JP6750999B2 - DC-DC converter and automobile - Google Patents

Description

The present invention relates to a DC-DC converter and an automobile.

BACKGROUND ART In recent years, with the background of exhaustion of fossil fuels and deterioration of global environmental problems, there is an increasing interest in vehicles using electric energy such as hybrid vehicles and electric vehicles.
A vehicle using such electric energy includes a motor for driving wheels and a high voltage battery for supplying electric power to the motor. The output voltage of the high-voltage battery is stepped down by a DC-DC converter, and a power supply system for supplying necessary power to low-voltage electric equipment is provided. Examples of low-voltage electrical equipment include air conditioners, audio systems, and automobile controllers.

A lithium ion battery is often used as the high voltage battery. However, when the voltage of the lithium-ion battery is not sufficiently low, the amount of current flowing through the high-voltage device including the DC-DC converter increases, which hinders downsizing and cost reduction of the high-voltage device. Patent Document 1 discloses a technique in which a booster circuit is provided between a high-voltage battery and a DC-DC converter to boost the voltage input to the DC-DC converter even when the voltage of the high-voltage battery is low. ing. According to this technology, an input voltage higher than the high-voltage battery voltage is applied to the DC-DC converter, so the amount of current flowing through the DC-DC converter is reduced, and the DC-DC converter becomes smaller and less expensive. It is possible to

JP, 2016-19322, A

In the technique of Patent Document 1, the number of circuit elements is increased by the amount of the added booster circuit, which hinders further size reduction and cost reduction.

A DC-DC converter according to the present invention is a DC-DC converter that performs voltage conversion of DC power supplied from a primary power source, in which a first switching element and a second switching element are connected in series via a first AC connection section. A first arm connected to the first arm, a bridge circuit having a second arm in which a third switching element and a fourth switching element are connected in series via a second AC connecting portion, the primary power source and the first arm. A booster circuit having an inductor connected between the AC connecting portions, a first capacitor connected in parallel to the first arm, and the first arm, one end of the booster circuit and the other end of the first AC connecting portion. A transformer having a primary winding connected to the second AC connecting portion, a secondary winding magnetically coupled to the primary winding, and a rectifier circuit connected to the secondary winding side of the transformer A control circuit for controlling each switching element of the first arm and the second arm, a first voltage detector for detecting a voltage value of the first capacitor, and a third capacitor connected in parallel with the primary power supply. And a third voltage detector that detects the voltage value of the third capacitor, the control circuit based on the voltage values detected by the first voltage detector and the third voltage detector, The ON time width of each switching element of the first arm and each switching element of the second arm is controlled.
A DC-DC converter according to the present invention is a DC-DC converter that performs voltage conversion of DC power supplied from a primary power source, in which a first switching element and a second switching element are connected in series via a first AC connection section. A first arm connected to the first arm, a bridge circuit having a second arm in which a third switching element and a fourth switching element are connected in series via a second AC connecting portion, the primary power source and the first arm. A booster circuit having an inductor connected between the AC connecting portions, a first capacitor connected in parallel to the first arm, and the first arm, one end of the booster circuit and the other end of the first AC connecting portion. A transformer having a primary winding connected to the second AC connecting portion, a secondary winding magnetically coupled to the primary winding, and a rectifier circuit connected to the secondary winding side of the transformer A control circuit for controlling each switching element of the first arm and the second arm, a first voltage detector for detecting a voltage value of the first capacitor, and a third capacitor connected in parallel with the primary power supply. And a third voltage detector that detects the voltage value of the third capacitor, the control circuit based on the voltage values detected by the first voltage detector and the third voltage detector, The phase difference of the ON time in each switching element of the second arm is controlled with respect to the ON time in each switching element of the first arm.
A DC-DC converter according to the present invention is a DC-DC converter that performs voltage conversion of DC power supplied from a primary power source, in which a first switching element and a second switching element are connected in series via a first AC connection section. A first arm connected to the first arm, a bridge circuit having a second arm in which a third switching element and a fourth switching element are connected in series via a second AC connecting portion, the primary power source and the first arm. A booster circuit having an inductor connected between the AC connecting portions, a first capacitor connected in parallel to the first arm, and the first arm, one end of the booster circuit and the other end of the first AC connecting portion. A transformer having a primary winding connected to the second AC connecting portion, a secondary winding magnetically coupled to the primary winding, and a rectifier circuit connected to the secondary winding side of the transformer , A control circuit for controlling each switching element of the first arm and the second arm, a first current detector for detecting a current value flowing in a primary winding of the transformer, and a current value flowing in the inductor And a third current detector that controls the switching element of the first arm and the third current detector based on the current values detected by the first current detector and the third current detector. The on-time width of each switching element of the two arms is controlled.
A DC-DC converter according to the present invention is a DC-DC converter that performs voltage conversion of DC power supplied from a primary power source, in which a first switching element and a second switching element are connected in series via a first AC connection section. A first arm connected to the first arm, a bridge circuit having a second arm in which a third switching element and a fourth switching element are connected in series via a second AC connecting portion, the primary power source and the first A booster circuit having an inductor connected between the AC connection parts, a first capacitor connected in parallel to the first arm, and the first arm, one end of the booster circuit and the other end of the first AC connection part. A transformer having a primary winding connected to the second AC connecting portion, a secondary winding magnetically coupled to the primary winding, and a rectifier circuit connected to the secondary winding side of the transformer. , A control circuit for controlling each switching element of the first arm and the second arm, a first current detector for detecting a current value flowing in a primary winding of the transformer, and a current value flowing in the inductor And a third current detector for controlling the ON time of each switching element of the first arm based on the current value detected by the first current detector and the third current detector. On the other hand, the phase difference of the ON time in each switching element of the second arm is controlled.
The motor vehicle according to the invention comprises a power supply system including a DC-DC converter.

