Control device for power conversion circuit

Abstract

The feedback control unit (430) has a controller (430) that calculates the duty cycle of the switching elements (203, 204) based on the command value and detection value of the electrical information. The current continuous / discontinuous mode determination unit (51) has a duty cycle increase / decrease determination unit (501) that determines the increase or decrease of the duty cycle and an output voltage detection value increase / decrease determination unit (502) that determines the increase or decrease of the detection value of the voltage of the second terminal (22). The current continuous / discontinuous mode determination unit (51) determines that the current is discontinuous when the duty cycle decreases and the voltage detection value increases or when the duty cycle increases and the voltage detection value decreases, and feeds back the determination result to the feedback control unit (430).

Description

Technical Field

[0001] This application relates to a control device for power conversion circuits. Background Technology

[0002] In power conversion circuits, when the load decreases, the circuit's operating state switches from continuous current mode to discontinuous current mode. The operating characteristics differ between continuous and discontinuous current modes, and the optimal control methods also differ, thus requiring a highly accurate method to determine which mode to use.

[0003] In conventional technology, the mode determination unit determines whether the sign of the current flowing through the inductor is reversed based on the average value of the current flowing through the inductor calculated by the average current calculation unit and the interval between the maximum and minimum values ​​of the current flowing through the inductor calculated by the peak current calculation unit. Furthermore, if the sign is reversed, the switching element is turned on or off depending on whether it is a power operation or a regenerative operation (see Patent Document 1).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2013-230073 Summary of the Invention

[0007] In the aforementioned Patent Document 1, the detection value of the reactor current is used to determine whether the current is in continuous mode or discontinuous mode. When determining these modes using this method, the following problem exists: the reactor current value in discontinuous mode is small, so due to errors in the sensor detecting the current value, an incorrect determination may be made.

[0008] This application discloses a technology for solving the above-mentioned problems, with the aim of providing a control device for a power conversion circuit that can determine the current continuous mode and the current discontinuous mode without using the detection value of the reactor current.

[0009] In the control device for the power conversion circuit disclosed in this application, the power conversion circuit connects a switching element and a reactor between a first terminal and a second terminal, and performs power conversion between the first terminal and the second terminal.

[0010] The control device includes:

[0011] The feedback control unit includes a controller that calculates the duty cycle of the switching element based on command values ​​and detection values ​​of electrical information related to the power conversion circuit; and

[0012] The current continuous / discontinuous mode determination unit includes a duty cycle increase / decrease determination unit for determining whether the duty cycle increases or decreases, and an output voltage detection value increase / decrease determination unit for determining whether the detected value of the voltage at the second terminal increases or decreases.

[0013] When the duty cycle increase / decrease determination unit determines that the previously measured duty cycle is greater than the currently measured duty cycle, and the output voltage detection value increase / decrease determination unit determines that the currently measured detection value is greater than the previously measured detection value, or when the duty cycle increase / decrease determination unit determines that the previously measured duty cycle is less than the currently measured duty cycle, and the output voltage detection value increase / decrease determination unit determines that the currently measured detection value is less than the previously measured detection value, the current continuous / discontinuous mode determination unit determines that the circuit's operating state is current discontinuous mode, and feeds back the determination result to the feedback control unit.

[0014] According to the control device of the power conversion circuit disclosed in this application, it is possible to determine the current continuous mode and the current discontinuous mode without using the detection value of the reactor current. Attached Figure Description

[0015] Figure 1 This is a schematic structural diagram showing the power conversion circuit and control device of Embodiment 1.

[0016] Figure 2 This is a block diagram illustrating the function of the control device in Embodiment 1.

[0017] Figure 3 This is a timing diagram used to illustrate the on / off control of a switching element based on duty cycle in the control device of Embodiment 1.

[0018] Figure 4 This is a timing diagram showing the behavior of the current sensor when an error occurs, in the case of using the detected value of the reactor current to determine the current continuous mode and the current discontinuous mode.

[0019] Figure 5 This is a flowchart illustrating the determination of the continuous / discontinuous current mode and the subsequent processing in the control device of Embodiment 1.

[0020] Figure 6 This is a timing diagram showing the actions taken when determining the continuous or discontinuous current mode in the control device of Embodiment 1 when the load changes.

[0021] Figure 7 This is a block diagram illustrating the function of the control device in Embodiment 2.

[0022] Figure 8This is a flowchart illustrating the determination of the continuous / discontinuous current mode and the subsequent processing in the control device of Embodiment 2.

[0023] Figure 9 This is a timing diagram showing the actions taken when determining the continuous or discontinuous current mode in the control device of Embodiment 2 when the load changes.

[0024] Figure 10 This is a block diagram illustrating the function of the control device in Embodiment 3.

[0025] Figure 11 This is a flowchart illustrating the determination of the continuous / discontinuous current mode and the subsequent processing in the control device of Embodiment 3.

[0026] (Symbol Explanation)

[0027] 10: Control device; 20: Power conversion circuit; 21: Terminal 1; 22: Terminal 2; 41: Feedback control unit; 51: Current continuous / discontinuous mode determination unit; 203, 204: Switching element; 413: Integral term correction unit; 420: Control constant changing unit; 430: PI controller; 440: Duty cycle correction control unit; 441: Duty cycle correction amount determination unit; 442: Duty cycle correction unit; 450: Integral term correction amount determination unit; 501: Duty cycle increase / decrease determination unit; 502: Output voltage detection value increase / decrease determination unit. Detailed Implementation

[0028] Implementation method 1.

[0029] Hereinafter, the power conversion circuit 20 of Embodiment 1 and the control device 10 of the power conversion circuit (hereinafter referred to as the control device 10) will be described with reference to the accompanying drawings. Figure 1 This is a schematic structural diagram showing the power conversion circuit and control device of this embodiment.

[0030] The power conversion circuit 20 includes two switching elements 203 and 204, which perform power conversion between the first terminal 21 and the second terminal 22. A power source or load is connected to the first terminal 21 and to the second terminal 22. In this embodiment, the power source 71 is connected to the first terminal 21, and the load 81 is connected to the second terminal 22. The power source 71 is a DC power source, using various energy storage devices, etc. The load 81 is an inverter or a motor.

[0031] In this embodiment, the power conversion circuit 20 is configured as a DC-DC converter for converting DC power. The power conversion circuit 20 is configured as a bidirectional chopper circuit that combines a boost chopper circuit that boosts the DC voltage from the first terminal 21 to the second terminal 22 and a buck chopper circuit that steps down the DC voltage from the second terminal 22 to the first terminal 21.

[0032] The power conversion circuit 20 has the following functions: boosting the DC power from the power supply 71 to supply the inverter and the motor, and using the inverter to convert the AC power generated by the motor into DC power and stepping down the DC power output by the inverter to supply the power supply 71.

[0033] Switching elements 203 and 204 are connected in series between the positive and negative sides of terminal 22. As switching elements, IGBTs (Insulated Gate Bipolar Transistors) with diodes connected in antiparallel, or MOSFETs (Metal Oxide Semiconductor Field-Effect Transistors) with diodes connected in antiparallel, can be used. Alternatively, various switching elements such as SiC (Silicon Carbide) MOSFETs, GAN (Gallium Nitride) FETs, and GAN-HEMTs (High Electron Mobility Transistors) can also be used.

[0034] The gate drive signals Gt1 and Gt2 output from the control device 10 are respectively input to the gate terminals of each switching element 203 and 204. According to each gate drive signal Gt1 and Gt2, each switching element 203 and 204 is turned on or off.

[0035] The positive side of terminal 21 is connected to the connection point of two switching elements 203 and 204 via reactor 202. The negative side of terminal 21 is connected to the negative side of terminal 22.

[0036] The smoothing capacitor 205 on the second terminal side is connected in parallel with the second terminal 22. The smoothing capacitor 205 on the second terminal side is located closer to the second terminal 22 than the two switching elements 203 and 204.

