output, the energy analysis circuit Y1 predicts that in the current complete switching cycle, that is, from During the period from the initial moment of the current switching cycle to the end of the current switching cycle, the BUCK circuit needs to provide energy W _outy to the load; when the control target of the BUCK circuit is constant current output, the energy analysis circuit predicts the size of W _outy ; ${\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; =</span>\frac{{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; f</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; d</span>}}}{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; d</span>}}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}<span\; class="notranslate">\; =</span>\frac{{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; f</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}$ In the formula U _ref is the given value of the output voltage of the BUCK circuit; U _outd is the latest output voltage value detected by the energy detection circuit W2; I _outd is the latest output current value detected by the energy detection circuit W2; R _L =U _outd /I _outd is the load equivalent resistance value of the BUCK circuit; T _S is the switching period of the PWM signal output by the pulse width modulation signal generating circuit P1; ${\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; =</span>\frac{{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; f</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; d</span>}}}{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; d</span>}}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}<span\; class="notranslate">\; =</span>{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; f</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}$ In the formula I _ref is the given value of the output current of the BUCK circuit; Calculate the size of the energy criterion ΔW ΔW＝W _ind η-W _outy If ΔW<0, the energy analysis circuit Y1 sets the digital output signal EN to 1; if ΔW≥0, the energy analysis circuit Y1 sets the digital output signal EN to 0; at the initial moment of each PWM signal switching cycle, the digital Quantity output signal EN is set to 1; The logic drive circuit performs AND logic operation on the input PWM signal and EN signal, and conducts electrical isolation and power amplification processing on the output signal after operation, so that it can meet the needs of driving power electronic devices. 2. A DC-DC power converter energy control circuit control method, is characterized in that, comprises the steps: (1) After the control circuit and the main circuit are powered on successively, the BUCK circuit starts to work, and the pulse width modulation signal generating circuit outputs a PWM signal with constant frequency and constant duty ratio; (2) The energy analysis circuit captures the PWM signal and defines the starting moment of the switching cycle; (3) If the current moment is the start moment of the switching cycle, then set EN to 1, otherwise directly execute step (4); (4) If EN=1, execute (5), otherwise execute (9); (5) The input energy detection circuit detects the input energy, and the detection result is sent to the energy analysis circuit; (6) The output energy detection circuit detects the output voltage, output current and output energy, and the detection results are sent to the energy analysis circuit; (7) The energy analysis circuit receives the data sent by the input energy detection circuit and the output energy detection circuit, and calculates ΔW; (8) If ΔW≥0, then set EN to 0; if ΔW<0, then EN remains unchanged; (9) and the logic drive circuit performs AND operation on the PWM signal output by the EN and the pulse width modulation signal generating circuit, and the operation result is used to drive the power electronic device after power amplification, thereby controlling the operation of the BUCK circuit; (10) If stop, then execute (11), otherwise execute (3); (11) Disconnect the main circuit power supply and the control circuit power supply successively, and the BUCK circuit stops working.