Power converter

Abstract

This invention provides a power converter that can detect better soft switching timing and suppress switching losses even when the amplitude of the soft switching resonant voltage changes due to fluctuations in the power supply voltage, etc. [Solution] The control unit 10 measures the period from the ON timing t0 of the auxiliary switch 34 to the resonance start timing t1, and measures the period from the resonance start timing t1 to the resonance center timing t2 (function of the measurement unit 13). Based on the measurement results, the control unit 10 estimates the resonance end timing t3, calculates the time from the ON timing t0 of the auxiliary switch 34 to the resonance end timing t3 to calculate the switching timing, and turns on the main switch S1 at that switching timing.

Description

[Technical Field]

[0001] This invention relates to a power conversion device. [Background technology]

[0002] Soft switching technology is attracting attention as a way to reduce the switching losses that have increased due to higher frequencies. Hereafter, switching will be referred to as SW. In ARCP-type soft switching technology, which is one type of soft switching technology, the ON timing of the auxiliary switch and the ON timing of the main switch are important for soft switching to be realized.

[0003] Specifically, switching must be performed at ZVS (Zero Voltage Switching) or ZCS (Zero Current Switching) timings, and methods for detecting ZVS and correcting the timing have been proposed conventionally. To detect this timing, there are methods for detecting current crossovers and methods for detecting the minimum value of the drain-source voltage of the main switch (hereinafter referred to as voltage Vds). Using the method of detecting current crossovers has disadvantages such as delays due to filters and costs. For this reason, a method for detecting the minimum value of voltage Vds has been proposed (see, for example, Patent Document 1).

[0004] In the technology described in Patent Document 1, the optimal timing is defined as the timing when the resonant voltage of voltage Vds becomes zero. Detecting this requires that the resonant voltage of voltage Vds be approximately zero. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2003-363643 [Overview of the project] [Problems that the invention aims to solve]

[0006] For example, if the resonant voltage amplitude of voltage Vds does not attenuate to zero voltage, zero voltage becomes undetectable. If zero voltage cannot be detected, the switch cannot be turned on at the appropriate timing, soft switching does not occur, and this causes an increase in switching losses. Specifically, this becomes a problem when the neutral voltage E / 2 fluctuates or when the amplitude is attenuated due to the effects of the inductor's ESR, for example.

[0007] The purpose of this disclosure is to provide a power converter that can detect appropriate soft switching timing and suppress switching losses even when the amplitude of the soft switching resonant voltage changes due to voltage fluctuations of the DC power supply, etc. [Means for solving the problem]

[0008] The invention described in claim 1 relates to an ARCP-type power conversion device equipped with a power conversion unit that drives a load using a DC power supply. The power conversion unit comprises a neutral voltage generation unit that generates a neutral voltage from a DC power supply to a neutral node, main switches constituting upper and lower arms, resonant capacitors connected in parallel to the main switches of the upper and lower arms, a series circuit of an auxiliary switch and a resonant inductor connected between the neutral node of the neutral voltage generation unit and the common connection point of the main switches of the upper and lower arms, a first voltage detection unit that detects the voltage of the parallel circuit of the main switches and the resonant capacitors constituting the upper and lower arms, and a second voltage detection unit that detects the resonant voltage generated in the series circuit.

[0009] The first voltage detection unit detects the resonance start timing according to the positive / negative condition of the current supplied to the load using the detected voltage, and the second voltage detection unit detects the resonance center timing, which is the timing when the resonance voltage changes from positive to negative or negative to positive. The control unit includes a measurement unit that measures the period from the ON timing of the auxiliary switch to the resonance start timing, and the period from the resonance start timing to the resonance center timing.

[0010] The control unit estimates the resonance termination timing based on the measurement results from the measurement unit, calculates the switching timing by calculating the time from the ON timing of the auxiliary switch to the resonance termination timing, and turns on the main switch at that switching timing. According to the invention described in claim 1, even if the amplitude of the soft switching resonance voltage changes due to voltage fluctuations of the DC power supply, an appropriate soft switching timing can be detected and switching losses can be suppressed. [Brief explanation of the drawing]