[0037] The smoothing capacitor 201 on the first terminal side is connected in parallel with the first terminal 21. The smoothing capacitor 201 on the first terminal side is located closer to the first terminal 21 than the reactor 202.

[0038] A voltage detection circuit 31 is provided to detect the voltage at the second terminal 22. The voltage detection circuit 31 detects the voltage between the two ends of the smoothing capacitor 205 on the second terminal side. The output signal of the voltage detection circuit 31 is input to the control device 10.

[0039] The control device 10 controls the power conversion circuit 20. Figure 2 This is a block diagram illustrating the functions of the control device. For example... Figure 2 As shown, the control device 10 includes a feedback control unit 41, a current continuous / discontinuous mode determination unit 51, and a switch control unit 61, which will be described later. The functions of the control device 10 will be explained in detail below.

[0040] The feedback control unit 41 calculates the duty cycle D of the switching element based on the command value and the detection value of the electrical information related to the power conversion circuit 20. In this embodiment, the electrical information related to the power conversion circuit 20 is set as the voltage of the second terminal 22 (hereinafter referred to as the second terminal voltage V2).

[0041] Furthermore, as described later, the feedback control unit 41 may also use the voltage, current or power input to the first terminal 21 as the command value and detection value of electrical information, and may also use the current or power output from the second terminal 22 as the command value and detection value of electrical information.

[0042] The feedback control unit 41 detects the voltage of the second terminal (hereinafter referred to as V2s) based on the output signal of the voltage detection circuit 31. The feedback control unit 41 includes a subtractor 401, which calculates the duty cycle D based on the command value V2ref of the second terminal voltage and the detected value V2s of the second terminal voltage. The command value V2ref of the second terminal voltage can be calculated within the control device 10 or can be transmitted from outside the control device 10.

[0043] The device is equipped with a subtractor 401 for calculating the difference between two values. The subtractor 401 subtracts the detected value V2s of the second terminal voltage from the command value V2ref of the second terminal voltage. The output signal of the subtractor 401 is input to the proportional control unit 411 and the integral control unit 412 as the error value V2er of the second terminal voltage.

[0044] The control constant changing unit 420 changes the control constant used by the proportional control unit 411 and the integral control unit 412 based on the current continuous / discontinuous mode determination flag Flag3 output from the current continuous / discontinuous mode determination unit 51.

[0045] When the current continuous / discontinuous mode determination flag Flag3 is ON (1), it is determined that the circuit operation state is current discontinuous mode. The control constant change unit 420 outputs the current discontinuous mode to the proportional control unit 411 using the proportional gain KpDCM as the proportional gain Kp, and then outputs the current discontinuous mode to the integral control unit 412 using the integral gain KiDCM as the integral gain Ki.

[0046] When the current continuous / discontinuous mode determination flag Flag3 is OFF(0), it is determined that the circuit operation state is current continuous mode. The control constant change unit 420 outputs the current continuous mode to the proportional control unit 411 using the proportional gain KpCCM as the proportional gain Kp, and then outputs the current continuous mode to the integral control unit 412 using the integral gain KiCCM as the integral gain Ki.

[0047] The proportional control unit 411 stores the proportional gain Kp (control constant) output from the control constant change unit 420, and performs proportional calculations using the previous value Kp0 of the proportional gain Kp, and outputs the proportional duty cycle Dpr (hereinafter referred to as the proportional term).

[0048] The integral control unit 412 stores the integral gain Ki (control constant) output from the control constant change unit 420, performs integral calculation using the previous value Ki0 of the integral gain Ki, and outputs the integral duty cycle Din (hereinafter referred to as the integral term).

[0049] An adder 402 is provided to calculate the sum of the two values ​​Dpr and Din. The adder 402 adds the proportional term Dpr and the integral term Din. The output signal of the adder 402 is input to the switch control unit 61 as the duty cycle D.

[0050] In this embodiment, the feedback control unit 41 includes a PI (Proportional Integral) controller 430. Various feedback controls, such as PID (Proportional Integral Differential) control, which performs integral calculations, can also be used instead of PI control. Furthermore, various controls, such as damping control and current control, can be performed between the feedback control unit 41 and the switching control unit 61. Damping control is the control that subtracts the calculation result based on the current detection value from the calculation result of PI control, and it suppresses changes in the duty cycle caused by current fluctuations.

[0051] The switch control unit 61 turns the switching elements 203 and 204 on and off according to the duty cycle D calculated by the feedback control unit 41. The switch control unit 61 generates gate drive signals Gt1 and Gt2 for each switching element 203 and 204 using PWM (Pulse Width Modulation) control based on the duty cycle D. In this embodiment, the duty cycle D is the on-duty cycle of the negative-side switching element 203 and the off-duty cycle of the positive-side switching element 204. When the negative-side switching element 203 is on, the positive-side switching element 204 is off. To avoid a short circuit between the positive and negative sides due to simultaneous on-duty cycles of both switching elements 203 and 204, a dead time is set between the on-duty periods of the positive-side switching element 204 and the on-duty periods of the negative-side switching element 203, during which both are off.

[0052] Figure 3 This is a timing diagram used to illustrate the on / off control of switching elements based on duty cycle. For example... Figure 3 As shown, the switch control unit 61 compares the duty cycle D with the carrier Vcr to generate gate drive signals Gt1 and Gt2 for each switch element 203, 204. The carrier Vcr is a triangular wave oscillating between 0 and 1. When the duty cycle D is greater than the carrier Vcr, the switch control unit 61 sets the gate drive signal Gt1 on the negative side to high; when the duty cycle D is less than the carrier Vcr, it sets the gate drive signal Gt1 on the negative side to low. Furthermore, when the duty cycle D+ΔDt (the value corresponding to the dead time) is greater than the carrier Vcr, the switch control unit 61 sets the gate drive signal Gt2 on the positive side to low; when the summed duty cycle D+ΔDt is less than the carrier Vcr, it sets the gate drive signal Gt2 on the positive side to high. The carrier Vcr can also be a sawtooth wave or an anti-sawtooth wave.

[0053] Next, the operation of the current continuous / discontinuous mode determination unit 51 will be explained.

[0054] Unlike this embodiment, instead of a current continuous / discontinuous mode determination unit 51, a current sensor is installed between the connection point of the smoothing capacitor 201 on the first terminal side and the two switching elements 203, 204. The determination of the current continuous mode and the current discontinuous mode is made using the detected value of the current flowing through the reactor 202 (hereinafter referred to as reactor current). In this case, incorrect determinations may sometimes be made due to errors in the current sensor.

[0055] When the determination of continuous and discontinuous current modes is performed using the detected value of the reactor current without setting up a continuous / discontinuous current mode determination unit 51, Figure 4The timing diagram illustrates the behavior when the current sensor encounters an error. Figure 4 The diagram illustrates the actions taken when a current sensor malfunctions and makes an incorrect judgment. Figure 4 In the diagram, the region X enclosed by a dotted line represents the region of discontinuous current mode.

[0056] like Figure 4 As shown in A, although the current IL flowing through the reactor 202 is actually a value of the current discontinuous mode, if it is detected as a value of the current continuous mode ILsenerrH due to the error of the current sensor, the circuit is determined to be in the current continuous mode in the determination method using the detection value of the reactor current.

[0057] In addition, such as Figure 4 As shown in B, although the actual current IL flowing through the reactor 202 is a value in the continuous current mode, it is detected as a value in the discontinuous current mode ILsenerrL due to the error of the current sensor. In the method of determining the detection value of the reactor current, the circuit is determined to be in the discontinuous current mode.

[0058] In use Figure 4 When using the detected value of the reactor current to determine whether the current is continuous or discontinuous, it is possible that an incorrect determination may occur near the boundary of the circuit's operation state being in discontinuous current mode due to the error of the current sensor.

[0059] Next, the determination of whether current sensor error will not occur will be explained using the current continuity / discontinuity mode determination unit 51 shown in this embodiment.

