JP4299570B2 - Power supply device and method of operating power supply device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to the technology of a power supply device, and more particularly to the technical field of a buck-boost power supply device.
[0002]
[Prior art]
Reference numeral 102 in FIG. 7 indicates a general buck-boost type power supply device.
The power supply apparatus 102 includes a choke coil 105, first and second switching elements 111 and 112, and first and second rectifying elements 113 and 114.
[0003]
Reference numeral 130 denotes a current source, and reference numeral 131 denotes an input terminal to which a positive voltage is input from the current source 130. Reference numeral 132 denotes a ground terminal connected to the ground potential.
[0004]
Reference numerals 141 and 142 denote terminals of the power supply apparatus 102. Among them, reference numeral 141 denotes an output terminal from which a positive voltage is output, and reference numeral 142 is electrically the same as the ground terminal 132 of the power supply apparatus 102. The ground terminal which is a part is shown.
[0005]
One end 151 of the choke coil 105 is connected to the input terminal 131 via the first switching element 111, and is connected to the ground terminals 132 and 142 via the first rectifying element 113.
[0006]
The other end 152 of the choke coil 105 is connected to the output terminal 141 via the second rectifying element 114 and is connected to the ground terminals 132 and 142 via the second switching element 112.
[0007]
A chargeable / dischargeable storage battery 140 is connected between the output terminal 141 and the ground terminal 142.
[0008]
In the power supply device 102, the control circuit 116 inputs the same signal to the first switching element 111 and the second switching element 112, and the switching operations of the first switching element 111 and the second switching element 112 are synchronized. is doing.
[0009]
When the first and second switching elements 111 and 112 are conducted together, current flows through the switching elements 111 and 112 and the choke coil 105, and energy is accumulated in the choke coil 105.
[0010]
When the first and second switching elements 111 and 112 are cut off together, an electromotive force is generated in the choke coil 105, and a current flows through the first and second rectifying elements 113 and 114. The current is supplied to the storage battery 140.
[0011]
When the voltage at the output terminal 141 is lower than the voltage at the input terminal 131, the power supply apparatus 102 as described above automatically steps down the voltage at the input terminal 131 and charges the storage battery 140. Conversely, when the voltage at the output terminal 141 is higher than the voltage at the input terminal 131, the voltage at the input terminal 131 is automatically boosted and the storage battery 140 is charged.
[0012]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-42550 [Patent Document 2]
JP-A-5-328712 [Patent Document 3]
Japanese Utility Model Publication No. 6-70486 [0013]
[Problems to be solved by the invention]
However, in the power supply device 102 configured as described above, the current supplied from the current source 130 to the storage battery 140 is the first and second switching elements 111, 112 during the conduction period of the first and second switching elements 111, 112. 112, and then flows through both the first and second rectifying elements 113 and 114 during the shut-off period of the first and second switching elements 111 and 112. Therefore, there is a problem that the loss occurs in the two switching elements 111 and 112 during the half period of one cycle and the loss occurs in the two rectifying elements 113 and 114 during the remaining half period, resulting in low efficiency.
The present invention has been created to solve the above-described disadvantages of the prior art, and an object thereof is to provide an efficient step-up / down power supply.
[0014]
[Means for Solving the Problems]
In order to solve the above problems, the invention according to claim 1 is a switching operation of the choke coil, the first switching element, the second switching element, the first switching element, and the second switching element. Control circuit, and when one of the high voltage side terminal and the low voltage side terminal of the current source is an input terminal and the other is a ground terminal, the first terminal of the choke coil is The first switching element is connected to the input terminal, and the first rectifying element is connected to the ground terminal, and the second terminal of the choke coil is connected to the second switching element. A power supply device connected to the ground terminal via the second rectifier element and connected to the output terminal to which the load is to be connected, wherein the control circuit cuts off the conduction signal The first and second switching elements are turned on when the conduction signal is input, and are cut off when the cutoff signal is input. The connection between the control circuit and the second switching element In between, the power supply device is provided with a delay circuit for delaying only the transmission of the conduction signal to the second switching element for a set delay time.
