Power converter
The power converter with multiple legs and controlled switch timing corrects voltage imbalances in three-phase inverter circuits by adjusting main and auxiliary switch timings, ensuring consistent output.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- DENSO CORP
- Filing Date
- 2024-11-11
- Publication Date
- 2026-05-21
AI Technical Summary
In three-phase inverter circuits, differences in resonance waiting times between phases lead to variations in duty cycle ratios, resulting in voltage imbalances and reduced maximum output.
A power converter with multiple legs, each comprising a series circuit of high-potential and low-potential main switches, resonant capacitors, and a series circuit of auxiliary switches and a resonant inductor, controlled by a unit that corrects the ON timing of main and auxiliary switches to maintain intended ON time ratios.
The solution ensures that the voltage output by each leg matches the target value, even when main switch ON timings are delayed due to auxiliary switch operations.
Smart Images
Figure 2026084383000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a power converter that performs switching control in an ARCP (Auxiliary Resonant Commutated Pole) manner.
Background Art
[0002] For example, in Patent Document 1, in a DC / DC converter circuit provided with an ARCP circuit, a control unit 11A that controls main switches S1, S2 and resonant switches S3, S4, and a storage unit 12A that stores a first calculation formula regarding the operation timing for turning on the main switches S1, S2 are provided. The control unit 11A calculates a first time from when the resonant switches S3, S4 are turned on until the main switches S1, S2 are turned on based on the first calculation formula, and performs switching processing for turning on the main switches S1, S2 at the end of the first time, and controls to correct and update the first calculation formula so that the deviation amount between the intersection timing where the falling of the resonant current IL2 and the reactor current IL1 intersect and the operation timing decreases.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] Specifically, in Patent Document 1, after a first time T1 has elapsed since the resonant switch is turned on, control is performed to turn on the main switch. The first time T1 increases or decreases in proportion to the output current amount I load from the first calculation formula. In a DC / DC converter circuit such as Patent Document 1, since there is one leg of the main switch, the delay due to the first time T1 does not pose a problem.
[0005] However, in a three-phase inverter circuit, for example, the ON timing of the main switch in each leg may be different, leading to problems with output control. In other words, in three-phase AC, the line-to-line voltage of the output is determined by the relative ON duty cycle ratio of the UVW pulses. If there is a difference in the resonance waiting time of each phase, the duty cycle will differ. This can result in a difference in voltage between the three phases or a decrease in maximum output.
[0006] The present invention has been made in view of the above circumstances, and its object is to provide a power converter that includes a plurality of legs and an auxiliary switch corresponding to each leg, and that can control the output voltage so that it is as intended. [Means for solving the problem]
[0007] According to the power converter described in claim 1, the power conversion unit (12, 22) comprises a plurality of legs (4) each having a series circuit of a high-potential side main switch (S1) and a low-potential side main switch (S2), resonant capacitors (C1, C2) connected in parallel to each main switch, and a series circuit of two auxiliary switches (A1, A2) and a resonant inductor (L) that constitute a bidirectional switch, with one end connected to the common connection point of the two main switches and the other end connected to a common connection point. The control unit (13, 23, 32) controls each leg to perform soft switching and corrects the timing of switching the main switches or auxiliary switches so that the ON time ratio of the main switches between each leg is as intended.
[0008] With this configuration, even if the timing at which the main switches of each leg turn ON is expected to be delayed from the intended timing due to the switching operation of the auxiliary switches, the control unit corrects the ON time ratio of the main switches between each leg to be as intended. This allows the voltage difference output by each leg of the power conversion unit to be controlled to reach the target value.
[0009] According to the power converter described in claim 2, the ideal ON timing calculation unit (14) of the control unit (13) calculates the turn-on time and ideal ON timing of the main switch in order to obtain the target output from the power conversion unit (12). The main switch control unit (17) controls the switching of the main switch according to the turn-on time and ideal ON timing. The auxiliary switch ON timing correction unit (15) corrects the preset ON timing of the auxiliary switch, and the auxiliary switch control unit (16) controls the switching of the auxiliary switch according to the corrected ON timing.
[0010] Specifically, the auxiliary switch ON timing correction unit calculates the ON timing delay time of the main switch in accordance with the switching operation of the auxiliary switch, and corrects the ON timing of the auxiliary switch based on that ON timing delay time. By making this correction, the timing at which the main switch turns ON can be advanced by the delay time, making it match the ideal ON timing.
