AC / DC converter

Abstract

To realize an inexpensive yet high-performance AC / DC converter. [Solution] This AC / DC converter 6 performs bidirectional conversion including a bridgeless PFC circuit 20. The PFC circuit 20 has a linkage switch 30 that switches the presence or absence of AC eac input on and off. The controller 14 has a peak current control unit 60 that performs peak current mode control and an AC tuning control unit 80 that matches the phase and period of the input voltage einv to AC eac and gradually increases the amplitude of the input voltage einv to match the amplitude of AC eac. When the AC tuning control unit 80 is activated at startup, and when the amplitude of the input voltage einv reaches a predetermined value, the linkage switch 30 switches from off to on, and the system switches to peak current mode control.

Description

[Technical Field]

[0001] The disclosed technology relates to a bidirectional AC / DC converter. [Background technology]

[0002] In recent years, the electrification of automobiles, such as electric vehicles and hybrid vehicles, has been remarkable. These vehicles that run on electricity are equipped with high-output batteries as their power source. In order to charge these batteries, these vehicles are also equipped with on-board chargers (OBCs) that convert AC power, which is the commercial power source, into DC power.

[0003] Many OBCs (Out-of-Bass Converters) use AC / DC converters equipped with a Power Factor Correction (PFC) circuit to improve the power factor drop caused by distortion of the input current waveform (for example, Patent Document 1). Among PFC circuits, bridgeless PFC circuits are widely used to improve efficiency by replacing the diodes in the lossy full-wave rectifier circuit with switching elements (MOSFETs).

[0004] Within bridgeless PFC circuits, totem-pole type PFC circuits, which include two switching elements connected in series, are widely used. In AC / DC converters equipped with totem-pole type PFC circuits, average current mode control is generally employed as the control method for switching the switching elements on and off.

[0005] However, average current mode control has the disadvantage that if the reactor capacity is small, the current control becomes unstable, requiring a larger reactor. Furthermore, since the switching frequency is fundamentally the same as the control frequency, it is difficult to increase the switching frequency, which is another disadvantage.

[0006] In an AC / DC converter, by forming a full-bridge circuit with switching elements and switching the switching pattern according to the polarity of the AC voltage, it is possible to improve the conversion efficiency. However, in this method, generally, the zero-cross at which the polarity of the AC voltage changes is determined, and the switching pattern is switched based on that determination.

[0007] However, in such a case, current distortion is likely to occur during switching. In order to solve this problem, a circuit using a predetermined bidirectional element has been proposed in place of the switching element (Patent Document 2).

[0008] Also, in a conventional AC / DC converter, it is common to include a precharge circuit so that inrush current and the like can be suppressed and smooth startup can be achieved.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0010] As one solution to the above-described demerits in average current mode control, the adoption of peak current mode control can be considered. By adopting peak current mode control, the pulsation of the reactor current can be increased compared to average current mode control, and current control is relatively stable even with a small reactor capacitance, so the reactor can be miniaturized.

[0011] However, peak current mode control requires slope compensation. Therefore, it is widely adopted in DC / DC converters that handle DC power with a constant voltage polarity. In AC / DC converters where the current polarity changes periodically, as described above, average current mode control is mostly adopted.

[0012] In the case of an OBC handling high power, the pre-charge circuit has disadvantages such as high cost, increased size, and increased weight of the device. Fig. 13 illustrates a conventional pre-charge circuit. The conventional pre-charge circuit is composed of a current-limiting resistor Rp and a plurality of switches SW1, SW2, Sp, etc.

[0013] At startup, switches Sp and SW2 are turned on. Then, the input-side voltage einv is gradually increased, and just before it becomes approximately equal to the voltage of the commercial power supply eac (maximum value), switch SW1 is turned on and switch Sp is turned off. By doing so, soft start is performed.

[0014] When handling a large amount of power, the current-limiting resistor Rp and each switch SW1, SW2, Sp also require a corresponding high power tolerance. As a result, the pre-charge circuit becomes costly and the device becomes larger and heavier.

[0015] Furthermore, in an AC / DC converter, especially when implemented in an OBC, it is required to be able to perform both the charging operation and the discharging operation, and to be able to switch between these operations continuously (seamlessly), and to be able to control the power factor to be constant according to requirements.

[0016] Therefore, in this specification, in an AC / DC converter equipped with a totem-pole type bridgeless PFC circuit, a technology that can solve these problems and realize the desired functions will be disclosed.

Means for Solving the Problems

[0017] The disclosed technology relates to an AC / DC converter that performs bidirectional conversion between AC and DC, comprising a converter mechanism including a bridgeless PFC circuit and a controller for controlling the converter mechanism.

[0018] The bridgeless PFC circuit includes a pair of input wirings for receiving AC, a pair of output wirings for outputting DC, a reactor located on at least one of the input wirings, a first leg, a second leg, and a third leg connected in parallel between the pair of output wirings, a first switching element and a second switching element and a third switching element and a fourth switching element arranged in series on the first leg and the second leg, respectively, with the current flow direction from the positive side to the negative side, and the controller performs switching and switching operations according to the polarity of the AC, an output capacitor located on the third leg, and a linkage switch located on the pair of input wirings that switches the presence or absence of the AC input on and off.

[0019] Furthermore, one output terminal of the input wiring is connected to the intermediate portion between the first switching element and the second switching element in the first leg, and the other output terminal of the input wiring is connected to the intermediate portion between the third switching element and the fourth switching element in the second leg.

[0020] The converter mechanism includes an input voltage sensor located on the output side of the input wiring above the linkage switch for measuring the AC input voltage, an output voltage sensor located on the output wiring for measuring the DC output voltage, and a current sensor located on the input wiring for measuring the reactor current flowing through the reactor.

[0021] The controller includes a peak current control unit that performs peak current mode control by using a first slope compensation circuit corresponding to the positive polarity of the AC and a second slope compensation circuit corresponding to the negative polarity of the AC, and outputs control signals to turn the first switching element and the second switching element on and off; and an AC tuning control unit that matches the phase and period of the input voltage to the AC and gradually increases the amplitude of the input voltage to match the amplitude of the AC. The controller is configured such that, at startup, the AC tuning control unit operates and when the amplitude of the input voltage reaches a predetermined value, the linkage switch switches from off to on, and the controller transitions to peak current mode control.

[0022] In other words, this AC / DC converter includes a predetermined bridgeless PFC circuit and is configured to convert bidirectionally between AC and DC. Therefore, the power factor can be efficiently improved. Furthermore, since the controller has a predetermined peak current control unit and performs switching operations in peak current mode control, the reactor can be made smaller.

[0023] Furthermore, the controller has an AC tuning control unit. When the AC tuning control unit starts up and charges by inputting AC, it performs a soft start with the linkage switch in the off state (no AC input). Then, when the phase, period, and amplitude of the input voltage input to the PFC circuit substantially match those of the AC, the linkage switch switches on, and the control switches to peak current mode.

[0024] Therefore, since it can start up smoothly without using a pre-charge circuit, a compact and high-performance AC / DC converter can be realized at a low cost.