[0060] like Figure 2 As shown, the current continuous / discontinuous mode determination unit 51 includes a duty cycle increase / decrease determination unit 501 for determining the increase or decrease of the duty cycle D, an output voltage detection value increase / decrease determination unit 502 for determining the increase or decrease of the detection value V2s of the second terminal voltage, and a current continuous / discontinuous mode determination mark generation unit 503.

[0061] The duty cycle increase / decrease determination unit 501 compares the measured duty cycle D with the previous duty cycle value D0 and outputs a duty cycle increase / decrease determination flag Flag1. The duty cycle increase / decrease determination flag Flag1 outputs 1 when the absolute value of the difference between D and D0 is greater than the first duty cycle threshold Dt1 and D0 is greater than D; outputs -1 when the absolute value of the difference between D and D0 is greater than the first duty cycle threshold Dt1 and D0 is less than D; and outputs 0 when the absolute value of the difference between D and D0 is less than the first duty cycle threshold Dt1.

[0062] The output voltage detection value increase / decrease determination unit 502 compares the current measured value V2s of the second terminal voltage with the previous value V2s0 of the second terminal voltage and outputs an output voltage detection value increase / decrease determination flag Flag2. The output voltage detection value increase / decrease determination flag Flag2 outputs 1 when the absolute value of the difference between V2s and V2s0 is greater than the first output voltage threshold Vt1 and V2s is greater than V2s0; outputs -1 when the absolute value of the difference between V2s and V2s0 is greater than the first output voltage threshold Vt1 and V2s is less than V2s0; and outputs 0 when the absolute value of the difference between V2s and V2s0 is less than the first output voltage threshold Vt1.

[0063] The current continuity / discontinuous mode determination flag generation unit 503 determines that the circuit is in a current discontinuous mode when both the duty cycle increase / decrease determination flag Flag1 and the output voltage detection value increase / decrease determination flag Flag2 are 1 or both are -1, and sets the current continuity / discontinuous mode determination flag Flag3 to 1 (ON). Otherwise, it determines that the circuit is in a current continuous mode and sets the current continuity / discontinuous mode determination flag Flag3 to 0 (OFF).

[0064] Based on the above structure, it is possible to determine the continuous current mode and the discontinuous current mode without using the detection value of the reactor current.

[0065] The current continuity / discontinuity mode determination flag Flag3 generated by the current continuity / discontinuity mode determination flag generation unit 503 is input to the feedback control unit 41, and the proportional gain Kp and integral gain Ki are determined in the control constant change unit 420.

[0066] Figure 5 This is a flowchart showing the current continuity / discontinuity mode determination process performed by the current continuity / discontinuity mode determination unit 51 of this embodiment and the post-determination processing in the control constant change unit 420.

[0067] exist Figure 5 In step S01, the proportional control unit 411 multiplies the previous value Kp0 of the proportional gain Kp with the error value V2er of the second terminal voltage and outputs the proportional term Dpr. Then, the integral control unit 412 adds the value obtained by multiplying the previous value Ki0 of the integral gain Ki, the error value V2er of the second terminal voltage, and the control period Tc with the previous value Din0 of the integral term and outputs the current value Din of the integral term.

[0068] In step S02, the adder 402 is used to add the proportional term Dpr and the integral term Din to output the duty cycle D.

[0069] In step S03, the current continuous / discontinuous mode determination unit 51 calculates the absolute value of the difference between the duty cycle D and the previous value D0 of the duty cycle. If it is determined that the value is greater than the first duty cycle threshold Dt1, it proceeds to step S04. If it is determined that the value is less than the first duty cycle threshold Dt1, it proceeds to step S05.

[0070] In step S04, the current continuous / discontinuous mode determination unit 51 confirms the relationship between the duty cycle D and the previous value D0 of the duty cycle. If D0 is greater than D, it proceeds to step S06; if D0 is less than D, it proceeds to step S07.

[0071] In step S05, the duty cycle increase / decrease determination unit 501 in the current continuous / discontinuous mode determination unit 51 sets the duty cycle increase / decrease determination flag Flag1 to 0.

[0072] In step S06, the duty cycle increase / decrease determination unit 501 sets the duty cycle increase / decrease determination flag Flag1 to 1.

[0073] In step S07, the duty cycle increase / decrease determination unit 501 sets the duty cycle increase / decrease determination flag Flag1 to -1.

[0074] In step S08, the current continuous / discontinuous mode determination unit 51 calculates the absolute value of the difference between the detected value V2s of the second terminal voltage and the previous value V2s0 of the detected value of the second terminal voltage. If it is determined that the value is greater than the first output voltage threshold Vt1, it proceeds to step S09. If it is determined that the value is less than the first output voltage threshold Vt1, it proceeds to step S10.

[0075] In step S09, the current continuous / discontinuous mode determination unit 51 confirms the relationship between the detected value V2s of the second terminal voltage and the previous value V2s0 of the detected value of the second terminal voltage. If V2s is greater than V2s0, it proceeds to step S11; if V2s is less than V2s0, it proceeds to step S12.

[0076] In step S10, the output voltage detection value increase / decrease determination unit 502 in the current continuous / discontinuous mode determination unit 51 sets the output voltage detection value increase / decrease determination flag Flag2 to 0.

[0077] In step S11, the output voltage detection value increase / decrease determination unit 502 sets the output voltage detection value increase / decrease determination flag Flag2 to 1.

[0078] In step S12, the output voltage detection value increase / decrease determination unit 502 sets the output voltage detection value increase / decrease determination flag Flag2 to -1.

[0079] In step S13, the circuit's operating state—whether it's in continuous current mode or discontinuous current mode—is determined based on the duty cycle increment / decrease determination flag Flag1 and the output voltage detection value increment / decrease determination flag Flag2, as determined in steps S06, S07, S05, S11, S12, or S10. If both the duty cycle increment / decrease determination flag Flag1 and the output voltage detection value increment / decrease determination flag Flag2 are 1 or both are -1, the circuit is determined to be in discontinuous current mode, and the process proceeds to step S14. Otherwise, the circuit is determined to be in continuous current mode, and the process proceeds to step S15.

[0080] In step S14, the current continuity / discontinuity mode determination flag generation unit 503 in the current continuity / discontinuity mode determination unit 51 sets the current continuity / discontinuity mode determination flag Flag3 to 1 (ON) and proceeds to step S16.

[0081] In step S15, the current continuity / discontinuity mode determination flag generation unit 503 sets the current continuity / discontinuity mode determination flag Flag3 to 0 (OFF) and proceeds to step S17.

[0082] In step S16, in the control constant changing unit 420, the proportional gain KpDCM for the discontinuous current mode is output as the proportional gain Kp to the proportional control unit 411, and the integral gain KiDCM for the discontinuous current mode is output as the integral gain Ki to the integral control unit 412. When the circuit is operating in the discontinuous current mode, the proportional gain KpDCM and the integral gain KiDCM for the discontinuous current mode are determined in a way that maximizes responsiveness while ensuring control stability. Typically, they are set to values ​​larger than the proportional gain KpCCM and the integral gain KiCCM for the continuous current mode, which will be described later.

[0083] In step S17, in the control constant changing unit 420, the proportional gain KpCCM for continuous current mode is output to the proportional control unit 411 as the proportional gain Kp, and the integral gain KiCCM for continuous current mode is output to the integral control unit 412 as the integral gain Ki. When the circuit is operating in continuous current mode, the proportional gain KpCCM and the integral gain KiCCM for continuous current mode are determined in a way that maximizes responsiveness while ensuring control stability.

[0084] When the power conversion circuit 20 is in continuous current mode, the first duty cycle threshold Dt1 is set to a value greater than the maximum value of the change in duty cycle D generated in each control cycle Tcnt when the circuit changes rapidly at maximum speed.

