Device and method for controlling power conversion device and power conversion system

Abstract

To disclose a control device capable of safely operating a power conversion device even outside a soft switching operation region.SOLUTION: A control device (20) includes first and second full-bridge circuits (101, 102) and an isolation transformer (103). The first full-bridge circuit mutually converts a primary side DC voltage and a primary side AC voltage by a first control signal (S1). The second full-bridge circuit mutually converts a secondary side DC voltage and a secondary side AC voltage by a second control signal (S2). The isolation transformer controls a power conversion device (10) that mutually converts the primary side AC voltage and the secondary side AC voltage. The control device determines a use range related to a voltage ratio (d) between the primary side DC voltage and the secondary side DC voltage and a phase difference command value (Φ*) for setting a phase difference between the first control signal and the second control signal based on any one of a primary side surge voltage ratio and a secondary side surge voltage ratio.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a control device and control method for a power conversion device, and a power conversion system. [Background technology]

[0002] In recent years, efforts are being made to build an energy system centered on renewable energy in order to achieve carbon neutrality. In particular, adjustable power sources such as storage batteries and EVs play a major role, and in order to ensure a stable power supply from renewable energy, it is necessary to be able to input and output the desired amount of power from adjustable power sources.

[0003] As a power conversion device connected to an adjustable power source, the application of a dual active bridge (DAB) type DC-DC converter, which is a type of isolated bidirectional DC-DC converter, is being promoted.

[0004] DAB DC-DC converters are capable of bidirectional operation, have a large output capacity, and have low loss during power conversion, making them promising power conversion devices for high-power control.

[0005] 2. Description of the Related Art As a conventional technique relating to a DC-DC converter for the DAB system, the technique described in Patent Document 1 is known.

[0006] In the technology described in Patent Document 1, when the output power is small, the switching operation is performed so that it includes a time when the current flowing through the winding of the isolation transformer is zero, making soft switching possible even when the output current is small. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2022-124170 A Summary of the Invention [Problem to be solved by the invention]

[0008] According to the above conventional technology, the soft switching operation range of the DAB DC-DC converter is expanded. However, when charging a storage battery, the voltage of the storage battery changes significantly, so if the DAB DC-DC converter is operated only within the soft switching operation range, it is difficult to charge the battery to a full charge state. In addition, if the DAB DC-DC converter is operated outside the soft switching operation range, there is a risk of overvoltage occurring due to a surge voltage.

[0009] Therefore, the present invention provides a control device and control method for a power conversion device, and a power conversion system, which are capable of safely operating the power conversion device even outside the soft switching operation region. [Means for solving the problem]

[0010] In order to solve the above problems, a control device for a power conversion device according to the present invention includes a first full bridge circuit having a plurality of primary side switching elements, a second full bridge circuit having a plurality of secondary side switching elements, and an isolation transformer, wherein the first full bridge circuit converts between a primary side DC voltage and a primary side AC voltage through a switching operation in response to a first control signal to the primary side switching elements, the second full bridge circuit converts between a secondary side DC voltage and a secondary side AC voltage through a switching operation in response to a second control signal to the secondary side switching elements, and the isolation transformer controls the power conversion device which transforms between the primary side AC voltage and the secondary side AC voltage. This control device includes a usage range determination unit that determines a usage range for a voltage ratio, which is the ratio between the primary side DC voltage and the secondary side DC voltage, and a phase difference command value that sets the phase difference between the first control signal and the second control signal, based on at least one of a primary side surge voltage ratio, which is the ratio between the primary side surge voltage generated by the switching operation of the first full bridge circuit and the primary side DC voltage, and a secondary side surge voltage ratio, which is the ratio between the secondary side surge voltage generated by the switching operation of the second full bridge circuit and the secondary side DC voltage.

[0011] In order to solve the above problems, a control method for a power conversion device according to the present invention is a method for controlling a power conversion device which includes a first full bridge circuit having a plurality of primary side switching elements, a second full bridge circuit having a plurality of secondary side switching elements, and an isolation transformer, wherein the first full bridge circuit converts between a primary side DC voltage and a primary side AC voltage by switching operation in response to a first control signal to the primary side switching elements, the second full bridge circuit converts between a secondary side DC voltage and a secondary side AC voltage by switching operation in response to a second control signal to the secondary side switching elements, and the isolation transformer transforms between the primary side AC voltage and the secondary side AC voltage. This control method determines the usage range for a voltage ratio, which is the ratio between the primary side DC voltage and the secondary side DC voltage, and a phase difference command value, which is the phase difference between the first control signal and the second control signal, based on at least one of a primary side surge voltage ratio, which is the ratio between the primary side surge voltage generated by the switching operation of a first full bridge circuit and the primary side DC voltage, and a secondary side surge voltage ratio, which is the ratio between the secondary side surge voltage generated by the switching operation of a second full bridge circuit and the secondary side DC voltage.

[0012] In order to solve the above problems, a power conversion system according to the present invention includes a power conversion device and a control device that controls the power conversion device. The power conversion device includes a first full bridge circuit having a plurality of primary side switching elements, a second full bridge circuit having a plurality of secondary side switching elements, an isolation transformer, and a control unit that outputs a first control signal to the primary side switching elements and a second control signal to the secondary side switching elements, the first full bridge circuit converts between a primary side DC voltage and a primary side AC voltage by switching operation in response to the first control signal, the second full bridge circuit converts between a secondary side DC voltage and a secondary side AC voltage by switching operation in response to the second control signal, and the isolation transformer transforms between the primary side AC voltage and the secondary side AC voltage. The control device includes a usage range determination unit that determines usage ranges for a voltage ratio, which is the ratio between the primary side DC voltage and the secondary side DC voltage, and a phase difference command value, which is the phase difference between the first control signal and the second control signal, based on at least one of a primary side surge voltage ratio, which is the ratio between the primary side surge voltage generated by the switching operation of the first full bridge circuit and the primary side DC voltage, and a secondary side surge voltage ratio, which is the ratio between the secondary side surge voltage generated by the switching operation of the second full bridge circuit and the secondary side DC voltage. Effect of the Invention