[0025] The second slope compensation circuit may include an inverting circuit that reverses the polarity of the AC, and may be configured using the same slope compensator as the first slope compensation circuit.

[0026] This allows peak current mode control to be performed using commercially available slope compensation components, enabling miniaturization of the reactor and providing an inexpensive, high-performance AC / DC converter.

[0027] The controller may further include: a DC bus voltage control unit that receives the command value of the output voltage and the measured value of the output voltage sensor and outputs a command value of the reactor current so that the output voltage becomes a set DC bus voltage; a limiter that limits the command value of the reactor current, having an upper limit that caps out above a predetermined positive value and a lower limit that caps out below a predetermined negative value; and a peak current command value setting unit that sets a peak current command value to be input to the peak current control unit from the limited command value of the reactor current output from the limiter.

[0028] In other words, this configuration corresponds to the case where the controller has a basic control circuit described later. This AC / DC converter allows for seamless and smooth control of both charging and discharging operations.

[0029] The controller may further include a reactive current control unit that calculates a command value for reactive current according to a predetermined operating power factor, and the peak current command value setting unit may set the peak current command value from both the limited command value of the reactor current and the command value of the reactive current.

[0030] In other words, this configuration corresponds to the case where the controller has an applied control circuit described later. This AC / DC converter allows for seamless and smooth control of both charging and discharging operations, and also has a reactive power control function, thus enabling constant power factor control. [Effects of the Invention]

[0031] The disclosed technology makes it possible to realize a high-performance AC / DC converter suitable for in-vehicle chargers without using complex and expensive circuits. [Brief explanation of the drawing]

[0032] [Figure 1] This is a schematic diagram illustrating an example of the application of the disclosed technology. [Figure 2] This is a circuit diagram showing a bidirectional bridgeless PFC circuit. [Figure 3A] This is a diagram illustrating the specific operation of an AC / DC converter. [Figure 3B] This is a diagram illustrating the specific operation of an AC / DC converter. [Figure 4A] This is a block diagram of the basic control circuit for the high-speed side. [Figure 4B] This is a block diagram of the high-speed application control circuit. [Figure 4C] This figure shows a summary of the equations used in the calculations of the control circuits in Figures 4A and 4B. [Figure 5] This is a block diagram of the control circuit in the peak current control unit. [Figure 6] This is a configuration table for the lookup table used by the determination unit. [Figure 7A] This diagram shows the switching pattern under peak current mode control. [Figure 7B] This diagram shows the switching pattern under peak current mode control. [Figure 8] This is a block diagram of the low-speed control circuit. [Figure 9A] This is a diagram showing the results of the simulation. [Figure 9B] This is a diagram showing the results of the simulation. [Figure 10] This is a diagram showing the results of the simulation. [Figure 11] This is a diagram showing the results of the simulation. [Figure 12] This is a diagram showing the results of the simulation. [Figure 13] This is a circuit diagram showing a conventional pre-charge circuit. [Modes for carrying out the invention]

[0033] The following describes the disclosed technology. However, the following description is merely illustrative in nature. Circuit components are also assigned predetermined symbols along with the alphanumeric codes that identify them. For convenience, there may be cases where only the symbols are used for description or illustration. The capital letter symbol "I" for current represents its maximum value (amplitude value), and the lowercase letter symbol "i" for current represents its instantaneous value.

[0034] <Overview of AC / DC Converter> FIG. 1 shows an application example in which the disclosed technology is used in an on-vehicle charger 3 (OBC). The on-vehicle charger 3 is mounted on a vehicle 1 that runs using electric power, such as an electric vehicle and a hybrid vehicle, together with a high-output battery 4 with a high driving voltage of several hundred volts.

[0035] The upper part of FIG. 1 shows the vehicle 1 and the commercial power supply 2 during charging. The commercial power supply 2 outputs a high-voltage alternating voltage (commercial system voltage) such as 100V and 200V. By connecting the commercial power supply 2 and the vehicle 1 with a cable, the battery 4 is charged. The on-vehicle charger 3 intervenes between the battery 4 and the commercial power supply 2 at that time and converts alternating current power into direct current power corresponding to the battery 4.

[0036] Furthermore, in the case of this on-vehicle charger 3, it is also configured to be able to output in the reverse direction. For example, the on-vehicle charger 3 can convert the direct current power obtained by discharging the battery 4 into a predetermined alternating current power and output it. Power can be supplied from the battery 4 to an external alternating current power system via the on-vehicle charger 3.

[0037] As shown in the middle part of FIG. 1, the on-vehicle charger 3 is composed of an isolated DC / DC converter 5, an AC / DC converter 6, etc. The disclosed technology is applied to this AC / DC converter 6.

[0038] The AC / DC converter 6 performs bidirectional conversion between alternating current (AC) and direct current (DC). Specifically, the AC / DC converter 6 takes the AC voltage from the commercial power supply 2 (commercial grid voltage eac) as input and converts it to a DC output voltage (DC bus voltage: Vdc) for output. This corresponds to the charging operation of the battery 4. The AC / DC converter 6 also takes the DC bus voltage Vdc as input and converts it to an AC voltage (eac) for output. This corresponds to the discharging operation from the battery 4.

[0039] Furthermore, although the AC / DC converter 6 performs bidirectional conversion, its primary function is charging. Discharging, where the input / output direction is opposite to charging, is secondary. Therefore, in this explanation, the AC side will be referred to as the input, and the DC side as the output.

[0040] The DC / DC converter 5 is a device that converts one DC voltage to another. The DC / DC converter 5 is connected to the output side of the AC / DC converter 6. The DC / DC converter 5 performs boost or buck operation and outputs bidirectionally. In other words, the DC / DC converter 5 interposes itself between the AC / DC converter 6 and the battery 4, enabling the charging and discharging of the battery 4, whose voltage changes.

[0041] The DC / DC converter 5 receives a DC bus voltage Vdc as input and converts it to a predetermined DC voltage Vhv for output. This corresponds to charging the battery 4. The DC / DC converter 5 also converts the predetermined DC voltage Vhv to a predetermined DC bus voltage Vdc for output. This corresponds to discharging the battery 4.

[0042] From the viewpoint of power conversion stability and other factors, it is preferable to control the DC bus voltage between the DC / DC converter 5 and the AC / DC converter 6 to a constant value. Therefore, in the example on-board charger 3, the DC bus voltage Vdc is set to a predetermined value (e.g., 400V).

[0043] As shown in the lower part of Figure 1, the AC / DC converter 6 comprises a converter mechanism 13 and a controller 14 that controls the converter mechanism 13. The converter mechanism 13 includes a current sensor 10, a first input voltage sensor 11a, a second input voltage sensor 11b, an output voltage sensor 12, a bidirectional bridgeless PFC circuit 20 (hereinafter also simply referred to as the PFC circuit 20), and the like.