The invention according to claim 2 includes a choke coil, a first switching element, a second switching element, and a control circuit for switching the first switching element and the second switching element, When one of the high-voltage side terminal and the low-voltage side terminal of the current source is an input terminal and the other is a ground terminal, the first terminal of the choke coil is The input terminal is connected to the ground terminal by a first rectifier element, the second terminal of the choke coil is connected to the ground terminal by the second switching element, and the second terminal An operation method of a power supply apparatus for operating a power supply apparatus connected to an output terminal by a rectifying element, wherein the first switching element is conductive and the second switch A first period in which the switching element is cut off, a second period after the first period and the first and second switching elements are conductive, and a second period after the second period. The first period and the third period during which the second switching element is cut off are repeated after the third period during the first period, and the storage battery as the load connected to the output terminal is charged. It is the operating method of a power supply device.
The invention according to claim 3 is the operation method of the power supply device according to claim 2, wherein the voltage of the output terminal is higher than the input voltage from a state where the voltage is lower than the input voltage supplied from the current source. It is the operating method of the power supply device which charges the said storage battery until it reaches | attains.
The invention according to claim 4 is the method for operating the power supply device according to claim 2 or 3, wherein the current supplied to the storage battery is measured, and the first and second switching devices are measured. This is a method of operating a power supply device in which the duty ratio between the conduction period and the cutoff period of the element is such that the current supplied to the storage battery becomes a constant current.
[0015]
The present invention is configured as described above. When the first and second switching elements are turned on, energy is stored in the choke coil, and when the first and second switching elements are cut off, An electromotive force is generated. Then, the first and second rectifying elements are forward-biased by the electromotive force of the choke coil, whereby current is output from the output terminal to the load.
[0016]
Accordingly, the current supplied from the current source is first lost when the energy is stored in the choke coil, and then the current is output by the electromotive force of the choke coil. Sometimes, loss occurs in the first and second rectifying elements.
[0017]
In the present invention, when the voltage of the output terminal is lower than the voltage of the input terminal, the second switching element is turned on when the first switching element is turned off and turned on while the second switching element is turned off. Until the current is supplied directly from the current source to the load. Therefore, the loss during this period is small and the efficiency is high.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Reference numeral 2 in FIG. 1 indicates a power supply device according to an example of the present invention.
The power supply device 2 includes first and second switching elements Q ₁ and Q ₂ , first and second rectifying elements D ₁ and D _2, and a choke coil L.
[0019]
Reference numeral 30 in the figure denotes a current source. The current source 30 is connected between the ground terminal 32 and the input terminal 31 of the power supply device 2 and is configured to supply a direct current to the input terminal 31.
[0020]
Reference numeral 42 denotes a terminal of the power supply device 2, which indicates a ground terminal having the same potential as the ground terminal 32 of the current source 30. Reference numeral 41 denotes the ground terminal 32, 42 as a reference. The output terminal from which a positive voltage or a negative voltage is output is shown. Here, the current source 30 is a DC power supply with a positive voltage output, a positive voltage is input from the current source 30 to the input terminal 31, and the power supply device 2 is configured to output a positive voltage to the output terminal 41. Has been.
[0021]
Choke coil L, first, has a second connection terminals 51 and 52, the first connection terminal 51 is connected to a first input terminal 31 via the switching element Q _1, the One rectifier element D ₁ is connected to the ground terminals 32 and 42.
[0022]
The second connection terminal 52 is connected to the output terminal 41 via the second rectifying element D ₂ and is connected to the ground terminals 32 and 42 by the second switching element Q ₂ .
[0023]
While the first and second connection direction of the rectifying element D _1, D _2, when assuming a state where the output terminal 41 and ground terminal 32, 42 are short-circuited, the second switching element Q ₂ is cut off, the When one switching element Q ₁ is turned on, the first rectifying element D ₁ is reverse-biased, and the second rectifying element D ₂ is connected in a forward-biased direction.
[0024]
The power supply device 2 includes a control circuit 16 has a delay circuit 17, control signals the control circuit 16 is output to the first switching element Q ₁ is directly input, the second switching element Q ₂ Is input via a delay circuit 17.
[0025]
In the control signal, a conduction command for switching the first and second switching elements Q ₁ and Q ₂ from the cutoff state to the conduction state and a cutoff command for switching from the conduction state to the cutoff state are alternately output. and turned by the delay circuit 17, only the conduction instruction for a certain delay time Δt delayed, thereby transmitting the second switching element Q _2.
[0026]
Accordingly, the second switching element Q ₂ becomes conductive with a delay time Δt from the first switching element Q ₁ . FIG. 5 is a timing chart showing the delay time Δt in the operation of the first and second switching elements Q ₁ and Q ₂ .