[0013] According to the present invention, the power conversion device can be safely operated even outside the soft switching operation region. Problems, configurations and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0014] [Figure 1] 1 is a block diagram showing a configuration of a power conversion system according to a first embodiment. [Diagram 2] 1 is a circuit diagram showing a configuration of a DC-DC converter 10 in a first embodiment. [Diagram 3] FIG. 11 is a circuit diagram showing the configuration of a modified example of the DC-DC converter 10. [Figure 4]13 is an example of voltage waveforms applied to switching elements Q7 and Q8 when the fourth leg is switched by soft switching. [Diagram 5] FIG. 2 is a block diagram showing a configuration of a control device according to the first embodiment. [Figure 6] 13 is an example of voltage waveforms applied to switching elements Q7 and Q8 when the fourth leg is switched by hard switching. [Figure 7] 13 is a mapping showing the relationship between the voltage ratio d, the phase difference command value Φ*, the voltage ratio between the primary side DC voltage E1 and the surge voltage E1_peak in the first full bridge circuit, and the voltage ratio between the secondary side DC voltage E2 and the surge voltage E2_peak in the second full bridge circuit. [Figure 8] 4 is a flowchart showing the operation of the control device in the first embodiment. [Figure 9] 11 is a graph showing the relationship between the voltage ratio d and the secondary surge voltage E2_peak in the second embodiment. [Figure 10] 13 is a graph showing the relationship between a phase difference command value Φ* and a secondary side surge voltage E2_peak. [Figure 11] FIG. 11 is a block diagram showing the configuration of a control device according to a third embodiment. [Figure 12] 11 is a flowchart showing the operation of the control device in the third embodiment. [Figure 13] 4 shows the relationship between the phase difference command value Φ* and the voltage ratio d during CCCV charging. [Figure 14] FIG. 13 is a block diagram showing the configuration of a control device according to a fourth embodiment. [Figure 15] 13 is a flowchart showing the operation of the control device in the fourth embodiment. [Figure 16] FIG. 13 is a block diagram showing the configuration of a control device in a fifth embodiment. [Figure 17] 13 is a flowchart showing the operation of the control device in the fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the embodiments of the present invention will be described with reference to the drawings by way of Examples 1 to 5. In each drawing, the same reference numbers indicate the same components or components having similar functions. EXAMPLES

[0016] FIG. 1 is a block diagram showing a configuration of a power conversion system according to a first embodiment of the present invention.

[0017] The power system 1 is connected to a primary terminal 151 of the DC-DC converter 10 via an AC / DC converter 2 .

[0018] The storage battery 3 is connected to a secondary terminal 152 of the DC-DC converter 10 .

[0019] The DC-DC converter 10 is a so-called dual active bridge type DC-DC converter.

[0020] The DC-DC converter 10 includes a first full-bridge circuit 101 having a plurality of primary-side switching elements 111, a second full-bridge circuit 102 having a plurality of secondary-side switching elements 112, an isolation transformer 103, and a control unit 104.

[0021] The first full-bridge circuit 101 is connected to a primary side terminal 151 and an isolation transformer 103, and converts between a primary side DC voltage and a primary side AC voltage by a switching operation.

[0022] The second full-bridge circuit 102 is connected to the secondary side terminal 152 and the isolation transformer 103, and converts between a secondary side DC voltage and a secondary side AC voltage by a switching operation.

[0023] The insulating transformer 103 mutually transforms the primary AC voltage and the secondary AC voltage.

[0024] The control unit 104 acquires the primary side DC voltage E1 and the secondary side DC voltage E2, and outputs a first control signal S1 for the primary side switching element 111 and a second control signal S2 for the secondary side switching element 112.

[0025] The control device 20 outputs a phase difference command value Φ * The control unit 104 outputs a phase difference command value Φ * In the DC-DC converter 10, the phase difference command value Φ * In response to this, power is transferred between the first full bridge circuit 101 and the second full bridge circuit 102. When the storage battery 3 is charged, power is transferred from the first full bridge circuit 101 side to the second full bridge circuit 102 side.

[0026] FIG. 2 is a circuit diagram showing the configuration of the DC-DC converter 10 in this embodiment.

[0027] FIG. 2 shows a circuit configuration for converting a DC voltage into a three-phase AC voltage and vice versa.

[0028] The insulating transformer 103 has a magnetic core, a primary winding n1 and a secondary winding n2 wound around the core, and a reactor L. The reactor L may be an inductance element such as a choke coil, or may be a leakage inductance of the primary winding n1 and the secondary winding n2.

[0029] In this embodiment, the connection states of the three-phase primary windings and the three-phase secondary windings are Y-connected and Δ-connected, respectively. However, the connection states of the primary windings and the three-phase secondary windings may be either Y-connected or Δ-connected.

[0030] The first full-bridge circuit 101 includes a plurality of primary side switching elements Q1 to Q6, a plurality of primary side diodes D1 to D6, and a plurality of primary side capacitors C1 to C6.

[0031] The second full-bridge circuit 102 includes a plurality of secondary side switching elements Q7 to Q 12 and multiple secondary diodes D7 to D 12 and multiple secondary capacitors C7 to C 12 And, it has.

[0032] FIG. 3 is a circuit diagram showing the configuration of a modified example of the DC-DC converter 10. In FIG.

[0033] FIG. 3 shows a circuit configuration for converting a DC voltage to a single-phase AC voltage and vice versa.

[0034] The differences from the circuit configuration shown in FIG. 2 will be described below.

[0035] The first full-bridge circuit 101 includes a plurality of primary side switching elements Q1 to Q4, a plurality of primary side diodes D1 to D4, and a plurality of primary side capacitors C1 to C4.

[0036] The second full-bridge circuit 102 includes a plurality of secondary side switching elements Q5 to Q8, a plurality of secondary side diodes D5 to D8, and a plurality of secondary side capacitors C5 to C8.