[0044] The current sensor 10 is a Hall element type sensor constructed using a Hall element. This type of sensor is well known. The current sensor 10 can detect the direction and magnitude of the current with high precision by utilizing the Hall effect. The current sensor 10 is installed at a predetermined position on the input wiring 21, which will be described later (see Figure 2).

[0045] The current sensor 10 directly measures the current (reactor current iinv) flowing through the reactor 27 and outputs it to the controller 14. The current sensor 10 measures the reactor current iinv flowing toward the output side, that is, the current flowing in the charging direction, as positive (the reactor current iinv flowing in the reverse direction, that is, the current flowing in the discharge direction, is measured as negative).

[0046] The first input voltage sensor 11a and the second input voltage sensor 11b are also installed at predetermined positions on the input wiring 21, which will be described later (see Figure 2). The first input voltage sensor 11a directly measures the commercial power grid voltage eac input to the AC / DC converter 6 and outputs it to the controller 14.

[0047] Note that the first input voltage sensor 11a is not essential. It is sufficient for the controller 14 to acquire information about the commercial power grid voltage eac input to the AC / DC converter 6, specifically information about the phase, period, and amplitude of the AC voltage.

[0048] The second input voltage sensor 11b is located on the output side of the input wiring 21, beyond the linkage switch 30, which will be described later. The second input voltage sensor 11b directly measures the AC voltage (input voltage einv) applied to the output side of the input wiring 21 beyond the linkage switch 30 and outputs it to the controller 14.

[0049] After startup, as will be described later, the phase, period, and amplitude of the commercial power grid voltage eac and the input voltage einv coincide (eac = einv). Therefore, the measured values ​​of the first input voltage sensor 11a and the second input voltage sensor 11b after startup will be the same.

[0050] The output voltage sensor 12 is installed at a predetermined position on the output wiring 22, which will be described later (see Figure 2). The output voltage sensor 12 directly measures the DC bus voltage Vdc output from the AC / DC converter 6 and outputs it to the controller 14.

[0051] Based on the measured values ​​from these sensors, the controller 14 outputs a drive voltage to the two switching elements S1 and S2 of the PFC circuit 20 to control them on and off. In other words, the controller 14 switches between energized (on) and de-energized (off) states of these switching elements S1 and S2 at predetermined timings to perform the switching operation.

[0052] The controller 14 also switches the two switching elements S3 and S4 of the PFC circuit 20 on and off according to the polarity of the AC, based on the measured values ​​of these sensors. The on / off operation of switching elements S1 and S2 is fast, while the on / off operation of switching elements S3 and S4 is slow.

[0053] The controller 14 further controls the on / off state of the linkage switch 30 based on the measured values ​​of these sensors. Specifically, when the AC / DC converter 6 is started, the controller 14 switches the linkage switch 30 from an electrically disconnected state (off) to an electrically connected state (on) at a predetermined timing.

[0054] (PFC circuit) Figure 2 shows the PFC circuit 20 of the AC / DC converter 6.

[0055] The PFC circuit 20 includes a pair of input wirings 21 (grounded N input wiring 21a and ungrounded L input wiring 21b), a pair of output wirings 22 (negative N output wiring 22a and positive P output wiring 22b), a first leg 23, a second leg 24, and a third leg 25, an input capacitor (Cinv) 26, a reactor (Linv) 27, a plurality of switching elements 28 (first switching element S1, second switching element S2, third switching element S3, fourth switching element S4), an output capacitor (Cdc) 29, and a linkage switch (Sw) 30.

[0056] A pair of input wirings 21 are located on the commercial power supply 2 side, and the commercial grid voltage eac is input to their input terminals (L and N). On the other hand, a pair of output wirings 22 are located on the battery 4 side, and the DC bus voltage Vdc is output from their output terminals (P and N).

[0057] The linkage switch 30 is located near the input terminals (L and N) of the pair of input wirings 21. The linkage switch 30 is configured to be switchable by on / off control between a state in which the pair of input wirings 21 are electrically connected (on) and a state in which the pair of input wirings 21 are electrically disconnected (off).

[0058] The input capacitor 26 is connected between a pair of input wirings 21 on the output side of the linkage switch 30. The input capacitor 26 can reduce noise in the AC current iac and stabilize the input voltage einv. Therefore, it is common for the PFC circuit 20 to include an input capacitor 26.

[0059] The reactor 27 is located at least one side of the connection point between the input side wiring 21 and the input side capacitor 26, on the output side. Specifically, the reactor 27 is located on the output side of the connection point between the input side wiring 21b and the input side capacitor 26.

[0060] The first leg 23, the second leg 24, and the third leg 25 are connected in parallel between a pair of output wirings 22a and 22b. The third leg 25 is located on the output side of the first leg 23 and the second leg 24. The output capacitor 29 is located on the third leg 25.

[0061] The first switching element S1 and the second switching element S2 are arranged in series in the first leg 23, starting from the positive terminal side of the P output wiring 22b. The third switching element S3 and the fourth switching element S4 are arranged in series in the second leg 24, starting from the positive terminal side of the P output wiring 22b.

[0062] Each of the first to fourth switching elements 28 consists of a known MOSFET or the like, equipped with gate, source, and drain terminals. They are turned on by applying a predetermined drive voltage to the gate terminal. Each of the first to fourth switching elements 28 is arranged such that when turned on, the direction of current flow is from the positive terminal side of the P output wiring 22b to the negative terminal side of the N output wiring 22a.

[0063] Each switching element 28 includes a freewheeling diode 28a connected in antiparallel. Therefore, when each switching element 28 is off, current can flow through this freewheeling diode 28a only in a predetermined direction (from the negative terminal to the positive terminal).

[0064] The output terminal of the L input wiring 21b is connected to the intermediate point between the first switching element S1 and the second switching element S2 in the first leg 23. The output terminal of the N input wiring 21a is connected to the intermediate point between the third switching element S3 and the fourth switching element S4 in the second leg 24.

[0065] <Operation by Specific Control of AC / DC Converter> Referring to FIGS. 3A and 3B, the specific operation of the AC / DC converter 6 under the control of the controller 14 will be described. In each figure, a load R (corresponding to the DC / DC converter 5) is schematically illustrated together with the PFC circuit 20.

[0066] FIG. 3A shows the operation during charging. The upper and lower figures (a1, a2) on the left side represent the operation when the polarity of the input-side voltage einv is positive (sin(θinv) ≧ 0) (during the positive half-cycle). The upper and lower figures (b1, b2) on the right side represent the operation when the polarity of the input-side voltage einv is negative (sin(θinv) < 0) (during the negative half-cycle).

[0067] The third switching element S3 and the fourth switching element S4 are switched according to the polarity of the input-side voltage einv. That is, during the positive half-cycle, the third switching element S3 is turned off and the fourth switching element S4 is turned on. During the negative half-cycle, the third switching element S3 is turned on and the fourth switching element S4 is turned off.

[0068] Then, in the first switching element S1 and the second switching element S2, switching operations are performed, and these first switching element S1 and second switching element S2 are alternately turned on and off at a predetermined timing. Thereby, a predetermined current path through which the input-side current iac flows is formed.