[0011] [Figure 1] This is an electrical configuration diagram illustrating the first embodiment and schematically showing the power conversion device. [Figure 2] A schematic diagram illustrating the functions of the control unit in the first embodiment. [Figure 3] Example 1 of the electrical configuration of the first voltage detection unit in the first embodiment [Figure 4] A schematic electrical configuration diagram showing the connection portion of the first voltage detection unit in the first embodiment. [Figure 5] Example 2 of the electrical configuration of the first voltage detection unit in the first embodiment [Figure 6] Example of electrical configuration of the second voltage detection unit in the first embodiment [Figure 7] Flowchart showing the processing content by the control unit in the first embodiment [Figure 8] A timing chart schematically shows the changes in each signal in response to time in the first embodiment. [Figure 9] A timing chart schematically shows the changes in each signal over time for the configuration of the comparative example. [Figure 10] A schematic electrical diagram showing the power conversion device in a modified example. [Figure 11] A schematic diagram illustrating the functions of the control unit in the second embodiment. [Figure 12] Flowchart showing the processing content by the control unit in the second embodiment [Figure 13]This is an electrical configuration diagram illustrating a third embodiment and schematically showing the power conversion device. [Figure 14] A schematic diagram illustrating the functions of the control unit in the fourth embodiment. [Figure 15] Flowchart showing the processing content by the control unit in the fourth embodiment [Modes for carrying out the invention]

[0012] The following describes several embodiments of the power conversion device. Parts that perform the same function between embodiments may be denoted by the same reference numerals and their descriptions may be omitted.

[0013] (First Embodiment) The first embodiment will be described with reference to Figures 1 to 10. Figure 1 shows an example of the configuration of a power converter 1 using the ARCP method, which includes a power conversion unit 30. The power converter 1 is a device that converts a DC power supply 20 into power and supplies power to a load L. The load L is an electrical load that is normally supplied with power. When the power converter 1 is configured as a DC-DC converter, for example, the current supplied to the electrical load L, such as an inductive load (hereinafter referred to as load current I) is supplied. load They supply (which they call).

[0014] A power conversion unit 30 is connected to the DC power supply 20. The power conversion unit 30 consists of a neutral voltage generation unit 30a, main switches S1 and S2, and a resonant capacitor C. r1 , C r2 , auxiliary switch 34 and series circuit 31 of resonant inductor Lr, first voltage detection unit 41, 42, second voltage detection unit 43, load current I load The system includes a current sensor 44 for detecting current and a control unit 10. The neutral voltage generation unit 30a is composed of two voltage generation capacitors C1 and C2 connected in parallel to the DC power supply 20, which divide the power supply voltage Vdd to generate a neutral voltage at the neutral node Na.

[0015] Main switches S1 and S2 constitute the upper and lower arms 35. Resonant capacitor C r1 , C r2are connected in parallel to main switches S1 and S2 of the upper and lower arms 35, respectively. Node Nb, which serves as a common connection point for main switches S1 and S2, is connected to load L via current sensor 44.

[0016] The upper arm-side main switch S1 includes a MOSFET and a freewheeling diode connected in parallel to the MOSFET. The lower arm-side main switch S2 includes a MOSFET and a freewheeling diode connected in parallel to the MOSFET. The aforementioned freewheeling diodes are parasitic diodes of the respective MOSFETs of the upper and lower arms 35. Node Nb, which serves as the common connection point for main switches S1 and S2, is an output terminal of the power conversion unit 30 and is connected to a supply terminal of load L.

[0017] The auxiliary switch 34 is configured by two N-channel MOSFETs A1 and A2 with their drains commonly connected. The series circuit 31 is connected between neutral node Na, which is the common connection point of voltage generating capacitors C1 and C2, and node Nb, which is the common connection point of main switches S1 and S2 of the upper and lower arms 35.

[0018] The first voltage detection unit 41 detects the voltage of the parallel circuit of the main switch S1 constituting the upper arm and the resonance capacitor C r1 . The first voltage detection unit 42 detects the voltage of the parallel circuit of the main switch S2 constituting the lower arm and the resonance capacitor C r2 . The second voltage detection unit 43 detects the resonance voltage V generated in the series circuit 31 r .

[0019] The control unit 10 is configured of a microcomputer or the like, and performs switching control on main switches S1 and S2 that constitute the upper and lower arms 35 of the power conversion unit 30. The control unit 10 also controls turning on and off of the auxiliary switch 34.

