JP2012253964A - Control method of power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method of a power supply device for reducing switching loss, miniaturizing a cooling fin of a bridge circuit, miniaturizing the whole device and reducing cost.SOLUTION: The power feeding device includes a power reception circuit 320 equipped with a bridge circuit where a switching arm serial circuit and a diode serial circuit are connected in parallel, receives power of a high frequency power supply 100 via a power reception coil 120 and a resonance capacitor C and supplies DC power to a load R. In the control method of the power supply device, a series of switching operations for turning on one of switches Qand Qand turning off the other at the same time as a first zero cross point in one period of a current i flowing in the coil 120, and inverting on/off states of the switches Qand Qafter arbitrary delay time shorter than a half period elapses from the zero cross point after the half period of the current i are repeated in synchronization with the period of the current i.

Description

  The present invention relates to a control method for a power feeding apparatus that mainly uses a magnetic coupling between coils to supply power via a space.

As a method of supplying power to a load using magnetic coupling between coils by electromagnetic induction, for example, contactless power feeding can be mentioned. The principle is that a plurality of coils are magnetically coupled through a space to form a transformer, and power is transferred using electromagnetic induction between the coils.
For example, a primary coil corresponding to a power supply source is arranged in a rail shape as a power supply line, and a secondary coil and a power receiving circuit are integrated to form a moving body, and the primary coil and the secondary coil are opposed to each other. By doing so, it is possible to perform non-contact power feeding to a moving body that moves along the power feeding line.

Here, FIG. 11 shows the prior art of the non-contact power feeding device described in Patent Document 1. In FIG. 11, a primary power supply line 110 as a coil is connected to both ends of the high-frequency power source 100. A power receiving coil 120 is magnetically coupled to the primary side power supply line 110, and the primary side power supply line 110 and the power receiving coil 120 constitute a kind of transformer.
Both ends of the power receiving coil 120 are connected to the AC terminal of the full-wave rectifier circuit 10 via the resonance capacitor C. Here, the power receiving coil 120 and the resonance capacitor C constitute a series resonance circuit.
Full-wave rectifier circuit 10 includes a diode _{D u, D v, D x} , is configured by full bridge connection _{D y.}

A constant voltage control circuit 20 that controls the direct current output voltage of the full wave rectifier circuit 10 to a reference voltage value is connected to the direct current terminal of the full wave rectifier circuit 10. The constant voltage control circuit 20 is constituted by, for example, a boost chopper circuit including a reactor L ₁ , a diode D ₁ , a smoothing capacitor C ₀ and a semiconductor switch SW ₁ . Further, both ends of the smoothing capacitor C _0, the load R is connected.
In FIG. 11, it is omitted a controller for switching the semiconductor switch SW _1.

In the prior art of FIG. 11, a high-frequency current is passed through the primary power supply line 110 from the high-frequency power source 100, and the high-frequency power supplied via the power receiving coil 120 is input to the full-wave rectifier circuit 10 and converted to DC power. .
In general, in this type of non-contact power feeding device, a voltage induced in the power receiving coil 120 changes due to a change in the gap length between the primary side power feeding line 110 and the power receiving coil 120 or a positional shift between the two. The DC output voltage of the wave rectifier circuit 10 varies. The characteristics of the load R also cause the DC output voltage of the full wave rectifier circuit 10 to fluctuate.
Therefore, in the prior art of FIG. 11, the DC output voltage of the full-wave rectifier circuit 10 is controlled to a constant value by the constant voltage control circuit 20.

  In the non-contact power feeding device, the higher the frequency of the current supplied through the coil, the smaller the exciting inductance necessary for power transmission, and the miniaturization of the coil and the core disposed around it. Can do. However, in a power converter that constitutes a high frequency power supply device or a power receiving circuit, the higher the frequency of the current flowing through the circuit, the higher the switching loss of the semiconductor switch and the lower the power supply efficiency. Generally, it is set to several [kHz] to several tens [kHz].

JP 2002-354711 A (paragraphs [0028] to [0031], [0041] to [0045], FIG. 1, FIG. 6, etc.)

The contactless power supply device shown in FIG. 11, particularly the power receiving circuit at the subsequent stage of the resonance capacitor C, has the following problems.
(1) Since the power receiving circuit is constituted by the full-wave rectifier circuit 10 and the constant voltage control circuit 20, the entire circuit becomes large, resulting in an increase in installation space and cost.
(2) In addition to the diodes D _u , D _v , D _x , and D _y of the full-wave rectifier circuit 10, losses also occur in the reactor L ₁ , the semiconductor switch SW ₁ , and the diode D _{1 of} the constant voltage control circuit 20. The loss of power supply is a factor in reducing power supply efficiency.