According to the present invention, it is possible to provide a DC-DC converter that can be reduced in size and cost, and an automobile using the DC-DC converter.

FIG. 3 is a circuit configuration diagram of a DC-DC converter according to the first embodiment. (A) (b) (c) (d) It is a time chart which shows ON/OFF of the 1st switching element H1-4th switching element H4. It is a circuit configuration diagram of a DC-DC converter using a current detector. It is a circuit block diagram which shows the example in case a switching element is used for the rectifier circuit of a DC-DC converter. It is an operation explanatory view in phase A of a DC-DC converter. It is an operation explanatory view in phase B of a DC-DC converter. It is an operation explanatory view in phase C of a DC-DC converter. It is an operation explanatory view in phase D of a DC-DC converter. It is an operation explanatory view in phase E of a DC-DC converter. It is an operation explanatory view in phase F of a DC-DC converter. It is a figure which shows a power supply system when applying a DC-DC converter to a motor vehicle. It is a circuit configuration diagram of a power supply system in which a DC-DC converter is applied to an automobile.

(First embodiment)
Hereinafter, a first embodiment according to the present invention will be described with reference to the drawings.
FIG. 1 is a circuit configuration diagram of a DC-DC converter 101 according to the first embodiment. The DC-DC converter 101 in this embodiment is connected between the primary power supply V1 and the secondary power supply V2, and exchanges electric power between the primary power supply V1 and the secondary power supply V2. Both the primary power source V1 and the secondary power source V2 are direct current power sources, and each is composed of a secondary battery. Note that transmitting power from the primary power source V1 to the secondary power source V2 is referred to as forward power transmission. A load R1 is connected in parallel to the primary power supply V1, and a load R2 is connected in parallel to the secondary power supply V2.

As shown in FIG. 1, the third capacitor C3 is connected in parallel with the primary power supply V1. In addition, the primary power supply V1 is connected to a first AC connecting portion of a bridge circuit described later via the first inductor L1. The bridge circuit includes a first arm in which a first switching element H1 and a second switching element H2 are connected in series via a first AC connecting portion, and a second arm including a third switching element H3 and a fourth switching element H4. The second arm is connected in series via an AC connecting portion. A first capacitor C1 is connected in parallel with the first arm and the second arm.

Diodes DH1 to DH4 are connected in antiparallel to the first switching element H1 to the fourth switching element H4, respectively. When Si-MOSFET or SiC-MOSFET is used as the first switching element H1 to the fourth switching element H4, the body diode of the MOSFET can be used instead of the diodes DH1 to DH4.

The first AC connection part of the first arm is connected to one end of the primary winding N1 of the transformer 4 via the resonance inductor Lr, and the second AC connection part of the second arm is connected to the transformer 4 via the transformer capacitor Cr. Is connected to the other end of the primary winding N1. The transformer 4 magnetically couples the primary winding N1 and the secondary windings N21 and N22. Diodes DS1 and DS2 forming a rectifying circuit are connected to both ends of the secondary windings N21 and N22. The midpoint between the secondary windings N21 and N22 is connected to the secondary power supply V2 via the second inductor L2. A second capacitor C2 is connected in parallel with the secondary power supply V2 on the output side of the rectifier circuit.

A first voltage detector 21 that detects the voltage value Vc1 of the first capacitor C1 is connected to the connection point between the first arm and the second arm. A third voltage detector 23 that detects the voltage value Vc3 of the third capacitor C3 is connected to the connection point between the first inductor L1 and the primary power supply V1.

The first voltage detector 21 and the third voltage detector 23 are connected to the control circuit 40. The control circuit 40 controls each switching element of the first arm and the second arm based on the voltage value detected by each voltage detector, as described later. A second voltage detector that detects the voltage value Vc2 of the second capacitor C2 is connected to the connection point between the second inductor L2 and the secondary power supply V2, and the control circuit 40 detects the second voltage detector. The switching elements of the first arm and the second arm may be controlled based on the voltage value Vc2, as described later.

