JP2016171704A - Power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply device that can suppress pulse-shaped surge noise.SOLUTION: A power source device that supplies DC current obtained through the output side of a reactor and a wire in turn to a primary-side winding of an insulation type transformer while the polarity of the current is alternately changed by combining the ON/OFF states of plural switching elements, and outputs DC power obtained by rectifying and smoothing AC power induced in a secondary-side winding of the insulation type transformer, comprises a capacitor charged from the wire through a diode, and a discharging switching element for discharging the charges charged in the capacitor when the terminal voltage of the capacitor is not less than a predetermined voltage.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power supply device having a current-type booster circuit.

In a power supply device having a current-type booster circuit in which the polarity is alternately changed to the primary winding of the insulated transformer and flows current, the AC power generated in the secondary winding of the insulated transformer is rectified and smoothed. It was output as DC power. This DC power can be controlled by controlling the current flowing through the primary winding, and is boosted by the electromagnetic energy stored in the reactor.

When the current supplied to the primary winding of the insulating transformer is controlled using the combination of the on / off states of the plurality of switching elements, the plurality of switching elements may all be in the off state. At this time, if electromagnetic energy is accumulated in the reactor, the electromagnetic energy has nowhere to go (the path through which current flows), and the voltage across the switching element is increased. When this inter-terminal voltage exceeds the breakdown voltage of the switching element, the switching element is damaged. Some have provided snubber circuits at both terminals of the reactor to release, discharge or consume the electromagnetic energy of the reactor in order to prevent damage to the switching element. (See Patent Document 1)

Japanese Patent No. 5138002

Patent Document 1 describes a snubber circuit connected in parallel to an inductor (corresponding to a reactor) and capable of absorbing a current flowing through the inductor. This snubber circuit absorbs the current flowing from the inductor when the current flowing through the transformer (corresponding to an insulating transformer) is interrupted. Absorbs the electromagnetic energy accumulated in the inductor (consumed by the resistor after being absorbed by the capacitor)
This prevents the applied voltage of the switching element from exceeding the withstand voltage and damages the switching element.

When the electromagnetic energy accumulated in the reactor is guided to the snubber circuit, an on / off state of a plurality of switching elements for controlling energization to the primary winding of the insulating transformer, and an on / off state of the snubber switching element Need to be synchronized. If the snubber switching element is turned on while a current is applied to the primary winding, the current does not flow through the primary winding, and the output voltage of the power supply device decreases. Further, when the snubber switching element is turned on while electromagnetic energy is accumulated in the reactor, the electromagnetic energy is absorbed by the snubber circuit and the output voltage of the power supply device is lowered.

For this reason, the snubber switching element is turned on after the current supply to the primary winding is cut off, but a time delay occurs during this time. The electromagnetic energy accumulated in the reactor during this time delay collides with the spike voltage associated with the change in the on / off state of the plurality of switching elements, and becomes a high-voltage spike-like voltage between the reactor and the plurality of switching elements. Occurs in connecting wires. Further, the capacitor needs to have a withstand voltage characteristic that can withstand at least the high spike voltage. Furthermore, since the electromagnetic energy of the reactor is absorbed by the capacitor in the device described in Patent Document 1, when the snubber switching element is turned off, the voltage on the output side (secondary side) of the reactor is substantially equal to the input side ( The voltage is reduced to the voltage on the primary side. For this reason, a time delay occurs until the voltage of the wiring rises, leading to a delay when the output voltage of the power supply apparatus converges to the target voltage, and the followability of the output voltage is suppressed.

Moreover, by discharging and consuming electromagnetic energy with a resistor, this electromagnetic energy is not output from the power supply device, leading to a decrease in conversion efficiency of the power supply device. The amount of electromagnetic energy loss increases as the output of the power supply device increases.

The power supply device of the present invention constitutes a series circuit from a diode and a capacitor to absorb the electromagnetic energy of the reactor and to control the terminal voltage of the capacitor.

In the power supply device of the present invention, the direct current obtained through the output side of the reactor and the wiring in order is combined with the on / off states of a plurality of switching elements to alternately change the polarity to the primary winding of the insulated transformer. In a power supply device that is energized and rectifies AC power induced in the secondary winding of the insulation transformer and outputs smooth DC power, a capacitor charged from a wiring through a diode and a terminal voltage of the capacitor are And a discharge switching element for discharging the charge charged in the capacitor when the voltage is higher than a predetermined voltage.

The power supply device of the present invention is intended to reduce the withstand voltage of the capacitor used by controlling the terminal voltage of the capacitor and to suppress the loss due to the voltage drop.

It is explanatory drawing of the circuit which shows the Example of this invention. It is explanatory drawing which shows the on / off state of a switching element.

