Rectifying circuit

Abstract

To provide a rectifying circuit that can be used with a simpler configuration and in which a variable reactor function and a rectifying function are integrated.SOLUTION: One end of LC resonance circuits 12a and 12b is connected to each of input terminals 11a and 11b to which AC power is input, respectively. A series circuit of switches S1 and S2 is connected between the other end of the LC resonance circuits 12a and 12b. Diodes D1 and D2 are connected in parallel to the switches S1 and S2, respectively, so as to have a common cathode. Capacitors C1 and C2 are connected in parallel to the diodes D1 and D2, respectively. A filter circuit 15 includes a series circuit of inductors 13a and 13b connected in parallel to a series circuit of the switches S1 and S2, and an output capacitor 15 connected between DC output terminals. A gate control circuit 5 variably controls reactance by switching the switches S1 and S2 at 180-degree phase difference.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a circuit for rectifying AC power to DC power. [Background technology]

[0002] In wireless power transfer (WPT) systems used in electric field coupling, magnetic field coupling and the like, in order to improve the efficiency of power transmission and to suppress power reflection, a matching circuit is provided to cancel the reactance component in the power transmission path or to match impedance, and a resonant circuit is provided to resonate with the LC value of the coupler and the AC power supply frequency.

[0003] The resonant frequency of the coupler and the reactance component on the power transmission path may fluctuate due to dimensional changes over time of the coupler, movement of the power receiving side, etc. If the matching circuit or resonant circuit is composed of LC elements with fixed constants, it cannot handle the generated reactance component, and there is a concern that power reflection will occur and the power transmission performance will deteriorate.

[0004] To address such issues, there is a method of inserting a variable reactor circuit and automatically adjusting the reactor value to cancel the effect. Variable reactor circuits can be mechanical or electronic, consisting of switching elements and LC components. However, in such cases, there is a concern that the circuit size may increase. In particular, there are many restrictions on the size and weight of the receiving circuit due to the assumption that it will be installed in moving objects or aircraft, and miniaturization is required. Therefore, in order to achieve both power transmission performance and miniaturization of the receiving circuit, a circuit that integrates a variable reactor circuit and a rectifier circuit has been proposed.

[0005] Non-Patent Document 1 discloses a rectifier circuit that includes an LC resonant circuit that applies a +jX or -jX component, two rectifier units that are each composed of two switches and a capacitor, and a DC-DC converter that is connected to each of these rectifier units. In this configuration, the input resistance of the converter and therefore the rectifier units is controlled by controlling the voltage conversion ratio of each DC-DC converter. This controls the contribution of +jX and -jX to control the impedance Zr and cancel the reactance on the power transmission path. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS, VOL.8,NO.3,SEPTEMBER 2020 Summary of the Invention [Problem to be solved by the invention]

[0007] In the above configuration, two sets of combinations of an LC series circuit, a rectifier, and a converter are required, and there is a concern that the circuit size may increase. The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a rectifier circuit that integrates a variable reactor function and a rectifier function and can be used with a simpler configuration. [Means for solving the problem]

[0008] According to the rectifier circuit of claim 1, one end of each of the two LC resonant circuits (12a, 12b) is connected to each of two input terminals (11a, 11b) to which AC power is input. A series circuit of first and second switching elements (S1, S2) connected in opposite directions is connected between the other ends of the two LC resonant circuits. The first and second diodes (D1, D2) are connected in parallel to the first and second switching elements, respectively, and have a common cathode or anode. The first and second capacitors (C1, C2) are connected in parallel to the first and second diodes, respectively. The filter circuit (15) has a series circuit of two inductors (13a, 13b) connected in parallel to the series circuit of the first and second switching elements, and an output capacitor (14) connected between the DC output terminals. The control unit (5) performs variable control of the reactance by switching the first and second switching elements with a phase difference of 180 degrees from each other.

[0009] If the reactance variably controlled by the control unit is -jXrec, the magnitude of its absolute value can be adjusted by the capacitance C of the first and second capacitors. If the variable control value required for the reactance is ΔX, the capacitance C of the first and second capacitors is set to satisfy ΔX≦(maximum value of |jXrec|). The reactance jXr seen from the input terminal is shifted to the positive side by the total value jX of the reactances of the two LC resonant circuits, making the variable range of the reactance jXr bipolar. The control unit turns on the first and second switching elements after the corresponding diodes are turned on, and turns off the switching elements after a predetermined time has elapsed after the diodes are turned off, thereby variably controlling the reactance by the off duty ratio.