In forward power transmission in which electric power is transmitted from the primary power source V1 to the secondary power source V2, the control circuit 40 controls each of the switching elements H1 to H4 of the bridge circuit to which the primary power source V1 that is a DC power source is applied, and the control circuit 1 AC voltage is applied to the next winding N1. In this case, the voltage applied to the first capacitor C1 is higher than the voltage of the primary power supply V1 by the booster circuit including the first inductor L1, the first capacitor C1, and the first arm. Then, the induced voltage generated in the secondary windings N21 and N22 of the transformer 4 is rectified by the rectifier circuit, and power is supplied to the secondary power source V2. In this way, by sharing the booster circuit and the switching element of the DC-DC converter, it is possible to reduce the size and cost of the circuit.
The control circuit 40 includes a cycle control circuit 41, a cycle limiting circuit 42, a phase difference control circuit 43, and a phase difference limiting circuit 44.
The voltage value Vc3 is input from the third voltage detector 23 to the cycle control circuit 41, and the voltage value Vc1 of the first capacitor C1 is adjusted to a desired voltage value from a host controller or control circuit 40 (not shown). The voltage command value Vc1_ref for inputting is input. The cycle control circuit 41 calculates the cycle time width τ1 of the first switching element H1 and the cycle time width τ2 of the second switching element H2 by the following equations (1) and (2).
τ1 = (Vc3/Vc1_ref) x T (1)
τ2 = (1-Vc3/Vc1_ref) x T (2)
Here, T is the time of one cycle in which the first switching element H1 and the second switching element H2 are repeatedly turned on and off.

FIG. 2A is a time chart showing an example of ON/OFF of the first switching element H1 to the fourth switching element H4 during forward power transmission of the DC-DC converter 101. As shown in this figure, the cycle time width τ1 is the time during which the first switching element H1 is on in one cycle T, and the cycle time width τ2 is the time during which the second switching element H2 is on. Is. The cycle time width τ1 is equal to the time when the third switching element H3 is on, and the cycle time width τ2 is equal to the time when the fourth switching element H4 is on.

Returning to the description of the control circuit 40 in FIG. 1, the cycle time widths τ1 and τ2 calculated by the cycle control circuit 41 are input to the cycle limiting circuit 42. Further, a time width limit value τ_limit is input to the cycle limiting circuit 42, and limits the cycle time widths τ1 and τ2 so as not to exceed the time width limit value τ_limit. This is to prevent an overvoltage from being applied to the switching element or the like due to the cycle time widths τ1 and τ2 increasing beyond the time width limit value τ_limit. The control circuit 40 controls ON/OFF of the first switching element H1 to the fourth switching element H4 based on the cycle time widths τ1 and τ2 output from the cycle limiting circuit 42, as shown in FIG. As a result, the voltage value Vc1 of the first capacitor C1 is adjusted to match the voltage command value Vc1_ref.

The voltage value Vc1 is input from the first voltage detector 21 to the phase difference control circuit 43, and the voltage value Vc2 of the second capacitor C2 is set to a desired voltage value from a host controller or control circuit 40 (not shown). The voltage command value Vc2_ref for adjustment is input. The phase difference control circuit 43 calculates the phase difference (superimposed time width) φ1 between the first switching element H1 and the fourth switching element H4 and the second switching element H2 and the third switching element H3 by the following equation (3). Calculate the phase difference (superimposition time width) φ2.
φ1=φ2=(Vc2_ref/Vc1)×T×N (3)
Here, N is the winding ratio of the transformer 4, and N=(N21+N22)/N1.

As shown in FIG. 2A, the phase difference φ1 is the time when the first switching element H1 is on and the time when the fourth switching element H4 is on, and the phase difference φ2 is , The time when the second switching element H2 is on and the time when the third switching element H3 is on overlap. This time overlap occurs because the phases of the on/off cycles of the first switching element H1 and the fourth switching element H4 and the on/off cycle of the second switching element H2 and the third switching element H3 are different.

Returning to the explanation of the control circuit 40 in FIG. 1, the phase differences φ1 and φ2 calculated by the phase difference control circuit 43 are input to the phase difference limiting circuit 44. The phase difference limiting circuit 44 further receives a phase difference limiting value φ_limit, and limits the phase difference φ1 and φ2 so that the phase difference limiting value φ_limit does not exceed the phase difference limiting value φ_limit. This is to limit the phase differences φ1 and φ2 so as not to exceed the period time widths τ1 and τ2. The control circuit 40 controls ON/OFF of the first switching element H1 to the fourth switching element H4 based on the phase differences φ1 and φ2 output from the phase difference limiting circuit 44, as shown in FIG. As a result, the voltage value Vc2 of the second capacitor C2 is adjusted to match the voltage command value Vc2_ref.

The output power of the DC-DC converter 101 is determined by the voltage-time product of the primary winding N1 of the transformer 4. Therefore, the phase difference between the ON times of the first switching element H1 and the fourth switching element H4 (superposition time width) φ1 or the phase difference between the ON times of the second switching element H2 and the third switching element H3 (superposition time width) φ2 is When the cycle time width τ1 of the first switching element H1 and the third switching element H3 and the cycle time width τ2 of the second switching element H2 and the fourth switching element H4 are equal to the smaller cycle time width, the DC-DC converter 101 The maximum output is obtained (see FIG. 2B described later). When the phase difference exceeds the maximum value, the output power of the DC-DC converter 101 does not increase even if the phase difference is increased. Therefore, the phase difference is limited by the phase difference limit value φ_limit.