[0085] The first output voltage threshold Vt1 is set to a value greater than the pulsation of the second terminal voltage V2 when the power conversion circuit 20 is operating stably, or when the power conversion circuit 20 is in continuous current mode, the first output voltage threshold Vt1 is set to a value greater than the maximum value of the change in V2 generated in each control cycle Tcnt when the circuit changes rapidly at maximum speed.

[0086] Figure 6 This is a timing diagram showing the actions taken when determining the continuous / discontinuous current mode during load changes, illustrating the control actions under conditions of sudden load changes. Figure 6 Figure A shows the reactor current IL flowing through reactor 202. Figure 6 B shows the detected value V2s and the command value V2ref of the voltage at terminal 2. Figure 6 In section B, the solid line represents the output voltage detection value, V2s, and the dashed line represents the output voltage command value, V2ref. Figure 6 C shows the duty cycle D. Figure 6 D shows the rising timing of the current continuous / discontinuous mode determination flag Flag3. Figure 6 E shows the control constants, namely the changes in proportional gain Kp and integral gain Ki.

[0087] exist Figure 6 At time T01, the reactor current IL begins to decrease from the start of power operation. Immediately afterwards, the detected value V2s of the second terminal voltage begins to slowly increase, and the duty cycle D begins to slowly decrease due to feedback control based on the feedback control unit 41. At this time, by setting the first duty cycle threshold Dt1 in the duty cycle increase / decrease determination unit 501 and the first output voltage threshold Vt1 in the output voltage detection value increase / decrease determination unit 502 according to the above method, it is possible to prevent the current continuous / discontinuous mode determination flag Flag3 from becoming ON.

[0088] At time T02, the circuit operates in discontinuous current mode. The detected voltage V2s at terminal 2 begins to increase sharply, and the duty cycle D begins to decrease sharply. Consequently, the continuous / discontinuous current mode determination flag Flag3 becomes ON, and the control constant switches from gain for continuous current mode to gain for discontinuous current mode. At this point, the control constant can be changed within one control cycle or over multiple control cycles.

[0089] When the reactor current exits the discontinuous current mode on the regeneration side at time T03, the detected value V2s of the second terminal voltage begins to decrease due to the feedback control based on the feedback control unit 41, and returns to the command value V2ref of the second terminal voltage at time T04.

[0090] At this time, the current continuous / discontinuous mode determination unit 51 can turn the current continuous / discontinuous mode determination flag Flag3 ON after performing one discontinuous mode determination, or it can turn the current continuous / discontinuous mode determination flag Flag3 ON after performing multiple discontinuous mode determinations. That is, the current continuous / discontinuous mode determination unit 51 can also determine that it is a current discontinuous mode if it is determined to be a current discontinuous mode at least twice.

[0091] By constructing the power conversion device described above, the continuous current mode and the discontinuous current mode can be determined without using the reactor current detection value, thus enabling accurate determination. Furthermore, based on the determination result, the feedback control unit 41 performs feedback control. Therefore, the responsiveness of the power conversion circuit 20 can be improved, and the maximum value of the second terminal voltage V2 can be suppressed. Consequently, the capacitance of the smoothing capacitor 205 on the second terminal side can be reduced.

[0092] Implementation method 2.

[0093] Next, the power conversion circuit and control device of Embodiment 2 will be described with reference to the accompanying drawings. Descriptions of structural parts identical to those in Embodiment 1 will be omitted. The basic structure and processing of the power conversion circuit and control device in this embodiment are the same as those in Embodiment 1.

[0094] Figure 7 This is a block diagram illustrating the function of the control device. In this embodiment, a duty cycle correction control unit 440 is provided, which corrects the duty cycle D based on the result of the current continuous / discontinuous mode determination unit 51.

[0095] The duty cycle correction control unit 440 includes: a duty cycle correction amount determination unit 441, which determines the current value αD of the duty cycle correction amount based on the result of the current continuous / discontinuous mode determination unit 51; and a duty cycle correction unit 442, which corrects the duty cycle D and outputs the corrected duty cycle Dcr.

[0096] The duty cycle correction unit 442 stores the current value αD of the duty cycle correction amount, multiplies the previous value αD0 of the duty cycle correction amount with the duty cycle D, thereby correcting the duty cycle D, and outputs the corrected duty cycle Dcr to the duty cycle increase / decrease determination unit 501 and the switch control unit 61.

[0097] When the previous value of the duty cycle correction αD0 is 1, the duty cycle correction control is OFF, and the output value of the PI controller 430, i.e., D, is the current duty cycle.

[0098] The duty cycle increase / decrease determination unit 501 compares the corrected duty cycle Dcr with the previous value Dcr0 and outputs a duty cycle increase / decrease determination flag Flag1. If the absolute value of the difference between Dcr and Dcr0 is greater than the second duty cycle threshold Dt2 and Dcr0 is greater than Dcr, the duty cycle increase / decrease determination flag Flag1 is set to 1. Furthermore, if the absolute value of the difference between Dcr and Dcr0 is greater than the second duty cycle threshold Dt2 and Dcr0 is less than Dcr, the duty cycle increase / decrease determination flag Flag1 is set to -1. Finally, if the absolute value of the difference between Dcr and Dcr0 is less than the second duty cycle threshold Dt2, the output is 0.

[0099] In the switch control unit 61, a corrected duty cycle Dcr is used instead of the duty cycle D in Embodiment 1 above, and the gate drive signals Gt1 and Gt2 of each switch element 203 and 204 are generated using the same means.

[0100] Figure 8 This is a flowchart illustrating the determination of continuous and discontinuous current modes based on Implementation Method 2, and the processing after determination. Figure 8 The diagram shows the current continuity / discontinuity mode determination process performed by the current continuity / discontinuity mode determination unit 51 and the post-determination processing in the duty cycle correction control unit 440. Figure 8 In step S18, the feedback control unit 41 outputs the correction duty cycle Dcr by multiplying the output value D from the PI controller 430 by the previous value αD0 of the duty cycle correction amount.

[0101] In step S19, the current continuous / discontinuous mode determination unit 51 calculates the absolute value of the difference between the corrected duty cycle Dcr and the previous value Dcr0 of the corrected duty cycle. If it is determined that the value is greater than the second duty cycle threshold Dt2, it proceeds to step S20. If it is determined that the value is less than the second duty cycle threshold Dt2, it proceeds to step S21.

[0102] In step S20, the current continuity / discontinuity mode determination unit 51 confirms the relationship between the corrected duty cycle Dcr and the previous value Dcr0 of the corrected duty cycle. If Dcr0 is greater than Dcr, it proceeds to step S22; if Dcr0 is less than Dcr, it proceeds to step S23. In step S21, the duty cycle increase / decrease determination unit 501 in the current continuity / discontinuity mode determination unit 51 sets the duty cycle increase / decrease determination flag Flag1 to 0. In step S22, the duty cycle increase / decrease determination unit 501 sets the duty cycle increase / decrease determination flag Flag1 to 1. In step S23, the duty cycle increase / decrease determination unit 501 sets the duty cycle increase / decrease determination flag Flag1 to -1.

[0103] In step S24, the current continuous / discontinuous mode determination unit 51 calculates the absolute value of the difference between the detected value V2s of the second terminal voltage and the previous value V2s0 of the detected value of the second terminal voltage. If it is determined that the value is greater than the first output voltage threshold Vt1, it proceeds to step S25. If it is determined that the value is less than the first output voltage threshold Vt1, it proceeds to step S26.

[0104] In step S25, the current continuous / discontinuous mode determination unit 51 confirms the relationship between the detected value V2s of the second terminal voltage and the previous value V2s0 of the detected value of the second terminal voltage. If V2s is greater than V2s0, it proceeds to step S27; if V2s is less than V2s0, it proceeds to step S28.

[0105] In step S26, the output voltage detection value increase / decrease determination unit 502 in the current continuous / discontinuous mode determination unit 51 sets the output voltage detection value increase / decrease determination flag Flag2 to 0.