  In view of the above points, the inventors have disclosed, as Japanese Patent Application No. 2010-257809 (hereinafter referred to as the prior application), a non-contact power supply apparatus (hereinafter referred to as the prior application) that enables small, low cost, high efficiency and stable power supply. Proposed invention).

FIG. 12 shows a first non-contact power feeding apparatus according to the prior application.
In FIG. 12, reference numeral 310 denotes a power receiving circuit. The power reception circuit 310 includes semiconductor switches Q _u , Q _x , Q _v , and Q _y that are connected in a full bridge, and diodes D _u that are connected in antiparallel to the switches Q _u , Q _x , Q _v , and Q _y , respectively. , D _x , D _v , D _y , capacitors C _x , C _y connected in parallel to the lower arm switches Q _x , Q _y , respectively, and a direct current of a full bridge circuit (full bridge inverter) composed of these elements and a, a smoothing capacitor C ₀ which is connected between the terminals. Between the AC terminals of the full bridge circuit, it is connected in series circuit with the power receiving coil 120 and the resonance capacitor C, the both ends of the smoothing capacitor C _0, the load R is connected.
Reference _numeral 200 denotes a control device that generates drive signals for switching the semiconductor switches Q _u , Q _x , Q _v , and Q _y . The control unit 200, based on the DC output voltage V _o of the current i and the receiving circuit 310 of the power receiving coil 120 which is detected by the current detection means CT, generates the driving signal.

In this non-contact power feeding device, the semiconductor switch Q _u, Q x, _{Q v,} by controlling the Q _y, the AC voltage v of the full bridge circuit is controlling the DC output voltage V _o to a positive or negative voltage to the peak value The Feeding power to the power receiving circuit 310 from the primary feed line 110 is the product of the voltage v of the current i and the full-bridge circuit of the power receiving coil 120, the control unit 200, based on the detected value of the DC output voltage V _o By adjusting the phase of the drive signals of the semiconductor switches Q _u , Q _x , Q _v , and Q _y , it is possible to control the feed power, that is, constant control of the DC output voltage V _o .
In addition, by configuring the power receiving circuit 310 with a full bridge circuit, it is possible to perform an operation of keeping power constant even when the load R is a regenerative load.

According to this non-contact power feeding device, the DC output voltage is controlled by phase control of the drive signals of the semiconductor switches Q _u , Q _x , Q _v , and Q _y without using a constant voltage control circuit as in the prior art of FIG. It can be controlled constantly. In addition, since the power receiving circuit 310 can be configured only by the full bridge circuit and the smoothing capacitor C ₀ , the circuit configuration can be simplified, downsized, and the cost can be reduced, and the loss can be reduced by reducing the number of components. Reduced, high efficiency and stable non-contact power feeding is possible.
In addition, the so-called soft switching is performed by the charging / discharging action of the capacitors C _x and C _y , and the switching loss is reduced, thereby further improving the efficiency.

FIG. 13 shows a second non-contact power feeding device according to the prior application.
In the non-contact power supply apparatus of FIG. 12, four semiconductor switches are required. Therefore, when the cooling means and the like are taken into consideration, there is a risk of increasing the size and cost of the apparatus. Therefore, the non-contact power feeding apparatus of FIG. 13 is intended to be further reduced in size and cost by corresponding only to the power running load and not corresponding to the regenerative load.

In FIG. 13, the power receiving circuit 320 includes a switching arm in which an arm in which a diode D _u is connected in antiparallel to the semiconductor switch Q _u and an arm in which the diode D _x is connected in antiparallel to the semiconductor switch Q _x. It has a series circuit and a diode series circuit in which the diodes D _v and D _y are connected in series. These switching arm series circuit and diode series circuit are connected in parallel, and smoothing capacitors _Co are connected to both ends of the diode series circuit. Note that configurations other than the power receiving circuit 320 are the same as those in FIG.