[0069] Specifically, as in (a1), when the polarity of the input-side voltage einv is positive and the first switching element S1 is off and the second switching element S2 is on, the input-side current iac flows in from the L input-side wiring 21b. Then, as indicated by the arrow broken line Ya1, the input-side current iac flows through a current path composed of the middle part of the first leg 23, the second switching element S2, the N output-side wiring 22a, the fourth switching element S4 (freewheel diode 28a), the middle part of the second leg 24, and the N input-side wiring 21a.

[0070] As shown in (a2), when the polarity of the input voltage einv is positive, and the first switching element S1 is turned on and the second switching element S2 is turned off, the input current iac flowing in from the L input wiring 21b flows through a current-carrying path consisting of the intermediate part of the first leg 23, the first switching element S1 (freewheeling diode 28a), the P output wiring 22b, the load R and output capacitor Cdc, the N output wiring 22a, the fourth switching element S4 (freewheeling diode 28a), the intermediate part of the second leg 24, and the N input wiring 21a, as indicated by the dashed arrow Ya2.

[0071] As shown in (b1), when the polarity of the input voltage einv is negative, when the first switching element S1 turns on and the second switching element S2 turns off, an input current iac flows in from the N input wiring 21a. This input current iac then flows through a current-carrying path consisting of the intermediate part of the second leg 24, the third switching element S3 (freewheeling diode 28a), the N output wiring 22a, the first switching element S1, the intermediate part of the first leg 23, and the L input wiring 21b, as indicated by the dashed arrow Yb1.

[0072] As shown in (b2), when the polarity of the input voltage einv is negative, and the first switching element S1 is off and the second switching element S2 is on, the input current iac flowing in from the N input wiring 21a flows through a current-carrying path consisting of the intermediate part of the second leg 24, the third switching element S3 (freewheeling diode 28a), the P output wiring 22b, the load R and output capacitor Cdc, the N output wiring 22a, the second switching element S2 (freewheeling diode 28a), the intermediate part of the first leg 23, and the L input wiring 21b, as indicated by the dashed arrow Yb2.

[0073] Figure 3B shows the operation during discharge. The upper and lower figures on the left (c1, c2) represent the operation when the polarity of the input voltage einv is positive (sin(θinv)≧0) (positive half-cycle). The upper and lower figures on the right (d1, d2) represent the operation when the polarity of the input voltage einv is negative (sin(θinv)<0) (negative half-cycle).

[0074] The third switching element S3 and the fourth switching element S4 are switched according to the polarity of the input voltage einv. That is, during a positive half-cycle, the third switching element S3 is turned off and the fourth switching element S4 is turned on. During a negative half-cycle, the third switching element S3 is turned on and the fourth switching element S4 is turned off.

[0075] Then, switching operations are performed in the first switching element S1 and the second switching element S2, and these first switching element S1 and second switching element S2 are alternately turned on and off at predetermined timings. As a result, a predetermined current path is formed through which the input current iac flows.

[0076] Specifically, as shown in (c1), when the polarity of the input voltage einv is positive, and the first switching element S1 is turned off and the second switching element S2 is turned on, the input current iac flowing in from the L input wiring 21b flows through a current-carrying path consisting of the intermediate part of the first leg 23, the second switching element S2, the N output wiring 22a, the fourth switching element S4 (freewheeling diode 28a), the intermediate part of the second leg 24, and the N input wiring 21a, as indicated by the dashed arrow Yc1.

[0077] As shown in (c2), when the polarity of the input voltage einv is positive, if the first switching element S1 turns on and the second switching element S2 turns off, the voltage difference between the input voltage einv and the output voltage Vdc (Vdc > einv) creates a current path consisting of the N input wiring 21a, the middle section of the second leg 24, the fourth switching element S4, the N output wiring 22a, the load R and output capacitor Cdc, the P output wiring 22b, the first switching element S1 (freewheel diode 28a), the middle section of the first leg 23, and the L input wiring 21b. As a result, a discharge current flows in the reverse direction through the reactor Linv.

[0078] As shown in (d1), when the polarity of the input voltage einv is negative, and the first switching element S1 turns on and the second switching element S2 turns off, the input current iac flowing in from the N input wiring 21a flows through a current-carrying path consisting of the intermediate part of the second leg 24, the third switching element S3 (freewheeling diode 28a), the N output wiring 22a, the first switching element S1, the intermediate part of the first leg 23, and the L input wiring 21b, as indicated by the dashed arrow Yd1.

[0079] As shown in (d2), when the polarity of the input voltage einv is negative, and the first switching element S1 is turned off and the second switching element S2 is turned on, the voltage difference between the input voltage einv and the output voltage Vdc (Vdc > einv) causes a current path to be formed, as shown by the dashed arrow Yd2, consisting of the N input wiring 21a, the middle section of the second leg 24, the third switching element S3 (freewheeling diode 28a), the P output wiring 22b, the load R and output capacitor Cdc, the N output wiring 22a, the second switching element S2 (freewheeling diode 28a), the middle section of the first leg 23, and the L input wiring 21b. As a result, a discharge current flows in the reverse direction through the reactor Linv.

[0080] <Controller control circuit> (Basic control circuit for the high-speed side) As described above, the controller 14 switches the first switching element S1 and the second switching element S2 at high speed. An example of a block diagram of the control circuit of the controller 14 is shown in Figures 4A and 4B. Figure 4C shows the equations used in the calculations of these control circuits.

[0081] Figure 4A shows a basic control circuit for handling active power (basic control circuit). The controller 14 includes a DC bus voltage control unit 40, a peak current command value setting unit 50, a peak current control unit 60, and a limiter 70.

[0082] The DC bus voltage control unit 40 controls the output voltage Vdc so that it becomes the set DC bus voltage. The DC bus voltage control unit 40 receives the command value Vdc for the output voltage. * The measured value Vdc of the output voltage measured by the output voltage sensor 12 is input.

[0083] Then, the DC bus voltage control unit 40 outputs a command value for the reactor current (first input side current command value Iinv) corresponding to the maximum value of the reactor current (iinv). * The output is Vdc. The measured value of the output voltage Vdc is used as a feedback value, and the DC bus voltage control unit 40 sets the command value Vdc to Vdc. * PID control is performed to match the first input side current command value Iinv * Output to limiter 70.

[0084] Limiter 70 has an upper limit (+Iinv.lim) that caps out the current above a predetermined value on the positive side, and a lower limit (-Iinv.lim) that caps out the current below a predetermined value on the negative side. As mentioned above, the current flowing during charging is positive and the current flowing during discharging is negative, so Limiter 70 corresponds to both charging and discharging operations and sets the reactor current command value (first input side current command value Iinv * ) restrict.

[0085] As the upper and lower limits, for example, after considering the rating of the in-vehicle charger 3, the maximum value of the rated current of the commercial power supply 2 (for example, about 20 A) may be set. The first input-side current command value Iinv whose magnitude is limited between the upper and lower limits by the limiter 70 * is input to the peak current command value setting unit 50.