[0106] In step S27, the output voltage detection value increase / decrease determination unit 502 sets the output voltage detection value increase / decrease determination flag Flag2 to 1.

[0107] In step S28, the output voltage detection value increase / decrease determination unit 502 sets the output voltage detection value increase / decrease determination flag Flag2 to -1.

[0108] In step S29, based on the duty cycle increment / decrease determination flag Flag1 and the output voltage detection value increment / decrease determination flag Flag2 determined in steps S22, S23, S21, S27, S28, or S26, it is determined whether the circuit's operating state is continuous current mode or discontinuous current mode. If both the duty cycle increment / decrease determination flag Flag1 and the output voltage detection value increment / decrease determination flag Flag2 are 1 or both are -1, the circuit is determined to be in discontinuous current mode, and the process proceeds to step S30. Otherwise, the circuit is determined to be in continuous current mode, and the process proceeds to step S31.

[0109] In step S30, the current continuity / discontinuity mode determination flag generation unit 503 in the current continuity / discontinuity mode determination unit 51 sets the current continuity / discontinuity mode determination flag Flag3 to 1 (ON) and proceeds to step S32.

[0110] In step S31, the current continuity / discontinuity mode determination flag generation unit 503 sets the current continuity / discontinuity mode determination flag Flag3 to 0 (OFF) and proceeds to step S33.

[0111] In step S32, the duty cycle correction amount determination unit 441 outputs a duty cycle correction amount αD that is not 1 to the duty cycle correction unit 442. The method for setting the duty cycle correction amount αD will be described below.

[0112] The duty cycle correction αD is set to a value greater than the maximum change in duty cycle D within each control cycle Tcnt relative to the maximum speed of circuit abrupt changes generated in the power conversion circuit 20. For example, when the load 81 changes from power operation to regenerative operation while the voltages V2 and V1 at the second terminal are constant, the duty cycle D decreases by twice the dead time ΔDt with respect to the switching element 203. Furthermore, when the load 81 changes from regenerative to power operation, the duty cycle D increases by twice the dead time ΔDt with respect to the switching element 203. The maximum value of the duty cycle correction αD is determined by converting a change of 2 × ΔDt within one control cycle Tcnt into the duty cycle.

[0113] In step S33, the duty cycle correction determination unit 441 outputs 1 to the duty cycle correction unit 442 as the duty cycle correction amount αD.

[0114] Figure 9 This is a timing diagram illustrating the actions taken when determining the continuous or discontinuous current mode during load changes, showing the control actions under conditions of sudden load changes. Figure 9 A shows the reactor current IL flowing through reactor 202. Figure 9 Figure A shows the reactor current when the correction control is OFF and the reactor current when the correction control is ON, and the two are consistent. Figure 9 B shows the detected value V2s and the command value V2ref of the voltage at terminal 2. Figure 9 In diagram B, the solid line B1 represents the output voltage detection value when the correction control is OFF, and the dashed line B2 represents the output voltage detection value when the correction control is ON. Additionally, the dotted-dash line B3 represents the output voltage command value. Figure 9 C indicates the duty cycle D. Figure 9 In line C, the solid line C1 represents the duty cycle D when the correction control is OFF, and the dashed line C2 represents the duty cycle when the correction control is ON. Figure 9 D indicates the rising timing of Flag3, which determines the continuous / discontinuous current mode.

[0115] exist Figure 9At time T11, the reactor current IL begins to decrease from the start of power operation. Immediately afterwards, the detected value V2s of the second terminal voltage begins to slowly increase, and the duty cycle D begins to slowly decrease due to feedback control by the feedback control unit 41. At this time, the second duty cycle threshold Dt2 in the duty cycle increase / decrease determination unit 501 and the first output voltage threshold Vt1 in the output voltage detection value increase / decrease determination unit 502 are set in the same manner as in Embodiment 1 above, thereby preventing the current continuous / discontinuous mode determination flag Flag3 from becoming ON.

[0116] At time T12, the circuit operates in discontinuous current mode. The detected voltage value V2s at terminal 2 begins to increase sharply, and the duty cycle D begins to decrease sharply. Consequently, the current discontinuous mode determination flag Flag3 becomes ON, and the duty cycle correction control becomes ON. As a result, the detected voltage value V2s at terminal 2 immediately begins to decrease.

[0117] When the reactor current IL exits the discontinuous current mode on the regeneration side at time T13, the detected value V2s of the second terminal voltage begins to decrease due to the feedback control of the feedback control unit 41, and returns to the command value V2ref of the second terminal voltage at time T14.

[0118] By constructing the power conversion device described above, the continuous current mode and the discontinuous current mode can be determined without using the reactor current detection value, thus enabling accurate determination. Furthermore, feedback control is performed by the feedback control unit 41 based on the determination result. Therefore, the responsiveness of the power conversion circuit 20 can be improved, and the maximum value of the second terminal voltage V2 can be suppressed. Consequently, the capacitance of the smoothing capacitor 205 on the second terminal side can be reduced.

[0119] Implementation method 3.

[0120] Next, the power conversion circuit and control device of Embodiment 3 will be described with reference to the accompanying drawings. Descriptions of structural parts identical to those in Embodiment 1 described above are omitted. The basic structure and processing of the power conversion circuit 20 and control device 10 in this embodiment are the same as in Embodiment 1.

[0121] Figure 10 This is a block diagram illustrating the function of the control device in this embodiment. The feedback control unit 41 is equipped with an integral term correction determination unit 450 that determines the current value αDing of the integral term correction, and the PI controller 430 is equipped with an integral term correction unit 413 that corrects the integral term Din and outputs the corrected integral term Dincr.

[0122] The integral term correction determination unit 450 determines the current value αDin of the integral term correction based on the result of the current continuous / discontinuous mode determination unit 51. The integral term correction unit 413 stores the current value αDin of the integral term correction and multiplies the previous value αDin0 of the integral term correction by the integral term (integral duty cycle) Din, thereby correcting the integral term Din and outputting the corrected integral term Dincr to the adder 402.

[0123] When the previous value αDin0 of the integral term correction is 1, the integral term correction control becomes OFF. Adder 402 adds the proportional term Dpr to the correction integral term Dincr and outputs the duty cycle D.

[0124] Figure 11 This is a flowchart illustrating the determination of the continuous / discontinuous current mode and the subsequent processing in Implementation Method 3. Figure 11 The diagram shows the current continuity / discontinuity mode determination process of the current continuity / discontinuity mode determination unit 51, the determination process of the integral term correction amount determination unit 450, and the post-determination process of the integral term correction unit 413.

[0125] exist Figure 11 In step S34, the integral term correction unit 413 multiplies the integral term Din by the previous value αDin0 of the integral term correction amount and outputs the correction integral term Dincr.

[0126] In step S35, the proportional term Dpr and the correction integral term Dincr are added together using adder 402, and the duty cycle D is output. In this embodiment, only the integral term Din is corrected, and the proportional term Dpr is not corrected. The reason for this is that in embodiment 2, the case of directly correcting the duty cycle is shown, but the proportional term among the elements constituting the duty cycle is an instantaneous value, while the integral term is a value obtained by adding the values ​​obtained by multiplying the deviation at each moment by the integral gain and the control period. As an effect of this application, the maximum value of the second terminal voltage V2 can be suppressed. Therefore, in order to suppress the maximum value of the second terminal voltage, the duty cycle needs to be rapidly reduced when the capacitance of the smoothing capacitor 205 on the second terminal side can be reduced. Therefore, it is an effective means to correct the integral term accumulated up to this point without correcting the instantaneously determined proportional term.

[0127] Next, in step S36, the current continuous / discontinuous mode determination unit 51 calculates the absolute value of the difference between the duty cycle D and the previous value D0 of the duty cycle. If it is determined that the value is greater than the first duty cycle threshold Dt1, it proceeds to step S37. If it is determined that the value is less than the first duty cycle threshold Dt1, it proceeds to step S38.

