Power conversion device

Abstract

To enable a peak current mode control by using a slope compensator in the market in an AC / DC converter with a bridge-less PFC circuit.SOLUTION: In an AC / DC converter 6, a bridge-less PFC circuit 20 has an input side capacitor 23, a reactor 24, and a first switching element 25 and a second switching element 26 performing a switchover operation and a switching operation according to a polarity of input voltage by a controller 14. The controller 14 has a peak current control unit 80 for executing peak current mode control by using a first slope compensation circuit corresponding to a positive polarity of the input voltage and a second slope compensation circuit corresponding to a negative polarity of the input voltage. The second slope compensation circuit includes an inversion circuit 85 and is constituted by the use of a second slope compensator 83 the same as a first slope compensator 81 of the first slope compensation circuit.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The disclosed technology relates to a power conversion device (AC / DC converter) that converts an alternating voltage into a direct voltage.

Background Art

[0002] In recent years, the electrification of automobiles such as electric vehicles and hybrid vehicles has been remarkable. Vehicles that run using this electric power are equipped with a high-output battery as their power source. In order to charge the battery, these vehicles are also equipped with a charging system (On Board Charger: OBC) that converts commercial alternating current power into direct current power.

[0003] In many OBCs, an AC / DC converter equipped with a power factor correction circuit (Power Factor Correction circuit: PFC circuit) is used to improve the power factor due to distortion of the input current waveform (for example, Patent Document 1). Among PFC circuits, a bridgeless PFC circuit in which a diode of a full-wave rectifier circuit with large losses is replaced with a switching element (MOSFET) in order to improve efficiency has been widely adopted.

[0004] In an AC / DC converter equipped with a bridgeless PFC circuit, since slope compensation is not required for its control method, it is common to adopt average current mode control.

[0005] However, in average current mode control, when the capacity of the reactor is small, the current control becomes unstable, so there is a drawback that the reactor becomes large. Also, since its switching frequency is basically the same as the control frequency, it is disadvantageous in that it is difficult to increase the switching frequency.

[0006] Regarding the disclosed technology, a bridgeless PFC circuit is disclosed in Patent Document 2. In that case, every time the polarity of the input voltage changes between positive and negative, the polarity is determined and two MOSFETs (Nch) are controlled to switch between an active switch and a synchronous rectifier switch. Because of the complex polarity determination, the circuit and control tend to become complex in that method.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] As one solution to the above-described demerits in average current mode control, the adoption of peak current mode control can be considered. If peak current mode control is adopted, the pulsation of the reactor current can be increased compared to average current mode control, and current control is relatively stable even if the capacity of the reactor is small, so the reactor can be miniaturized. However, in the case of peak current mode control, slope compensation is necessary to ensure stable operation.

[0009] On the other hand, electronic components such as ICs and microcontrollers that perform the function of slope compensation are commercially available. Therefore, it is conceivable to use these electronic components (slope compensation functional components) in an AC / DC converter equipped with a bridgeless PFC circuit.

[0010] However, since commercially available slope compensation functional components are developed for DC / DC converters that handle DC power, they are structured to be able to perform only signal processing for positive slope compensation. On the other hand, in an AC / DC converter that handles AC power, signal processing for negative slope compensation is required. Therefore, peak current mode control cannot be achieved simply by using commercially available slope compensation functional components as they are. As described above, it is considered that this reason largely accounts for the fact that average current mode control is the mainstream in AC / DC converters equipped with a bridgeless PFC circuit.

[0011] Therefore, this specification discloses a technique that enables peak current mode control using commercially available slope compensation functional components in an AC / DC converter equipped with a bridgeless PFC circuit.

Means for Solving the Problem

[0012] The disclosed technique relates to a power conversion device, that is, an AC / DC converter, which includes a converter mechanism including a bridgeless PFC circuit and a controller that controls the converter mechanism, and converts an AC input voltage into a DC output voltage.

[0013] The bridgeless PFC circuit has a pair of input-side wirings for inputting the input voltage, a pair of output-side wirings for outputting the output voltage, a capacitor connected between the pair of input-side wirings, a reactor disposed on at least one of the output sides of the connection portion of the capacitor in the input-side wiring, and a first switching element and a second switching element disposed between the input-side wiring and the output-side wiring, and the controller performs a switching operation and a switching operation according to the polarity of the input voltage.

[0014] The controller has 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 input voltage and a second slope compensation circuit corresponding to the negative polarity of the input voltage. The second slope compensation circuit includes an inversion circuit that inverts the polarity of the input voltage, and is configured by using the same slope compensator as the first slope compensation circuit.

[0015] That is, according to this power conversion device, the second slope compensation circuit corresponding to the negative polarity includes an inversion circuit that inverts the polarity of the input voltage, and is configured by using the same slope compensator as the first slope compensation circuit. Thereby, peak current mode control can be executed by using a commercially available slope compensation functional component, so that the reactor can be miniaturized, and an inexpensive and high-performance AC / DC converter can be provided.

[0016] The controller further has a DC voltage control unit that outputs a first input current command value corresponding to the maximum value of the input current flowing on the output side rather than the connection part with the capacitor in the input side wiring according to the output request of the output voltage. The first input current command value is converted into a second input current command value corresponding to the instantaneous value based on the phase of the input voltage, and the peak current command value introduced into the peak current control unit is set by adding a predetermined current correction amount to the second input current command value.