[0037] In this embodiment, the primary side switching elements Q1 to Q6 and the secondary side switching elements Q7 to Q 12 However, the present invention is not limited to this and other semiconductor switching elements such as metal oxide semiconductor field effect transistors (MOSFETs) and insulated gate bipolar transistors (IGBTs) may also be used.

[0038] Primary and secondary diodes D1 to D 12 , and the primary side capacitors and secondary side capacitors C1 to C 12 represent the primary side switching elements and the secondary side switching elements Q1 to Q 12 are connected in parallel.

[0039] Primary and secondary diodes D1 to D 12 The primary and secondary capacitors C1 to C2 may be parasitic diodes or individual elements. 12 may be parasitic capacitance, discrete elements, or a combination of parasitic capacitance and discrete elements.

[0040] The primary side switching elements Q1 to Q6 form the first to third legs 11, 12, and 13, and the secondary side switching elements Q7 to Q 12 constitute the 4th to 6th legs 14, 15, and 16.

[0041] The primary side switching element and the secondary side switching element are controlled by the control unit 104 to perform a switching operation.

[0042] Power conversion is performed by periodically performing switching operations on the first to third legs in the first full bridge circuit 101, and on the fourth to sixth legs in the second full bridge circuit 102. Through the switching operations, the first full bridge circuit 101 converts the primary side DC voltage into a primary side three-phase AC voltage, and the second full bridge circuit 102 converts the secondary side DC voltage into a secondary side three-phase AC voltage, and vice versa.

[0043] At this time, a phase difference is provided between the operations of the first full-bridge circuit 101 and the second full-bridge circuit 102, so that power is output from the primary side terminal 151 to the secondary side terminal 152.

[0044] FIG. 4 shows an example of voltage waveforms applied to switching elements Q7 and Q8 when the fourth leg is switched by soft switching.

[0045] In the switching operation, the switching elements in each leg are switched between ON and OFF states. For example, in the fourth leg, the combination of switching element Q7 in the OFF state and switching element Q8 in the ON state is switched to the combination of switching elements Q7 and Q8 in the OFF state, and switching element Q7 in the ON state and switching element Q8 in the OFF state. The period when all the switching elements in each leg are in the OFF state is called the dead time T dead He said.

[0046] Dead time T dead During this time, current continues to flow due to the constant current function of the reactor, discharging capacitor C7 and charging capacitor C8. When capacitor C7 is fully discharged and capacitor C8 is fully charged, the voltage applied to switching element Q7 becomes zero. In this state, switching element Q7 is switched to the ON state, achieving soft switching.

[0047] In order to achieve soft switching, the capacitor connected in parallel to the switching element is charged and discharged by the constant current function of the reactor. Whether the capacitor can be charged or discharged is determined by the voltage ratio between the primary side voltage and the secondary side voltage and the phase difference between the first full bridge circuit 101 and the second full bridge circuit 102.

[0048] In this embodiment, as will be described later, a usage range is set for safely performing power conversion even when soft switching is not established, that is, even under hard switching operation conditions.

[0049] FIG. 5 is a block diagram showing the configuration of the control device 20 in the first embodiment.

[0050] The control device 20 includes a calculation unit 21 and a storage unit 22 .

[0051] The calculation unit 21 includes a mapping creation unit 211 , a use range determination unit 212 , a phase difference command value input unit 214 , and a phase difference command value determination unit 213 .

[0052] The mapping creation unit 211 creates a mapping map that indicates the relationship between the surge voltage, the operating voltage, the voltage ratio, and the phase difference command value.

[0053] The usage range determination unit 212 determines the usage range based on the mapping map and the operating voltage. The method of determining the usage range will be described later.

[0054] The phase difference command value input unit 214 receives a phase difference command value Φ * and transmits it to the phase difference command value determining unit 213.

[0055] The phase difference command value determination unit 213 determines the phase difference command value Φ * is corrected based on the range of use to determine the phase difference command value.

[0056] FIG. 6 shows an example of voltage waveforms applied to switching elements Q7 and Q8 when the fourth leg is switched by hard switching.

[0057] Under hard switching conditions, the switching element Q7 is switched to the ON state while the capacitor C7 is not fully discharged and the capacitor C8 is not fully charged. This causes a sudden change in the voltage applied to the switching elements Q7 and Q8, resulting in a surge voltage E2 larger than the voltage E2 applied during steady state. 2_peak occurs.

[0058] The mapping creation unit 211 calculates the operating voltage E2 and the surge voltage E 2_peak and the operating voltage E2 and surge voltage E 2_peak , a voltage ratio d between the primary side voltage and the secondary side voltage, and a phase difference command value Φ given to the first full bridge circuit 101 and the second full bridge circuit 102. * is stored in the storage unit 22.

[0059] FIG. 7 shows the relationship between the voltage ratio d between the primary side voltage and the secondary side voltage and the phase difference command value Φ* , the primary side DC voltage E1 and the surge voltage E in the first full bridge circuit 101 1_peak and the voltage ratio between the secondary side DC voltage E2 and the surge voltage E in the second full bridge circuit 102. 2_peak The voltage ratio d and the phase difference command value Φ * The inventors of the present invention have found that there exists the above relationship.

[0060] The storage unit 22 may store mapping obtained in advance.

[0061] Fig. 8 is a flowchart showing the operation of the control device 20 in the present embodiment 1. Each step (S101 to S108) in Fig. 8 will be described below.

[0062] (Step S101) The mapping creation unit 211 measures the primary side DC voltage E1 and the secondary side DC voltage E2 using the control unit 104. The primary side DC voltage E1 and the secondary side DC voltage E2 may be measured directly by the calculation unit 21 by attaching a sensor to the power conversion device.