[0086] The peak current command value setting unit 50 is composed of a phase synchronization circuit 51, a multiplier 52, an adder 53, etc., and based on the measured values of the first input-side voltage sensor 11a and / or the second input-side voltage sensor 11b and the measured value of the output-side voltage sensor 12, the first input-side current command value Iinv * is used to set a predetermined peak current command value.

[0087] Specifically, first, when the first input-side current command value Iinv * is input to the multiplier 52, based on the phase of the commercial system voltage eac (= input-side voltage einv), it is converted into a command value of the reactive current corresponding to the instantaneous value (the second input-side current command value iinv * ). That is, the measured value of the commercial system voltage eac measured by the first input-side voltage sensor 11a is input to the phase synchronization circuit 71. Based on that measured value, the phase angle θac is obtained. And from that phase angle θac, a predetermined signal (phase signal: sin(θac)) is obtained.

[0088] That phase signal sin(θac) is output from the phase synchronization circuit 51 and input to the multiplier 52. In the multiplier 52, the phase signal sin(θac) is multiplied by the first input-side current command value Iinv * . By doing so, the second input-side current command value iinv * is calculated, and that value is output to the adder 53.

[0089] In the adder 53, the second input-side current command value iinv * is added with a predetermined current correction amount Δiinv. By doing so, the peak current command value iinv as the instantaneous value introduced into the peak current control unit 60 *.p is set. The current correction amount Δiinv is an estimate of the pulsating component of the reactor current and is obtained by equation (1) shown in Figure 4C.

[0090] In equations (1) to (3) shown in Figure 4C, Linv is the inductance of reactor 27. As will be described later, a PWM method that changes the duty cycle is used for the switching operation of the first switching element S1 and the second switching element S2. TPWM is a periodic signal that indicates the timing corresponding to the switching period (a predetermined constant value) in that PWM control (see Figures 7A and 7B).

[0091] In equation (2), Ks is the slope value used for slope compensation in the peak current mode control described later. In equation (3), d is the ratio of the input voltage to the output voltage. The measured value of the output voltage sensor 12 is used to calculate Ks and d.

[0092] The peak current control unit 60 controls the timing of turning the first switching element S1 and the second switching element S2 on and off by peak current mode control. Specifically, the peak current control unit 60 receives a peak current command value iinv * Along with .p, the measured value iinv of the reactor current measured by the current sensor 10 is input as its feedback value. The peak current control unit 60 also receives TPWM, Ks, TZRO, etc. TZRO is a set signal that indicates the timing corresponding to 0 degrees (360 degrees) of the switching period in PWM control.

[0093] As a result, the peak current control unit 60 outputs control signals Q1 and Q2 that indicate the timing for turning the first switching element S1 and the second switching element S2 on and off.

[0094] (High-speed application control circuit) Figure 4B shows a control circuit (also called an applied control circuit) that has a reactive power control function by applying the basic control circuit on the high-speed side. In other words, this applied control circuit has a reactive current control circuit 69 in addition to the DC bus voltage control unit 40, peak current command value setting unit 50, peak current control unit 60, and limiter 70 described above.

[0095] Most applied control circuits are common to the basic control circuits described above. Therefore, the same components will be described using the same reference numerals, and their explanations will be simplified or omitted, while components with different components will be described.

[0096] The second input side current command value iinv is calculated in the peak current command value setting unit 50 of the basic control circuit. * This corresponds to the active power Pac. Therefore, in the applied control circuit, the command value for the current corresponding to the active power Pac is the second input side current command value iinv. * The effective current command value is ip * It is said that...

[0097] The reactive current control unit 69 is set to correspond to the reactive power Qac, and according to a predetermined operating power factor PF, it controls the reactive current command value (reactive current command value iQ). * ) is calculated. Figure 4C shows equations (4) to (12) related to this calculation.

[0098] In these equations, Pac in equation (6) corresponds to the active power of the commercial power supply 2 input to the AC / DC converter 6. Tac is the period of the active power Pac. Tac is obtained from the phase-locked circuit 51, as shown in Figure 4B. Eac.rms in equation (4) corresponds to the RMS value of the voltage of the active power Pac. Iac.rms in equation (5) corresponds to the RMS value of the current of the active power Pac. Sac in equation (7) corresponds to the apparent power. Qac in equation (8) corresponds to the reactive power.

[0099] In the phase-locked circuit 51, a predetermined signal (second phase signal: cos(θac)) is obtained from the phase angle θac. This second phase signal cos(θac) is output from the phase-locked circuit 51 and input to the second multiplier 69a. In the second multiplier 69a, the reactive current command value (maximum value) IQ is determined. * The second phase signal cos(θac) is multiplied to this. As a result, the reactive current command value iQ is obtained as the command value of the current corresponding to the reactive power Qac. * This is calculated.

[0100] Here, the reactive current command value (maximum value) IQ * Qac is the command value of the reactive power Qac * It is calculated by equation (9). FQ corresponds to the definition of reactive power Qac (leading reactive power and lagging reactive power) and is determined by equations (10) and (11). Note that in the case of control using leading reactive power, a suppression effect on the voltage drop of commercial power supply 2 is obtained. In the case of control using lagging reactive power, a suppression effect on the voltage rise of commercial power supply 2 is obtained.

[0101] Command value of reactive power Qac * In equation (12), the command value PF is the operating power factor PF. * This can be obtained by setting [the appropriate parameter].

[0102] The reactive current command value iQ is calculated by the reactive current control unit 69. * This is output to the peak current command value setting unit 50. Then, the current command value integrator 69b provided in the peak current command value setting unit 50 sets the effective current command value ip * and the reactive current command value iQ * From both sides, the command value for the current corresponding to the apparent power Sac is the third input side current command value iinv * The third input current command value iinv is calculated in the adder 73. * By adding the current correction amount Δiinv, the peak current command value iinv input to the peak current control unit 60 is determined. * The .p file will be set.

[0103] This applied control circuit enables control that maintains a constant power factor according to both charging and discharging power. Moreover, by combining it with peak current mode control, it is possible to stably track the power factor with a simple circuit configuration without current feedback control. That is, the third input side current command value iinv * By simply inputting this to the peak current control unit 60, a current waveform corresponding to the apparent power Sac can be generated. Active power Pac and reactive power Qac can be freely controlled, and constant power factor control can be achieved with a simple circuit configuration.

[0104] (Details of the peak current control unit) Figure 5 shows a block diagram of the control circuit in the peak current control unit 60. The control circuit of the peak current control unit 60 is connected to the control circuit of the AC tuning control unit 80. The AC tuning control unit 80 is used during startup (when charging starts), so it will be described separately later. Figure 6 shows the setting table of the lookup table of the determination unit 67, which will be described later.

[0105] Figure 7A shows the switching pattern under peak current mode control during charging. Figure 7B shows the switching pattern under peak current mode control during discharge. Figure 7A(a) is the switching pattern during a positive half-cycle, and Figure 7A(b) is the switching pattern during a negative half-cycle. On the other hand, Figure 7B(a) is the switching pattern during a negative half-cycle, and Figure 7B(b) is the switching pattern during a positive half-cycle.