[0017] In this way, peak current mode control can be executed with a relatively simple circuit.

[0018] The controller further has an AC current control unit that introduces the second input current command value and outputs a third input current command value corresponding to the instantaneous value of the input current flowing on the input side rather than the connection part with the capacitor in the input side wiring. The peak current command value introduced into the peak current control unit is set by adding the current correction amount to the third input current command value.

[0019] If so, an improvement in the responsiveness of the reactor current and an improvement in the distortion rate can be expected. Specifically, since crossover distortion can be suppressed, the total harmonic distortion rate of the reactor current can be improved. Therefore, a higher-performance AC / DC converter can be provided.

[0020] As the bridgeless PFC circuit, various types can be considered.

[0021] For example, the bridgeless PFC circuit further includes a first diode and a second diode, and a first leg and a second leg connected in parallel between the pair of output-side wirings. In the first leg, the first switching element and the first diode are arranged in series such that both energization directions are outward and opposite to each other. In the second leg, the second switching element and the second diode are arranged symmetrically with the first switching element and the first diode. One output end of the input-side wiring is connected to an intermediate portion between the first switching element and the first diode in the first leg, and the other output end of the input-side wiring is connected to an intermediate portion between the second switching element and the second diode in the second leg.

[0022] The bridgeless PFC circuit also further includes a first diode and a second diode, and a first leg and a second leg connected in parallel between the pair of output-side wirings. In the first leg, the first diode and the second diode are arranged in series such that both energization directions are the same. In the second leg, the first switching element and the second switching element are arranged in series such that both energization directions are opposite to those of the first diode and the second diode. One output end of the input-side wiring is connected to an intermediate portion between the first diode and the second diode in the first leg, and the other output end of the input-side wiring is connected to an intermediate portion between the first switching element and the second switching element in the second leg.

[0023] The bridgeless PFC circuit also further includes a first diode, a second diode, a third diode, and a fourth diode; a first leg and a second leg connected in parallel between the pair of output-side wirings; and a third leg connected between portions on the output side of the reactor in the pair of input-side wirings. In the first leg, the first diode and the second diode are arranged in series such that both current conduction directions are the same. In the second leg, the third diode and the fourth diode are arranged symmetrically with respect to the first diode and the second diode. In the third leg, the first switching element and the second switching element are arranged in series such that both current conduction directions face each other. One output end of the input-side wiring is connected to an intermediate portion between the first diode and the second diode in the first leg, and the other output end of the input-side wiring is connected to an intermediate portion between the third diode and the fourth diode in the second leg. This may be the case.

[0024] In the case of an AC / DC converter provided with these types of bridgeless PFC circuits, the disclosed technology can be effectively applied.

Advantages of the Invention

[0025] According to the disclosed technology, in an AC / DC converter provided with a bridgeless PFC circuit, peak current mode control can be performed using commercially available slope compensation functional components, so that an inexpensive and high-performance AC / DC converter can be provided.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9A

Figure 9B

Figure 10

Mode for Carrying Out the Invention

[0027] Hereinafter, the disclosed technology will be described. However, the following description is merely illustrative in nature. Predetermined symbols are also attached to the components of the circuit together with alphanumeric symbols for identifying 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 small letter symbol "i" for current represents its instantaneous value.

[0028] <Overview of Power Conversion Device> FIG. 1 shows an application example in which a power conversion device according to the disclosed technology is used in an in-vehicle charging system 3 (OBC). The charging system 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 for driving.

[0029] 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 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 charging system 3 converts the alternating voltage into a direct current voltage corresponding to the battery 4 while intervening between the battery 4 and the commercial power supply 2 at that time.

[0030] As shown in the middle figure of FIG. 1, the charging system 3 is composed of a DC / DC converter 5, an AC / DC converter 6, etc. The AC / DC converter 6 is a device that converts an AC input voltage (e inv ) into a DC output voltage (Vdc), which corresponds to a "power conversion device". That is, the disclosed technology is applied to this AC / DC converter 6.

[0031] The DC / DC converter 5 is a device that converts a DC voltage into a different DC voltage. The DC / DC converter 5 converts the DC voltage (Vdc) converted by the AC / DC converter 6 into a predetermined DC voltage (Vdc') and outputs it to the battery 4 side.

[0032] As shown in the lower figure of FIG. 1, the AC / DC converter 6 includes a converter mechanism 13 including a current sensor 10, an input voltage sensor 11, an output voltage sensor 12, a bridgeless PFC circuit 20, etc., and a controller 14 that controls the converter mechanism 13.

[0033] The current sensor 10 is a Hall element type sensor and is installed at a predetermined position on the input side wiring 21 as will be described later. The current sensor 10 directly measures the input current (reactor current i inv ) flowing through the reactor 24 and outputs it to the controller 14. The input voltage sensor 11 is also installed at a predetermined position on the input side wiring 21, and directly measures the AC input voltage e inv input to the AC / DC converter 6 and outputs it to the controller 14. The output voltage sensor 12 is installed at a predetermined position on the output side wiring 22, and directly measures the DC output voltage Vdc output from the AC / DC converter 6 and outputs it to the controller 14.