[0063] (Step S102) The mapping creation unit 211 calculates the primary side surge voltage E 1_peak and the secondary surge voltage E 2_peak Measure the primary surge voltage E 1_peak and the secondary surge voltage E 2_peak The values ​​of and may be measured directly by the calculation unit 21 by attaching a sensor to the power conversion device.

[0064] (Step S103) The mapping creation unit 211 calculates the primary side surge voltage E 1_peak and the primary DC voltage E1. 1_peak / E1 and secondary surge voltage E 2_peak and the secondary DC voltage E2, which is the voltage ratio 2_peak / E2 and determine.

[0065] (Step S104) The use range determination unit 212 determines from the storage unit 22 the upper limit voltage E 1_lim and the upper limit voltage E of the secondary DC voltage 2_lim The upper limit voltage may be determined based on the upper limit voltage of the connected device, the voltage at which a protection function is activated, or the like.

[0066] (Step S105) The usage range determination unit 212 measures the primary side DC voltage E1 and the secondary side DC voltage E2 via the control unit 104. The primary side DC voltage E1 and the secondary side DC voltage E2 may be measured directly by the calculation unit 21 by attaching a sensor to the power conversion device.

[0067] (Step S106) The use range determination unit 212 determines the voltage ratio d and the phase difference command value Φ based on the mapping, the primary side DC voltage E1, and the secondary side DC voltage E2. * The use range of the phase difference command value determining unit 213 is determined and transmitted to the phase difference command value determining unit 213.

[0068] (Step S107) The phase difference command value input unit 214 receives a phase difference command value Φ * and transmits it to the phase difference command value determiner 213.

[0069] (Step S108) The phase difference command value determination unit 213 calculates a voltage ratio d based on the primary side DC voltage E1 and the secondary side DC voltage E2, and determines a use range and a phase difference command value Φ * Based on this, the phase difference command value Φ * and transmits it to the control unit 104.

[0070] Phase difference command value Φ based on the range of use * By determining the primary surge voltage E 1_peak is the upper limit voltage E of the primary DC voltage 1_lim Does not exceed the secondary surge voltage E 2_peak is the upper limit voltage E of the secondary DC voltage2_lim Power conversion can be performed within a range not exceeding

[0071] The DC-DC converter according to the first embodiment has a primary side DC voltage E1, a secondary side DC voltage E2, and an upper limit voltage E 1_lim and the upper limit voltage E of the secondary DC voltage 2_lim and the primary surge voltage E that occurs during switching operation. 1_peak and the secondary surge voltage E that occurs during switching operation. 2_peak From the voltage ratio d, the phase difference command value Φ * Calculate the range of use for the phase difference command value Φ * By providing the above, the primary side DC voltage E1 and the secondary side DC voltage E2 are set to the upper limit voltage E 1_lim and the upper limit voltage E of the secondary DC voltage 2_lim Power conversion can be performed within a range not exceeding the above. EXAMPLES

[0072] In the above-described first embodiment, the voltage ratio d and the phase difference command value Φ * For each, the primary surge voltage E 1_peak and the secondary surge voltage E 2_peak By measuring the voltages, the mapping shown in Fig. 7 was created. At this time, at least the primary surge voltage E 1_peak and the secondary surge voltage E 2_peak Either of the above may be estimated.

[0073] In the second embodiment, the secondary surge voltage E 2_peak The difference from the first embodiment is that the device configuration and the control means of the second embodiment are the same as those of the first embodiment (FIGS. 1, 2, and 5).

[0074] FIG. 9 shows the relationship between the voltage ratio d and the secondary surge voltage E 2_peak 13 is a graph showing the relationship between

[0075] As shown in FIG. 4, in the soft switching operation region, the switching element Q7 is switched to the ON state after the voltage applied to the switching element Q7 becomes zero. Therefore, no overvoltage occurs due to the switching operation, and the secondary surge voltage E 2_peak is equal to the secondary DC voltage E2.

[0076] As shown in FIG. 6, in the hard switching operation region, the switching element Q7 is switched to the ON state when a voltage equal to or greater than zero is applied to the switching element Q7. Therefore, an overvoltage occurs due to the switching operation, and the secondary surge voltage E 2_peak is greater than the secondary DC voltage E2.

[0077] At this time, the larger the voltage applied to the switching element Q7 immediately before it switches to the ON state, the greater the secondary surge voltage E 2_peak The voltage applied to the switching element Q7 immediately before it switches to the ON state is proportional to the amount of discharge from the capacitor C7 during the dead time.

[0078] The discharge amount is proportional to the current flowing through the capacitor during the dead time. In other words, the discharge amount changes according to the current flowing through the reactor just before the dead time. The current flowing through the reactor L just before the dead time is determined by the voltage ratio d. Therefore, the secondary surge voltage E 2_peak is determined by the voltage ratio d. As the voltage ratio d becomes larger than 1, the amount of discharge from the capacitor C7 during the dead time becomes smaller, so the secondary surge voltage E 2_peak becomes larger.

[0079] If the voltage ratio d is increased, the discharge amount from the capacitor C7 during the dead time becomes zero. At this time, the secondary surge voltage E 2_peak Even if the voltage ratio d is increased further, the discharge amount from the capacitor C7 during the dead time remains zero, and the secondary surge voltage E 2_peak does not become large.

[0080] Soft switching operating region and secondary surge voltage E 2_peak By obtaining the region where is maximum and the secondary surge voltage E in the hard switching operation region, 2_peak can be estimated 。 The interpolation method in this case may be linear approximation or polynomial approximation.

[0081] The surge voltage is also determined by the phase difference command value Φ * It may be estimated from

[0082] Figure 10 shows the phase difference command value Φ * and the secondary surge voltage E 2_peak 13 is a graph showing the relationship between

[0083] As shown in the mapping of Fig. 7, there is a dependency between the surge voltage and the phase difference command value. At the same voltage ratio d, the larger the phase difference command value Φ * The greater the value, the more the surge voltage is suppressed. As mentioned above, the maximum value of the surge voltage is fixed. Therefore, as the phase difference command value approaches zero, the operation region changes from the soft switching operation region to the hard switching operation region, and as the value approaches zero further, the surge voltage becomes saturated.