[0020] Figure 2 shows the functions of the control unit 10. The control unit 10 includes a main switch drive unit 11 for driving the main switches S1 and S2, an auxiliary switch drive unit 12 for driving the auxiliary switch 34, a counter 13, and first voltage detection units 41 and 42 that detect the voltage V ds1 , V ds2 The drain-source voltage acquisition unit 14 acquires the resonant voltage V generated across the series circuit 31. r It includes a resonant voltage acquisition unit 15, a calculation unit 16, and a standby time control unit 17 to acquire the resonant voltage.

[0021] Counter 13 is used during the period T described below. wait , T r1 It is provided to measure and consists of a first measurement unit and a second measurement unit. The calculation unit 16 measures the period T described later. r2 It is provided to calculate the waiting time control unit 17. The waiting time control unit 17 is provided to wait for the period determined by the counter 13 and the calculation unit 16.

[0022] <Specific examples of the first voltage detection units 41 and 42> Specific examples of the first voltage detection units 41 and 42 are shown in Figure 3. The first voltage detection units 41 and 42 each include a first amplifier AMP1 that takes an input voltage Vin as input and amplifies it, and a first comparator CMP1. The inverting input terminal of the first comparator CMP1 is grounded to the ground node through a resistor R1.

[0023] The output of the first amplifier AMP1 is applied to the non-inverting input terminal of the first comparator CMP1. The first comparator CMP1 compares the output of the first amplifier AMP1 with the ground potential, and the timing at which it crosses zero V is defined as its outputs out1 and out2. Outputs out1 and out2 are input to the drain-source voltage acquisition unit 14 of the control unit 10.

[0024] <Modified versions of the first voltage detection units 41 and 42> Instead of the first voltage detection units 41 and 42, first voltage detection units 141 and 142 may be provided, connected as shown in Figure 4. As illustrated in Figure 5, the first voltage detection units 141 and 142 input the divided voltages obtained by dividing a predetermined threshold voltage Vt using voltage divider resistors R2 and R3 to the inverting input terminal of comparator CMP3. Alternatively, the first voltage detection units 141 and 142 input the divided voltages obtained by dividing a predetermined threshold voltage Vt using voltage divider resistors R4, R5 and R6 to the non-inverting input terminal of comparator CMP3.

[0025] The first voltage detection units 141 and 142 then detect the input voltage V in The voltage is input to comparator CMP3 via reverse-connected diode D1 and resistor R7, and then through voltage divider resistors R4~R6. Comparator CMP3 receives the input voltage V in The system is configured to change the logical levels of outputs out1 and out2 when a threshold is crossed. A similar configuration can be achieved with this type of setup.

[0026] <Specific example of the second voltage detection unit 43> The second voltage detection unit 43 detects the resonant voltage V generated in the series circuit 31. r The system detects the voltage. A specific example is shown in Figure 1. The second voltage detection unit 43 includes a first amplifier AMP2, a second amplifier AMP3, and a comparator CMP2. The first amplifier AMP2 detects and amplifies the voltage between the neutral node Na and the ground node and inputs it to the inverting input terminal of the comparator CMP2. The second amplifier AMP3 detects and amplifies the voltage between node Nb and the ground node and inputs it to the non-inverting input terminal of the comparator CMP2.

[0027] The comparator CMP2 compares the output of the first amplifier AMP2 and the output of the second amplifier AMP3 to determine which is larger, and outputs the result of this determination as output out3. This output out3 is input to the resonant voltage acquisition unit 15 of the control unit 10. The control unit 10 detects the timing when the voltage acquired by the resonant voltage acquisition unit 15 reverses from positive to negative, or from negative to positive, thereby detecting the timing when it crosses zero V.

[0028] <Modified example of the second voltage detection unit 43> Instead of the second voltage detection unit 43, a second voltage detection unit 143, as shown in Figure 6, may be provided. The second voltage detection unit 143 is mainly composed of a comparator CMP4. The inverting input terminal of the comparator CMP4 is connected to the neutral node Na via a voltage divider circuit using resistors R8 and R9, and resistor R10 and diode D2. The non-inverting input terminal of the comparator CMP4 is connected to the voltage V at node Nb via a voltage divider circuit using resistors R11, R12, and R13 that divide the threshold voltage Vt, and resistor R14 and diode D3. ds It is configured to take the input V. With this configuration, the comparator CMP4 will take the input voltage V in The resulting resonant voltage V r The system is configured to change the logical level of output out3 when the threshold is crossed.