[0034] Based on these measured values, the controller 14 outputs a drive voltage to the two switching elements S1, S2 of the bridgeless PFC circuit 20 to perform on / off control. That is, the energized state (on) and non-energized state (off) of these switching elements S1, S2 are switched at a predetermined timing.

[0035] (Bridge-less type PFC circuit) Figure 2 shows types A to C of the bridge-less type PFC circuit 20 applicable to the AC / DC converter 6. These types of bridge-less type PFC circuits 20 all have a common basic circuit.

[0036] That is, each of the bridge-less type PFC circuits 20 of types A to C includes a pair of input-side wirings 21 (a grounded N input-side wiring 21a and a non-grounded L input-side wiring 21b), a pair of output-side wirings 22 (a negative-pole-side N output-side wiring 22a and a positive-pole-side P output-side wiring 22b), an input-side capacitor 23 (Cinv), a reactor 24 (L inv ), a first switching element 25 (S1), and a second switching element 26 (S2).

[0037] The pair of input-side wirings 21 are arranged on the side of the commercial power supply 2, and an AC input voltage e inv is input to their input terminals. On the other hand, the pair of output-side wirings 22 are arranged on the side of the battery 4, and a DC output voltage Vdc is output from their output terminals. The input-side capacitor 23 is connected between the pair of input-side wirings 21 in the vicinity of the input terminals.

[0038] The reactor 24 is arranged on at least one of the output sides of the connection part with the input-side capacitor 23 in the input-side wiring 21. Specifically, the reactor 24 is arranged at a part on the output side of the connection part with the input-side capacitor 23 in the L input-side wiring 21b. And the first switching element 25 and the second switching element 26 are arranged between the input-side wiring 21 and the output-side wiring 22, although the arrangement is different depending on each type.

[0039] The first switching element 25 and the second switching element 26 are composed of a known MOSFET or the like having terminals such as a gate, a source, and a drain. They turn on by applying a predetermined driving voltage to the gate terminal. The first switching element 25 and the second switching element 26 both include a freewheel diode 27 connected in anti-parallel.

[0040] In the case of the bridgeless type PFC circuit 20 of type A, in addition to the basic circuit described above, it further has a first diode 31 (D1), a second diode 32 (D2), a first leg 33, a second leg 34, an output-side capacitor 35 (Cdc), and a second reactor 36. The second reactor 36 is arranged on the N input-side wiring 21a at a position symmetrical to the reactor 24. Note that the second reactor 36 may be omitted.

[0041] The output-side capacitor 35 is connected between a pair of output-side wirings 22a and 22b in the vicinity of the output terminal. The first leg 33 and the second leg 34 are connected in parallel between the pair of output-side wirings 22a and 22b on the input side of the output-side capacitor 35. And in the first leg 33, the first switching element 25 and the first diode 31 are arranged in series so that the energization directions of both are outward and opposite.

[0042] Specifically, the first switching element 25 and the first diode 31 are arranged in order from the side of the N output-side wiring 22a toward the side of the P output-side wiring 22b. The first switching element 25 when on is arranged in the direction of energizing from the side of the P output-side wiring 22b to the side of the N output-side wiring 22a, and the first diode 31 is arranged in the direction of energizing from the side of the N output-side wiring 22a to the side of the P output-side wiring 22b.

[0043] In the second leg 34, the second switching element 26 and the second diode 32 are arranged symmetrically to the first switching element 25 and the first diode 31.

[0044] Specifically, the second switching element 26 and the second diode 32 are arranged in order from the side of the N output side wiring 22a toward the side of the P output side wiring 22b. The second switching element 26 when on is arranged in a direction to conduct current from the side of the P output side wiring 22b toward the side of the N output side wiring 22a, and the second diode 32 is arranged in a direction to conduct current from the side of the N output side wiring 22a toward the side of the P output side wiring 22b.

[0045] And the output end of the N input side wiring 21a is connected to an intermediate part between the first switching element 25 and the first diode 31 in the first leg 33. The output end of the L input side wiring 21b is connected to an intermediate part between the second switching element 26 and the second diode 32 in the second leg 34.

[0046] In the case of the bridgeless type PFC circuit 20 of type B, in addition to the basic circuit described above, it further has a first diode 41, a second diode 42, a third diode 43 (D3), a fourth diode 44 (D4), a first leg 45, a second leg 46, a third leg 47, and an output side capacitor 48.

[0047] The output side capacitor 48 is connected between a pair of output side wirings 22a, 22b in the vicinity of the output terminal. The first leg 45 and the second leg 46 are connected in parallel between a pair of output side wirings 22a, 22b on the input side with respect to the output side capacitor 48. The third leg 47 is connected between parts on the output side with respect to the reactor 24 in a pair of input side wirings 21a, 21b. And in the first leg 45, the first diode 41 and the second diode 42 are arranged in series so that the current conduction directions of both are the same.

[0048] Specifically, the second diode 42 and the first diode 41 are arranged in order from the side of the N output side wiring 22a toward the side of the P output side wiring 22b. And these first diode 41 and second diode 42 are arranged in a direction to conduct current from the side of the N output side wiring 22a toward the side of the P output side wiring 22b.