[0084] Therefore, the soft switching operation area and the secondary surge voltage E 2_peak By obtaining the region where is maximum and the secondary surge voltage E in the hard switching operation region, 2_peak can be estimated 。 The interpolation method in this case may be linear approximation or polynomial approximation.

[0085] According to the second embodiment, the voltage ratio d or the phase difference command value Φ * Based on either of the above, at least the primary surge voltage E 1_peak and the secondary surge voltage E 2_peak As a result, it is possible to create a mapping such as that shown in Fig. 7 with a smaller number of measurement points. EXAMPLES

[0086] In the above-described first embodiment, the phase difference command value Φ * At this time, the current command value is determined, and the phase difference command value Φ * By determining the above, the primary side DC voltage E1 and the secondary side DC voltage E2 are determined to be equal to the upper limit voltage E 1_lim and the upper limit voltage E of the secondary DC voltage 2_lim A current can be output within a range not exceeding the above.

[0087] The third embodiment of the present invention will be described below, focusing mainly on the differences from the first embodiment.

[0088] FIG. 11 is a block diagram showing the configuration of the control device 20 in the third embodiment.

[0089] As shown in FIG. 11, the control device 20 includes a storage unit 22 and a calculation unit 21.

[0090] The calculation unit 21 includes a mapping creation unit 211 , a use range determination unit 212 , a current command value input unit 215 , a phase difference command value determination unit 213 , and an operating voltage determination unit 216 .

[0091] The storage unit 22 stores the operating frequencies of the primary side switching element and the secondary side switching element, the turns ratio of the insulating transformer 103, and the inductance.

[0092] The current command value input unit 215 determines the value of a current flowing through either the primary side terminal 151 or the secondary side terminal as a current command value, and transmits it to the phase difference command value determination unit 213. In the third embodiment, the secondary side DC current command value I2 * is determined.

[0093] The phase difference command value determination unit 213 determines a phase difference command value Φ based on the primary side DC voltage E1, the secondary side DC voltage E2, the operating frequency, the turns ratio of the insulating transformer 103, and the inductance. * Determine.

[0094] The mapping creation unit 211, like the first embodiment, calculates the primary side surge voltage ratio E 1_peak / E1 and secondary surge voltage ratio E 2_peak / E2, voltage ratio d, and phase difference command value Φ * Create a mapping for .

[0095] The use range determination unit 212 determines the phase difference command value Φ * The operating voltage determining unit 216 determines the operating range for the power supply 211 and transmits it to the operating voltage determining unit 216.

[0096] The operating voltage determination unit 216 determines the primary side DC voltage E1 and the operating range ((d, Φ * )) and the phase difference command value Φ * Based on this, the primary side DC voltage command value E1 * and transmits it to the AC / DC converter 2.

[0097] FIG. 12 is a flowchart showing the operation of the control device 20 in the third embodiment.

[0098] Hereinafter, steps S201 to S206 in the flowchart shown in Fig. 12 are respectively similar to steps S101 to S106 in the flowchart shown in Fig. 8. Below, steps S207 to S210 which are different from Fig. 8 will be described.

[0099] (Step S207) The current command value input unit 215 receives the secondary DC current command value I2 * to the phase difference command value determining unit 213.

[0100] (Step S208) The phase difference command value determination unit 213 acquires the operating frequency ω, the turns ratio N of the insulating transformer 103, and the inductance L from the storage unit 22, and determines the phase difference command value Φ *The relationship between the secondary DC current command I2, the operating frequency ω, the turns ratio N of the insulating transformer 103, the primary DC voltage E1, the secondary DC voltage E2, and the phase difference Φ is expressed by the formula (1). The formula (1) is known for a general DAB type DC-DC converter.

[0101]

number

[0102] Determined phase difference command value Φ * is transmitted to the control unit 104.

[0103] (Step S209) The operating voltage determination unit 216 determines the phase difference command value Φ * is the phase difference command value Φ determined in step S206. * If the control device 20 determines that the usage range is satisfied (YES in step S209), the control device 20 ends the series of processes, and if the control device 20 determines that the usage range is not satisfied (NO in step S209), the control device 20 executes step S210.

[0104] (Step S210) The operating voltage determination unit 216 determines a primary DC voltage command value E1 based on the primary DC voltage E1. * and sends the primary side DC voltage command value E1 to the AC / DC converter 2. * Send.

[0105] As shown in the mapping of Fig. 7, the smaller the voltage ratio d, the greater the secondary surge voltage E 2_peak In other words, the smaller the value of the primary side DC voltage E1, the smaller the phase difference command value Φ * Therefore, the range of use of the primary DC voltage command value E1 * The value of is commanded to be smaller than the primary side DC voltage E1.

[0106] In addition, such a primary side DC voltage command value E1 *The determination means is just one example, and may be based on a mathematical formula or may be a fixed value.

[0107] After executing step S210, the control device 20 then executes step S205.

[0108] The control device 20 repeats the operations of steps S201 to S210 to obtain a phase difference command value Φ * While satisfying the range of use of the secondary DC current command value I2 * Phase difference command value Φ for flowing * Determine.

[0109] According to the third embodiment, the secondary DC current command value I2 * Based on the operating frequency ω, the turns ratio N of the insulating transformer 103, the primary side DC voltage E1, and the secondary side DC voltage E2, a phase difference command value Φ * The determined phase difference command value Φ * is the phase difference command value Φ * If the range of use is not met, at least one of the primary side DC voltage E1 and the secondary side DC voltage E2 is changed to determine whether the primary side DC voltage E1 and the secondary side DC voltage E2 are within the upper limit voltage E 1_lim and the upper limit voltage E of the secondary DC voltage 2_lim A current can be output within a range not exceeding the above. EXAMPLES

[0110] In the DC-DC converter according to the fourth embodiment, when the storage battery is charged to a full charge state, the primary side DC voltage E1 and the secondary side DC voltage E2 are equal to or lower than the upper limit voltage E 1_lim and the upper limit voltage E of the secondary DC voltage 2_lim The charging operation can be performed so as not to exceed 1. The following mainly describes the differences from the first and third embodiments regarding the control device 20.