[0128] In step S37, the current continuous / discontinuous mode determination unit 51 confirms the relationship between the duty cycle D and the previous value D0 of the duty cycle. If D0 is greater than D, it proceeds to step S39; if D0 is less than D, it proceeds to step S40.

[0129] In step S38, the duty cycle increase / decrease determination unit 501 in the current continuous / discontinuous mode determination unit 51 sets the duty cycle increase / decrease determination flag Flag1 to 0.

[0130] In step S39, the duty cycle increase / decrease determination unit 501 sets the duty cycle increase / decrease determination flag Flag1 to 1.

[0131] In step S40, the duty cycle increase / decrease determination unit 501 sets the duty cycle increase / decrease determination flag Flag1 to -1.

[0132] In step S41, the current continuous / discontinuous mode determination unit 51 calculates the absolute value of the difference between the detected value V2s of the second terminal voltage and the previous value V2s0 of the detected value of the second terminal voltage. If it is determined that the value is greater than the first output voltage threshold Vt1, it proceeds to step S42. If it is determined that the value is less than the first output voltage threshold Vt1, it proceeds to step S43.

[0133] In step S42, the current continuous / discontinuous mode determination unit 51 confirms the relationship between the detected value V2s of the second terminal voltage and the previous value V2s0 of the detected value of the second terminal voltage. If V2s is greater than V2s0, it proceeds to step S44; if V2s is less than V2s0, it proceeds to step S45.

[0134] In step S43, the output voltage detection value increase / decrease determination unit 502 in the current continuous / discontinuous mode determination unit 51 sets the output voltage detection value increase / decrease determination flag Flag2 to 0.

[0135] In step S44, the output voltage detection value increase / decrease determination unit 502 sets the output voltage detection value increase / decrease determination flag Flag2 to 1.

[0136] In step S45, the output voltage detection value increase / decrease determination unit 502 sets the output voltage detection value increase / decrease determination flag Flag2 to -1.

[0137] In step S46, based on the duty cycle increment / decrease determination flag Flag1 and the output voltage detection value increment / decrease determination flag Flag2 determined in steps S39, S40, S38, S44, S45, or S43, it is determined whether the circuit's operating state is continuous current mode or discontinuous current mode. If both the duty cycle increment / decrease determination flag Flag1 and the output voltage detection value increment / decrease determination flag Flag2 are 1 or both are -1, the circuit is determined to be in discontinuous current mode, and the process proceeds to step S47. Otherwise, the circuit is determined to be in continuous current mode, and the process proceeds to step S48.

[0138] In step S47, the current continuity / discontinuity mode determination flag generation unit 503 in the current continuity / discontinuity mode determination unit 51 sets the current continuity / discontinuity mode determination flag Flag3 to 1 (ON) and proceeds to step S49.

[0139] In step S48, the current continuity / discontinuity mode determination flag generation unit 503 sets the current continuity / discontinuity mode determination flag Flag3 to 0 (OFF) and proceeds to step S50.

[0140] In step S49, the integral term correction determination unit 450 outputs the integral term correction amount αDin, which is not 1, to the integral term correction unit 413.

[0141] The method for setting the integral term correction αDin is explained below. The integral term correction αDin is set to a value greater than the maximum change in duty cycle D relative to the maximum speed of the circuit abrupt change generated in the power conversion circuit 20 within each control cycle Tcnt. For example, when the load 81 changes from power operation to regenerative operation while the voltages V2 and V1 at the second terminal are constant, the duty cycle D decreases by twice the dead time ΔDt with respect to the switching element 203. Furthermore, when the load 81 changes from regenerative to power operation, the duty cycle D increases by twice the dead time ΔDt with respect to the switching element 203. The maximum value of the integral term correction αDin is determined by converting a change of 2 × ΔDt within one control cycle Tcnt into an integral term.

[0142] In step S50, the integral term correction determination unit 450 outputs 1 to the integral term correction unit 413 as the integral term correction amount αDin.

[0143] In this embodiment, under the condition of a sudden load change, it becomes... Figure 9 The same control actions are shown.

[0144] By constructing the power conversion device described above, the continuous current mode and the discontinuous current mode can be determined without using the reactor current detection value, thus enabling accurate determination. Furthermore, feedback control is performed by the feedback control unit 41 based on the determination result. Therefore, the responsiveness of the power conversion circuit 20 can be improved, and the maximum value of the second terminal voltage V2 can be suppressed. Consequently, the capacitance of the smoothing capacitor 205 on the second terminal side can be reduced.

[0145] Implementation method 4.

[0146] The structures of the embodiments described below are not limited to being applied individually; they can also be combined with the structures of other embodiments, provided that there is no contradiction.

[0147] In the embodiments described above, the power conversion circuit 20 is illustrated as an example of a bidirectional chopper circuit that combines a boost chopper circuit that boosts DC voltage from the first terminal 21 to the second terminal 22 and a buck chopper circuit that steps down DC voltage from the second terminal 22 to the first terminal 21. However, the embodiments of this application are not limited to this. That is, the power conversion circuit 20 can be any circuit that includes switching elements and performs power conversion between the first terminal 21 and the second terminal 22, and various power conversion circuits can be used. For example, the power conversion circuit 20 can be a boost chopper circuit that boosts DC voltage from the first terminal 21 to the second terminal 22, or it can be a buck chopper circuit that steps down DC voltage from the first terminal 21 to the second terminal 22. Alternatively, it can be an insulated type power conversion circuit with an insulated transformer, or it can be a power conversion circuit in which elements of multiple power conversion circuits are interleaved or connected in parallel.

[0148] Furthermore, in the embodiments described above, the case where the power supply 71 is connected to the first terminal 21 and the inverter and motor load 81 are connected to the second terminal 22 is used as an example. However, the embodiments of this application are not limited to this. That is, the power supply or load may be connected to the first terminal 21, or the power supply or load may be connected to the second terminal 22. Moreover, various power supplies and loads can be used as the power supply and load.

[0149] In the above embodiments, the example described is the case where the feedback control unit 41 calculates the duty cycle D or the corrected duty cycle Dcr based on the command value and the detection value of the voltage V2 at the second terminal. However, the embodiments of this application are not limited to this. That is, in the feedback control unit 41, command values ​​and detection values ​​of other electrical information can be used as long as they are various electrical information related to the power conversion circuit 20. The feedback control unit 41 can also use, for example, the voltage, current or power input or output to the first terminal 21 or the second terminal 22 as electrical information related to the power conversion circuit 20.

[0150] In the above embodiments, the duty cycle increase / decrease determination unit 501 in Embodiment 1 determines the duty cycle increase / decrease determination flag Flag 1 based on the previous value D0 of the duty cycle and the duty cycle D. In Embodiment 2, the duty cycle increase / decrease determination unit 501 determines the duty cycle increase / decrease determination flag Flag 1 based on the previous value Dcr0 of the corrected duty cycle and the corrected duty cycle Dcr. However, the embodiments of this application are not limited to these.

[0151] That is, a duty cycle Dfilt ​​that has undergone various smoothing processes such as low-pass filtering or moving average processing can be used instead of the previous duty cycle value D0. Furthermore, a corrected duty cycle Dcrfilt that has undergone various smoothing processes such as low-pass filtering or moving average processing can be used instead of the previous corrected duty cycle value Dcr0. Additionally, a duty cycle Dfilt ​​that has undergone various smoothing processes such as low-pass filtering or moving average processing can be used instead of the current duty cycle value D, and a previous value Dfilt0 that has undergone various smoothing processes such as low-pass filtering or moving average processing can be used instead of the previous duty cycle value D0. In other words, the value after moving average processing can be used as at least one of the previously measured duty cycle and the currently measured duty cycle. Furthermore, the value after low-pass filtering processing can be used as at least one of the previously measured duty cycle and the currently measured duty cycle. Furthermore, the value after moving average processing can be used as at least one of the previously obtained corrected duty cycle and the currently obtained corrected duty cycle. Furthermore, the value processed by the low-pass filter can be used as at least one of the previously obtained correction duty cycle and the current correction duty cycle.