FIG. 14 is an operation explanatory diagram of the second non-contact power feeding device.
In this non-contact power feeding device, by controlling the semiconductor switch Q _u, the Q _x by the driving signal having a duty ratio of 0.5, the AC voltage v is controlling the DC output voltage V _o to a positive or negative voltage to the peak value The Feeding power to the power receiving circuit 320 from the primary feed line 110 is a product of the current i and the voltage v in FIG. 14, the control unit 200, the DC output voltage V _o semiconductor switch on the basis of the detected value of Q _u, by adjusting the phase of the drive signal Q _x, the control of the supply power, that is, enables constant control of the DC output voltage V _o.

  According to the second non-contact power feeding device, since no semiconductor switch is required for two of the four elements constituting the bridge circuit, the switching loss can be greatly reduced and the cooling fin for the bridge circuit can be downsized. Thus, the entire apparatus can be further reduced in size and cost.

As described above, according to the invention of the prior application, it is possible to significantly reduce the switching loss and to reduce the size and cost of the device as compared with the prior art according to Patent Document 1.
However, when the switching frequency becomes several [kHz] or more, the switching loss generally tends to be larger than the conduction loss. Therefore, the switching loss still accounts for more than half of the loss of the bridge circuit. This is a factor that hinders downsizing of the cooling fins.

  Therefore, the problem to be solved by the present invention is to control the power feeding device that can reduce the switching loss of the semiconductor switch more than the prior invention, downsize the cooling fin of the bridge circuit, and reduce the overall size and cost of the device. It is to provide a method.

In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a coil for transmitting and receiving electric power by magnetic coupling with the outside, one end of the coil connected to one AC terminal via a capacitor, A bridge circuit having the other end connected to the other AC terminal, and a smoothing capacitor connected between the DC terminals of the bridge circuit, and a load is connected to both ends of the smoothing capacitor,
The bridge circuit comprises a parallel connection of a switching arm series circuit in which two switching arms composed of an antiparallel connection circuit of a semiconductor switch and a diode are connected in series, and a diode series circuit in which two diodes are connected in series. The connection point of the switching arms and the connection point of the diodes are used as the AC terminal of the bridge circuit, and the connection point of the switching arm series circuit and the diode series circuit is the DC terminal of the bridge circuit. In the control method for controlling the power supply device as
Of one cycle of current flowing through the coil, one semiconductor switch is turned on simultaneously with the first zero-cross point, the other semiconductor switch is turned off, and from the zero-cross point after the half cycle of the current, the half cycle of the current A series of switching operations for inverting the on / off state of the semiconductor switch after an arbitrary shorter delay time is repeated in synchronization with the period of the current.

According to a second aspect of the present invention, there is provided a coil for transmitting and receiving electric power by magnetic coupling with the outside, one end of the coil connected to one AC terminal via a capacitor, and the other end of the coil to the other AC terminal. A bridge circuit connected, and a smoothing capacitor connected between the DC terminals of the bridge circuit, and a load is connected to both ends of the smoothing capacitor,
The bridge circuit has a full bridge configuration in which two switching arm series circuits in which two switching arms composed of an antiparallel connection circuit of a semiconductor switch and a diode are connected in series are connected in parallel, and the switching arms are connected to each other. In a control method for controlling a power feeding device having a point as the AC terminal of the bridge circuit and a connection point between the switching arm series circuits as the DC terminal of the bridge circuit,
In one switching arm series circuit of the switching arm series circuit, the semiconductor switch of one of the two switching arms simultaneously with the first zero cross point in one cycle of the current flowing through the coil The semiconductor switch of the other arm is turned on, the on / off state of the semiconductor switch is reversed simultaneously with the zero-cross point after a half cycle of the current, and
In the other switching arm series circuit of the switching arm series circuit, the semiconductor switch of any one of the two switching arms is turned on simultaneously with the first zero cross point in one cycle of the current, The semiconductor switch of the other arm is turned off, and after an arbitrary delay time shorter than the half cycle of the current has elapsed from the zero cross point after the half cycle of the current, the on / off state of the semiconductor switch is inverted,
A series of switching operations of each of the semiconductor switches is repeated in synchronization with the cycle of the current.

According to a third aspect of the present invention, in the method for controlling the power feeding device according to the first or second aspect,
During the period when power supply from the outside to the coil is stopped, all the semiconductor switches are turned off, and when power supply is started, the zero crossing point of the current flowing through the coil is detected and then the switching of each semiconductor switch is performed. The operation is performed.