[0049] On the second leg 46, the third diode 43 and the fourth diode 44 are arranged symmetrically with respect to the first diode 41 and the second diode 42. Specifically, the fourth diode 44 and the third diode 43 are arranged in this order from the side of the N output side wiring 22a toward the side of the P output side wiring 22b. And these third diode 43 and fourth diode 44 are arranged in the direction of energization from the side of the N output side wiring 22a toward the side of the P output side wiring 22b.

[0050] On the third leg 47, the first switching element 25 and the second switching element 26 are arranged in series so that the energization directions of both face each other. Specifically, the second switching element 26 and the first switching element 25 are arranged in this order from the side of the N input side wiring 21a toward the side of the P input side wiring 21. The second switching element 26 when on is arranged in the direction of energization from the side of the N input side wiring 21a toward the side of the L input side wiring 21b, and the first switching element 25 when on is arranged in the direction of energization from the side of the L input side wiring 21b toward the side of the N input side wiring 21a.

[0051] And the output end of the N input side wiring 21a is connected to the intermediate part between the first diode 41 and the second diode 42 in the first leg 45. The output end of the L input side wiring 21b is connected to the intermediate part between the third diode 43 and the fourth diode 44 in the second leg 46.

[0052] In the case of the bridgeless type PFC circuit 20 of type C, in addition to the basic circuit described above, it further has a first diode 51, a second diode 52, a first leg 53, a second leg 54, and an output side capacitor 55.

[0053] The output side capacitor 55 is connected between a pair of output side wirings 22a, 22b in the vicinity of the output terminal. The first leg 53 and the second leg 54 are connected in parallel between a pair of output side wirings 22a, 22b on the input side with respect to the output side capacitor 55.

[0054] In the first leg 53, the first diode 51 and the second diode 52 are arranged in series such that the current conduction directions of both are the same. Specifically, the second diode 52 and the first diode 51 are arranged in order from the side of the N output side wiring 22a toward the side of the P output side wiring 22b. Both the first diode 51 and the second diode 52 are arranged in a direction of conducting current from the side of the N output side wiring 22a toward the side of the P output side wiring 22b.

[0055] In the second leg 54, the first switching element 25 and the second switching element 26 are arranged in series such that the current conduction directions of both are opposite to those of the first diode 51 and the second diode 52. Specifically, the second switching element 26 and the first switching element 25 are arranged in order from the side of the N output side wiring 22a toward the side of the P output side wiring 22b. And both the first switching element 25 and the second switching element 26 are arranged in a direction of conducting current from the side of the P output side wiring 22b toward the side of the N output side wiring 22a when turned on.

[0056] The output end of the N input side wiring 21a is connected to an intermediate portion between the first diode 51 and the second diode 52 in the first leg 53. The output end of the L input side wiring 21b is connected to an intermediate portion between the first switching element 25 and the second switching element 26 in the second leg 54.

[0057] <Operation by specific control of the power conversion device> With reference to FIG. 3, the specific operation of the AC / DC converter 6 under the control of the controller 14 will be described. FIG. 3 shows different operating states in the bridgeless type PFC circuit 20 of type A.

[0058] The symbol R shown in FIG. 3 represents the load resistance on the side of the battery 4. The current sensor 10, the input voltage sensor 11, and the output voltage sensor 12 are also schematically illustrated in FIG. 3(a). Note that in types B and C, although the circuit structures are different and the current conduction paths are different, the control targets are the same first switching element S1 and second switching element S2, so their operation descriptions are omitted.

[0059] In FIG. 3, (a) and (b) represent the operation when the polarity of the input voltage e inv is positive (during the positive half-cycle). On the other hand, (c) and (d) represent the operation when the polarity of the input voltage e inv is negative (during the negative half-cycle). Depending on the polarity of the input power e inv , the operations of (a) and (b) and (c) and (d) are repeated.

[0060] That is, the controller 14 executes the switching operation of the first switching element S1 and the second switching element S2 according to the polarity of the periodically changing input voltage e inv and changes the object to be switched. Specifically, when the polarity of the input voltage e inv is positive, as in (a) and (b), the first switching element S1 is turned off and the switching operation is performed by the second switching element S2. When the polarity of the input voltage e inv is negative, as in (c) and (d), the second switching element S2 is turned off and the switching operation is performed by the first switching element S1.

[0061] And, as in (a), when the polarity of the input voltage e inv is positive and the second switching element S2 is turned on, the input current i ac flows in from the L input side wiring 21b. Then, the input current i ac flows through the current path consisting of the middle part of the second leg 54, the second switching element S2, the N output side wiring 22a, the first switching element S1 (free wheel diode 27), and the middle part of the first leg 53 and the N input side wiring 21a, as indicated by the arrow dashed line Y1. That is, the input current i ac does not flow to the battery 4 side.

[0062] As in (b), when the polarity of the input voltage e inv is positive and the second switching element S2 is turned off, the input current i ac flows in from the L input side wiring 21bAs shown by the dashed arrow Y2, it flows through the energization path consisting of the middle part of the second leg 54, the second diode 52, the P output side wiring 22b, the load resistor R, the N output side wiring 22a, the first switching element S1 (freewheel diode 27), the middle part of the first leg 53, and the N input side wiring 21a. That is, the input current i ac flows toward the battery 4 side.