[0029] The operation of the above configuration will now be explained. The control unit 10 complementaryly switches the main switches S1 and S2 of the upper and lower arms 35 to control the supply of power to the load L. The control unit 10 also uses the auxiliary switch 34 to perform soft switching operation using the ARCP (Auxiliary Resonant Commutated Pole) method.

[0030] Figure 7 shows the operation flow, and Figure 8 shows the load current I load This diagram schematically shows the change in the on / off state of the auxiliary switch 34 along with the change in the on / off state of the main switch S1 of the upper arm when the condition is positive.

[0031] As shown in Figure 7, the control unit 10 turns on the auxiliary switch 34 at timing t0 (S11). The resonant voltage V across the series circuit 31 r When the polarity becomes negative, the control unit 10 turns on the auxiliary switch 34 at timing t0, causing a resonant current I r The number begins to increase.

[0032] The control unit 10 detects the voltage V of the first voltage detection units 41 and 42. ds1 , V ds2 Using the load current I loadThe resonance start timing t1 is detected and determined according to the positive / negative condition of (S12). For example, as shown in Figure 8, the load current I load When it is positive, the detected voltage V of the first voltage detection unit 41 ds1 Using the detected voltage V ds1 Power supply voltage V dd The timing of the change from is detected as the resonance start timing t1. Specifically, the load current I load When it is positive, the detected voltage V of the first voltage detection unit 41 ds1 Power supply voltage V dd The timing at which the signal deviates from a predetermined range is detected as the resonance start timing t1.

[0033] In addition, the detected voltage V of the first voltage detection unit 42 ds2 Using the detected voltage V ds2 The timing at which the value deviates from zero may be detected as the resonance start timing t1. Specifically, the detected voltage V of the first voltage detection unit 42 may be used. ds2 It is preferable to detect the timing at which the value deviates from zero to a predetermined range as the resonance start timing t1.

[0034] Then, the counter 13 of the control unit 10 measures the period T from the ON timing t0 of the auxiliary switch 34 to the resonance start timing t1. wait The value is measured by counting it using counter 13 (S12a: Function of the measurement unit).

[0035] Subsequently, the control unit 10 acquires the output of the second voltage detection unit 43 from the resonant voltage acquisition unit 15 and determines the resonant voltage V r The timing t2 at which the value changes from negative to positive is detected (S13). The counter 13 of the control unit 10 detects the period T from the resonance start timing t1 to the resonance center timing t2. r1 Measure the following (S13a: Function of the measurement unit).

[0036] The control unit 10 controls the period T between timings t1 and t2. r1 Based on the timing t2~t3 period T r2 The resonance voltage V is calculated (S14), and the resonance termination timing t3 is estimated based on the measurement results. rSince the period is constant, in an ideal state, the period T r1 = period T r2 This is considered to be the case. Specifically, for example, during period T r1 is period T r2 We consider this to be the same time period and determine the resonance termination timing t3.

[0037] The control unit 10 calculates the period T r2 The control unit 210 waits for a specified time (S15: function of the waiting time control unit 17). Then the control unit 210 turns on the main switch S1 (S16). In other words, the control unit 10 calculates the time from the ON timing t0 of the auxiliary switch 34 to the end timing t3 of the resonance, calculates the switching timing of the main switch S1, and turns on the main switch S1 at that switching timing.

[0038] Subsequently, the control unit 10 controls the period T wait Wait for this amount of time (S17: Function of the waiting time control unit 17). wait This is the same time as the time between timings t0 and t1 determined above. Then the control unit 10 turns off the auxiliary switch 34 at timing t4 (S19). As illustrated in Figure 8, the resonant current Ir gradually decreases from timing t2 to t4, and becomes negative after timing t4. Here, the ON operation of the main switch S1 has been described, but after turning off the main switch S1, the process moves on to turning on the main switch S2.

[0039] <Load current I load If it is negative > In the above, the load current I load The example given was for the positive case, but now we will explain the operation for the negative case. Load current I load When the value is negative, the operation is symmetrical to the one described above, so the diagram is omitted. In this case, the auxiliary switch 34 is in the off state, and both main switches S1 and S2 are in the off state. The timing for turning on the main switch S2 is measured by soft switching control.

[0040] Load current I load When it is negative, the detected voltage V of the first voltage detection unit 42 ds2 Using the detected voltage V ds2 Power supply voltage V dd The timing of the change from is detected as the resonance start timing t1. Specifically, the load current I load When it is negative, the detected voltage V of the first voltage detection unit 42 ds2 Power supply voltage V dd The timing at which the signal deviates from a predetermined range is detected and determined as the resonance start timing t1.