According to a fourth aspect of the present invention, in the method for controlling a power feeding device according to the first or second aspect,
During the period when power supply from the outside to the coil is stopped, all the semiconductor switches are kept in the switching state immediately before the current flowing through the coil becomes zero due to the stop of power supply to the coil, and power supply to the coil is performed. When started, the switching operation of each semiconductor switch is performed after detecting the zero cross point of the current flowing through the coil.

According to the first or second aspect of the invention, even when operating at a frequency at which the switching loss is larger than the conduction loss, the switching loss is reduced and the cooling fins of the bridge circuit are downsized. Miniaturization and cost reduction can be achieved.
Further, according to the invention described in claim 3 or 4, in addition to the above effect, even when power supply to the coil is resumed at the time of power recovery after a power failure, the power supply operation can be performed without any trouble. .

1 is a circuit diagram illustrating a first embodiment of a power feeding apparatus to which a control method of the present invention is applied. It is operation | movement explanatory drawing which shows 1st Embodiment of the control method of this invention. It is operation | movement explanatory drawing which shows 1st Embodiment of the control method of this invention. It is operation | movement explanatory drawing which shows 2nd Embodiment of the control method of this invention. It is a circuit diagram which shows 2nd Embodiment of the electric power feeder to which the control method of this invention is applied. It is operation | movement explanatory drawing which shows 3rd Embodiment of the control method of this invention. It is operation | movement explanatory drawing which shows 3rd Embodiment of the control method of this invention. It is operation | movement explanatory drawing which shows 4th Embodiment of the control method of this invention. It is operation | movement explanatory drawing which shows 5th Embodiment of the control method of this invention. It is operation | movement explanatory drawing which shows 6th Embodiment of the control method of this invention. It is a circuit diagram of the prior art described in Patent Document 1. It is a circuit diagram which shows the 1st non-contact electric power feeder which concerns on a prior application. It is a circuit diagram which shows the 2nd non-contact electric power feeder which concerns on a prior application. It is operation | movement explanatory drawing of the non-contact electric power supply shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a circuit diagram showing a first embodiment of a power feeding apparatus according to the present invention, to which a control method according to claims 1, 3, and 4 is applied. Note that the control method of the present invention can be applied to both a non-contact type and a contact type power supply device, but in the following embodiments, a case where the control method is applied to a non-contact power supply device will be described.

Non-contact power feeding apparatus shown in FIG. 1 has the same structure as FIG. 13, the power receiving circuit 320, an arm connected to the diode D _u in antiparallel semiconductor switch Q _u, reverse diode D _x to the semiconductor switch Q _x It has a switching arm series circuit in which arms connected in parallel and a series of switching arms connected in series, and a diode series circuit in which diodes D _v and D _y are connected in series. To these switching arms series circuit and a diode series circuit is connected in parallel, the smoothing capacitor C ₀ is connected to both ends of the diode series circuit. The internal connection point of the switching arm series circuit and the internal connection point of the diode series circuit are AC terminals of the bridge circuit, and both ends of the diode series circuit are DC terminals.
The AC terminals of the bridge circuit, is connected to a series circuit of the power receiving coil 120 and the resonance capacitor C, the load R is connected across the smoothing capacitor C _0. In addition, 100 is a high frequency power supply, 110 is a primary side electric power feeding line.

On the other hand, the control device 200 generates and outputs drive signals for the switches Q _u and Q _x based on the DC output voltage V _o and the current i of the power receiving coil 120 detected by the current detection means CT.

Next, the normal operation of this non-contact power feeding device will be described. This operation is based on the control method (first embodiment, second embodiment) described in claim 1.
FIG. 2 corresponds to the first embodiment of the control method according to the present invention, and the operation waveform of the current i flowing through the power receiving coil 120 of FIG. 1 and the voltage v between the AC terminals of the bridge circuit, and the switch Q _u. , Q _x drive signals. As shown in FIG. 2, the switches Q _u and Q _x perform a switching operation at a constant frequency synchronized with the current i.
At this time, the switches Q _u and Q _x are controlled by a drive signal whose duty ratio is not 0.5 as shown in FIG. 2, unlike FIGS.
Hereinafter, the operation in each of the periods I to III in FIG. 2 will be described.

(1) Period I (switch Q _u is on, diode D _y is conductive): current i flows through the path of resonant capacitor C → diode D _u → smoothing capacitor C ₀ → diode D _y → receiving coil 120, and voltage v is a positive voltage level corresponding to the DC output voltage V _o as shown. During this period, the smoothing capacitor C ₀ is charged by the current i.