[0063] As shown in (c), when the polarity of the input voltage e inv is negative and the first switching element S1 is turned on, the input current i ac flows in from the N input side wiring 21a. Then, the input current i ac flows through the energization path consisting of the middle part of the first leg 53, the first switching element S1, the N output side wiring 22a, the second switching element S2 (freewheel diode 27), the middle part of the second leg 54, and the N input side wiring 21a, as shown by the dashed arrow Y3. That is, the input current i ac does not flow toward the battery 4 side.

[0064] As shown in (d), when the polarity of the input voltage e inv is negative and the first switching element S1 is turned off, the input current i ac flowing in from the N input side wiring 21a flows through the energization path consisting of the middle part of the first leg 53, the first diode 51, the P output side wiring 22b, the load resistor R, the N output side wiring 22a, the second switching element S2 (freewheel diode 27), the middle part of the second leg 54, and the N input side wiring 21a, as shown by the dashed arrow Y4. That is, the input current i ac flows toward the battery 4 side.

[0065] <Control circuit of the controller> As described above, the controller 14 outputs the required output voltage Vdc by switching and operating the first switching element S1 and the second switching element S2. For this purpose, an example of the block diagram of the control circuit that the controller 14 has is shown in FIG. 4.

[0066] The controller 14 has a DC voltage control unit 60 that controls so that a predetermined output voltage Vdc is output in response to an output request of the output voltage Vdc, and a peak current control unit 80 that controls the timing of turning on and off the first switching element S1 and the second switching element S2. The controller 14 also has a phase synchronization circuit 61, a multiplier 62, an adder 63, and the like.

[0067] The DC voltage control unit 60 receives a command value Vdc of the output voltage * and a measured value Vdc of the output voltage measured by the output voltage sensor 12. Then, from the DC voltage control unit 60, on the output side rather than the connection part with the input side capacitor 23 in the input side wiring 21, that is, the input current (reactor current i inv ) flowing through the reactor 24, a command value (first input current command value I inv * ) corresponding to the maximum value is output. The measured value Vdc of the output voltage is used as a feedback value, and the DC voltage control unit 60 controls the first input current command value I * so that the measured value Vdc coincides with the command value Vdc inv * .

[0068] The first input current command value I inv * is input to the multiplier 62, and is converted into a command value (second input current command value i inv ) corresponding to the instantaneous value based on the phase of the input voltage e inv * .

[0069] Specifically, the phase synchronization circuit 61 receives the measured value of the input voltage e inv measured by the input voltage sensor 11. Based on the measured value, the phase angle θ inv of the input voltage e inv is obtained, and a predetermined signal (phase signal, sin(θ inv )) is output from the phase synchronization circuit 61 and input to the multiplier 62. In the multiplier 62, the first input current command value I inv inv * ​is multiplied by a phase signal sin(θ inv ), thereby calculating a second input current command value i inv * , and outputting the value.

[0070] The second input current command value i inv * is input to an adder 63 and a predetermined current correction amount Δi inv is added. By doing so, a peak current command value i inv * .p as an instantaneous value introduced into the peak current control unit 80 is set. The current correction amount Δi inv is an estimated value of the pulsating component of the reactor current and is obtained by the formula (1) shown in FIG. 4.

[0071] In formulas (1) to (3), L inv is the inductance of the reactor 24. As will be described later, a PWM method of changing the duty ratio is used for the switching operations of the first switching element S1 and the second switching element S2. T PWM is a periodic signal indicating a timing corresponding to the switching period (a preset constant value) in the PWM control (see FIG. 8). Note that Ks in formula (2) is a value of a slope used for slope compensation in the peak current mode control described later. D in formula (3) is a ratio of the input voltage to the output voltage.

[0072] To the peak current control unit 80, together with the peak current command value i inv * .p, as its feedback value, an actually measured value i inv of the reactor current measured by a voltage sensor is introduced. Further introduced into the peak current control unit 80 are T PWM , Ks, T ZRO and so on. T ZRO is a set signal indicating a timing corresponding to 0 degrees of the switching period in the PWM control.

[0073] Thereby, the peak current control unit 80 outputs control signals Q1 and Q2 indicating the timing for turning on and off the first switching element S1 and the second switching element S2.

[0074] (Application Example of Controller) FIG. 5 shows an application example (improved controller 14A) of the controller 14 with a devised control circuit. In the control circuit of the improved controller 14A, an alternating current control unit 70 is added between the multiplier 62 and the adder 63 in the above-described control circuit.

[0075] Specifically, the improved controller 14A further has an alternating current control unit 70 that introduces the second input current command value i inv * and outputs a command value (third input current command value i inv corresponding to the instantaneous value of the input current (alternating current i ac ) flowing on the input side of the connection part between the input side capacitor C ac * ) on the input side wiring 21. Then, the third input current command value i ac * input to the adder 63 is added with the above-described current correction amount Δi inv so that the peak current command value i inv * .p introduced into the peak current control unit 80 is set. Here, the second current command value i inv * shown in FIG. 5 is the target current command value (before correction) of the alternating current control unit 70, and the third current command value i ac * is the output current command value (output value of the feedback control block) after correction from the alternating current control unit 70.