[0010] With this configuration, it is only necessary to connect one DC-DC converter to the output capacitor, and the rectifier circuit can variably control the reactance jXr in both polarities, making it possible to reduce the circuit scale compared to conventional configurations.

[0011] According to the rectifier circuit of claim 2, a series circuit of an LC resonant circuit (12) and a switching element (S1) is connected between input terminals (11a, 11b) to which AC power is input. A diode (D1) is connected in parallel to the switching element with its cathode on the LC resonant circuit side, and a capacitor (C1) is connected in parallel to the diode. A filter circuit (52) having an inductor (13) and an output capacitor (14) is connected in parallel to the switching element. A control unit (5) variably controls the reactance by switching the switching element. The capacitance C of the capacitor connected in parallel to the diode is set so as to satisfy ΔX≦(maximum value of |jXrec|), where ΔX is a variable control value required for the reactance and -jXrec is a reactance variably controlled by the control unit. The reactance jX of the LC resonant circuit shifts the reactance jXr seen from the input terminals to the positive side, making the variable range of the reactance jXr bipolar.

[0012] The control unit turns on the switching element after the diode is turned on, and turns off the switching element a predetermined time after the diode is turned off, and performs variable control of the reactance based on the off duty ratio. Even with this configuration, the reactance jXr can be variably controlled in both polarities by the rectifier circuit. Therefore, the circuit scale can be reduced compared to the conventional configuration. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram illustrating a configuration of a power supply system according to a first embodiment. [Diagram 2] Diagram showing the configuration of a variable reactor rectifier circuit [Diagram 3] A diagram showing the change in reactance value versus the switch off duty ratio [Figure 4] FIG. 1 shows the configuration of a phase difference detection circuit. [Diagram 5] A diagram showing the change in output voltage of the phase difference detection circuit according to the voltage-current phase difference. [Figure 6] A diagram showing the configuration of a gate control circuit. [Figure 7] 1 is a timing chart showing the operation of a phase adjustment circuit; [Figure 8] A timing chart showing the operation of the variable reactor rectifier circuit for switch S1 [Figure 9] 1 is a timing chart showing the operation of the variable reactor rectifier circuit for switches S1 and S2. [Figure 10] FIG. 11 is a diagram showing a configuration of a variable reactor rectifier circuit according to a second embodiment. [Figure 11] A timing chart showing the operation of the variable reactor rectifier circuit for switch S1 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] (First embodiment) As shown in Fig. 1, the power supply system of this embodiment includes a phase difference detection circuit 2, matching circuit / coupler etc. 3, variable reactor rectifier circuit 4, and gate control circuit 5 connected to a high frequency power source 1, and supplies DC power converted by these to a load 6. The phase difference detection circuit 2 detects a phase difference between the voltage and current of the AC power input from the high frequency power source 1, and outputs a DC voltage Vb according to the phase difference to the gate control circuit 5. The matching circuit / coupler etc. 3 performs impedance matching and coupling to the input of the variable reactor rectifier circuit 4 in the next stage. The variable reactor rectifier circuit 4 is controlled by the gate control circuit 5, and converts AC power to DC power while operating to compensate for fluctuations in reactance components occurring due to aging and the like in the matching circuit / coupler etc. 3.

[0015] As shown in Fig. 2, in the variable reactor rectifier circuit 4, one end of LC resonant circuits 12a, 12b, which are series circuits of an inductor and a capacitor, is connected to each of input terminals 11a, 11b. A series circuit of switches S1 and S2 is connected between the other ends of the LC resonant circuits 12a, 12b. The switches S1 and S2, which are the first and second switching elements, are both N-channel MOSFETs. The drains of the FETs are commonly connected, and the other ends of the LC resonant circuits 12a, 12b are each connected to their respective sources.

[0016] A first and a second diode D1 and D2 are connected in parallel to the switches S1 and S2, respectively, and the cathodes of these diodes are common. A first and a second capacitor C1 and C2 are connected in parallel to the diodes D1 and D2, respectively. A series circuit of inductors 13a and 13b is connected in parallel to the series circuit of the switches S1 and S2. An output capacitor 14 is connected between the commonly connected drains of the switches S1 and S2 and the common connection point of the inductors 13a and 13b. The output capacitor 14, together with the inductors 13a and 13b, constitutes a filter circuit 15. Both ends of the output capacitor 14 become output terminals of DC power.