[0152] When the circuit switches from continuous current mode to discontinuous current mode, especially from power operation to regenerative operation, the duty cycle determined by the detected value of the voltage at terminal 2 overshoots. However, strictly speaking, due to factors such as reactor current ripple, it does not become a completely monotonically increasing value. Therefore, when making judgments using only the current and previous values, misjudgments can sometimes occur. Therefore, by applying a moving average or low-pass filter to the duty cycle, these values ​​can be smoothed, thus improving the accuracy of the judgment.

[0153] Regarding the specific processing method, in each embodiment, the average of the current duty cycle value and the previous value is taken in the moving average processing (or further traced back), and the value after moving average processing is replaced with the previous value in embodiments 1 to 3. Pattern determination can be performed based on the difference between the current value and the previous value. Furthermore, the value after moving average processing can be replaced with the current value in embodiments 1 to 3, and the previous value after moving average processing can be replaced with the previous value in embodiments 1 to 3, and pattern determination can be performed based on the difference between the two.

[0154] Furthermore, in each embodiment, after the duty cycle is output during low-pass filter processing, the input enters the low-pass filter. The value processed by the low-pass filter is replaced with the previous value in embodiments 1 to 3, and mode determination can be performed based on the difference between the current value and the previous value. Additionally, by replacing the value processed by the low-pass filter with the current value in embodiments 1 to 3, and replacing the previous value processed by the low-pass filter with the previous value in embodiments 1 to 3, mode determination can be performed based on the difference between the two.

[0155] In the above embodiments, the example described is the case where the output voltage detection value increase / decrease determination unit 502 determines the output voltage detection value increase / decrease determination flag Flag2 based on the previous value V2s0 of the second terminal voltage detection value and the second terminal voltage detection value V2s. However, the embodiments of this application are not limited to this. That is, the second terminal voltage detection value V2sfilt, which has undergone various smoothing processes such as low-pass filter processing or moving average processing, can be used instead of the previous value V2s0 of the second terminal voltage detection value.

[0156] Furthermore, instead of the current value V2s of the detected value of the second terminal voltage, the detected value V2sfilt of the second terminal voltage, after various smoothing processes such as low-pass filtering or moving average processing, can be used; instead of the previous value V2s0 of the detected value of the second terminal voltage, the previous value V2sfilt0 of the detected value V2sfilt of the second terminal voltage, after various smoothing processes such as low-pass filtering or moving average processing, can be used. That is, the value after moving average processing can be used as at least one of the previously measured detected value and the currently measured detected value. Furthermore, the value after low-pass filtering processing can be used as at least one of the previously measured detected value and the currently measured detected value.

[0157] When the circuit switches from continuous current mode to discontinuous current mode, especially when switching from power operation to regenerative operation, the detected value of the second terminal voltage may overshoot. However, strictly speaking, due to factors such as reactor current ripple, it will not be a completely monotonically increasing value. Therefore, when making a judgment using only the current value and the previous value, misjudgments may sometimes occur. By applying a moving average or low-pass filter to the detected value of the second terminal voltage, these values ​​can be smoothed, thus improving the judgment accuracy.

[0158] Regarding the specific processing method, in each embodiment, the average of the current value and the previous value of the detected voltage of the second terminal is taken in the moving average processing (or further traced back). The value after moving average processing is replaced with the previous value in embodiments 1 to 3, and pattern determination can be performed based on the difference between the current value and the previous value. Furthermore, by replacing the value after moving average processing with the current value in embodiments 1 to 3, and replacing the previous value after moving average processing with the previous value in embodiments 1 to 3, pattern determination can be performed based on the difference between the two.

[0159] Furthermore, in each embodiment, after the detected value of the second terminal voltage is output during low-pass filter processing, the input is fed into the low-pass filter. The value processed by the low-pass filter is replaced with the previous value in embodiments 1 to 3, and mode determination can be performed based on the difference between the current value and the previous value. Additionally, by replacing the value processed by the low-pass filter with the current value in embodiments 1 to 3, and by replacing the previous value processed by the low-pass filter with the previous value in embodiments 1 to 3, mode determination can be performed based on the difference between the two.

[0160] In Embodiment 2 described above, the example is given where the duty cycle correction unit 442 corrects the duty cycle D by multiplying it by the previous value αD0 of the duty cycle correction amount and outputs the corrected duty cycle Dcr. However, the embodiments of this application are not limited to this. That is, the duty cycle D can also be corrected by adding the previous value αD0 of the duty cycle correction amount to the duty cycle D and outputting the corrected duty cycle Dcr.

[0161] In the above embodiment 3, the example described is that the integral term correction unit 413 corrects the integral term Din by multiplying the integral term Din by the previous value αDin0 of the integral term correction amount and outputs the corrected integral term Dincr. However, the embodiments of this application are not limited to this. That is, the integral term Din can also be corrected by adding the previous value αDin0 of the integral term correction amount to the integral term Din and outputting the corrected integral term Dincr.

[0162] In the embodiments described above, the method for determining the continuous current mode and the discontinuous current mode is illustrated using the case where the detected value of the reactor current is not used at all. However, the embodiments of this application are not limited to this. That is, considering the maximum error caused by the current sensor, the reactor current value, which serves as the boundary between the continuous current mode and the discontinuous current mode, can be added as a threshold to the determination condition of the continuous current mode / discontinuous current mode determination flag. This improves the accuracy of determining the continuous current mode and the discontinuous current mode.

[0163] Continuous and discontinuous current modes are physically distinguished based on the movement of the reactor current. Therefore, ideally, where the influence of current sensor error can be ignored, it is best to use the reactor current to determine the continuous and discontinuous current modes. However, in reality, where the influence of current sensor error cannot be ignored, the impact of the current sensor error is relatively large compared to the reactor current value, which serves as the boundary between continuous and discontinuous current modes, making it difficult to use the reactor current alone as the determination criterion.

[0164] On the other hand, the above embodiments can make a determination by using the detected value of the voltage of the second terminal and the duty cycle, which can be done without being affected by the current sensor, but false determinations may still occur as described above.

[0165] Based on the above two backgrounds, by using the boundary of the current continuous mode and the current discontinuous mode, which takes into account the influence of the current sensor, as the third determination condition instead of the physically determined boundary of the current continuous mode and the current discontinuous mode, it is possible to eliminate the influence of the current sensor while improving the determination accuracy of the current continuous mode and the current discontinuous mode.

[0166] Regarding the specific processing method, in each embodiment, the threshold for the physically determined continuous current mode and discontinuous current mode takes into account the value of the maximum error caused by the current sensor, and adds a determination flag that is 1 (ON) when the detected value of the reactor current is less than the threshold and 0 (OFF) when the detected value of the reactor current is greater than the threshold. When the determination flag is ON and Flag3 is ON, it is determined to be a discontinuous current mode.

[0167] This application describes various exemplary implementation methods and embodiments, but the various features, methods and functions described in one or more implementation methods are not limited to the application of a specific implementation method, and can be applied to the implementation method alone or in various combinations.

[0168] Therefore, numerous variations not illustrated are contemplated within the scope of the technology disclosed in this application. These include variations of at least one structural element, additions, omissions, and combinations of at least one structural element with structural elements from other embodiments.