[0076] The alternating current control unit 70 includes a subtractor 71, an alternating current compensator 72, and a second adder 73. The alternating current control unit 70 introduces the second input current command value i inv * and the reactor current value i inv measured by the current sensor 10. In the subtractor 71, the second input current command value iinv * from the reactor current value i inv By subtracting, a current difference value Δi is calculated.

[0077] The output value obtained by inputting this current difference value Δi to an alternating current compensator 72 having a predetermined transfer function is added in a second adder 73 to a second input current command value i inv * Thereby, the alternating current control unit 70 calculates and outputs a third input current command value i ac *

[0078] As will be described later, since the peak current control unit 80 has a function of performing feedback control, originally, there is no need to provide such an alternating current control unit 70, and since the peak current control unit 80 also performs control based on instantaneous values, there is also a problem that the alternating current control unit 70 and the peak current control unit 80 are likely to interfere with each other. Therefore, usually, such an alternating current control unit 70 is not considered.

[0079] However, by providing such an alternating current control unit 70, an improvement in the responsiveness of the reactor current i inv and an improvement in the distortion rate can be expected. Specifically, crossover distortion, which is an inherent problem of the PFC circuit, can be suppressed. Thereby, as will be described later, the total harmonic distortion rate of the reactor current i inv can be improved. Regarding the interference between the alternating current control unit 70 and the peak current control unit 80, it can be avoided by appropriately designing the alternating current compensator 72.

[0080] (Peak Current Control Unit) FIG. 6 shows a block diagram of the control circuit in the peak current control unit 80. FIG. 7 shows a setting table of the look-up table included in a determination unit 87 described later. FIG. 8 shows a switching pattern by peak current mode control. (a) of FIG. 8 is a switching pattern during a positive half cycle, and (b) of FIG. 8 is a switching pattern during a negative half cycle.

[0081] ​ In this controller 14 (or improved controller 14A, hereinafter omitted), in order to provide a slope compensation function essential for peak current mode control, it is devised so that inexpensive commercially available electronic components can be used.

[0082] That is, although electronic components such as ICs and microcontrollers (slope compensation functional components) that perform the function of slope compensation are commercially available, these slope compensation functional components are developed for DC / DC converters that handle DC power, and thus have a structure that can only perform signal processing for positive slope compensation.

[0083] On the other hand, since this controller 14 handles AC power that also requires signal processing for negative slope compensation, peak current mode control cannot be achieved simply by using commercially available slope compensation functional components as they are.

[0084] On the other hand, in this controller 14, the peak current control unit 80 executes peak current mode control by using a first slope compensation circuit corresponding to the positive polarity of the input voltage e inv and a second slope compensation circuit corresponding to the negative polarity of the input voltage e inv . And the second slope compensation circuit includes an inversion circuit that inverts the polarity of the input voltage e inv , and is configured by using the same slope compensator as the first slope compensation circuit, that is, a slope compensator corresponding to the positive polarity.

[0085] Therefore, in the case of this controller 14, peak current mode control can be executed by using only commercially available slope compensation functional components for the slope compensator. Thereby, peak current mode control can be executed with a simple and inexpensive circuit configuration. As a result, stable operation can be realized even when the reactor 24 is miniaturized.

[0086] Specifically, the peak current control unit 80 includes a first slope compensator 81, a first comparator 82, a second slope compensator 83, a second comparator 84, an inverting amplifier circuit 85, a PWM control unit 86, a determination unit 87, a gate driver 88, and the like. The first slope compensator 81 and the first comparator 82 constitute a first slope compensation circuit, and the second slope compensator 83, the second comparator 84, and the inverting amplifier circuit 85 constitute a second slope compensation circuit.

[0087] As described above, the first slope compensator 81 and the second slope compensator 83 have the same function corresponding to the positive polarity of the input voltage e inv and are configured using commercially available slope compensation functional components such as analog ICs and control microcontrollers.

[0088] A positive peak current command value i inv * .p and Ks are input to the first slope compensator 81. Ks corresponds to a value of a predetermined slope given to the positive peak current control command value i inv * .p. Ks is generally used to suppress the occurrence of low-frequency oscillation that occurs when the duty ratio exceeds 50%.

[0089] A pulse-shaped set signal T ZRO and a first reset signal TripA are also input to the first slope compensator 81. As shown in FIG. 8, the set signal T ZRO 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 i inv .

[0090] The set signal T ZRO is input from the PWM control unit 86 based on a periodic signal. The first reset signal TripA is fed back after the output from the first comparator 82. The first slope compensator 81 is based on these set signal T ZRO and the first reset signal TripA, and the positive peak current command value iinv * Set or reset.p.

[0091] The first slope compensator 81 is the positive peak current command value i inv * .p and Ks, based on the positive peak current command value i inv * Add a slope to.p and output it to the first comparator 82 (the slanted broken line part in Fig. 8(a)).

[0092] The first comparator 82 compares its output value with the reactor current i inv of the value. Then, when the output value of the first comparator 82 and the value of the reactor current i inv match (the matching part in Fig. 8(a)), the first reset signal TripA is output. The first reset signal TripA is fed back to the first slope compensator 81. The first reset signal TripA is also output to the determination unit 87.