(2) Period II (switch Q _u is on, diode D _v is conductive): current i flows through the path of resonant capacitor C → receiving coil 120 → diode D _v → switch Q _u , and voltage v is as shown At zero voltage level.

(3) Period III (switch Q _x is on, diode D _v is conductive): current i flows through the path of resonant capacitor C → receiving coil 120 → diode D _v → smoothing capacitor C ₀ → diode D _x , voltage v is a negative voltage level corresponding to the DC output voltage V _o as shown. During this period, the smoothing capacitor C ₀ is charged by the current i.
Thereafter, the mode is changed to the switching mode of period I, and the same operation is repeated.

As described above, in this embodiment, one switch (Q _{u in} FIG. 2) is turned on simultaneously with the first zero cross point in one cycle of the current i flowing through the power receiving coil 120, and the other switch (Q Q in FIG. 2). _x ) is turned off, and after a delay time shorter than the half cycle of the current i (corresponding to the period II) has elapsed from the zero cross point after a half cycle, a series of inverting the on / off states of the switches Q _u and Q _x the switching operation, by repeating in synchronization with the period of the current i, the AC terminal voltage v of the bridge circuit is controlling the DC output voltage V _o to a positive or negative voltage to the peak value.
Feeding power to the power receiving circuit 320 from the primary feed line 110 is a product of the current i and the voltage v shown in FIG. 1, the control unit 200, the switch Q _u on the basis of the detected value of the DC output voltage V _o , by adjusting the phase of the drive signal Q _x, the control of the supply power, that is, allows constant control of the DC output voltage V _o.

Next, switching losses that occur in the semiconductor switches Q _u and Q _x in this embodiment will be described.
As shown in FIG. 2, the switches Q _u and Q _x are switched on / off in the period II (switch Q _u is on and the diode D _v is conductive) → period III (switch Q _x is on and the diode D _v is on when migrating conductive), and the period III (switch _{Q x} is on, diode _{D v} conduction) → period I (switch _{Q u} is on, diode _{D y} is generated during the migration of conductive). At this time, the currents i _u and i _x flowing through the switching arms constituted by the switches Q _u and Q _x and the diodes D _u and D _x connected in antiparallel are respectively as shown in FIG.

During the period II → period III transition, switch Q _u is turned off, switch Q _x is turned on. At this time, the turn-off losses in the switch Q _u occurs, the current in the switch Q _x the diode D _x is commutated, becomes zero current switching, the turn-on loss is not generated.
In addition, at the time of the transition period III → period I, switch Q _u is turned on, the switch Q _x is turned off. At this time, since both switches in a period when the currents of the switches Q _u and Q _x are zero, neither turn-on loss nor turn-off loss occurs.

As described above, according to the control method described in claim 1, the switching loss occurring in the switch Q _u, Q _x is only the turn-off loss of the switch Q _u. Accordingly, since only one element of the four elements constituting the bridge circuit is turned off, the switching loss can be greatly reduced.

The drive signals for the switches Q _u and Q _x may be as shown in FIG. 4 which is the second embodiment.
Below, the operation | movement in each period i-iii of FIG. 4 is demonstrated.
(1) Period i: Same as period I in FIG.
(2) Period ii: Same as period III in FIG.
(3) Period iii (switch Q _x is on, diode D _y is conducting): current i flows through the path of resonance capacitor C → switch Q _x → diode D _y → receiving coil 120, and voltage v is as shown At zero voltage level.
Thereafter, the mode is changed to the switching mode of period i, and the same operation is repeated.

That is, also in FIG. 4, one switch (Q _{x in} FIG. 4) is turned on at the same time as the first zero cross point (at the time of transition from period i to period ii) in one cycle of current i, and the other switch (FIG. 4, Q _u ) is turned off, and the switch Q _u , Q _x is turned on / off after an arbitrary delay time (corresponding to period iii) shorter than the half cycle of the current i has elapsed from the zero cross point after half a cycle. a series of switching operations of inverting, by repeating in synchronization with the period of the current i, the AC terminal voltage v of the bridge circuit is controlling the DC output voltage V _o to a positive or negative voltage to the peak value.

In the periods i to iii, the switching loss occurring in the switches Q _u and Q _x is only the turn-off loss of the switch Q _x . Therefore, also in this case, since only one element of the four elements constituting the bridge circuit has a turn-off loss, the same switching loss reduction effect as in FIG. 2 can be obtained.