[0027]
The operation of the power supply device 2 when the storage battery 40 is connected as a load between the output terminal 41 and the ground terminal 42 and the storage battery 40 is charged will be described.
[0028]
When the storage battery 40 is in an uncharged or discharged state and the voltage of the output terminal 41 is lower than that of the input terminal 31, the power supply device 2 operates in the step-down mode and charges the storage battery 40.
[0029]
In this case, when only the first switching element Q ₁ is turned on while the second switching element Q ₂ is cut off, the input terminal 31 is connected to the first switching element Q ₁ , the choke coil L, and the second switching element Q ₁ . via the rectifier element D ₂ is connected to the output terminal 41. In this state, the second rectifying element D ₂ is forward-biased, and the current I ₁ is directly supplied from the current source 30 to the storage battery 40 as shown in FIG.
[0030]
Next, after the lapse of the delay time Δt, when the second switching element Q ₂ changes from cutoff to conduction while maintaining the first switching element Q ₁ in the conducting state, the second connection terminal 52 of the choke coil L, That is, the portion where the choke coil L and the second rectifying element D ₂ are connected is connected to the ground terminals 32 and 42.
[0031]
In this state, the second rectifier element D ₂ has the same voltage at both ends or is reverse-biased, so that the current supplied from the current source 30 is not supplied to the storage battery 40, and the symbol I in FIG. _As shown in FIG. ₂ , it flows through the second switching element Q2.
[0032]
The current I _2, since the first and also the flow switching element Q _1, a choke coil L, first and second switching elements Q _1, Q ₂ is cut off, electromotive force is generated across the choke coil L .
[0033]
The electromotive force has a polarity for forward-biasing the first and second rectifying elements D ₁ and D ₂ , and the current I ₃ for charging the storage battery 40 as shown in FIG. 4 by the energy accumulated in the choke coil L. Flows. When the storage battery 40 is charged, the voltage at the output terminal 41 increases.
[0034]
From this state, when the first switching element Q ₁ becomes conductive, the state shown in FIG. 2 is restored.
[0035]
As described above, when the voltage at the output terminal 41 is lower than that at the input terminal 31 and the first switching element Q ₁ is turned on while the second switching element Q ₂ is cut off, the current source 30 The supplied current is directly supplied to the storage battery 40. As in the prior art, current is supplied from the current source 30 only during the period in which both the first and second switching elements Q ₁ and Q ₂ are in conduction, and the current flowing during that period is large. Compared to the case where the loss occurs in both the conduction period and the cutoff period of the first and second switching elements Q ₁ and Q ₂ , the amount of current supplied to the storage battery 40 is longer during the delay period Δt. Since the loss is small, the storage battery 40 can be charged with high efficiency.
[0036]
Further, when charging of the storage battery 40 proceeds and the voltage of the output terminal 41 rises above the voltage of the input terminal 31, the power supply device 2 operates in the boost mode and charges the storage battery 40.
[0037]
In the step-up mode, both the first and second switching elements Q ₁ and Q ₂ are turned on, and after the current I ₂ is supplied from the current source 30 to the choke coil L as shown in FIG. When the first and second switching elements Q ₁ and Q ₂ are cut off, a current I ₃ for charging the storage battery 40 flows due to the electromotive force generated in the choke coil L as shown in FIG.
[0038]
Then, first, during the blocking of the second switching element Q _1, Q _2, the electromotive force generated in the choke coil L in a state in which a current of the storage battery 40 is supplied, the first switching element Q ₁ is conductive then, the electromotive force occurring in the choke coil L, since is applied to the second rectifier D ₂ is added to the output voltage of the current source 30, the second rectifier D ₂ conducts and the choke coil L A current for charging the storage battery 40 is supplied by the energy stored in the battery. This current flows through the same path as the current I _{1 in} FIG.
[0039]
Next, when the second switching element Q ₂ is turned on with a delay time Δt, the current I ₂ is supplied from the current source 30 to the choke coil L as described above.
[0040]
As described above, in both the step-down mode and the step-up mode, the operation of the power supply device 2 during the delay time Δt increases the efficiency of the power supply.
[0041]
The delay time Δt is set to several% to several tens% of one cycle T in the delay circuit 17. For example, when the frequency is 50 kHz (T = 20 μsec), it is about 1 μsec to 5 μsec.