[0106] Slope compensation is essential for peak current mode control. In response to this, this controller 14 is designed to enable slope compensation even in the AC / DC converter 6 using inexpensive commercially available electronic components.

[0107] In other words, while electronic components such as ICs and microcontrollers that perform slope compensation (slope compensation components) are commercially available, these slope compensation components are developed for DC / DC converters that handle DC power. For this reason, these slope compensation components are structured to only be capable of processing signals for positive slope compensation.

[0108] In contrast, since the AC / DC converter 6 handles alternating current power whose polarity changes between positive and negative, the controller 14 also requires signal processing for negative slope compensation. Therefore, simply using commercially available slope compensation components as they are will not enable peak current mode control in the controller 14.

[0109] In contrast, in this controller 14, the peak current control unit 60 performs peak current mode control by using a first slope compensation circuit corresponding to the positive polarity of the input voltage einv and a second slope compensation circuit corresponding to the negative polarity of the input voltage einv. The second slope compensation circuit includes an inverting circuit that reverses the polarity of the AC and is configured using the same slope compensator as the first slope compensation circuit, that is, a slope compensator corresponding to the positive polarity.

[0110] Therefore, in the case of this controller 14, peak current mode control can be performed using only commercially available slope compensation components in the slope compensator. As a result, peak current mode control can be performed with a simple and inexpensive circuit configuration. Consequently, stable operation can be achieved even when the reactor 27 is miniaturized.

[0111] Specifically, the peak current control unit 60 includes a first slope compensator 61, a first comparator 62, a second slope compensator 63, a second comparator 64, an inverting amplifier circuit 65, a PWM control unit 66, a determination unit 67, a high-speed gate driver 68, and the like. The first slope compensator 61 and the first comparator 62 constitute the first slope compensation circuit, while the second slope compensator 63, the second comparator 64, and the inverting amplifier circuit 65 constitute the second slope compensation circuit.

[0112] As described above, the first slope compensator 61 and the second slope compensator 63 have the same function corresponding to the positive polarity of the input voltage einv. Therefore, commercially available slope compensation components such as analog ICs and control microcontrollers can be used for the first slope compensator 61 and the second slope compensator 63.

[0113] The first slope compensator 61 receives a positive peak current command value iinv corresponding to a positive half-cycle. * .p and Ks are input. Ks is the positive peak current control command value iinv * This corresponds to a predetermined slope value applied to .p. Ks is generally used to suppress the occurrence of low-frequency oscillations that occur when the duty cycle exceeds 50%.

[0114] The first slope compensator 61 also receives a pulsed set signal TZRO and a first reset signal TripA. As shown in Figures 7A and 7B, the set signal TZRO is output at a timing corresponding to 0 degrees of the switching period. The first reset signal TripA is output at a timing corresponding to the upper limit (peak) of the reactor current iinv.

[0115] The set signal TZRO is input from the PWM control unit 66 based on the periodic signal TPWM. The first reset signal TripA is fed back after the output from the first comparator 62. The first slope compensator 61 calculates a positive peak current command value iinv based on these set signals TZRO and TripA. * Set or reset the .p file.

[0116] The first slope compensator 61 controls the positive peak current command value iinv * Based on .p and Ks, the positive peak current command value iinv * A slope is applied to .p and output to the first comparator 62 (the sloped dashed line portion in Figures 7A and 7B(a)).

[0117] The first comparator 62 compares its output value with the value of the reactor current iinv. When the output value of the first comparator 62 matches the value of the reactor current iinv (the matching portion in Figures 7A and 7B(a)), the first comparator 62 outputs a first reset signal TripA. The first reset signal TripA is fed back to the first slope compensator 61. The first reset signal TripA is also output to the determination unit 67.

[0118] The second slope compensator 63 has a negative peak current command value -iinv corresponding to a negative half-cycle. * .p and Ks are input. The second slope compensator 63 also receives the set signal TZRO and the second reset signal TripB, similar to the first slope compensator 61. Based on these set signal TZRO and second reset signal TripB, the second slope compensator 63 sets a negative peak current command value -iinv * Set or reset the .p file.

[0119] The second slope compensator 63 controls the negative peak current command value -iinv * Based on .p and Ks, the negative peak current command value -iinv * A slope is applied to .p and output to the second comparator 64 (the sloped dashed line portion in Figures 7A and 7B(b)).

[0120] The inverting amplifier circuit 65 takes a reactor current iinv as input and outputs a reactor current (negative reactor current value -iinv) with the positive and negative signs of that value inverted.

[0121] The second comparator 64 compares the output value from the second slope compensator 63 with its negative reactor current value -iinv. When the output value of the second comparator 64 matches the negative reactor current value -iinv (the matching portion in Figures 7A and 7B(b)), the second comparator 64 outputs a second reset signal TripB. The second reset signal TripB is fed back to the second slope compensator 63. The second reset signal TripB is also output to the determination unit 67.

[0122] The determination unit 67 has a lookup table configured as shown in the table in Figure 6. The lookup table includes two types: one for charging and one for discharging. Peak current mode control is performed after startup (after the input voltage einv has stabilized), that is, when the linkage switch 30 is ON (Sw=1). Therefore, these lookup tables include determination information corresponding to this.

[0123] On the other hand, during charging, the system includes a pre-charging operation during the transient state before reaching a steady state (until the input voltage einv stabilizes). In other words, the lookup table for charging includes determination information for when the linkage switch 30 is off (Sw=0) (this will be explained later).

[0124] The determination unit 67 determines the input first reset signal TripA and second reset signal TripB based on the on / off signal of the linkage switch (Sw=1), the phase signal sin(θac) input from the phase synchronization circuit 51, and the lookup table. Based on this, the determination unit 67 outputs control signals (first control signal Q1 and second control signal Q2) for turning the first switching element S1 and the second switching element S2 on and off.

[0125] Specifically, as shown in Figure 7A(a), in the case of a positive half-cycle during charging (phase signal sin(θac) is 0 or greater), and as shown in Figure 7B(a), in the case of a negative half-cycle during discharge (phase signal sin(θac) is less than 0), when the first reset signal TripA is input, the determination unit 67 outputs a first control signal Q1 for a high state (1) and a second control signal Q2 for a low state (0).

[0126] On the other hand, even if the second reset signal TripB is input, the determination unit 67 ignores it and does not output a control signal. When the set signal TZRO is input, the determination unit 67 outputs the first control signal Q1 in a low state and the second control signal in a high state.

[0127] Furthermore, as shown in Figure 7A(b), in the case of a negative half-cycle during charging (phase signal sin(θac) is less than 0), and as shown in Figure 7B(b), in the case of a positive half-cycle during discharge (phase signal sin(θac) is 0 or greater), even if the first reset signal TripA is input, the determination unit 67 ignores it and does not output a control signal.