[0111] The charging method for storage batteries is generally constant current constant voltage (CCCV) charging. First, constant current (CC) charging is performed at the beginning of charging, and when the storage battery reaches a certain voltage, it switches to constant voltage (CV) charging. During CV charging, the current value is gradually reduced, and charging is terminated when a certain current value is reached. The current value during CC charging is I CC , the voltage during CV charging is E CV Let us assume that.

[0112] Figure 13 shows the phase difference command value Φ * and the voltage ratio d are shown below. The charging operation of the DC-DC converter between each operating point in FIG.

[0113] (Between operating points A and B: at the start of charging) When charging starts, the phase difference command value Φ * At this time, when a current flows through the storage battery, the secondary DC voltage E2 increases by the resistance of the storage battery. In other words, if the primary DC voltage E1 is constant, the voltage ratio d decreases.

[0114] (Between operating points B and C: CC charging) CC charging is performed with a constant current. At this time, the voltage of the storage battery increases as charging progresses. Therefore, the secondary DC voltage E2 increases, and the voltage ratio d decreases. Also, as shown in equation (1), when the secondary DC current I2 is constant, the phase difference Φ is constant regardless of the magnitude of the secondary DC voltage E2. Therefore, there is a transition from operating point B to operating point C in parallel with the direction of the voltage ratio d.

[0115] (Between operating points C and D: CV charging) The secondary DC voltage E2 is the voltage E during CV charging CV When the charging voltage E2 reaches the operating point D, the charging is switched from CC charging to CV charging. During CV charging, the secondary DC voltage E2 remains constant and the secondary DC current I2 is reduced. As shown in equation (1), the secondary DC current I2 is proportional to the phase difference Φ. Therefore, the phase difference command value Φ * Transition parallel to the direction.

[0116] FIG. 14 is a block diagram showing the configuration of the control device 20 in the fourth embodiment.

[0117] In the fourth embodiment, the control device 20 includes a storage unit 22 and a calculation unit 21. The calculation unit 21 includes a mapping creation unit 211, a use range determination unit 212, a target voltage input unit 221, a target current input unit 222, an operating voltage determination unit 216, and a phase difference command value determination unit 213.

[0118] The storage unit 22 stores the operating frequencies of the primary side switching element and the secondary side switching element, the turns ratio of the insulating transformer 103, and the inductance.

[0119] The mapping creation unit 211, like the first embodiment, calculates the primary side surge voltage ratio E 1_peak / E1 and secondary surge voltage ratio E 2_peak / E2, voltage ratio d, and phase difference command value Φ * Create a mapping for .

[0120] The use range determination unit 212 determines the phase difference command value Φ * The operating voltage determining unit 216 determines the operating range for the power supply 211 and transmits it to the operating voltage determining unit 216.

[0121] The target voltage input unit 221 determines the voltage value of either the primary side terminal 151 or the secondary side terminal 152 during CV charging as the target voltage. In the fourth embodiment, the secondary side target voltage E 2_CV * This will be explained as determining

[0122] The target current input unit 222 determines the value of a current flowing through either the primary side terminal 151 or the secondary side terminal during CC charging as a current command value, and transmits it to the phase difference command value determination unit 213. In the fourth embodiment, the secondary side target current I 2_CC is determined.

[0123] The operating voltage determination unit 216 determines the voltage E 2_CV Based on the range of use, the primary DC voltage command value E1* and transmits it to the AC / DC converter 2 and the phase difference command value determiner 213.

[0124] The phase difference command value determination unit 213 determines the primary side DC voltage command value E1 * Based on the secondary DC voltage E2, the operating frequency, the turns ratio of the insulating transformer 103, and the inductance, a phase difference command value Φ * Determine.

[0125] FIG. 15 is a flowchart showing the operation of the control device 20 in the fourth embodiment.

[0126] Steps S301 to S304 in the flowchart of Fig. 15 are respectively similar to steps S101 to S104 in the flowchart shown in Fig. 8. Below, steps S305 to S309 which are different from the flowchart shown in Fig. 8 will be described.

[0127] (Step S305) The target voltage input unit 221 is a target voltage E 2_CV The target voltage E during CV charging is determined and transmitted to the operating voltage determination unit 216. 2_CV may be input from the outside or may be obtained from the storage unit 22.

[0128] (Step S306) The operating voltage determination unit 216 performs mapping and determines the target voltage E 2_CV From this, the target voltage ratio d CV The voltage ratio d is determined to be the minimum value within the determined operating range, as shown in Fig. 13. This makes it possible to ensure a wide operating range during CC charging. The voltage ratio d may be determined by other means, or may be a value obtained by adding a certain value to the minimum value. (Step S307) The operating voltage determination unit 216 determines the voltage ratio d and the target voltage ratio d CV Based on this, the primary side DC voltage command value E1 * The determined primary DC voltage command value E1* is transmitted to the AC / DC converter 2 and the phase difference command value determiner 213. (Step S308) The target current input unit 222 receives the target current I 2_CC and transmits it to the operating voltage determination unit 216. 2_CC may be input from the outside or may be obtained from the storage unit 22. (Step S309) The phase difference command value determination unit 213 acquires the operating frequency ω, the turns ratio N of the insulating transformer 103, and the inductance L from the storage unit 22, and determines the target current I 2_CC Based on this, the phase difference command value Φ CC * Determine.