[0017] As shown in the figure, the input reactance seen from the input terminals 11a and 11b is jXr, and the reactance of each of the LC resonant circuits 12a and 12b is jX / 2. Although details of the operation will be described later, if the magnitude of the reactance controlled by the variable reactor rectifier circuit 4 is -jXrec, then jXr=jX-jXrec.

[0018] As shown in Fig. 3, this shifts the input reactance jXr to the positive side by jX, which is the sum of the reactances of the LC resonant circuits 12a and 12b. As a result, the input reactance jXr controlled by the variable reactor rectifier circuit 4 ranges from positive to negative. The maximum value of |jXrec| is determined by the capacitance C of the first and second capacitors C1 and C2. In other words, there is a relationship of -jXrec ∝ -j / (ωC). Therefore, the capacitance C is set so as to satisfy the maximum value of |jXrec| required in the system.

[0019] 4, in the phase difference detection circuit 2, a series circuit of capacitors 17a and 17b is connected between AC input terminals 16a and 16b. A circuit combining a transformer 18, a capacitor 19, and diodes 20a and 20b is connected in parallel to the capacitor 17a. The primary winding of the transformer 18 is connected to the AC input terminal 16a, and the capacitor 19 is connected in parallel to the secondary winding.

[0020] The cathode of the diode 20a and the anode of the diode 20b are connected to a common connection point of the capacitors 17a and 17b. The anode of the diode 20a and the cathode of the diode 20b are connected to one end and the other end of the capacitor 19, respectively. A voltage Vb is output from the common connection point of the capacitors 17a and 17b via a resistor element 21. A parallel circuit of a capacitor 22 and a resistor element 23 is connected between the output terminal of the voltage Vb and the ground.

[0021] If the voltage at the common connection point of the capacitors 17a and 17b2 is Vvd and the terminal voltage of the capacitor 19 is Vid, the output voltage Vb of the phase difference detection circuit 2 is a value according to the phase difference of the voltage Vid relative to the voltage Vvd, that is, the current-voltage phase difference, as shown in Fig. 5. Depending on the lag or lead of the phase difference, the voltage Vb changes from a negative value to a positive value.

[0022] As shown in Fig. 6, the gate control circuit 5, which corresponds to the control unit, includes an error amplifier 24, a phase adjustment circuit 25, a 180° delay circuit 26, and gate drivers 27(1) and 27(2). The error amplifier 24 is composed of an operational amplifier 31, resistive elements 32 and 33, and a capacitor 34. The output voltage Vb of the phase difference detection circuit 2 is input to the inverting input terminal of the operational amplifier 31 via the resistive element 32, and a reference voltage is input to the non-inverting input terminal of the same via the resistive element 33. The capacitor 4 is connected between the inverting input terminal and the output terminal of the operational amplifier 31. The error amplifier 24 outputs an error voltage according to the difference between the voltage Vb and the reference voltage.

[0023] In the phase adjustment circuit 25, the rectangular wave signal generated by the rectangular wave generator 35 is input to a triangular wave generating section 36, which is composed of a resistor Rtr and a capacitor Ctr and corresponds to a triangular wave output circuit. A common connection point of the resistor Rtr and the capacitor Ctr is connected to a clock terminal CLK of a D flip-flop 39 via a coupling capacitor 37 and a buffer 38. An output terminal of an operational amplifier 31 constituting the error amplifier 24 is connected to ground via a series circuit of resistors 40 and 41. A common connection point of the resistors 40 and 41 is connected to an input terminal of the buffer 38. The resistors 40 and 41 correspond to an offset applying section.

[0024] The input terminal D of the D flip-flop 39 is pulled up to the power supply. The output terminal Q is directly connected to the input terminal of the gate driver 27(1) and is also connected to the input terminal of the gate driver 27(2) via the 180° delay circuit 26. The output terminal Q is connected to ground via a series circuit of a resistor 42 and a capacitor 43. The output terminal Q is also connected to the common connection point of the resistor 42 and the capacitor 43 via a series circuit of a resistor 44 and a diode 45. When the level of the output terminal Q becomes low, the capacitor 43 is discharged and the D flip-flop 39 is cleared.