[0093] The second slope compensator 83 receives the negative peak current command value -i corresponding to the negative half cycle inv * .p and Ks are input. Similar to the first slope compensator 81, the set signal T ZRO and the second reset signal TripB are also input to the second slope compensator 83. The second slope compensator 83 is based on these set signal T ZRO and the second reset signal TripB, the negative peak current command value -i inv * Set or reset.p.

[0094] The second slope compensator 83 is the negative peak current command value -i inv * .p and Ks, based on the negative peak current command value -i inv * Add a slope to.p and output it to the second comparator 84 (the slanted broken line part in Fig. 8(b)).

[0095] The inverting amplifier circuit 85 receives the reactor current i inv and outputs the reactor current inverted to a negative value (negative reactor current value -i inv ).

[0096] The second comparator 84 compares the output value from the second slope compensator 83 with the negative reactor current value -i inv . When the output value of the second comparator 84 matches the negative reactor current value -i inv (the matching part in Fig. 8(b)), the second reset signal TripB is output. The second reset signal TripB is fed back to the second slope compensator 83. The second reset signal TripB is also output to the determination unit 87.

[0097] The determination unit 87 has a look-up table set as shown in the table of Fig. 7. The determination unit 87 determines the input first reset signal TripA and second reset signal TripB based on the phase signal input from the phase synchronization circuit 61 and the look-up table. Thereby, the determination unit 87 outputs control signals (first control signal Q1 and second control signal Q2) for turning on and off the first switching element S1 and the second switching element S2.

[0098] Specifically, as shown in Fig. 8(a), when the phase signal sin(θ inv ) is 0 or more, that is, during the positive half cycle, when the first reset signal TripA is input, the determination unit 87 outputs the first control signal Q1 in the high state and the second control signal Q2 in the low state. On the other hand, even when the second reset signal TripB is input, the determination unit 87 ignores it and does not output a control signal. When the set signal T PWM is input, the determination unit 87 outputs the first control signal Q1 in the low state and the second control signal in the high state.

[0099] And as shown in Fig. 8(b), when the phase signal sin(θ inv) is less than 0, that is, during the negative half cycle, even if the first reset signal is input, the determination unit 87 ignores it and does not output the control signal. On the other hand, when the second reset signal is input, the determination unit 87 outputs the first control signal in the low state and the second control signal in the high state. When the set signal is input, the determination unit 87 outputs the first control signal Q1 in the high state and the second control signal Q2 in the low state.

[0100] As shown in FIG. 6, the first control signal Q1 and the second control signal Q2 output by the determination unit 87 in this way are input to the gate driver 88. A predetermined dead time Td is also input to the gate driver 88.

[0101] The gate driver 88 turns on and off the first switching element S1 based on the first control signal Q1, and turns on and off the second switching element S2 based on the second control signal Q2. Specifically, when the first control signal Q1 is in the high state, a drive voltage is output to the first switching element S1 to turn on the first switching element S1. When the first control signal Q1 is in the low state, the drive voltage is not output to the first switching element S1 to turn off the first switching element S1. Similarly, for the second switching element S2, the second switching element S2 is turned on or off according to the state of the second control signal Q2.

[0102] Although the present invention is realized using the controller 14 as shown in FIGS. 6 to 8, for example, it may be output using a controller having a DAC output of positive and negative peak current command values (i inv * .p, -i inv * .p), and then all or some of the circuit blocks may be designed with analog circuits.

[0103] <Verification of the effect by simulation> Simulations were performed in two cases to verify the effect regarding the miniaturization of the reactor 24. The inductance of the reactor 24 in Case 1 was set to 340 μH. The inductance of the reactor 24 in Case 2 was set to 170 μH, which is half of that in Case 1.

[0104] The respective parameters of the circuits used in the simulations for both Case 1 and Case 2 are as follows.

[0105] Capacitance of the input-side capacitor 23 (C inv ): 5.5 μF PWM frequency: 24 kHz Input voltage (e inv ): 240 V / 60 Hz DC load: 4 kW Dead time: 2 μs Capacitance of the output-side capacitor 55 (Cdc): 2200 μF Output voltage (Vdc): 400 V.

[0106] Fig. 9A shows the simulation results of Case 1. Fig. 9B shows the simulation results of Case 2. It was confirmed that even with a small reactor 24 having an inductance of 170 μH, a stable waveform of the reactor current can be obtained, which has little difference from that of the reactor 24 having an inductance of 340 μH in practical use.

[0107] That is, according to the disclosed technology, it becomes possible to make the inductance of the reactor 24 170 μH or less.

[0108] Furthermore, the effect of the improved controller 14A was also verified. That is, the effects with and without the AC current control unit 70 were compared. Specifically, simulations were performed in the circuit of the simulation of Case 2 described above, with and without the AC current control unit 70.

[0109] The results are shown in Fig. 10. The left side of Fig. 10 shows the case without the AC current control unit 70, and the right side shows the case with the AC current control unit 70. Crossover distortion was observed when the AC current control unit 70 was not present, but almost no crossover distortion was observed when the AC current control unit 70 was present (see Δi).

[0110] As a result, it was confirmed that the total harmonic distortion rate (THDi) of the reactor current i inv also improved from 3.12% to approximately 0.5%.

[0111] Thus, according to the disclosed technology, peak current mode control can be executed using a simple and inexpensive circuit, enabling miniaturization of the reactor 24 and improving the total harmonic distortion rate of the reactor current i inv as well.