The on-time phase difference (superposition time width) φ1 between the first switching element H1 and the fourth switching element H4 and the on-time phase difference (superposition time width) φ2 between the second switching element H2 and the third switching element H3 are It is equal to the time width of the voltage applied to the primary winding N1 of the transformer 4 for each polarity. When the time widths φ1 and φ2 of the voltage applied to the primary winding N1 of the transformer 4 are different, the voltage-time product of the primary winding N1 of the transformer 4 is different depending on the polarity. May cause saturation. Therefore, the on-time phase difference φ1 between the first switching element H1 and the fourth switching element H4 and the on-time phase difference φ2 between the second switching element H2 and the third switching element H3 are controlled to be equal. .. If there is no problem even if the voltage-time product of the primary winding N1 of the transformer 4 differs depending on the polarity due to the influence of disturbance, etc., the phase difference φ1 between the ON times of the first switching element H1 and the fourth switching element H4, The phase difference φ2 between the ON times of the second switching element H2 and the third switching element H3 does not necessarily have to be equal.

FIG. 2B is a time chart showing ON/OFF of the first switching element H1 to the fourth switching element H4 when the output of the DC-DC converter 101 is maximized. In this case, as the voltage command value Vc2_ref, a command value that maximizes the voltage value Vc2 is input to the phase difference control circuit 43. If the phase differences φ1 and φ2 exceed the phase difference limit value φ_limit, the phase differences φ1 and φ2 are limited so as not to exceed the cycle time widths τ1 and τ2. The control circuit 40 controls ON/OFF of the first switching element H1 to the fourth switching element H4 based on the phase differences φ1 and φ2 output from the phase difference limiting circuit 44, as shown in FIG. 2B.

FIG. 2C is a time chart showing ON/OFF of the first to fourth switching elements H1 to H4 when the output of the DC-DC converter 101 is minimized. In this case, as the voltage command value Vc2_ref, a command value that minimizes the voltage value Vc2, that is, 0V is input to the phase difference control circuit 43. The control circuit 40 controls ON/OFF of the first switching element H1 to the fourth switching element H4 based on the phase differences φ1 and φ2 output from the phase difference limiting circuit 44, as shown in FIG. 2C. In this case, as shown in FIG. 2C, the phase differences φ1 and φ2 are zero.

In the time chart shown in FIG. 2A, the cycle time width τ1 of the first switching element H1 and the third switching element H3 of the DC-DC converter 101 is the cycle time width of the second switching element H2 and the fourth switching element H4. This is the case when it is smaller than τ2. In this case, the on-time phase difference φ1 between the first switching element H1 and the fourth switching element H4 and the on-time phase difference φ2 between the second switching element H2 and the third switching element H3 are the same as those of the DC-DC converter 101. The value is less than or equal to the cycle time width τ1 of the first switching element H1 and the third switching element H3, and has the relationship of the following expression (4). Under the condition shown by the equation (4), the voltage value Vc1 is larger than twice the voltage value Vc3.
τ2 >τ1 ≧φ1, φ2 (4)

In the time chart shown in FIG. 2D, the cycle time width τ1 of the first switching element H1 and the third switching element H3 of the DC-DC converter 101 is the cycle time width τ1 of the second switching element H2 and the fourth switching element H4. It is the case of τ2 or more. This is realized by inputting a desired voltage command value Vc1_ref to the cycle control circuit 41. In this case, the phase difference φ1 between the first switching element H1 and the fourth switching element H4 and the phase difference φ2 between the second switching element H2 and the third switching element H3 are the same as the second switching element H2 and the second switching element H2 of the DC-DC converter 101. The value becomes equal to or less than the cycle time width τ1 of the 4-switching element H4, and the relationship of the following equation (5) is established. Under the condition represented by the equation (5), the voltage value Vc1 is 1 to 2 times or less the voltage value Vc3.
τ1 ≧τ2 ≧φ1, φ2 (5)

In the present embodiment, an example has been described in which the first voltage detector 21 that detects the voltage value Vc1 of the first capacitor C1 and the third voltage detector 23 that detects the voltage value Vc3 of the third capacitor C3 are provided. Then, the control circuit 40 controls each switching element of the first arm and the second arm based on the voltage value Vc3 and the voltage command value Vc1_ref and the voltage value Vc1 and the voltage command value Vc2_ref. However, this is an example, and other voltage values such as a second voltage detector for detecting the voltage value Vc2 of the second capacitor C2 and the voltage command value can be appropriately combined and used.