[0128] On the other hand, when the second reset signal TripB is input, the determination unit 67 outputs the first control signal Q1 in a low state and the second control signal Q2 in a high state. When the set signal TZRO is input, the determination unit 67 outputs the first control signal Q1 in a high state and the second control signal Q2 in a low state.

[0129] As shown in Figure 5, the first control signal Q1 and the second control signal Q2 output by the determination unit 67 are input to the high-speed gate driver 68. A predetermined dead time Td is also input to the high-speed gate driver 68.

[0130] The high-speed gate driver 68 turns the first switching element S1 on and off based on the first control signal Q1, and turns the second switching element S2 on and off based on the second control signal Q2. Specifically, when the first control signal Q1 is high, it outputs a drive voltage to the first switching element S1 to turn it on. When the first control signal Q1 is low, it does not output a drive voltage to the first switching element S1 and turns it off. Similarly, the second switching element S2 is turned on or off depending on the state of the second control signal Q2.

[0131] (Slow-speed control circuit) To achieve both charging and discharging operations, the controller 14 switches the third switching element S3 and the fourth switching element S4 as described above. An example of a block diagram of the low-speed control circuit of the controller 14 for this purpose is shown in Figure 8.

[0132] The low-speed control circuit consists of a third comparator 90, a fourth comparator 91, a negation circuit 92, and a low-speed gate driver 93. The third comparator 90 and the fourth comparator 91 are each input to a phase signal sin(θac) obtained from the phase-locking circuit 43a.

[0133] The third comparator 90 and the fourth comparator 91 are each input to predetermined judgment signals +A and -A, which have opposite signs. "A" is a numerical value in the range of 0 to 1. The ideal value of A is 0, but to avoid noise near the zero crossing, a value close to 0 is preferable (for example, 0.01).

[0134] The third comparator 90 and the fourth comparator 91 each compare the phase signal sin(θac) with their respective decision signals. Then, each of the third comparator 90 and the fourth comparator 91 outputs a signal of 0 or 1 depending on the relative magnitudes of the phase signal sin(θac) and their respective decision signals.

[0135] The third comparator 90 outputs the signal as is (third control signal Q3) to the low-speed gate driver 93. On the other hand, the fourth comparator 91 outputs the signal inverted through the negation circuit 92 (fourth control signal Q4) to the low-speed gate driver 93. As a result, the third control signal Q3 and the fourth control signal Q4 are different from each other (0 or 1). A predetermined dead time Td is also input to the low-speed gate driver 93.

[0136] The low-speed gate driver 93 turns the third switching element S3 on and off based on the third control signal Q3, and turns the fourth switching element S4 on and off based on the fourth control signal Q4.

[0137] <Startup behavior> Conventional AC / DC converters typically include a pre-charge circuit to suppress inrush current and ensure smooth startup. However, in the case of OBCs (On-Board Converters) that handle high power, pre-charge circuits have disadvantages such as high cost and increased size and weight of the device.

[0138] Therefore, this AC / DC converter 6 is configured to start up smoothly without using a precharge circuit by utilizing peak current mode control. Specifically, as shown in Figure 5, an AC tuning control unit 80 is attached to the peak current control unit 60.

[0139] The AC tuning control unit 80 includes a soft start unit 81, a multiplier 82, a divider 83, and a second PWM control unit 84. The soft start unit 81 receives the effective value Eac.rms of the commercial power grid voltage eac as input. The soft start unit 81 increases the effective value Eac.rms from 0% to 100% at a predetermined rate. The soft start unit 81 includes a coefficient Tsoft that corresponds to the time required for the increase. For example, if the coefficient Tsoft is 1 second, the soft start unit 81 gradually increases the effective value Eac.rms from 0% to 100% in 1 second and outputs that value.

[0140] The value output from the soft-start unit 81 is multiplied by √2sin(θac) in the multiplier 82. This converts it to a value (amplitude value) corresponding to the amplitude of the commercial power grid voltage eac. This amplitude value is then divided by the DC bus voltage Vdc in the divider 83 to obtain the PWM command value dac. * It generates the PWM command value dac. * This is input to the second PWM control unit 84. The periodic signal TPWM described above is also input to the second PWM control unit 84.

[0141] The second PWM control unit 84 processes these PWM command values ​​dac * Furthermore, PWM control is performed based on the periodic signal TPWM, and the first activation signal Qa and the second activation signal Qb are output to the determination unit 87.

[0142] The phase and period of the first start signal Qa and the second start signal Qb are synchronized with the commercial power grid voltage eac. Their amplitudes gradually increase according to the settings of the soft start unit 81, eventually matching the amplitude of the commercial power grid voltage eac.

[0143] The controller 14 has predetermined determination conditions set for switching the linkage switch 30, and controls the on / off state of the linkage switch 30 based on these conditions to enable smooth startup. Specifically, the controller switches the linkage switch 30 from off to on at the timing when the input voltage einv perfectly matches the commercial grid voltage eac.

[0144] For example, the determination is made based on whether the difference (ΔE) between the measured values ​​(commercial grid voltage eac and input voltage einv) of both the first input voltage sensor 11a and the second input voltage sensor 11b is less than or equal to a predetermined value (for example, less than or equal to 5% of the nominal voltage (effective value) of the commercial grid voltage eac). The controller 14 turns off the linkage switch 30 if ΔE is less than or equal to the predetermined value, and turns on the linkage switch 30 if ΔE exceeds the predetermined value.

[0145] As shown in Figure 6, the lookup table for charging in the determination unit 87 includes determination information for when the linkage switch 30 is off (Sw=0), corresponding to the pre-charging operation at startup. During the pre-charging operation at startup, the determination unit 87 does not perform the original peak current mode control. Instead of the original peak current mode control, it performs AC tuning control by the AC tuning control unit 80. That is, the determination unit 87 outputs a first startup signal Qa as the first control signal Q1 and a second startup signal Qb as the second control signal Q2.

[0146] In this way, the AC tuning control unit 80, upon startup, matches the phase and period of the input voltage einv to the phase and period of the commercial power grid voltage eac, and gradually increases the amplitude of the input voltage einv to match the amplitude of the commercial power grid voltage eac. In other words, it tunes the input voltage einv to the commercial power grid voltage eac.

[0147] When the amplitude of the input voltage einv reaches a predetermined value and the input voltage einv substantially matches the commercial power grid voltage eac, the coupling switch 30 switches from off to on, and the system switches to peak current mode control.

[0148] Therefore, with this AC / DC converter 6, smooth startup is possible without using a conventional pre-charge circuit.

[0149] <Verification of effects through simulation> (Verification 1) To verify the effect of miniaturizing reactor 27, simulations were performed in two cases. In Case 1, the inductance of reactor Linv was set to 340 μH. In Case 2, the inductance of reactor Linv was set to half that, 170 μH.

[0150] The parameters of the circuits used in the simulations for Case 1 and Case 2 are as follows:

[0151] Capacitance of input capacitor (Cinv): 5.5μF PWM frequency: 24kHz Input voltage (einv): 240V / 60Hz DC load: 4kW Dead time: 2μs Output capacitor (Cdc) capacitance: 2200μF Output voltage (Vdc): 400V.