Explanation of Signs

[0112] 1 Vehicle 2 Commercial power supply 3 Charging system 4 Battery 5 DC / DC converter 6 AC / DC converter (power conversion device) 10 Current sensor 11 Input voltage sensor 12 Output voltage sensor 13 Converter mechanism 14 Controller 14A Improved controller 20 Bridgeless PFC circuit 21 Input side wiring 21a N Input side wiring 21b L Input side wiring 22 Output side wiring 22a N Output side wiring 22b P Output side wiring 23 Input side capacitor 24 Reactor 25 First switching element 26 Second switching element 27 Freewheel Diode 31 First Diode 32 Second Diode 33 First Leg 34 Second Leg 35 Output Side Capacitor 36 Second Reactor 41 First Diode 42 Second Diode 43 Third Diode 44 Fourth Diode 45 First Leg 46 Second Leg 47 Third Leg 48 Output Side Capacitor 51 First Diode 52 Second Diode 53 First Leg 54 Second Leg 55 Output Side Capacitor 60 DC Voltage Control Unit 61 Phase Synchronization Circuit 62 Multiplier 63 Adder 70 AC Current Control Unit 80 Peak Current Control Unit 81 First Slope Compensator 82 First Comparator 83 Second Slope Compensator 84 Second Comparator 85 Inverting Amplification Circuit (Inverting Circuit) 86 PWM Control Unit 87 Judgment Unit 88 Gate Driver

Claims

1. A power conversion device comprising a converter mechanism including a bridgeless PFC circuit and a controller for controlling the converter mechanism, the power conversion device converting an AC input voltage into a DC output voltage, wherein the bridgeless PFC circuit includes a pair of input-side wirings for inputting the input voltage, a pair of output-side wirings for outputting the output voltage, a capacitor connected between the pair of input-side wirings, a reactor disposed on at least one of the output sides of the connection portion with the capacitor in the input-side wiring, a first switching element and a second switching element disposed between the input-side wiring and the output-side wiring, and the controller performs a switching operation and a switching operation according to the polarity of the input voltage, and has the controller has a peak current control unit that executes peak current mode control by using a first slope compensation circuit corresponding to the positive polarity of the input voltage and a second slope compensation circuit corresponding to the negative polarity of the input voltage, the second slope compensation circuit includes an inversion circuit that inverts the polarity of the input voltage, and the power conversion device is configured by using the same slope compensator as the first slope compensation circuit.

2. In the power conversion device according to claim 1, the controller further has a DC voltage control unit that outputs a first input current command value corresponding to the maximum value of the input current flowing on the output side of the connection portion with the capacitor in the input-side wiring according to the output request of the output voltage, the first input current command value is converted into a second input current command value corresponding to an instantaneous value based on the phase of the input voltage, and the peak current command value introduced into the peak current control unit is set by adding a predetermined current correction amount to the second input current command value.

3. In the power conversion device according to claim 2, the controller further has an alternating current control unit that introduces the second input current command value and outputs a third input current command value corresponding to the instantaneous value of the input current flowing on the input side of the connection part with the capacitor in the input side wiring, and a power conversion device in which the peak current command value introduced into the peak current control unit is set by adding the current correction amount to the third input current command value.

4. In the power conversion device according to any one of claims 1 to 3, the bridgeless PFC circuit further has a first diode and a second diode, and a first leg and a second leg connected in parallel between the pair of output side wirings, and in the first leg, the first switching element and the first diode are arranged in series so that both energization directions are outward in opposite directions, and in the second leg, the second switching element and the second diode are arranged symmetrically with the first switching element and the first diode, and a power conversion device in which one output end of the input side wiring is connected to an intermediate part between the first switching element and the first diode in the first leg, and the other output end of the input side wiring is connected to an intermediate part between the second switching element and the second diode in the second leg.

5. In the power conversion device according to any one of claims 1 to 3, the bridgeless PFC circuit further has a first diode and a second diode, and a first leg and a second leg connected in parallel between the pair of output side wirings, and In the first leg, the first diode and the second diode are arranged in series such that the energization directions of both are the same, and in the second leg, the first switching element and the second switching element are arranged in series such that the energization directions of both are opposite to those of the first diode and the second diode. A power conversion device in which one output end of the input-side wiring is connected to an intermediate portion between the first diode and the second diode in the first leg, and the other output end of the input-side wiring is connected to an intermediate portion between the first switching element and the second switching element in the second leg.

6. In the power conversion device according to any one of Claims 1 to 3, The bridgeless PFC circuit includes a first diode, a second diode, a third diode, and a fourth diode, and a first leg and a second leg connected in parallel between a pair of the output-side wirings, and a third leg connected between portions on the output side of the reactors in a pair of the input-side wirings, and further includes in the first leg, the first diode and the second diode are arranged in series such that the energization directions of both are the same, and in the second leg, the third diode and the fourth diode are arranged symmetrically with respect to the first diode and the second diode, in the third leg, the first switching element and the second switching element are arranged in series such that the energization directions of both face each other, A power conversion device in which one output end of the input-side wiring is connected to an intermediate portion between the first diode and the second diode in the first leg, and the other output end of the input-side wiring is connected to an intermediate portion between the third diode and the fourth diode in the second leg.

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