For example, the voltage command value Vc3_ref for adjusting the voltage value Vc1 and the voltage value Vc3 of the third capacitor C3 to a desired voltage value is input to the cycle control circuit 41, and the first equation is calculated by the following equations (6) and (7). The cycle time width τ1 of the switching element H1 and the cycle time width τ2 of the second switching element H2 are calculated.
τ1=(Vc3_ref/Vc1)×T (6)
τ2=(1-Vc3_ref/Vc1)×T (7)

Further, for example, the voltage value Vc2 and the voltage command value Vc1_ref are input to the phase difference control circuit 43, and the phase difference (superposition time width) between the first switching element H1 and the fourth switching element H4 is calculated by the following equation (8). φ1, and the phase difference (superposition time width) φ2 between the second switching element H2 and the third switching element H3 is calculated.
φ1=φ2=(Vc2/Vc1_ref)×T×N (8)
Here, N is the winding ratio of the transformer 4, and N=(N21+N22)/N1.

FIG. 3 is a circuit configuration diagram of a DC-DC converter 101 using a current detector instead of the voltage detector. The same parts as those in FIG. Further, details of the control circuit 40 are omitted from the drawing.
In this example, a current detector is provided to control the switching elements H1 to H4 of the first arm and the second arm based on the detected current value. As shown in FIG. 3, a first current detector 31 for detecting a current value Ic1 flowing through the primary winding N1 of the transformer 4 is provided. Further, a second current detector 32 for detecting a current value Ic2 flowing through the secondary windings N21 and N22 of the transformer 4 is provided. Further, a third current detector 33 for detecting the current value Ic3 flowing through the first inductor L1 is provided. Then, the control circuit 40 obtains the cycle time widths τ1 and τ2 and the phase differences φ1 and φ2 from the following equations (9) to (11).
τ1 = (Ic1_ref /Ic3) × T (9)
τ2=(1-Ic1_ref/Ic3)×T (10)
φ1=φ2=(Ic1/Ic2_ref)×T×N (11)
Here, Ic1_ref is a current command value of a current to be supplied to the primary winding N1 of the transformer 4, and Ic2_ref is a current command value to be supplied to the secondary windings N21 and N22 of the transformer 4.
The control circuit 40 may appropriately use the above voltage detector and current detector in a mixed manner. Furthermore, some of the voltage detectors or current detectors may be used instead of all.

FIG. 4 is a circuit configuration diagram showing an example in which a switching element is used in the rectifier circuit of the DC-DC converter 101. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. Further, details of the control circuit 40 are omitted from the drawing.
In FIG. 1, the rectifier circuit is composed of diodes DS1 and DS2. In FIG. 4, the switching element S1 and the switching element S2, and the diode DS1 and the diode DS2 are used as the rectifier circuit. When MOSFETs are used as the switching elements S1 and S2, if the switching element S1 is turned on, the current flowing through the diode DS1 is divided into the switching element S1 to reduce the loss. In this way, when the forward current of the diode flows through the diode that is connected in anti-parallel with the MOSFET or the body diode of the MOSFET, turning on this MOSFET to reduce the loss is hereinafter referred to as synchronous rectification. The control circuit 40 performs a synchronous rectification operation for rectifying the switching elements S1 and S2. In addition, the rectifier circuit after the secondary windings N21 and N22 is not limited to the center tap rectifier circuit method, but it is also a combination of a current source center tap circuit with active clamp, a surge absorption circuit, a current doubler circuit, and a current source full bridge circuit. But it's okay.

5 to 10 are operation explanatory diagrams of the DC-DC converter 101 in FIG. 1 during forward power transmission. Each of FIGS. 5 to 10 corresponds to phases A to F of the operation of each of the switching elements H1 to H4 shown in FIG. 2D.
In Phase A, as shown in FIG. 5, the first switching element H1 is in the ON state, the voltage of the primary power source V1 is not applied to the first inductor L1, and the energy of the first inductor L1 is released. Further, the energy of the primary power source V1 is stored in the first capacitor C1. Further, the fourth switching element H4 is in the ON state, the voltage of the primary power source V1 is applied to the primary winding N1 of the transformer 4, and the current of the resonant inductor Lr increases. The current flowing through the first capacitor C1 decreases, and when it reaches zero, the phase B is entered.

In phase B, as shown in FIG. 6, the first switching element H1 is in the ON state, the voltage of the primary power source V1 is not applied to the first inductor L1, and the energy of the first inductor L1 is released. Energy is also released from the first capacitor C1. Further, the fourth switching element H4 is in the ON state, the voltage of the primary power source V1 is applied to the primary winding N1 of the transformer 4, and the current of the resonant inductor Lr increases. When the fourth switching element H4 is turned off and the third switching element H3 is turned on, the phase C is entered.

In phase C, as shown in FIG. 7, the first switching element H1 is in the ON state, the voltage of the primary power source V1 is not applied to the first inductor L1, and the energy of the first inductor L1 is released. Further, the third switching element H3 is in the ON state, and energy is stored in the first capacitor C1. Further, since the voltage of the primary power source V1 is not applied to the primary winding N1 of the transformer 4, the current of the resonance inductor Lr decreases. When the current of the resonance inductor Lr decreases and becomes zero, the phase D is entered.