[0129] The DC-DC converter according to the fourth embodiment has an upper limit voltage E 1_lim and the voltage ratio E between the primary side DC voltage and the primary side surge voltage 1_peak / E1 and the upper limit voltage E of the secondary DC voltage 2、LIM and the voltage ratio E between the secondary DC voltage and the secondary surge voltage 2_peak Based on / E2, the voltage ratio d during CV charging CV and the phase difference command value Φ during CC charging CC * As a result, the primary side DC voltage E1 and the secondary side DC voltage E2 are determined to be equal to or lower than the upper limit voltage E 1_lim and the upper limit voltage E of the secondary DC voltage 2_lim CCCV charging for full charge operation can be performed without exceeding the limit. EXAMPLES

[0130] The DC-DC converter according to the fifth embodiment has a primary side surge voltage E 1_peak and the secondary surge voltage E 2_peak Measure the primary surge voltage E 1_peak and the secondary surge voltage E 2_peak The range of use is corrected based on the above. The following describes differences from the other embodiments, mainly related to the control device 20.

[0131] FIG. 16 is a block diagram showing the configuration of the control device 20 in the fifth embodiment.

[0132] In the fifth embodiment, the control device 20 includes a storage unit 22 and a calculation unit 21. The calculation unit 21 includes a mapping creation unit 211, a use range determination unit 212, an operating voltage determination unit 216, and a phase difference command value determination unit 213.

[0133] The storage unit 22 stores the operating frequencies of the primary side switching element and the secondary side switching element, the turns ratio of the insulating transformer 103, and the inductance.

[0134] The mapping creation unit 211, like the first embodiment, calculates the primary side surge voltage ratio E 1_peak / E1 and secondary surge voltage ratio E 2_peak / E2, voltage ratio d, and phase difference command value Φ * Create a mapping for .

[0135] The use range determination unit 212 performs mapping and the primary side surge voltage ratio E 1_peak and the secondary surge voltage ratio E 2_peak Based on this, the voltage ratio d and the phase difference command value Φ * The operating voltage determining unit 216 determines the usage range for the above and transmits it to the operating voltage determining unit 216.

[0136] The operating voltage determination unit 216 determines the primary side DC voltage E1, the operating range, and the phase difference command value Φ * Based on this, the primary side DC voltage command value E1 * and transmits it to the AC / DC converter 2.

[0137] The phase difference command value determination unit 213 determines a phase difference command value Φ based on the primary side DC voltage command value E1, the secondary side DC voltage E2, the operating frequency, the turns ratio of the insulating transformer 103, and the inductance. * and transmits it to the control unit 104.

[0138] Fig. 17 is a flowchart showing the operation of the control device 20 in this embodiment 5. Steps S401 to S405 are similar to steps S101 to S105 in the flowchart shown in Fig. 8. Steps S406 to S410 which are different from the flowchart shown in Fig. 8 will be described below.

[0139] (Step S406) The use range determination unit 212 determines the phase difference command value Φ * and the first surge voltage E 1_peak and the second surge voltage E 2_peak And get.

[0140] (Step S407) The usage range determination unit 212 determines the first surge voltage E 1_peak and the upper limit voltage E of the primary DC voltage 1_lim Comparison of the magnitude of the second surge voltage E 2_peak and the upper limit voltage E of the secondary DC voltage 2_lim The control device 20 performs a comparison of the magnitude with the use range determination unit 212. 1_peak ≦E 1_lim And E 2_peak ≦E 2_lim If it is determined that the answer is yes (YES in step S407), the series of processes ends, and if it is determined that the answer is no (NO in step S407), step S408 is executed next.

[0141] (Step S408) The use range determination unit 212 determines the voltage ratio d and the phase difference command value Φ * and the primary surge voltage E 1_peak and the second surge voltage E 2_peak The range of use is corrected based on the voltage ratio d and phase difference command value Φ that reduce the value of the primary side surge voltage ratio or the secondary side surge voltage ratio by a predetermined fixed value. * The range of use of the voltage ratio d and the phase difference command value Φ * Alternatively, the phase difference command value Φ may be corrected to narrow the range by a fixed value, or may be corrected based on a different correction method and formula. *may be corrected.

[0142] (Step S409) The operating voltage determination unit 216 determines the primary side DC voltage command value E1 based on the range of use. * and sends the primary side DC voltage command value E1 to the AC / DC converter 2. * Send. (Step S410) The phase difference command value determination unit 213 acquires the operating frequency ω, the turns ratio N of the insulating transformer 103, and the inductance L from the storage unit 22, and determines these and the primary side DC voltage command value E1 * Based on this, the phase difference command value Φ * After executing step S410, the control device 20 then executes step S405.

[0143] According to the fifth embodiment, the primary surge voltage E 1_peak and the secondary surge voltage E 2_peak Measure the primary surge voltage E 1_peak and secondary surge voltage E 2_peak Based on this, the range of use is corrected. 1_peak is the upper limit voltage E of the primary DC voltage 1_lim If the secondary surge voltage E 2_peak is the upper limit voltage E of the secondary DC voltage 2_lim If the phase difference command value Φ * By correcting the above, the primary side DC voltage E1 and the secondary side DC voltage E2 are adjusted to the upper limit voltage E 1_lim and the upper limit voltage E of the secondary DC voltage 2_lim Power conversion can be performed without exceeding the above.