Claims

1. A control device for a power conversion circuit, wherein the power conversion circuit connects a switching element and a reactor between a first terminal and a second terminal and performs power conversion between the first terminal and the second terminal. The control device includes: The feedback control unit includes a controller that calculates the duty cycle of the switching element based on command values ​​and detection values ​​of electrical information related to the power conversion circuit; and The current continuous / discontinuous mode determination unit includes a duty cycle increase / decrease determination unit for determining whether the duty cycle increases or decreases, and an output voltage detection value increase / decrease determination unit for determining whether the detected value of the voltage at the second terminal increases or decreases. When the duty cycle increase / decrease determination unit determines that the previously measured duty cycle is greater than the currently measured duty cycle and the output voltage detection value increase / decrease determination unit determines that the currently measured detection value is greater than the previously measured detection value, or when the duty cycle increase / decrease determination unit determines that the previously measured duty cycle is less than the currently measured duty cycle and the output voltage detection value increase / decrease determination unit determines that the currently measured detection value is less than the previously measured detection value, the current continuity / discontinuous mode determination unit determines that the circuit's operating state is current discontinuous mode. When the duty cycle increase / decrease determination unit determines that the previously measured duty cycle is greater than the currently measured duty cycle and the output voltage detection value increase / decrease determination unit determines that the currently measured detection value is less than the previously measured detection value, or when the duty cycle increase / decrease determination unit determines that the previously measured duty cycle is less than the currently measured duty cycle and the output voltage detection value increase / decrease determination unit determines that the currently measured detection value is greater than the previously measured detection value, the current continuous / discontinuous mode determination unit determines that the circuit's operating state is current continuous mode. The judgment result is fed back to the feedback control unit.

2. The control device for the power conversion circuit as described in claim 1, wherein, The feedback control unit has a control constant changing unit that changes the control constants used in the controller. The controller stores the control constant output from the control constant changing unit, and uses the previous value of the control constant to calculate the duty cycle. When the duty cycle increase / decrease determination unit determines that the absolute value of the difference between the current measured duty cycle and the previously measured duty cycle is greater than the first duty cycle threshold and the previously measured duty cycle is greater than the current measured duty cycle, and the output voltage detection value increase / decrease determination unit determines that the absolute value of the difference between the current measured detection value and the previously measured detection value is greater than the first output voltage threshold and the current measured detection value is greater than the previously measured detection value, or when the duty cycle increase / decrease determination unit determines that the absolute value of the difference between the current measured duty cycle and the previously measured duty cycle is greater than the first duty cycle threshold and the previously measured duty cycle is less than the current measured duty cycle, and the output voltage detection value increase / decrease determination unit determines that the absolute value of the difference between the current measured detection value and the previously measured detection value is greater than the first output voltage threshold and the current measured detection value is less than the previously measured detection value, the current continuous / discontinuous mode determination unit determines that the circuit's operating state is a current discontinuous mode, and the control constant change unit determines the control constant based on this determination result.

3. The control device for the power conversion circuit as described in claim 1, wherein, The feedback control unit includes: a duty cycle correction amount determination unit, which determines the value of the duty cycle correction amount; And a duty cycle correction unit, which corrects the duty cycle and outputs a corrected duty cycle. The duty cycle correction unit stores the duty cycle correction amount measured this time, and calculates the corrected duty cycle by multiplying the duty cycle correction amount measured previously by the duty cycle. When the duty cycle increase / decrease determination unit determines that the absolute value of the difference between the current corrected duty cycle and the previously obtained corrected duty cycle is greater than the second duty cycle threshold and the previously obtained corrected duty cycle is greater than the current corrected duty cycle, and when the output voltage detection value increase / decrease determination unit determines that the absolute value of the difference between the current measured detection value and the previously measured detection value is greater than the first output voltage threshold and the current measured detection value is greater than the previously measured detection value, or when the duty cycle increase / decrease determination unit determines that the absolute value of the difference between the current corrected duty cycle and the previously obtained corrected duty cycle is greater than the previously obtained corrected duty cycle, the duty cycle increase / decrease determination unit determines that the absolute value of the difference between the current measured detection value and the previously obtained corrected duty cycle is greater than the second duty cycle threshold and the previously obtained corrected duty cycle is greater than the previously obtained corrected duty cycle, the duty cycle increase / decrease determination unit determines that the absolute value of the difference between the current measured detection value and the previously measured detection value is greater than the first output voltage threshold and the currently measured detection value is greater than the previously measured detection value. If the absolute value of the difference between the corrected duty cycle and the previous corrected duty cycle is greater than the second duty cycle threshold and the previously obtained corrected duty cycle is less than the current corrected duty cycle, and the output voltage detection value increase / decrease determination unit determines that the absolute value of the difference between the current measured detection value and the previously measured detection value is greater than the first output voltage threshold and the current measured detection value is less than the previously measured detection value, the current continuous / discontinuous mode determination unit determines that the circuit's operating state is a current discontinuous mode, and the duty cycle correction amount determination unit determines the value of the duty cycle correction amount based on this determination result.

4. The control device for the power conversion circuit as described in claim 1, wherein, The feedback control unit has: The proportional control unit outputs a proportional term based on the instruction value and the detection value; The integral control unit outputs an integral term based on the instruction value and the detection value; The integral term correction determination unit determines the integral term correction amount used to correct the integral term; The integral term correction unit stores the current value of the integral term correction quantity and calculates the correction integral term by multiplying the previous value of the integral term correction quantity by the integral term. as well as The adder adds the proportional term and the correction integral term and outputs the duty cycle. When the duty cycle increase / decrease determination unit determines that the absolute value of the difference between the current measured duty cycle and the previously measured duty cycle is greater than the first duty cycle threshold and the previously measured duty cycle is greater than the current measured duty cycle, and when the output voltage detection value increase / decrease determination unit determines that the absolute value of the difference between the current measured detection value and the previously measured detection value is greater than the first output voltage threshold and the current measured detection value is greater than the previously measured detection value, or when the duty cycle increase / decrease determination unit determines that the absolute value of the difference between the current measured duty cycle and the previously measured duty cycle is greater than the previously measured duty cycle, If the absolute value of the difference between the duty cycles is greater than the first duty cycle threshold and the previously measured duty cycle is less than the current measured duty cycle, and the output voltage detection value increase / decrease determination unit determines that the absolute value of the difference between the current measured detection value and the previously measured detection value is greater than the first output voltage threshold and the current measured detection value is less than the previously measured detection value, the current continuous / discontinuous mode determination unit determines that the circuit's operating state is a current discontinuous mode, and the integral term correction determination unit determines the integral term correction amount based on this determination result.

5. The control device for the power conversion circuit as described in claim 2, wherein, The value processed by moving average is used as at least one of the previously measured duty cycle and the current measured duty cycle.

6. The control device for the power conversion circuit as described in claim 4, wherein, The value processed by moving average is used as at least one of the previously measured duty cycle and the current measured duty cycle.

7. The control device for the power conversion circuit as described in claim 2, wherein, The value processed by the low-pass filter is used as at least one of the previously measured duty cycle and the current measured duty cycle.

8. The control device for the power conversion circuit as described in claim 4, wherein, The value processed by the low-pass filter is used as at least one of the previously measured duty cycle and the current measured duty cycle.

9. The control device for the power conversion circuit as described in claim 3, wherein, The value processed by moving average is used as at least one of the previously obtained corrected duty cycle and the currently obtained corrected duty cycle.

10. The control device for the power conversion circuit as described in claim 3, wherein, The value processed by the low-pass filter is used as at least one of the previously obtained correction duty cycle and the current correction duty cycle.

11. The control device for the power conversion circuit according to any one of claims 1 to 10, wherein, The value processed by moving average is used as the value of at least one of the previously measured detection value and the current measured detection value.

12. The control device for the power conversion circuit according to any one of claims 1 to 10, wherein, The value processed by the low-pass filter is used as at least one of the previously measured detection value and the current measured detection value.

13. The control device for the power conversion circuit according to any one of claims 1 to 10, wherein, The current continuity / discontinuity mode determination unit determines that the current is discontinuous if it determines that the current is discontinuous mode more than twice.

14. The control device for the power conversion circuit according to any one of claims 1 to 10, wherein, The electrical information is the voltage, current, or power input to the first terminal, or the voltage, current, or power output from the second terminal.

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