[0042]
Further, in the power supply device 2 of the present invention, the current supplied to the storage battery 40 is measured, and when the frequency is constant, the on / off duty of the first and second switching elements Q ₁ and Q ₂ is determined. The ratio is determined such that the current supplied to the storage battery 40 is a constant current.
[0043]
On the other hand, the upper limit value of the voltage at the output terminal 41 relative to the voltage at the input terminal 31, that is, the step-up rate required for the power supply device 2 depends on the charging voltage required by the storage battery 40 and the output voltage of the current source 30. .
[0044]
When the frequency is constant, if the voltage of the output terminal 41 is increased to the required charging voltage while maintaining a constant current, it is advantageous that the delay time Δt is small.
[0045]
On the other hand, since a large delay time Δt is advantageous in terms of efficiency, the length of the delay time Δt is determined by the type of the storage battery 40 and the usage method of the power supply device 2.
[0046]
In addition, although the said power supply device 2 output the positive voltage with respect to the ground terminals 32 and 42 from the output terminal 41, it may connect like the power supply device shown with the code | symbol 3 of FIG. 6, and may output a negative voltage. .
[0047]
As the switching elements Q ₁ and Q ₂ , switching elements such as IGBTs can be widely used in addition to MOS transistors and bipolar transistors.
[0048]
Furthermore, the first and second rectifying elements 12 and 22 include a case where a MOS transistor is used in addition to a pn junction diode and a Schottky diode, and a current is passed in the opposite direction.
[0049]
【The invention's effect】
A highly efficient buck-boost power supply can be provided.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of a power supply device according to an example of the present invention. FIG. 2 is a diagram for explaining how a current flows in the power supply device (1).
FIG. 3 is a diagram (2) for explaining how current flows in the power supply device;
FIG. 4 is a diagram (3) for explaining how current flows in the power supply device;
FIG. 5 is a timing chart for explaining the operation of the power supply apparatus. FIG. 6 is a circuit diagram of a negative voltage output buck-boost power supply apparatus. FIG. 7 is a circuit diagram of a conventional buck-boost power supply apparatus.
L ... Choke coil Q ₁ ... First switching element Q ₂ ... Second switching element D ₁ ... First rectifying element D ₂ ... Second rectifying element 2, 3 ... Power supply device 16 ... ... Control circuit 17 ... Delay circuit 30 ... Current source 31 ... Input terminals 32, 42 ... Ground terminal 41 ... Output terminal 51 ... First connection terminal 52 ... Second connection terminal

Claims (4)

A choke coil, a first switching element, a second switching element, and a control circuit for switching the first switching element and the second switching element;
When one of the high-voltage side terminal and the low-voltage side terminal of the current source is an input terminal and the other is a ground terminal, the first terminal of the choke coil is connected via the first switching element. Connected to the input terminal and connected to the ground terminal via a first rectifying element,
A second terminal of the choke coil is connected to the ground terminal via the second switching element, and is connected to an output terminal to which a load is to be connected via a second rectifier element. A device,
The control circuit outputs a conduction signal and a cutoff signal, and the first and second switching elements are configured to be turned on by the input of the conduction signal and cut off by the input of the cutoff signal,
Between the connection of the control circuit and the second switching element, a power supply device provided with a delay circuit that delays only the transmission of the conduction signal to the second switching element for a set delay time. A choke coil, a first switching element, a second switching element, and a control circuit for switching the first switching element and the second switching element;
When one of the high-voltage side terminal and the low-voltage side terminal of the current source is an input terminal and the other is a ground terminal, the first terminal of the choke coil is Connected to the input terminal and connected to the ground terminal by a first rectifying element;
The second terminal of the choke coil is an operation method of a power supply apparatus that operates a power supply apparatus that is connected to the ground terminal by the second switching element and connected to the output terminal by a second rectifier element. And
A first period in which the first switching element is conductive and the second switching element is shut off;
A second period following the first period and in which the first and second switching elements are conductive;
A third period after the second period and when the first and second switching elements are cut off is repeatedly performed after the third period after the third period, and the output terminal The operation method of the power supply device which charges the storage battery which is the load connected to.   The operation method of the power supply device according to claim 2, wherein the storage battery is charged from a state where the voltage of the output terminal is smaller than the input voltage supplied from the current source until reaching a voltage higher than the input voltage. The current supplied to the storage battery is measured, and the duty ratio between the conduction period and the cutoff period of the first and second switching elements is set so that the current supplied to the storage battery becomes a constant current. The operation method of the power supply device according to claim 3.

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