In phase D, as shown in FIG. 8, the first switching element H1 is in the ON state, the voltage of the primary power supply V1 is not applied to the first inductor L1, and the energy of the first inductor L1 is released. In addition, the third switching element H3 is in the ON state, and the energy of the first capacitor C1 is released. When the first switching element H1 is turned off and the second switching element H2 is turned on, the phase E is entered.

In Phase E, as shown in FIG. 9, the second switching element H2 is in the ON state, the voltage of the primary power source V1 is applied to the first inductor L1, and energy is stored in the first inductor L1. In addition, the third switching element H3 is in the ON state, and the energy of the first capacitor C1 is released. Further, since the voltage of the primary power source V1 is applied to the primary winding N1 of the transformer 4, the current of the resonant inductor Lr increases. When the third switching element H3 is turned off and the fourth switching element H4 is turned on, the phase F is entered.

In phase F, as shown in FIG. 10, the second switching element H2 is in the ON state, the voltage of the primary power source V1 is applied to the first inductor L1, and energy is stored in the first inductor L1. In addition, the fourth switching element H4 is in the ON state, and the energy of the first capacitor C1 is released. Further, since the voltage of the primary power source V1 is not applied to the primary winding N1 of the transformer 4, the current of the resonance inductor Lr decreases. When the second switching element H2 is turned off and the first switching element H1 is turned on, the phase A is entered. The subsequent operation is the repetition of Phase A to Phase F.

According to this embodiment, the voltage applied to the DC-DC converter 101 can be boosted to control the input voltage range, and the booster circuit and the switching element of the DC-DC converter are shared. As a result, the circuit can be downsized and the cost can be reduced.

(Second embodiment)
FIG. 11 is a diagram showing a power supply system when the DC-DC converter 101 shown in the first embodiment is applied to an automobile 100.
In the power supply system of the present embodiment, when the charger side of the DC-DC converter 101 is the C side, the high voltage side is the D side, and the low voltage side is the E side, the high voltage battery 104 is on the D side of the DC-DC converter 101. It is connected via the relay 106. The low voltage battery 105 is connected to the E side of the DC-DC converter 101. Charger 108 that transmits the electric power from external power supply 109 to automobile 100 is connected to the C side of DC-DC converter 101.

The motor M is connected to the HV system device 102 such as a motor drive inverter, and the HV system device 102 is connected to the D side of the DC-DC converter 101. Auxiliary equipment 103 such as an air conditioner is connected to the E side of DC-DC converter 101. The control circuit 401 controls the switching operation of each of the switching elements H1 to H4 of the DC-DC converter 101, the power transmission direction of power, the amount of power, and the like. The relay 106 may be omitted.

FIG. 12 is a circuit configuration diagram of the power supply system according to the present embodiment.
Since the circuit configuration of the DC-DC converter 101 is the same as that of the first embodiment, the same parts are designated by the same reference numerals and the description thereof will be omitted. The charger 108 includes an AC-DC converter 51 that converts an AC voltage input from the external power supply 109 into a DC voltage. A switching circuit 52 is connected to the output side of the AC-DC converter 51 via a fourth smoothing capacitor C4. The switching circuit 52 is composed of a bridge circuit composed of four switching elements, and converts the DC voltage into an AC voltage under the control of the control circuit 401. The switching circuit 52 is connected to the primary winding side of the transformer 53, and the rectifying circuit 54 is connected to the secondary winding side of the transformer 53. The output of the rectifier circuit 54 is connected to both ends of the first capacitor C1 of the DC-DC converter 101.

The AC-DC converter 51 may have a circuit configuration in which a bridge rectifier circuit and a boost chopper are combined, or a circuit configuration in which an AC voltage is a DC voltage, such as a totem pole circuit. If the external power supply 109 is a DC power supply, the AC-DC converter 51 can be omitted. The switching circuit 52 may have a circuit configuration for converting a DC voltage into an AC voltage, such as a half bridge circuit, a full bridge circuit, or a resonance circuit. The rectifier circuit 54 may have a circuit configuration such as a diode rectifier, a synchronous rectifier, a center tap circuit, a current doubler system, or the like that converts an AC voltage into a DC voltage.

As shown in FIG. 12, the switching time ratio of the first switching element H1 and the second switching element H2, which is the first arm of the DC-DC converter 101 and is the step-down circuit A′, and the third switching which is the second arm. In order to control the switching time ratio of the device H3 and the fourth switching device H4, the voltage Vc3 of the third capacitor C3 is detected by the third voltage detector 23. The detected voltage Vc3 is input to the cycle control circuit 41 of the control circuit 401 together with the target voltage command value Vc1_ref of the first capacitor C1, and the cycle time width τ1 of the first switching element H1 and the third switching element H3, The cycle time width τ2 of the second switching element H2 and the fourth switching element H4 is calculated. The operations of the cycle control circuit 41 and the cycle limiting circuit 42 are the same as those in the first embodiment, and the description thereof will be omitted.