[0144] The present invention is not limited to the above-described embodiments and modifications, but includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the configurations described. In addition, it is possible to add, delete, or replace part of the configuration of the embodiments with other configurations. [Explanation of symbols]

[0145] 1...power system, 2...AC / DC converter, 3...storage battery, 10...DC-DC converter, 11,12,13,14,15,16...leg, 20...control device, 21...calculation unit, 22...storage unit, 101...first full bridge circuit, 102...second full bridge circuit, 103...insulation transformer, 104...control unit, 111...primary side switching element, 112...secondary side switching element, 151...primary side terminal, 152...secondary side terminal, 211...mapping creation unit, 212...usage range determination unit, 213...phase difference command value determination unit, 214...phase difference command value input unit, 215...current command value input unit, 216...operating voltage determination unit, 221...target voltage input unit, 222...target current input unit

Claims

1. In a control device for a power conversion device, The power conversion device includes a first full bridge circuit having a plurality of primary side switching elements, a second full bridge circuit having a plurality of secondary side switching elements, and an isolation transformer, the first full-bridge circuit converts between a primary-side DC voltage and a primary-side AC voltage by a switching operation in response to a first control signal to the primary-side switching element; the second full bridge circuit converts between a secondary DC voltage and a secondary AC voltage by a switching operation in response to a second control signal of the secondary switching element; The isolation transformer mutually transforms the primary AC voltage and the secondary AC voltage, a usage range determination unit that determines usage ranges for a voltage ratio that is a ratio between the primary side DC voltage and the secondary side DC voltage and a phase difference command value that is a phase difference between the first control signal and the second control signal, based on at least one of a primary side surge voltage ratio that is a ratio between a primary side surge voltage generated by the switching operation of the first full bridge circuit and the primary side DC voltage, and a secondary side surge voltage ratio that is a ratio between a secondary side surge voltage generated by the switching operation of the second full bridge circuit and the secondary side DC voltage.

2. The control device for a power conversion device according to claim 1, A control device for a power conversion device, comprising: a storage unit that stores either the primary side surge voltage ratio or the secondary side surge voltage ratio, and a relationship between the voltage ratio and the phase difference command value.

3. The control device for a power conversion device according to claim 1, the usage range determination unit determines the usage range based on either a primary-side upper limit voltage that is an upper limit value of the primary-side DC voltage, or a secondary-side upper limit voltage that is an upper limit value of the secondary-side DC voltage.

4. The control device for a power conversion device according to claim 1, A control device for a power conversion device, comprising: a phase difference command value determination unit that determines the phase difference command value based on the usage range.

5. The power conversion device control device according to claim 4, A current command value input unit that determines a current command value, The control device for a power conversion device, wherein the phase difference command value determiner determines the phase difference command value based on the current command value.

6. The control device for a power conversion device according to claim 5, A storage unit is provided to store a transformer winding ratio, an inductance, and an operating frequency of the switching operation, The control device for a power conversion device, wherein the phase difference command value determiner determines the phase difference command value based on the current command value, the transformer winding ratio, the inductance, and the operating frequency.

7. The control device for a power conversion device according to claim 1, an operating voltage determination unit that transmits either a primary side DC voltage command value or a secondary side DC voltage command value; The control device for a power conversion device, wherein the operating voltage determination unit determines at least one of the primary side DC voltage command value and the secondary side DC voltage command value based on the usage range.

8. The control device for a power conversion device according to claim 1, A control device for a power conversion device, comprising: a control circuit for estimating at least one of the primary side surge voltage ratio and the secondary side surge voltage ratio based on either the voltage ratio or the phase difference command value.

9. The control device for a power conversion device according to claim 7, A target voltage input unit for determining a target voltage is provided, The control device for a power conversion device, wherein the operating voltage determination unit determines at least one of the primary side DC voltage command value and the secondary side DC voltage command value based on the usage range and the target voltage.

10. The power conversion device control device according to claim 4, A target current input unit for determining a target current is provided, The control device for a power conversion device, wherein the phase difference command value determiner determines the phase difference command value based on the usage range and the target current.

11. The control device for a power conversion device according to claim 1, the usage range determination unit measures at least one of the primary side surge voltage and the secondary side surge voltage, The control device for a power conversion device, wherein the usage range determination unit determines the usage range based on the usage range and at least one of the primary side surge voltage and the secondary side surge voltage.

12. 1. A method for controlling a power conversion device, comprising: The power conversion device is The power supply includes a first full-bridge circuit having a plurality of primary-side switching elements, a second full-bridge circuit having a plurality of secondary-side switching elements, and an isolation transformer, the first full-bridge circuit converts between a primary-side DC voltage and a primary-side AC voltage by a switching operation in response to a first control signal to the primary-side switching element; the second full bridge circuit converts between a secondary DC voltage and a secondary AC voltage by a switching operation in response to a second control signal of the secondary switching element; The isolation transformer mutually transforms the primary AC voltage and the secondary AC voltage, a primary side surge voltage ratio which is a ratio between a primary side surge voltage generated by the switching operation of the first full bridge circuit and the primary side DC voltage, and a secondary side surge voltage ratio which is a ratio between a secondary side surge voltage generated by the switching operation of the second full bridge circuit and the secondary side DC voltage, and a phase difference command value which is a phase difference between the first control signal and the second control signal are determined based on at least one of the primary side surge voltage ratio which is a ratio between a primary side surge voltage generated by the switching operation of the first full bridge circuit and the primary side DC voltage, and a secondary side surge voltage ratio which is a ratio between a secondary side surge voltage generated by the switching operation of the second full bridge circuit and the secondary side DC voltage.

13. A power conversion device; A control device that controls the power conversion device; In a power conversion system comprising: The power conversion device is a first full bridge circuit having a plurality of primary side switching elements; a second full-bridge circuit having a plurality of secondary side switching elements; An isolation transformer, a control unit that outputs a first control signal to the primary side switching element and a second control signal to the secondary side switching element; Equipped with the first full-bridge circuit converts between a primary-side DC voltage and a primary-side AC voltage by a switching operation in response to the first control signal; the second full-bridge circuit converts between a secondary-side DC voltage and a secondary-side AC voltage by a switching operation in response to the second control signal; The isolation transformer mutually transforms the primary AC voltage and the secondary AC voltage, The control device includes: a usage range determination unit that determines usage ranges for a voltage ratio that is a ratio between the primary side DC voltage and the secondary side DC voltage and a phase difference command value that is a phase difference between the first control signal and the second control signal, based on at least one of a primary side surge voltage ratio that is a ratio between a primary side surge voltage generated by the switching operation of the first full bridge circuit and the primary side DC voltage, and a secondary side surge voltage ratio that is a ratio between a secondary side surge voltage generated by the switching operation of the second full bridge circuit and the secondary side DC voltage.

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