[0025] 7, in phase adjustment circuit 25, the error voltage output by error amplifier 24 is applied as an offset to a triangular wave generated by triangular wave generating unit 36 ​​based on input pulse signal 1. This changes the timing at which the amplitude of the triangular wave exceeds threshold value Vth of buffer 38. In response to this change, the phase output from output terminal Q of D flip-flop 39 changes.

[0026] Next, the operation of this embodiment will be described. The switches S1 and S2 have the same switching pattern with a phase difference of 180 degrees, so the operation of the switch S1 will be described. Note that the numbers in parentheses attached to the sections correspond to the circled numbers in the figure. In section (1) shown in FIG. 8, the diode D1 is turned on by AC input, and a forward current Id1 starts to flow. In the following section (2), after the drain-source voltage Vds of the switch S1 becomes approximately zero, the gate signal Vgs1 of the switch S1 is set to a high level to turn on the switch S1. At this time, the turn-on of the switch S1 is zero voltage switching; ZVS.

[0027] In section (3), diode D1 is off but switch S1 is on, so current Is1 continues to flow through switch S1. After a predetermined time has elapsed, the gate signal Vgs1 of switch S1 is set to low level to turn switch S1 off. At this time, capacitor C1 connected in parallel to switch S1 ensures that turn-off is also ZVS. In the following section (4), switch S1 is turned off, causing the drain-source voltage Vds to rise.

[0028] 9 shows an operation timing chart of the switches S1 and S2. That is, the reactance -jXrec controlled by the variable reactor rectifier circuit 4 becomes a negative value due to the capacitors C1 and C2. The magnitude is determined by the off-duty ratio of the switches S1 and S2, that is, the length of the off-period shown in FIG. 9. In this embodiment, the off-period of the switches S1 and S2 is controlled by the gate signals Vgs1 and Vgs2, and the value of the reactance -jXrec is varied as shown in FIG. 3 to variably control the input reactance jXr.

[0029] As described above, according to the present embodiment, in the variable reactor rectifier circuit 4, one end of the LC resonant circuits 12a and 12b is connected to the input terminals 11a and 11b to which AC power is input, respectively. A series circuit of the switches S1 and S2 is connected between the other ends of the LC resonant circuits 12a and 12b. Diodes D1 and D2 are connected in parallel to the switches S1 and S2, respectively, with their cathodes in common. Capacitors C1 and C2 are connected in parallel to the diodes D1 and D2, respectively. The filter circuit 15 has a series circuit of inductors 13a and 13b connected in parallel to the series circuit of the switches S1 and S2, and an output capacitor 15 connected between the DC output terminals. The gate control circuit 5 performs variable control of the reactance by switching the switches S1 and S2 with a phase difference of 180 degrees from each other.

[0030] More specifically, of the switches S1 and S2, the switch is turned on after the corresponding diode is turned on, and the switch is turned off a predetermined time after the diode is turned off, thereby variably controlling the reactance based on the off-duty ratio. With this configuration, it is sufficient to connect one DC-DC converter to the output capacitor 14, and the reactance jXr can be variably controlled in both polarities by the variable reactance rectifier circuit 4. Therefore, the circuit scale can be reduced compared to the conventional configuration.

[0031] Second embodiment Hereinafter, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted, and the different parts will be described. As shown in FIG. 10, the variable reactor rectifier circuit 51 of the second embodiment is configured as if one side of the variable reactor rectifier circuit 4 is cut out in order to apply it to a single-ended system. An LC resonant circuit 12 and a series circuit of a switch S1 are connected between AC input terminals 11a and 11b. This switch S1 and a diode D1 and a capacitor C1 connected in parallel correspond to the switch S2, diode D2, and capacitor C2 of the first embodiment, and have the same orientation as those. A filter circuit 52 replacing the filter circuit 15 is configured by a series circuit of an inductor 13 and an output capacitor 14.

[0032] As shown in FIG. 11, the variable reactor rectifier circuit 51 is controlled by the gate control circuit 5 of the first embodiment using a signal pattern that controls one of the switches. In the second embodiment, the reactance of the LC resonant circuit 12 is set to jX, so that the input reactance jXr is jXr=jX-jXrec. The switching of the switch S1 is controlled in the same manner as in the first embodiment, and the reactance is variably controlled by the off-duty ratio. If the capacitance of the capacitor C1 is set to the same value as in the first embodiment, the variable range of the reactance becomes narrower, but the circuit scale becomes smaller.