In FIG. 12, the first voltage detector 21 detects the voltage value Vc1 of the first capacitor C1. The detected voltage value Vc1 is input to the phase difference control circuit 43 together with the target voltage command value Vc2_ref of the second capacitor C2, and the phase difference φ1 between the first switching element H1 and the fourth switching element H4 and the second switching The phase difference φ2 between the element H2 and the third switching element H3 is calculated. The operations of the phase difference control circuit 43 and the phase difference limiting circuit 44 are the same as those in the first embodiment, and the description thereof will be omitted.

In FIG. 12, the fourth voltage detector 24 detects the voltage value Vc4 of the fourth capacitor C4. The detected voltage value Vc4 is input to the switching control circuit 45 together with the target voltage command value Vc1_ref applied to the DC-DC converter 101, and the control amount α of the switching circuit 52 is calculated. The voltage command value Vc1_ref is input as a command value for designating the voltage value Vc1 of the first capacitor C1 in the DC-DC converter 101 to a desired voltage value from a host controller or control circuit 40 (not shown). The control amount α calculated by the switching control circuit 45 is compared with the maximum control amount α_limit of the predetermined switching circuit 52 by the switching limit circuit 46. When the calculated control amount α does not exceed the maximum control amount α_limit, the switching control circuit 45 outputs the calculated control amount α. When the calculated control amount α exceeds a predetermined maximum control amount α_limit, the switching limiting circuit 46 outputs the maximum control amount α_limit as the control amount α. The amount of electric power is limited by the maximum control amount α_limit. The control circuit 401 controls the switching circuit 52 based on the control amount α so that the voltage applied to the DC-DC converter 101 becomes the voltage command value Vc1_ref. In this way, by suppressing the output voltage of the rectifier circuit 54, which is the output side of the charger 108, within the output voltage range based on the control amount α, it is possible to increase the degree of freedom in designing the charger 108.

Although the control circuit 401 detects the voltage value Vc4 of the fourth capacitor C4 by the fourth voltage detector 24, the current value is detected by detecting the current value flowing to the input side of the switching circuit 52 by the current detector. You may control using it.

According to this embodiment, the power of the external power supply 109 can be sent from the charger 108 to the DC power supply 104 and the DC power supply 105 via the DC-DC converter 101. In this case, it is possible to suppress the voltage range applied to the DC-DC converter 101, and by sharing the step-down circuit A′ and the switching element of the DC-DC converter 101, it is possible to reduce the size of the power supply system. Therefore, cost reduction can be achieved.

According to the embodiment described above, the following operational effects can be obtained.
(1) The DC-DC converter 101 is a DC-DC converter 101 that converts the voltage of the DC power supplied from the primary power source V1, and the first switching element H1 and the second switching element H2 are connected by a first AC connection. A bridge circuit having a first arm connected in series via a section and a second arm in which a third switching element H3 and a fourth switching element H4 are connected in series via a second AC connection section, A booster circuit having an inductor L1 connected between the primary power source V1 and a first AC connection portion, a first capacitor C1 connected in parallel with the first arm, and a first arm, and one end having a first AC connection And a transformer having a primary winding N1 whose other end is connected to the second AC connecting portion, and secondary windings N21 and N22 magnetically coupled to the primary winding N1, and a secondary winding side of the transformer. A rectifier circuit connected to N21 and N22, and a control circuit 40 for controlling each switching element of the first arm and the second arm are provided. As a result, it is possible to provide a DC-DC converter that can be reduced in size and cost.
The vehicle has a power supply system including a DC-DC converter. As a result, it is possible to provide a DC-DC converter that can be reduced in size and cost, and an automobile using the DC-DC converter.

The present invention is not limited to the above-described embodiment, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention as long as the characteristics of the present invention are not impaired. ..

101 DC-DC converter
V1 primary power supply
V2 secondary power supply
R1, R2 load
L1 1st inductor
L2 Second inductor
H1 First switching element
H2 Second switching element
H3 Third switching element
H4 4th switching element
C1 first capacitor
C2 Second capacitor
C3 3rd capacitor
C4 4th capacitor 4 transformer
DS1, DS2 diode
21 1st voltage detector
23 Third voltage detector
40 control circuit
41 Period control circuit
42 Cycle limit circuit
43 Phase difference control circuit
44 Phase difference limiting circuit
100 cars
104 high voltage battery
105 low voltage battery
108 charger
109 External power supply system
401 control circuit

Claims (13)