Next, FIG. 5 is a circuit diagram showing a second embodiment of the non-contact power feeding device according to the present invention, to which the control method according to claims 2, 3 and 4 is applied.
In the circuit of FIG. 1, the switching loss is reduced by having a diode series circuit in the bridge circuit, but it cannot cope with the regenerative load. Therefore, in the power supply apparatus of FIG. 5, it is possible to simultaneously realize the response to the regenerative load and the reduction of the switching loss by configuring the bridge circuit by the switching arm.

In FIG. 5, a power receiving circuit 330 includes a switching arm in which an arm in which a diode D _u is connected in antiparallel to a semiconductor switch Q _u and an arm in which a diode D _x is connected in antiparallel to a semiconductor switch Q _x. which has a series circuit, and an arm connected to the diode D _v in reverse parallel to the semiconductor switch Q _v, an arm connecting the diode D _y in reverse parallel to the semiconductor switch Q _y, the switching arm series circuits were connected in series Have. Then, these switching arm series circuits are connected in parallel, the smoothing capacitor C ₀ is connected to the connection point.
The internal connection point of the two switching arm series circuits is an AC terminal of the bridge circuit, and the parallel connection point of the two switching arm series circuits is a DC terminal. Similar to FIG. 1, the AC terminals of the bridge circuit is connected to a series circuit of the power receiving coil 120 and the resonance capacitor C, the load R is connected across the smoothing capacitor C _0.
Further, the control device 200 generates and outputs drive signals for the switches Q _u , Q _x , Q _v , and Q _y based on the detected value of the DC output voltage V _o and the current i flowing through the power receiving coil 120.

Next, the normal operation of the non-contact power feeding apparatus will be described. This operation is based on the control method described in claim 2 (third embodiment, fourth embodiment).
FIG. 6 corresponds to a third embodiment of the control method of the present invention. The operation waveform of the current i flowing through the power receiving coil 120 of FIG. 5 and the voltage v between the AC terminals of the bridge circuit, and the switches Q _u , Drive signals for Q _x , Q _v , and Q _y are shown. As shown in FIG. 6, the switch _Q u, _{Q x} the switching operation similarly to the switch _Q u, _{Q x} of FIG. 2, the switch _Q v, at _{Q y} is a constant frequency which is synchronized with zero-cross point of current i Switching operation is performed. The operation in each of the periods I to III in FIG. 6 is the same as that in each of the periods I to III in FIG.

That is, in this embodiment, in one switching arm series circuit (a series circuit of Q _v and Q _{y in} FIG. 6) of the two switching arm series circuits, the first zero cross point in one period of the current i At the same time, either one of the upper and lower arms (Q _{v in} FIG. 6) is turned off, the other switch (Q _{y in} FIG. 6) is turned on, and the switches Q _v and Q _y are turned on simultaneously with the zero-cross point after a half cycle. Invert the OFF state, and in the other switching arm series circuit (the series circuit of Q _u and Q _{x in} FIG. 6) of the two switching arm series circuits, the first zero cross point in one period of the current i At the same time either turn one switch (in FIG. 6 Q _u) of the upper and lower arms, turning off the other switch (in FIG. 6 Q _x), after a half cycle After a lapse of short arbitrary delay time than the half period of the current i (corresponding to the period II) from the zero-cross point, the switch Q _u, a series of the switching operations so as to reverse the on and off states of Q _x, the current i It is repeated in synchronism with the period.

FIG. 7 shows currents i _u , i _x , i _v and i _y flowing through the switching arms in the periods I to III.
Like the non-contact power feeding device of Fig. 1, switching loss switch _{Q u, Q x, Q v} , at _{Q y} occurs is only the turn-off loss of the switch _{Q u.} Accordingly, since only one element of the four elements constituting the bridge circuit is turned off, the switching loss can be greatly reduced.

Further, the drive signals of the switches Q _u , Q _x , Q _v , and Q _y may be as shown in FIG. 8 that is the fourth embodiment. The operations in the periods i to iii in FIG. 8 are the same as those in the periods i to iii in FIG. 4. After the period iii, the operation is switched to the switching mode in the period i and the same operations are repeated.
At this time, the switching loss that occurs in the switches Q _u , Q _x , Q _v , and Q _y is only the turn-off loss of the switch Q _x . Accordingly, since only one element of the four elements constituting the bridge circuit is turned off, the switching loss can be greatly reduced.