[0011] According to the power converter described in claim 3, the ON timing detection unit (24) of the control unit (23) detects the actual ON timing of the main switch in the power converter. The auxiliary switch ON timing correction unit further corrects the ON timing of the auxiliary switch so that the actual ON timing matches the ideal timing. As a result, even if there is a difference between the actual ON timing and the ideal timing of the main switch as a result of correction based on the calculated ON timing delay time, the additional correction can be used to control the system so that both timings match. [Brief explanation of the drawing]
[0012] [Figure 1] Figure 1 is a circuit diagram showing the power circuit section of the power converter in the first embodiment. [Figure 2] Figure 2 is a functional block diagram showing the overall configuration of the power converter. [Figure 3] Figure 3 is a flowchart showing the control details. [Figure 4]Figure 4 is a timing chart corresponding to the control details shown in Figure 3. [Figure 5] Figure 5 is a circuit diagram showing the power circuit section of the power converter in the second embodiment. [Figure 6] Figure 6 is a functional block diagram showing the overall configuration of the power converter. [Figure 7] Figure 7 is a flowchart showing the control process. [Figure 8] Figure 8 is a timing chart corresponding to the control details in Figure 7. [Figure 9] Figure 9 is a flowchart showing the control contents of the third embodiment. [Figure 10] Figure 10 is a timing chart corresponding to the control details in Figure 9. [Figure 11] Figure 11 is a functional block diagram showing the overall configuration of the power converter in the fourth embodiment. [Figure 12] Figure 12 is a flowchart showing the control process. [Figure 13] Figure 13 is a timing chart corresponding to the control details in Figure 12. [Figure 14] Figure 14 is a circuit diagram that primarily shows the power circuit section of a power converter when the legs are arranged in a parallel configuration of three. [Figure 15] Figure 15 shows a mathematical formula. [Modes for carrying out the invention]
[0013] (First Embodiment) As shown in Figure 1, the ARCP-type power circuit section 1 of this embodiment is connected in parallel to the DC power supply 3 together with a series circuit of capacitors 2a and 2b. The power circuit section 1 is configured by connecting legs 4(n) and 4(n+1) in parallel. Leg 4 includes a series circuit of a high-potential side main switch S1 and a low-potential side main switch S2 connected in parallel to the DC power supply 3, auxiliary switches A1 and A2 connected between the midpoint of capacitors 2a and 2b, i.e., the neutral point, and the common connection point of main switches S1 and S2, and a series circuit of an inductor L.
[0014] In this embodiment, the main switches S1 and S2 and the auxiliary switches A1 and A2 are all, for example, N-channel MOSFETs. Parasitic diodes of each FET are shown with simplified symbols. The series circuit of auxiliary switches A1 and A2 is a bidirectional switch, connected such that, for example, their sources or drains are common. Capacitors C1 and C2, consisting of parasitic capacitances or added capacitors, are connected in parallel to the main switches S1 and S2.
[0015] Main switch S1 is the output terminal of Leg 4(n) n and S2 n The common connection point and the main switch S1, which is the output terminal of leg 4 (n+1). n+1 and S2 n+1 A load 5 is connected between the common connection point. A current sensor 6 is positioned between the output terminal of leg 4(n) and load 5.
[0016] As shown in Figure 2, the power converter 11 of this embodiment comprises a power conversion unit 12 including a power circuit unit 1 and a control unit 13. The main SW ideal ON timing calculation unit 14 of the control unit 13 receives a target output from a higher-level control device (not shown) and the load current I detected by the current sensor 6. load The amount of current is input. The main switch ideal ON timing calculation unit 14 calculates the ideal ON timing of the main switches S1 and S2 based on the input signals and outputs it to the auxiliary switch ON timing correction unit 15 and the main switch output control unit 17.
[0017] The auxiliary SW_ON timing correction unit 15 corrects the ON timing of the auxiliary switches A1 and A2 based on the input signal, and outputs correction information to the auxiliary SW output control unit 16. The auxiliary SW output control unit 16 calculates the switching timing of the auxiliary switches A1 and A2 based on the above correction information, and outputs a switching control signal to the gate drive unit 18 of the power conversion unit 12.