[0041] Alternatively, load current I load When it is positive, the detected voltage V of the first voltage detection unit 41 ds1 Using the detected voltage V ds1 The timing at which the value deviates from zero may be detected as the resonance start timing t1. Specifically, the detected voltage V of the first voltage detection unit 41 ds1 The timing at which the value deviates from zero to a predetermined range is detected and determined as the resonance start timing t1.

[0042] The control unit 10's counter 13 measures the period from the ON timing t0 of the auxiliary switch 34 to the resonance start timing t1 by counting the time (function of the measurement unit). The control unit 10 also acquires the output of the second voltage detection unit 43 from the resonance voltage acquisition unit 15 and obtains the resonance voltage V r The system detects the resonance center timing t2, which is the timing when the signal changes from positive to negative. The counter 13 of the control unit 10 measures the period from the resonance start timing t1 to the resonance center timing t2 (function of the measurement unit).

[0043] The control unit 10 controls the period T between timings t1 and t2. r1 Based on the timing t2~t3 period T r2 The resonance voltage V is calculated, and the resonance termination timing t3 is estimated based on the measurement results. r Since the period is constant, in an ideal state, the period T r1 = period T r2 This is considered to be the case. Therefore, specifically, for example, period T r1 is period T r2The resonance termination timing t3 is determined by considering it to be the same time. The control unit 10 calculates the time from the ON timing t0 of the auxiliary switch 34 to the resonance termination timing t3, calculates the switching timing of the main switch S2, and turns on the main switch S2 at that switching timing. In this way, soft switching control can be realized.

[0044] <Technology of the comparative example> Figure 9 shows a diagram corresponding to Figure 8 for the technology of the comparative example. When soft switching is performed, if the voltages of voltage generating capacitors C1 and C2 (neutral voltage) are matched, the detection voltage V of the main switch S1 is ds1 , Main switch S2 detection voltage V ds2 The amplitudes of all of them are sufficient. Therefore, as shown in the upper part of Figure 9, the detected voltage V ds1 (or V ds2 The main switch S1 can be controlled to turn on by detecting when the value becomes zero.

[0045] However, if the neutral voltages of voltage generating capacitors C1 and C2 do not match between the upper and lower arms, especially if the neutral voltage shifts to less than half, the detected voltage V ds1 or detected voltage V ds2 There are cases where the voltage amplitude becomes smaller. In particular, the voltage across capacitor C2 V hf2 The voltage across the voltage generating capacitor C1 is V hf1 In cases where the value is significantly smaller, the detection voltage V of the main switch S1 is as shown in the lower diagram of Figure 9. ds1 This will result in insufficient amplitude.

[0046] The lower part of Figure 9 shows the load current I load This shows an example when the output is positive, and the voltage across capacitor C1 is V hf1 >Voltage across voltage generating capacitor C2 hf2 Detection becomes difficult at this time. Although not shown in the diagram, the load current I load When the output is negative, conversely, the voltage across the voltage generating capacitor C1 is V hf1 <Voltage across voltage generating capacitor C2> hf2detection becomes difficult at this time.

[0047] Therefore, the detected voltage V ds1 , V ds2 has a fluctuating amplitude, which changes the timing at which the resonance voltage V r crosses zero. As a result, the timing at which the detected voltage V ds1 or V ds2 becomes zero cannot be detected, making soft switching control difficult. If the main switches S1 and S2 cannot be turned on at an appropriate timing, the loss reduction effect will decrease.

[0048] The detected voltage V ds1 or V ds2 is not limited to the method of obtaining the detection timing when the voltage becomes 0V; a method of performing switching when a condition that the voltage is equal to or less than a threshold is satisfied can also be used. However, as a trade-off, the detection timing is advanced during normal operation, which may cause deviation from the appropriate timing.

[0049] <Summary of the Present Embodiment> In contrast, in the present embodiment, the detection voltages V of the first voltage detection units 41 and 42 ds1 , V ds2 are used to detect the resonance start timing t1 according to the positive / negative condition of the load current I load , and the second voltage detection unit 43 detects the resonance center timing t2, which is the timing at which the resonance voltage V r changes from positive to negative or from negative to positive.