In the present invention, a direct current obtained via a reactor is energized with alternating polarity to the primary winding of an insulating transformer by combining the on / off states of a plurality of switching elements, It can be used for a power supply circuit that outputs DC power that is rectified and smoothed by AC power induced in the secondary winding.

FIG. 1 is an explanatory diagram of a circuit showing an embodiment of the present invention. In FIG. 1, P and N are terminals to which DC power is input. For example, a DC power source that outputs DC power whose output voltage varies depending on the natural environment, such as a solar battery, can be connected.

1 is a reactor, and 2 is an IPM (Intelligent Power Module) in which six power switching elements (2a to 2f) are housed in a single package. The power MOSFET and insulated gate bipolar transistor (IGBT) control power. )
And a power semiconductor element incorporating a drive circuit and a self-protection function of these switching elements. The switching elements 2a and 2b may be packaged elements separately from the switching elements that form a single-phase bridge connection.

In the IPM 2, switching elements 2a to 2f are arranged adjacent to each other on the same insulating base, and a drive circuit and a drive power supply circuit of these switching elements are simultaneously accommodated in the package. The IPM 2 includes at least switching elements 2a to 2f.
Each of the emitter terminal, the collector terminal, and the signal L, S,
A terminal for inputting the signal D is provided. (Emitter terminal and collector terminal are names when a transistor is used as a switching element, and are read according to the type of switching element such as a drain terminal and a source terminal.)

The signal L is an analog level voltage signal (digital / analog converted voltage level signal) output from the comparator 3, and is used to control the on / off state of the switching element 2b. The signal S controls the on / off state of the switching element 2a. Signal D
Controls the on / off states of the switching elements 2c to 2f. The signal L, signal S, and signal D are output from the control unit 4.

A wiring 5 (or a wiring conductor or a wiring pattern on an electrical board) is connected to the output terminal (secondary side) 1b of the reactor 1. A switching element 2a, a switching element 2c, and a switching element 2e are connected to the wiring 5 via a diode 6. Diode 6
The series circuit of the switching elements 2a constitutes a first snubber circuit that connects the wiring 5 to the input end (primary side) 1a of the reactor 1.

The switching elements 2c to 2f are controlled to be turned on / off by the signal D from the control unit 4, the switching elements 2c and 2f are turned on, and the switching elements 2d to 2e are turned off. When the elements 2c and 2f are turned off and the switching elements 2d to 2e are turned on alternately, the polarity is changed alternately to the primary winding 7a of the insulating transformer 7 and the current flows. Energized.

The AC power induced in the secondary winding 7b of the insulating transformer 7 is rectified by a full-wave rectifier circuit 8 in which four diodes are connected in a bridge shape and then smoothed by a capacitor 9 to become DC power.
The voltage of the DC power is based on the amount of current flowing through the primary winding 7a and the winding ratio of the insulating transformer 7, and the ripple is based on the switching frequency of the switching elements 2c to 2f. The ripple decreases as the frequency increases, but the loss of the insulating transformer 7 increases. This DC power is equivalent to the output of the power supply device. This DC power is converted into a three-phase pseudo sine wave by an inverter unit 10 in which six switching elements are connected to a three-phase inverter circuit, and then composed of a capacitor and a reactor. After the high-frequency component is removed or attenuated through the filter 11, the three-phase AC power UVW is output. This three-phase AC power can be superimposed on an AC load or system. A signal I for controlling the on / off state of the switching element of the inverter unit 10 is output from the control unit. This signal I is, for example, PWM (Pulse Wi).
dth Modulation) system. The circuit connection of the inverter unit 10 may be a circuit connection such as an NPC (neutral point clamp) method or a gradation method, and the signal I may be generated by the control unit 4 in accordance with each circuit connection. .

FIG. 2 is an explanatory diagram showing changes in the on / off states of the switching element 2a and the switching elements 2c to 2f. In the period of T1, the switching element 2c and the switching element 2f are turned on and the switching element 2d and the switching element 2e are turned off, and the switching element 2c and the switching element 2f are turned off and the switching element 2d and the switching element 2e are turned on. The AC power for one cycle is generated by alternately repeating the case of the state and supplied to the primary winding 7a of the insulating transformer 7.

During the period T2, the switching elements 2c to 2f are turned off and the switching element 2a is turned on. Accordingly, the electromagnetic energy output from the secondary side 1b of the reactor 1 is absorbed by the primary side 1a of the reactor 1 through the diode 6 and the switching element 2a. The period T2 is set taking into account the time during which this electromagnetic energy is consumed by the resistance of the reactor 1. In addition, before and after the period T2, the switching element 2a is turned on early and turned off after a delay in consideration of the operation delay of each switching element. If the withstand voltage and response speed of the switching element are sufficient, it can be omitted. Further, if there is a current flowing through the primary winding 7a of the insulating transformer 7, it is absorbed simultaneously.