[0018] Next, the operation of this embodiment will be described with reference to FIGS. 3 and 4. First, the main SW ideal ON timing calculation unit 14 of the control unit 13 calculates the ideal ON timing TR n , S2 n of the main switches S1 n in each leg 4 to obtain the target output, and the ON time TO n (S1). Let the ideal switching waveform of the main switch S1 shown in FIG. 4 be Sr n . Here, the ideal ON timing is an arbitrary timing obtained by output control. n
[0019] Also, the optimal SW timing Tw n which is the ON timing of the auxiliary switches A1 n , A2 n required for soft switching each leg 4 with zero current switching; ZCS n is tentatively calculated. The optimal SW timing Tw n is calculated by the formula (1) shown in FIG. 15 so as to estimate the resonance current I load from the output current I rn and the inductance L and capacitor C for resonance in each leg 4. Here, the optimal SW timing Tw n may also use a map calculated and set in advance. In the ARCP method, when the polarity of the output current is positive, a positive current is passed through the inductor L by the auxiliary switch A1 n , and when the polarity of the output current is negative, a negative current is passed through the inductor L by the auxiliary switch A2 n . Hereinafter, the case where the polarity of the output current is positive will be described.
[0020] Next, the auxiliary SW_ON timing correction unit 15 calculates the ideal ON timing TR to obtain the target output. n The provisionally calculated optimal SW timing Tw n The difference between Terr n Calculate and use that for auxiliary switch A1 n A2 n This value is used to correct the timing (S2). Then, the calculated correction value Terr n Auxiliary switch A1 n A2 n The ON timing is corrected, and the auxiliary SW output control unit 16 controls the auxiliary switch A1 n A2 n Switching control is performed (S3). Differential Terr n This corresponds to the delay time.
[0021] Next, the main SW output control unit 17 controls the main switch S1 n S2 n Switching control is performed (S4). As shown in the "corrected" timing chart in Figure 4, auxiliary switch A1 n A2 n The ON timing of the main switch S1 has been corrected. n S2 n The ON timing will match the ideal ON timing. Furthermore, when the output current polarity is negative, the main switch S2 and auxiliary switch A2 should be controlled similarly.
[0022] As described above, according to this embodiment, the power conversion unit 1 of the power converter 11 comprises a plurality of legs 4, each having a series circuit of a high-potential side main switch S1 and a low-potential side main switch S2, resonant capacitors C1 and C2 connected in parallel to each main switch S1 and S2, and a series circuit of two auxiliary switches A1 and A2 and a resonant inductor L, one end of which is connected to the common connection point of the main switches S1 and S2 and the other end of which is connected to a common connection point. The control unit 13 controls each leg 4 to perform soft switching and corrects the timing of switching the auxiliary switches A1 and A2 so that the ON time ratio of the main switches S1 and S2 between each leg 4 is as intended.
[0023] With this configuration, even if the timing at which the main switches S1 and S2 of each leg 4 turn ON is expected to be delayed from the intended timing due to the switching operation of auxiliary switches A1 and A2, the control unit 13 can correct the ON time ratio of the main switches between each leg 4 to be as intended, thereby controlling the voltage difference output by each leg 4 to be at the target value.
[0024] Then, the main switch ideal ON timing calculation unit 14 of the control unit 13 calculates the turn ON time of the main switches S1 and S2 to obtain the target output from the power conversion unit 12. n and ideal ON timing TR n The main SW output control unit 17 calculates the turn ON time TO n and ideal ON timing TR n The main switches S1 and S2 are switched accordingly. The auxiliary SW_ON timing correction unit 15 corrects the preset ON timing of the auxiliary switches A1 and A2, and the auxiliary SW output control unit 16 controls the switching of the auxiliary switches A1 and A2 according to the corrected ON timing.
[0025] Specifically, the auxiliary SW_ON timing correction unit 15 adjusts the ON timing delay time Terr of the main switches S1 and S2 according to the switching operation of the auxiliary switches A1 and A2. nCalculate the ON timing delay time Terr n Based on this, the ON timing of auxiliary switches A1 and A2 is corrected. By correcting in this way, the timing at which main switches S1 and S2 turn ON is delayed by a delay time Terr n By moving it forward by a few minutes, the ideal ON timing TR n It can be matched to that.