[0050] The control unit 10 measures the period T from the on-timing t0 of the auxiliary switch 34 to the resonance start timing t1 r1 , sets a period T r1 as a period equal to the aforementioned period T r2 , measures the period T from the resonance start timing t1 to the resonance center timing t2 r2 , estimates the resonance end timing t3 based on the measurement result. The control unit 10 calculates the time from the on-timing t0 of the auxiliary switch 34 to the resonance end timing t3 to obtain the timing t3, and turns on the main switches S1 and S2 at the timing t3.

[0051] By performing the control described above, the resonance start timing t1 and the resonance center timing t2 are detected in succession. Based on the ON timing t0 of the auxiliary switch 34, the resonance start timing t1, and the resonance center timing t2, the resonance end timing t3 is estimated. This timing t3 is then used as the switching timing to turn on the main switch S1, thereby enabling soft switching control. When this method is adopted, the drain-source voltage V ds Since it doesn't refer to the minimum value, there's no need to search for it.

[0052] Furthermore, since the soft switching process utilizes resonance processing, the resonant voltage V r It always crosses zero V. Therefore, detection becomes more reliable and easier than with the comparative example's technology. This allows for soft switching control to minimize switching power loss. Furthermore, it can be implemented without using high-speed, high-performance current detectors.

[0053] (Variation in connection configuration of the second voltage detection unit 43) Figure 10 shows a modified configuration of the connection of the second voltage detection unit 43. In the configuration described above, the input node of the first amplifier AMP2 constituting the second voltage detection unit 43 was set to the neutral node Na, but it is not limited to this, and as shown in Figure 10, the input node of the first amplifier AMP2 may be set to the common connection node Nc between the auxiliary switch 34 and the resonant inductor Lr. In such a configuration as well, the second voltage detection unit 43 will have the same resonant voltage V as described above. r It can be detected.

[0054] (Second Embodiment) A second embodiment will be described with reference to Figures 11 and 12. In the first embodiment, an ideal case was illustrated, but due to various timings t1, t2, and t3 caused by heat generation, overcurrent, etc., the resonant voltage V r Attenuation is expected, and the resonant voltage V rIf a change in the cycle is anticipated, it is advisable to adjust the timing of soft switching of main switches S1 and S2.

[0055] The control unit 210 receives a predetermined theoretical formula, for example, the function f(T r1 Based on referring to the period T r2 It is recommended to obtain this from the memory unit 18 and correct the timing t3 for turning on the main switches S1 and S2. Here, the period T r1 Based on period T r2 We can list methods for defining and constructing theoretical formulas and functions.

[0056] In addition, for example, a lookup table Lut may be predefined with numerical values ​​or function values ​​based on a theoretical formula, and the period T may be determined based on referencing the lookup table Lut. r2 Obtain the acquisition period T r2 The timing t3 may be adjusted accordingly.

[0057] Figure 11 shows the functions of the control unit 210 of the second embodiment, which replaces the control unit 10 of the first embodiment. The control unit 210 stores theoretical formulas or lookup tables (Lut) in the storage unit 18.

[0058] Figure 12 shows the operation flow. First, the control unit 210 turns on the auxiliary switch 34 at timing t0 (S11) and detects the resonance start timing t1 (S12). The control unit 210 then performs a period T from timing t0 to t1. wait The control unit 210 calculates (S12a). Then, the control unit 210 detects the resonance center timing t2 (S13). The control unit 210 calculates the period T from the timings t0 to t2. r1 The calculation (S13a) is performed by the control unit 210, which refers to the theoretical formula or lookup table Lut stored in the storage unit 18, and the calculation unit 16 calculates the period T. r2 Calculate (S14a).

[0059] The control unit 210 calculates the period T r2Wait for a certain amount of time (S15: function of the waiting time control unit 17). Then the control unit 210 turns on the main switch S1 (S16). Furthermore, the control unit 210 controls the period T wait The system waits for a specified time (S17: function of the waiting time control unit 17). Then the control unit 210 turns off the auxiliary switch 34 at timing t4 (S18). This provides the same effects as the previously described embodiment, and also maintains the same duration as the period T r2 The timing t3 can be corrected accordingly.

[0060] (modified version) As mentioned above, period T r1 From period T r2 The theoretical formula for calculating the voltage and the method of referencing the lookup table Lut were explained. In addition, the detected voltage V of the first voltage detection units 41 and 42 was explained. ds1 , V ds2 , the resonant voltage V of the second voltage detection unit 43 r , load current I load Theoretical formulas, functions, and lookup tables (Lut) may be defined based on this.