  In addition, FIGS. 6-8 mentioned above have shown the case where it respond | corresponds to a power running load in the circuit of FIG. Even in the case of dealing with a regenerative load, the switching loss can be reduced by the same principle.

Next, fifth and sixth embodiments of the control method according to the present invention will be described. In addition, each embodiment described below is a case where the power supply to the power receiving coil 120 is temporarily stopped due to a power failure or the like, and the power supply is resumed due to a subsequent power recovery.
FIG. 9 is a view for explaining a fifth embodiment corresponding to the invention of claim 3, and for the non-contact power feeding device of FIG. 1, the power receiving coil in the power supply stop and restart of the primary power supply line 110. 120 current i, the operation waveforms of the AC terminal voltage v of the bridge circuit, and shows the driving signal of the switch _Q u, _{Q x.}
When the power supply by the power receiving coil 120 is stopped at the timing (1) in FIG. 9 from the normal power supply state, the current detection means CT in FIG. 1 detects the disappearance of the current i and turns off both the switches Q _u and Q _x Keep the state.

Thereafter, when the power supply is started at the timing (2) in FIG. 9, a voltage corresponding to the high-frequency current of the primary power supply line 110 is induced in the power receiving coil 120. At this time, the bridge circuit of the power receiving circuit 320 is equivalent to a diode full-wave rectifier circuit because the switches Q _u and Q _x are in the off state as described above. For this reason, a resonance current flows through the path of the power receiving coil 120 → the diode D _v → the smoothing capacitor C ₀ → the diode D _x → the resonance capacitor C. This current polarity is reversed at a timing of FIG. 9 (3), it flows through a path of the power reception coil 120 → resonance capacitor C → diode D _u → smoothing capacitor C ₀ → diode D _y.

In the control device 200, the current detection means CT detects the zero crossing point of the current i at the timing (3) and performs control so as to restart the switching operations of the switches Q _u and Q _x . As a result, the power supply resumption time temporarily performs a full-wave rectification operation using a diode, thereby securing a path of the resonance current flowing through the power receiving coil 120 and detecting a zero cross point of the current i, and then performing a desired switching operation. The power feeding device can be normally restarted by starting.
Note that even when the present invention is applied to the non-contact power feeding apparatus shown in FIG. 5, it can be restarted by the same method.

Incidentally, the circuit operation of the fifth embodiment described above, in which satisfied the conditions of the power supply resumption of the power receiving coil induced voltage> DC output voltage V _{o (smoothing} capacitor C ₀ voltage). Therefore, in a case where the load characteristics to be connected the power receiving coil induced voltage <DC output voltage V _o of the power feeding resumed, it is possible to perform a restart operation by the sixth embodiment as described below.

FIG. 10 is a view for explaining a sixth embodiment corresponding to the invention of claim 4. Similarly to FIG. 9, the power supply of the primary power supply line 110 is stopped for the non-contact power supply device of FIG. 1. ~ Operation waveforms of current i and voltage v at restart, and driving signals of switches Q _u and Q _x are shown.

When the power supply by the power receiving coil 120 is stopped at the timing (1) in FIG. 10 from the normal power supply state, in this embodiment, the disappearance of the current i is detected by the current detection means CT, and the switches Q _u and Q _{x are} detected. Is maintained in the same manner as the control state immediately before the current i disappears.
The on / off control at this time corresponds to the period I or the period III shown in FIG. In FIG. 10, since the current i is negative, the switches Q _u and Q _x are held in the same switching state as in the period III in FIG.

Next, when the power supply is started at the timing (2) in FIG. 10, a voltage corresponding to the high-frequency current of the primary power supply line 110 is induced in the power receiving coil 120. In this case, the bridge circuit of the power receiving circuit 320, the above on-off state (switch _{Q u} is turned off, the switch _{Q x} is on) is in the power receiving coil 120 → diode _{D v} → smoothing capacitor _{C 0} → diode _{D x} → the resonance current path of the resonant capacitor C is about to flow, when a power receiving coil induced voltage <DC output voltage V _o of the power feeding resumed, can not current flows in this path.