[0152] Figure 9A shows the simulation results for Case 1. Figure 9B shows the simulation results for Case 2. It was confirmed that even with a small reactor Linv with an inductance of 170 μH, a stable reactor current iinv with a waveform that is practically indistinguishable from that of a reactor Linv with an inductance of 340 μH can be obtained.

[0153] In other words, the disclosed technology makes it possible to reduce the inductance of the reactor Linv compared to conventional methods.

[0154] (Verification 2) A simulation was conducted to verify the effectiveness of AC tuning control during startup. The parameters of the circuit used in the simulation were the same as those in Verification 1 (and so on). In the simulation, the system was restarted with the linkage switch 30 in the OFF position.

[0155] An example of the simulation results is shown in Figure 10. Pac is the active power. As shown in Figure 10, the linkage switch 30 is turned on when the input voltage einv and the commercial grid voltage eac match, confirming that a smooth restart is possible.

[0156] (Verification 3) A simulation was conducted to verify whether seamless charging and discharging were possible, that is, whether the switching between discharging and charging operations could be performed smoothly and continuously. An example of the simulation results is shown in Figure 11.

[0157] Figure 11(a) shows the transition from discharge operation to charge operation, and Figure 11(b) shows the transition from charge operation to discharge operation. The transition from discharge operation to charge operation occurs at timing t1, and the transition from charge operation to discharge operation occurs at timing t2. In both cases, the operating power factor is 1 (corresponding to the case where the power factor is set to 1 in the basic control circuit or applied control circuit).

[0158] It was confirmed that the inductor current Iinv during discharge, which has the opposite phase to the input voltage einv waveform, switches smoothly and continuously between the inductor current Iinv during charging, which has the same phase. It was also confirmed that the DC bus voltage Vdc switches without significant fluctuations.

[0159] (Verification 4) To verify whether the reactive power control function of the applied control circuit can be seamlessly charged and discharged, a simulation was conducted. An example of the simulation results is shown in Figure 12.

[0160] In the simulation, the operating power factor was set to 0.8, and the system switched from discharge to charge. The switch occurred at timing t1. It was confirmed that seamless charging and discharging were possible, and stable constant power factor control could be achieved even with the operating power factor set to 0.8.

[0161] Thus, the following effects can be obtained with the disclosed technology. • Peak current mode control can be performed with a simple circuit configuration. • By employing peak current mode control, the capacitance of the reactor Linv can be reduced. • During startup, a soft start is performed to match the input voltage einv to the commercial grid voltage eac before power is supplied to the PFC circuit 20, allowing for smooth startup even without a precharge circuit. • Seamless charging and discharging operations can be achieved even with high distortion rates in the commercial power grid voltage EAC. • Reactive power control can be performed with relatively simple control methods, enabling constant power factor control.

[0162] The disclosed technology is not limited to the embodiments described above, but also encompasses various other configurations. For example, in the embodiments, an inverting circuit that reverses the polarity corresponding to the negative polarity of AC was used to perform peak current mode control with a simple and inexpensive circuit configuration, but peak current mode control may also be performed using two current sensors corresponding to positive and negative polarities. [Explanation of Symbols]

[0163] 3 On-board charger 5 DC / DC Converters 6. AC / DC converter (power conversion device) 10 Current Sensor 11 Input voltage sensor 12 Output Voltage Sensor 13 Converter mechanism 14 Controllers 20. Bridgeless PFC Circuit 21 Input side wiring 22 Output side wiring 23 Leg 1 24 Leg 2 25 Third Leg 26 Input capacitor 27 Reactor 28 switching elements 28a Freewheeling Diode 29 Output capacitor 30-link switch 40 DC bus voltage control unit 50 Peak current command value setting unit 60 Peak current control unit 61. First slope compensator 62 First Comparator 63. Second slope compensator 64 Second Comparator 65. Inverting Amplifier Circuit (Inverting Circuit) 66 PWM Control Unit 67 Judgment section 68 Gate Driver 69 Reactive current control unit 70 Limiter 80 AC tuning control unit

Claims

1. An AC / DC converter comprising a converter mechanism including a bridgeless PFC circuit and a controller for controlling the converter mechanism, which performs bidirectional conversion between AC and DC, The aforementioned bridgeless PFC circuit is The pair of input wirings that receive the AC current, The pair of output wirings that output DC, A reactor located on at least one of the input wirings, A first leg, a second leg, and a third leg are connected in parallel between the pair of output wirings, Each of the first and second legs is provided with a first switching element, a second switching element, a third switching element, and a fourth switching element, which are arranged in series such that the current flow direction is from the positive terminal to the negative terminal, and which are switched and reconfigured by the controller according to the polarity of the AC. The output capacitor located in the third leg, A coupling switch is arranged in a pair of the aforementioned input wirings and switches the presence or absence of the AC input on or off, It has, One output terminal of the input wiring is connected to the intermediate portion between the first switching element and the second switching element in the first leg, and the other output terminal of the input wiring is connected to the intermediate portion between the third switching element and the fourth switching element in the second leg. The converter mechanism is An input voltage sensor is located on the output side of the input wiring, above the linkage switch, and measures the AC input voltage. An output voltage sensor is located in the output wiring and measures the DC output voltage, A current sensor is placed in the input wiring and measures the reactor current flowing through the reactor, Equipped with, The aforementioned controller, A peak current control unit performs peak current mode control by using a first slope compensation circuit corresponding to the positive polarity of the AC and a second slope compensation circuit corresponding to the negative polarity of the AC, and outputs a control signal to turn the first switching element and the second switching element on and off. An AC tuning control unit that matches the phase and period of the input voltage to the AC, and gradually increases the amplitude of the input voltage to match the amplitude of the AC, It has, An AC / DC converter in which, upon startup, the AC tuning control unit operates, and when the amplitude of the input voltage reaches a predetermined value, the linkage switch switches from off to on, and the system transitions to peak current mode control.

2. In the AC / DC converter according to claim 1, An AC / DC converter in which the second slope compensation circuit includes an inverting circuit for reversing the polarity of the AC, and is configured using the same slope compensator as the first slope compensation circuit.

3. In the AC / DC converter according to claim 1 or 2, The aforementioned controller, A DC bus voltage control unit receives the command value of the output voltage and the measured value of the output voltage sensor as input and outputs the command value of the reactor current so that the output voltage becomes the set DC bus voltage. An upper limit is set on the positive side, which caps out above a predetermined value, and a lower limit is set on the negative side, which caps out below a predetermined value, thereby limiting the command value of the reactor current. A peak current command value setting unit sets a peak current command value to be input to the peak current control unit from a limited command value of the reactor current output from the limiter, An AC / DC converter that further possesses the following features.

4. In the AC / DC converter according to claim 3, The controller further includes a reactive current control unit that calculates a command value for reactive current according to a predetermined operating power factor. An AC / DC converter in which the peak current command value setting unit sets the peak current command value from both the limited command value of the reactor current and the command value of the reactive current.

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