[0026] (Second Embodiment) In the following description, parts identical to those in the first embodiment are denoted by the same reference numerals and their descriptions are omitted, while the differences are described. As shown in Figure 5, in the power circuit section 21 of the second embodiment, the main SW_ON timing detection circuit sections 7(n) and 7(n+1), whose official names are shown in Figure 6, are connected to the output terminals of leg 4(n) and leg 4(n+1), respectively.
[0027] As shown in Figure 6, the power converter 20 comprises a power conversion unit 22 including a power circuit unit 21 and a control unit 23. The main SW_ON timing detection unit 24 of the control unit 23 receives detection signals for the ON timing of the main switches S1 and S2 from the main SW_ON timing detection circuit unit 7 of the power conversion unit 21. The ON timing of the main switches S1 and S2 detected by the main SW_ON timing detection unit 24 is input to the auxiliary SW_ON timing correction unit 15. The auxiliary SW_ON timing correction unit 15 corrects the ON timing of the auxiliary switches A1 and A2 based on the input signals, and makes additional corrections as described later, and outputs the correction information to the auxiliary SW output control unit 16. The auxiliary SW output control unit 16 also outputs the switching control signals of the auxiliary switches A1 and A2 to the main SW output control unit 17.
[0028] Next, the operation of the second embodiment will be described with reference to Figures 7 and 8. The flowchart shown in Figure 7 is executed following steps S1 to S4 of the first embodiment. When step S4 is executed, the main SW_ON timing detection unit 24 of the control unit 23 detects the main switch S1 in real time. n S2 n The actual ON timing Son is the result of the operation. nDetects (S5). Specifically, for example, the main switch S1 n S2 n The drain-source voltage Vds is measured, and when this voltage Vds falls below a threshold, for example, 10% of the input voltage Vin, the actual ON timing Son is set. n It detects the following. Note that when the polarity of the output current is positive, the main switch S1 n When the same polarity is negative, the main switch S2 n Drain-source voltage Use Vds.
[0029] Next, the actual ON timing Son n And, the ideal ON timing TR n Difference from Terr2 n When this is detected (S6), the auxiliary SW_ON timing correction unit 15 performs an additional correction (S7). As a result, as shown in the timing chart of "additional correction" in Figure 8, the actual ON timing Son is corrected as a result of the correction in the first embodiment. n And the ideal ON timing TR n Even if there is a difference, the ON timing of the main switches S1n and S2n can be made to match the ideal ON timing.
[0030] (Third embodiment) The configuration of the third embodiment is the same as that of the first embodiment, but the control content is different. As shown in Figures 9 and 10, in the third embodiment, step S8 is executed instead of step S2. That is, auxiliary switch A1 in leg 4(n) n A2 n The timing is not corrected, and the ideal ON timing TR n For the (n+1) and subsequent legs 4, the provisionally calculated optimal SW timing Tw n+1 The difference with Terr n Calculated as, and the difference Terr n Based on this, the timing of auxiliary switches A1 and A2 from leg 4(n+1) onwards is corrected.
[0031] In the third embodiment, leg 4(n) corresponds to the master leg, and leg 4(n+1) corresponds to the slave leg. Even with this control, the ON time ratio of the main switches S1 and S2 between each leg 4 can be corrected to be as intended.
[0032] (Fourth Embodiment) As shown in Figure 11, the power converter 31 of the fourth embodiment includes a control unit 32 that replaces the control unit 13 in the power converter 11 of the first embodiment. In the control unit 32, the auxiliary SW_ON timing correction unit 15 has been removed, and instead, a main SW_OFF timing correction unit 33 is arranged between the main SW ideal ON timing calculation unit 14 and the main SW output control unit 17.
[0033] Next, the operation of the fourth embodiment will be explained with reference to Figures 12 and 13. As shown in Figure 12, in the fourth embodiment, step S9 is executed instead of step S2 to correct the OFF timing of the main switches S1 and S2. The first to third embodiments were control systems that assumed the OFF timing of the main switches S1 and S2 were fixed.
[0034] In contrast, in the fourth embodiment, as shown in Figure 14, the main SW_OFF timing correction unit 33 corrects the ideal ON timing TR, similar to the first embodiment. n The provisionally calculated optimal SW timing Tw n The difference between Terr n When you calculate the difference, Terr n Based on this, the OFF timing of main switches S1 and S2 is corrected. Even with this control, the ON time ratio of main switches S1 and S2 between each leg 4 can be corrected to be as intended.