Next, when the polarity of the current i is reversed at the timing (3) in FIG. 10, the current i starts flowing through the path of the resonance capacitor C → the switch Q _x → the diode D _y → the receiving coil 120, and the voltage v is zero voltage as shown in the figure. Become a level. Further, when the polarity of the current i is reversed at the timing (4) in FIG. 10, the control device 200 detects the zero cross point of the current i from the output of the current detection means CT.
Then, the control device 200 performs control so as to resume the switching operation similar to the normal operation shown in FIG. 2, so that the switch Q _u is turned on and the switch Q _x is turned off, as shown in FIG. Current flows through the same path as in period II.
That is, even if the switches Q _u and Q _x are set to the same control state as immediately before the disappearance of the current i, a path for the resonance current flowing in the power receiving coil 120 at the time of resumption of power supply is secured, and the zero cross point of the current i is detected. By restarting the switching operation, the power feeding apparatus can be normally restarted.
Note that even when the present invention is applied to the non-contact power feeding apparatus shown in FIG. 5, it can be restarted by the same method.

100: high-frequency power supply 110: the primary feed line 120: power receiving coil 200: Control unit 320, 330: receiving circuit C: resonance capacitor CT: current detecting means _{Q u, Q x, Q v} , Q y: semiconductor switch D _{u, D x, D v, D y} : diode C _0: smoothing capacitor R: load

Claims (4)

A coil that transfers power by magnetic coupling with the outside, a bridge circuit in which one end of the coil is connected to one AC terminal via a capacitor, and the other end of the coil is connected to the other AC terminal; A smoothing capacitor connected between the DC terminals of the bridge circuit, and a load is connected to both ends of the smoothing capacitor,
The bridge circuit comprises a parallel connection of a switching arm series circuit in which two switching arms composed of an antiparallel connection circuit of a semiconductor switch and a diode are connected in series, and a diode series circuit in which two diodes are connected in series. The connection point of the switching arms and the connection point of the diodes are used as the AC terminal of the bridge circuit, and the connection point of the switching arm series circuit and the diode series circuit is the DC terminal of the bridge circuit. In the control method for controlling the power supply device as
Of one cycle of current flowing through the coil, one semiconductor switch is turned on simultaneously with the first zero-cross point, the other semiconductor switch is turned off, and from the zero-cross point after the half cycle of the current, the half cycle of the current A method for controlling a power feeding apparatus, comprising: repeating a series of switching operations for inverting an on / off state of the semiconductor switch after a shorter arbitrary delay time has elapsed in synchronization with a cycle of the current. A coil that transfers power by magnetic coupling with the outside, a bridge circuit in which one end of the coil is connected to one AC terminal via a capacitor, and the other end of the coil is connected to the other AC terminal; A smoothing capacitor connected between the DC terminals of the bridge circuit, and a load is connected to both ends of the smoothing capacitor,
The bridge circuit has a full bridge configuration in which two switching arm series circuits in which two switching arms composed of an antiparallel connection circuit of a semiconductor switch and a diode are connected in series are connected in parallel, and the switching arms are connected to each other. In a control method for controlling a power feeding device having a point as the AC terminal of the bridge circuit and a connection point between the switching arm series circuits as the DC terminal of the bridge circuit,
In one switching arm series circuit of the switching arm series circuit, the semiconductor switch of one of the two switching arms simultaneously with the first zero cross point in one cycle of the current flowing through the coil The semiconductor switch of the other arm is turned on, the on / off state of the semiconductor switch is reversed simultaneously with the zero-cross point after a half cycle of the current, and
In the other switching arm series circuit of the switching arm series circuit, the semiconductor switch of any one of the two switching arms is turned on simultaneously with the first zero cross point in one cycle of the current, The semiconductor switch of the other arm is turned off, and after an arbitrary delay time shorter than the half cycle of the current has elapsed from the zero cross point after the half cycle of the current, the on / off state of the semiconductor switch is inverted,
A method for controlling a power feeding device, wherein a series of switching operations of each of the semiconductor switches is repeated in synchronization with a cycle of the current. In the control method of the power feeding device according to claim 1 or 2,
During the period when power supply from the outside to the coil is stopped, all the semiconductor switches are turned off, and when power supply is started, the zero crossing point of the current flowing through the coil is detected and then the switching of each semiconductor switch is performed. A method for controlling a power feeding device, characterized by performing an operation. In the control method of the power feeding device according to claim 1 or 2,
During the period when power supply from the outside to the coil is stopped, all the semiconductor switches are kept in the switching state immediately before the current flowing through the coil becomes zero due to the stop of power supply to the coil, and power supply to the coil is performed. A control method for a power feeding device, comprising: when started, performing a switching operation of each semiconductor switch after detecting a zero cross point of a current flowing through the coil.

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