[0061] (Third embodiment) A third embodiment will be described with reference to Figure 13. The power converter 301 shown in Figure 13 according to this embodiment includes a third voltage detection unit 45 in addition to the configuration of the control unit 210 for controlling the power converter 1 of the first embodiment. The third voltage detection unit 45 detects the power supply voltage V of the DC power supply 20. dd Detects.

[0062] The control unit 210 receives the power supply voltage V detected by the third voltage detection unit 45. dd Furthermore, the soft switching timing is estimated based on a predetermined theoretical formula or lookup table Lut, and after turning on the auxiliary switch 34, the main switch S1 is turned on after the calculated soft switching timing. In other words, the control unit 210 controls the on / off status of the main switches S1 and S2 of the power conversion unit 30, taking into account the power supply voltage Vdd.

[0063] In this case, it is desirable to calculate the time t from the ON timing t0 of the auxiliary switch 34 to the timing t3 of the main switch S1 based on the theoretical formula in equation (1) below.

[0064]

number

[0065] Here, time T1 is the time that corresponds to the first term of equation (1), and period T wait Corresponding to the power supply voltage V dd This represents the time after correction according to the power supply voltage V. Time T2 is the time shown in the second term of equation (1), and represents the theoretical formula for the time that arises according to the resonance phenomenon. Furthermore, the theoretical formula for calculating this time t is given by the power supply voltage V. dd or load current I load The control unit 210 may store the variable as a lookup table Lut in the storage unit 18, and then calculate the time t by referring to the lookup table Lut. In this way, the control unit 210 calculates the time t by referring to the power supply voltage V dd By performing corrections according to the above embodiment, the same effects as in the above embodiment are achieved, and the power supply voltage V dd This enables soft switching processing that can respond to changes in [the system].

[0066] (Fourth Embodiment) The fourth embodiment will be described with reference to Figures 14 and 15. Parts identical or similar to those in the third embodiment are denoted by the same reference numerals, and their descriptions will be omitted as needed. Different parts will be described.

[0067] The control unit 410 of the fourth embodiment is provided in place of the control units 10 and 210 of the above-described embodiment. In addition to the configuration of the control unit 10, the control unit 410 further includes a power supply voltage detection unit 15b, an error calculation unit 19, and a unit 21 for calculating the on-timing t0 of the auxiliary switch 34. The error calculation unit 19 calculates the error T for the next timing t0 based on the previous timings t1 to t4. e It is established to calculate [something].

[0068] The control unit 410 compares the estimated soft switching timing with the soft switching timing estimated based on equation (1) of the theoretical formula described in the third embodiment, or by referring to the lookup table Lut (on timing t0 of the auxiliary switch 34 + time t of equation (1)), and corrects the soft switching timing by adding the difference to the next pulse output.

[0069] A concrete example of the process will be explained with reference to Figure 15. Here, the previous error T e(n-1) The following describes the process assuming that the input T e(n-1) The timing t0 is calculated taking this into consideration (S10a). As shown in Figure 15, the control unit 410 turns on the auxiliary switch 34 at timing t0 (S11), detects the resonance start timing t1 (S12), and calculates the timing t0~t1 period T wait The control unit 410 then detects the resonance center timing t2 (S13) and calculates the period T from timings t0 to t2. r1 The control unit 410 calculates (S13a). r1 From period T r2 Calculate (S14).

[0070] The control unit 410 waits for a time t calculated from the theoretical formula ((1)) or the lookup table Lut, and then turns on the main switch S1 (S16: function of the waiting time control unit 17). Furthermore, the control unit 410 waits for a period T wait Instead, the system waits for a corrected period T1 (S17a: function of the waiting time control unit 17). Then the control unit 410 turns off the auxiliary switch 34 at timing t4 (S18). This time T1 is, as mentioned above, the power supply voltage V dd or load current I load It is set to a time that depends on the power supply voltage V. dd or load current I load The auxiliary switch 34 can be turned off after waiting for a time T1 that matches the specified duration.

[0071] Next, the control unit 410 calculates the error Te(n) The error T is calculated (S19). e(n) It is preferable to perform the calculation based on equation (2) below.

[0072]

number

[0073] This error T e This value is obtained by subtracting the value of the second term, based on the theoretical formula, from the corrected value of the first term, and represents the error component that is carried over to the next (n+1)th operation. Thus, the error T e This allows for sequential adjustments while correcting the issue.