[0035] (Other embodiments) Figure 14 shows a configuration where the load is a three-phase motor, and the power conversion unit has three legs 4 corresponding to it. Furthermore, the number of legs 4 may be more than four. Each switch is not limited to an N-channel MOSFET. This disclosure is described in accordance with the embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the equivalence. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and concept of this disclosure. [Explanation of Symbols]
[0036] In the diagram, 1 is the power circuit section, 3 is the DC power supply, 4 is the REG, 11 is the power converter, 12 is the power conversion section, 13 is the control section, 14 is the main switch ideal ON timing calculation section, 15 is the auxiliary switch ON timing correction section, 16 is the auxiliary switch output control section, 17 is the main switch output control section, S1 is the high-potential side main switch, S2 is the low-potential side main switch, A1 and A2 are auxiliary switches, L is an inductor, and C1 and C2 are capacitors.
Claims
1. A series circuit of a high-potential side main switch (S1) and a low-potential side main switch (S2), Resonant capacitors (C1, C2) are connected in parallel to the high-potential main switch and the low-potential main switch, respectively. A power conversion unit (12, 22) having a series circuit of two auxiliary switches (A1, A2) which are two transistors having a common drain or emitter and which constitute a bidirectional switch, and a resonant inductor (L), with one end connected to the common connection point of the high-potential side main switch and the low-potential side main switch and the other end connected to a common connection point, and a series circuit of a resonant inductor (L), wherein each leg (4) is provided, This power conversion unit includes a control unit (13, 23, 32) that controls the switching of each switch constituting this power conversion unit, The control unit controls each leg to perform soft switching, A power converter that corrects the timing of switching the main switch or the auxiliary switch so that the ON time ratio of the main switch between each leg is as intended.
2. The control unit (13) An ideal ON timing calculation unit (14) calculates the turn-on time and ideal ON timing of the main switch in order to obtain the target output from the power conversion unit (12), A main switch control unit (17) that controls the switching of the main switch according to the turn-on time and the ideal ON timing, An auxiliary switch ON timing correction unit (15) corrects the preset ON timing of the auxiliary switch, The system includes an auxiliary switch control unit (16) that performs switching control of the auxiliary switch according to the corrected ON timing, The power converter according to claim 1, wherein the auxiliary switch ON timing correction unit calculates the ON timing delay time of the main switch in accordance with the switching operation of the auxiliary switch, and corrects the ON timing of the auxiliary switch based on the ON timing delay time.
3. The control unit (23) includes an ON timing detection unit (24) that detects the actual ON timing of the main switch in the power conversion unit (22). The power converter according to claim 2, wherein the auxiliary switch ON timing correction unit further corrects the ON timing of the auxiliary switch so that the actual ON timing matches the ideal timing.
4. If one of the aforementioned multiple legs is designated as the master leg (4(n)) and the other legs as slave legs (4(n+1)), The control unit (23) An ideal ON timing calculation unit (14) calculates the turn-on time and ideal ON timing of the main switch in each leg in order to obtain the target output from the power conversion unit, A main switch control unit (17) that controls the switching of the main switch according to the turn-on time and the ideal ON timing, An auxiliary switch ON timing correction unit (15) corrects the preset ON timing of the auxiliary switch in the slave leg according to the ideal ON timing, The system includes an auxiliary switch control unit (16) that controls the switching of the auxiliary switch of the slave leg according to the corrected ON timing, The power converter according to claim 1, wherein the auxiliary switch ON timing correction unit calculates the difference between the ideal timing in the master leg and the ideal timing in the slave leg, and corrects the ON timing of the auxiliary switch in the slave leg according to the difference.
5. The control unit (32) An ideal ON timing calculation unit (14) calculates the turn-on time and ideal ON timing of the main switch in order to obtain the target output from the power conversion unit, A main switch control unit (17) that controls the switching of the main switch according to the turn-on time and the ideal ON timing, An auxiliary switch control unit (16) that controls the switching of the auxiliary switch, The power converter according to claim 1, further comprising: a main switch OFF timing correction unit (33) that calculates an ON timing delay time of the main switch in accordance with the switching operation of the auxiliary switch, and corrects the OFF timing of the main switch based on the ON timing delay time.