In FIG. 2, the switching element 2c to the switching element 2f are all turned on, and the combination of the switching element 2c and the switching element 2f or the switching element 2d
And the output side 1b of the reactor 1 when the combination of the switching element 2e changes to the OFF state.
Between the primary winding 7a and the output 1b of the reactor 1 due to the electromagnetic energy (current) output from the primary transformer 7 and the leakage inductance on the primary side of the insulated transformer 7 collide with the wiring 5 and instantaneously. It becomes a spike-like high voltage (it reaches several thousand volts depending on conditions). This spike-like surge voltage (energy) is absorbed by the second snubber circuit including the diode 12 and the capacitor 13 connected to the wiring 5.

The comparator 3 turns on the switching element 2b when the terminal voltage of the capacitor 13 charged from the wiring 5 via the diode 12 exceeds a predetermined value. Switching element 2b
Is turned on to form a discharge circuit in which the wiring 5 is connected to the primary side 1a of the reactor 1 through a series circuit of the resistor 14 and the switching element 2b. Accordingly, a portion of the spike-like surge voltage generated in the wiring 5 that exceeds the predetermined voltage flows to the primary side 1a of the reactor 1 and is consumed by the resistor 14 and attenuates. The electric charge of the capacitor 13 may be discharged between the terminals of the capacitor via a resistor, and is not limited to the circuit connection shown in FIG.

The terminal voltage of the capacitor 13 is divided by the resistors 15 and 16 and then applied to one terminal of the comparator 3. A signal L (voltage signal) is applied to the other terminal of the comparator 3, and this signal L is an output (digital / analog converted voltage) of the D / A terminal of the control unit 4. Controlled arbitrarily. Accordingly, since the terminal voltage of the capacitor 13 is controlled to be equal to or lower than a predetermined voltage corresponding to the signal L, the withstand voltage of the capacitor 13 is sufficiently lower than the peak of the spiked surge voltage and higher than the predetermined voltage. It ’s fine. It should be noted that a predetermined differential can be set for the operation of the comparator 3. Further, in place of the operation circuit using the comparator 3, the terminal voltage of the capacitor 13 is taken into the control unit 4, and a switching signal whose on-duty is controlled is output from the control unit 4 to the switching element 2b. Is also possible.

If the rising voltage of the diode 12 is ignored, the terminal voltage of the capacitor 13 can be a predetermined voltage close to the voltage of the wiring 5. By setting the terminal voltage of the capacitor 13 in this way, energy loss associated with the terminal voltage (charge discharge) of the capacitor 13 can be suppressed. That is, the conversion efficiency of the power supply device can be increased. Further, when a solar cell is connected to the terminal P and the terminal N and this solar cell is controlled to generate power at the optimum operating point, the voltage of the wiring 5 fluctuates, so the control unit 4 detects this voltage, and this voltage If the voltage level of the signal L is changed based on the above and the predetermined voltage of the capacitor 13 is variably controlled, the conversion efficiency can be increased over the power generation region of the solar cell.

The present invention is used for a power supply apparatus that suppresses a pulsed surge voltage caused by an operation of a switching element when an up-and-down voltage of a DC output voltage, such as a solar cell, is varied using an insulating transformer.

As mentioned above, although one Embodiment of this invention was described, the above description is for making an understanding of this invention easy, and does not limit this invention. It goes without saying that the present invention can be changed and improved without departing from the gist thereof, and that the present invention includes equivalents thereof.

1 Reactor 2 IPM
4 Control unit 5 Wiring 6 Diode 7 Insulated transformer 8 Full-wave rectification circuit 9 Capacitor 10 Inverter unit 11 Filter

Claims (3)

A DC current obtained through the output side of the reactor and the wiring in order is energized by changing the polarity alternately to the primary winding of the insulating transformer by combining the on / off states of a plurality of switching elements. In the power supply device that outputs the DC power that is rectified and smoothed by the AC power induced in the secondary winding of
A power source comprising: a capacitor charged from the wiring through a diode; and a discharge switching element for discharging the charge charged in the capacitor when a terminal voltage of the capacitor is equal to or higher than a predetermined voltage. apparatus. The power supply apparatus according to claim 1, wherein the switching element for discharging discharges the electric charge of the capacitor to the input side of the reactor through a resistor. The combination of the on / off states of the plurality of switching elements is one of the insulating transformers 1.
2. A snubber switching element that operates in a combination in which no current is supplied to the next winding and discharges electromagnetic energy output from the reactor to the input side of the reactor. Item 3. The power supply device according to Item 2.

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