[0074] The control unit 410 repeats the series of processes described in S11 to S19, and the error T for each iteration e The on-timing t0 of the next auxiliary switch 34 is calculated by performing the calculation (S10a) and reflected in the next calculation loop. This embodiment also produces the same effects as the previously described embodiment, and the error T e The process can be repeated while sequentially correcting the values.

[0075] (Other embodiments) The embodiments described above are not limited to those described above, and for example, the following modifications or extensions are possible. The load L can be any electrical load, but for example, the windings of a three-phase motor used for driving an electric vehicle (EV) may be used as the load L. In this case, the configuration shown in Figure 2 represents one phase of the three phases of the UVW phase. The neutral voltage generation unit 30a may generate the neutral voltage by connecting an external DC power supply in series with the intermediate voltage.

[0076] The methods described in this disclosure may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the methods described in this disclosure may be implemented by a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. Alternatively, the methods described in this disclosure may be implemented by one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions to be executed by the computer on a computer-readable non-transitional tangible recording medium.

[0077] This disclosure is written in accordance with the embodiments described above, but it is understood that this disclosure is not limited to such embodiments or the structures described in those embodiments. This disclosure also includes various modifications and variations within the scope of equivalents. 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]

[0078] In the drawing, 1 is a power converter, 10, 210, and 410 are control units, 30a is a neutral voltage generation unit, 31 is a series circuit, 34 is an auxiliary switch, 41 and 42 are first voltage detection units, 43 is a second voltage detection unit, 45 is a third voltage detection unit, C1 and C2 are neutral voltage generation capacitors, S1 and S2 are main switches, and C r1 , C r2 indicates a resonant capacitor, and Lr indicates a resonant inductor.

Claims

1. An ARCP-type power converter (1) is equipped with a power conversion unit (30) that drives a load using a DC power supply, The power conversion unit is A neutral voltage generation unit (30a) generates a neutral voltage at the neutral node from the DC power supply, The main switches (S1, S2) that make up the upper and lower arms, A resonant capacitor (C) is connected in parallel to the main switches of the upper and lower arms. ｒ１ , C ｒ２ )and, A series circuit (31) of an auxiliary switch (34) and a resonant inductor (Lr) is connected between the neutral node of the neutral voltage generation unit and the common connection point of the main switches of the upper and lower arms, A first voltage detection unit (41, 42) detects the voltage of the parallel circuit of the main switch and the resonant capacitor that constitute the upper and lower arms, The system includes a second voltage detection unit (43) for detecting the resonant voltage generated in the series circuit, Using the voltage detected by the first voltage detection unit, the resonance start timing is detected according to the positive or negative condition of the current supplied to the load. The second voltage detection unit detects the resonance center timing, which is the timing at which the resonance voltage changes from positive to negative or from negative to positive. A control unit (10;210;410) is provided, which measures the period from the ON timing of the auxiliary switch to the resonance start timing, and the period from the resonance start timing to the resonance center timing, estimates the resonance end timing based on the measurement results of the measurement unit, calculates the switching timing by calculating the time from the ON timing of the auxiliary switch to the resonance end timing, and turns on the main switches (S1, S2) at the switching timing. A power conversion device equipped with the following features.

2. The power conversion device according to claim 1, wherein the control unit obtains the time until the resonance termination timing based on a predetermined theoretical formula (1) or a lookup table, and corrects the switching timing according to the obtained time. [Math 1]

3. A third voltage detection unit (45) for detecting the voltage of the DC power supply, The power conversion device according to claim 2, wherein the control unit (410) estimates the soft switching timing based on the detected voltage of the third voltage detection unit and a predetermined theoretical formula (1), or the lookup table, and after turning on the auxiliary switch, turns on the main switch after the calculated soft switching timing.

4. The power conversion device according to claim 3, wherein the control unit corrects the soft switching timing by comparing the estimated soft switching timing with the soft switching timing estimated based on the theoretical formula or the lookup table, and adding the difference to the next pulse output.

5. The neutral voltage generation unit comprises two voltage generating capacitors (C) connected in parallel to the DC power supply and used to divide the power supply voltage to generate the neutral voltage. １ , C ２ The power conversion device according to claim 1, comprising )

6. The power conversion device according to claim 1, wherein the neutral voltage generation unit generates the neutral voltage by connecting the DC power supply in series with an external device.

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