[0033] (Other embodiments) The first and second diodes may be built-in diodes of the MOSFET. The first and second capacitors may be formed only from a parasitic capacitance between the drain and source of a MOSFET, or may be formed from that parasitic capacitance and a capacitor connected in parallel to the MOSFET. The switches S1 and S2 in the first embodiment may be connected in such a way that the sources of the N-channel MOSFETs are common. The switching element is not limited to an N-channel MOSFET. The capacitance C of the first and second capacitors may be set so as to satisfy ΔX<(maximum value of |jXrec|).

[0034] Although the present disclosure has been described based on the embodiment, it is understood that the present disclosure is not limited to the embodiment or structure. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, and other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and concept of the present disclosure. [Explanation of symbols]

[0035] In the drawing, 1 is a high frequency power supply, 2 is a phase difference detection circuit, 4 is a variable reactor rectifier circuit, 5 is a gate control circuit, 6 is a load, 11a and 11b are input terminals, 12a and 12b are LC resonant circuits, 13a and 13b are inductors, 14 is an output capacitor, 15 is a filter circuit, S1 and S2 are switches, C1 and C2 are capacitors, and D1 and D2 are diodes.

Claims

1. Two LC resonant circuits (12a, 12b) each having one end connected to two input terminals (11a, 11b) to which AC power is input, a series circuit of first and second switching elements (S1, S2) connected in reverse directions between the other ends of the two LC resonant circuits; first and second diodes (D1, D2) connected in parallel to the first and second switching elements, respectively, so that the cathode or the anode of each diode is common; a first capacitor (C1) and a second capacitor (C2) connected in parallel to the first diode (C2) and the second diode (C3), respectively; a filter circuit (15) having a series circuit of two inductors (13a, 13b) connected in parallel to the series circuit of the first and second switching elements, and an output capacitor (14) connected between a DC output terminal; a control unit (5) that performs variable control of reactance by switching the first and second switching elements with a phase difference of 180 degrees from each other, where a variable control value required for the reactance is ΔX and the reactance variably controlled by the control unit is −jXrec, the capacitance C of the first and second capacitors is set to satisfy ΔX≦(maximum value of |jXrec|), The reactance jXr seen from the input terminal is shifted to the positive side by the sum jX of the reactances of the two LC resonant circuits, and the variable range of the reactance jXr is set to be bipolar; the control unit turns on the first and second switching elements after a corresponding diode of the first and second switching elements is turned on; A rectifier circuit that turns off the switching element when a predetermined time has elapsed after the diode is turned off, and performs variably controlling the reactance according to an off duty ratio of the switching element.

2. a series circuit including an LC resonant circuit (12) and a switching element (S1) connected between input terminals to which AC power is input; a diode (D1) connected in parallel to the switching element such that a cathode of the diode is on the LC resonant circuit side; A capacitor (C1) connected in parallel to the diode; a filter circuit (52) having an inductor (13) and an output capacitor (14) connected in parallel to the switching element; A control unit (5) that performs variable control of reactance by switching the switching element, where a variable control value required for the reactance is ΔX and the reactance variably controlled by the control unit is −jXrec, the capacitance C of the capacitor connected in parallel with the diode is set to satisfy ΔX≦(maximum value of |jXrec|), The reactance jX of the LC resonant circuit is used to shift the reactance jXr seen from the input terminal to the positive side, so that the variable range of the reactance jXr is bipolar; The control unit turns on the switching element after the diode is turned on, A rectifier circuit that turns off the switching element when a predetermined time has elapsed after the diode is turned off, and performs variably controlling the reactance according to an off duty ratio of the switching element.

3. the control unit includes a phase difference detection unit that detects a phase difference between a voltage and a current of the AC power, 3. The rectifier circuit according to claim 1, wherein an off-duty ratio of the switching element is changed based on the phase difference.

4. the phase difference detection unit outputs a voltage Vb according to the phase difference; The control unit includes an error amplifier (24) that outputs an error voltage between the voltage Vb and a reference voltage; A triangular wave output circuit (36) for outputting a triangular wave signal; an offset applying unit (40, 41) that offsets the triangular wave signal by an amount corresponding to the error voltage; a flip-flop (39) that is triggered by the offset-added triangular wave signal and is cleared a certain time after the triggering; 4. The rectifier circuit according to claim 3, wherein said switching element is driven based on an output signal of said flip-flop.

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