A DC-DC converter for converting the voltage of DC power supplied from a primary power supply,
A first arm in which a first switching element and a second switching element are connected in series via a first AC connection section, and a third arm and a fourth switching element in series via a second AC connection section A bridge circuit having a second arm connected thereto,
A booster circuit including an inductor connected between the primary power supply and the first AC connection unit, a first capacitor connected in parallel to the first arm, and the first arm;
A transformer having a primary winding whose one end is connected to the first AC connecting portion and the other end being connected to the second AC connecting portion, and a secondary winding which is magnetically coupled to the primary winding,
A rectifier circuit connected to the secondary winding side of the transformer,
A control circuit for controlling each switching element of the first arm and the second arm;
A first voltage detector for detecting a voltage value of the first capacitor;
A third capacitor connected in parallel with the primary power supply,
A third voltage detector for detecting a voltage value of the third capacitor,
The control circuit, based on the voltage values detected by the first voltage detector and the third voltage detector, the ON time width of each switching element of the first arm and each switching element of the second arm. DC-DC converter to control the . In the DC-DC converter according to claim 1 ,
The control circuit, based on the voltage values detected by the first voltage detector and the third voltage detector, with respect to the ON time in each switching element of the first arm, each switching element of the second arm. -DC converter that controls the phase difference of on-time at. A DC-DC converter for converting the voltage of DC power supplied from a primary power supply,
A first arm in which a first switching element and a second switching element are connected in series via a first AC connection section, and a third arm and a fourth switching element in series via a second AC connection section A bridge circuit having a second arm connected thereto,
A booster circuit having an inductor connected between the primary power supply and the first AC connection section, a first capacitor connected in parallel to the first arm, and the first arm,
A transformer having a primary winding whose one end is connected to the first AC connecting portion and the other end being connected to the second AC connecting portion; and a secondary winding which is magnetically coupled to the primary winding.
A rectifier circuit connected to the secondary winding side of the transformer,
A control circuit for controlling each switching element of the first arm and the second arm;
A first voltage detector for detecting a voltage value of the first capacitor;
A third capacitor connected in parallel with the primary power supply,
A third voltage detector for detecting a voltage value of the third capacitor,
The control circuit, based on the voltage values detected by the first voltage detector and the third voltage detector, with respect to the ON time in each switching element of the first arm, each switching element of the second arm. -DC converter that controls the phase difference of on-time at. A DC-DC converter for converting the voltage of DC power supplied from a primary power supply,
A first arm in which a first switching element and a second switching element are connected in series via a first AC connection section, and a third arm and a fourth switching element in series via a second AC connection section A bridge circuit having a second arm connected thereto,
A booster circuit having an inductor connected between the primary power supply and the first AC connection section, a first capacitor connected in parallel to the first arm, and the first arm,
A transformer having a primary winding whose one end is connected to the first AC connecting portion and the other end being connected to the second AC connecting portion; and a secondary winding which is magnetically coupled to the primary winding.
A rectifier circuit connected to the secondary winding side of the transformer,
A control circuit for controlling each switching element of the first arm and the second arm;
A first current detector for detecting a current value flowing in the primary winding of the transformer;
A third current detector for detecting a value of a current flowing through the inductor,
The control circuit, based on the current value detected by the first current detector and the third current detector, the ON time width of each switching element of the first arm and each switching element of the second arm. DC-DC converter to control the. The DC-DC converter according to claim 4 ,
The control circuit, based on the current value detected by the first current detector and the third current detector, with respect to the ON time in each switching element of the first arm, each switching element of the second arm. -DC converter that controls the phase difference of on-time at. A DC-DC converter for converting the voltage of DC power supplied from a primary power supply,
A first arm in which a first switching element and a second switching element are connected in series via a first AC connection section, and a third arm and a fourth switching element in series via a second AC connection section A bridge circuit having a second arm connected thereto,
A booster circuit having an inductor connected between the primary power supply and the first AC connection section, a first capacitor connected in parallel to the first arm, and the first arm,
A transformer having a primary winding whose one end is connected to the first AC connecting portion and the other end being connected to the second AC connecting portion; and a secondary winding which is magnetically coupled to the primary winding.
A rectifier circuit connected to the secondary winding side of the transformer,
A control circuit for controlling each switching element of the first arm and the second arm;
A first current detector for detecting a current value flowing in the primary winding of the transformer;
A third current detector for detecting a value of a current flowing through the inductor,
The control circuit, based on the current value detected by the first current detector and the third current detector, with respect to the ON time in each switching element of the first arm, each switching element of the second arm. -DC converter that controls the phase difference of on-time at. The DC-DC converter according to claim 2, 3, 5 or 6 ,
The DC-DC converter wherein the ON time width of the switching element of the first arm is equal to or more than the superposition time width of the ON time width of the switching element of the first arm and the ON time width of the switching element of the second arm. An automobile provided with a power supply system including the DC-DC converter according to any one of claims 1 to 7 . In the vehicle according to claim 8 ,
An automobile in which electric power from an external power supply is input to the bridge circuit of the DC-DC converter and a charger for charging the primary power supply is connected in parallel. In the vehicle according to claim 9 ,
The vehicle includes an AC-DC converter, a DC-AC converter, a charger transformer, and a charger rectifier circuit, and supplies electric power from the AC external power supply. The vehicle according to claim 10 ,
A smoothing capacitor is provided on the input side of the DC-AC converter,
The control circuit controls the switching element of the DC-AC converter of the charger based on the voltage value of the smoothing capacitor. In the vehicle according to any one of claims 9 to 11 ,
The charger includes a DC-AC converter, a transformer for the charger, and a rectifier circuit for the charger, and supplies electric power from the DC external power supply. The vehicle according to claim 12 ,
The control circuit controls a switching element of the DC-AC converter of the charger based on a voltage value of the first capacitor.

Images