JP3518344B2 - Half-bridge type inverter circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a half-bridge type inverter circuit, and more specifically, to a DC voltage boosting means, which boosts the DC voltage by the first means and which is connected in series. The present invention relates to a half-bridge type inverter circuit configured to balance the voltage applied to the second capacitor.

[0002]

2. Description of the Related Art A half-bridge type inverter circuit includes a DC power supply, a series connection circuit of first and second capacitors,
A series connection circuit of first and second switching elements, and a series connection point of the first and second capacitors and the first and second switching elements.
The load is connected between the second switching element and the series connection point, which has the advantage that the number of switching elements is half that of the full-bridge inverter circuit. It is widely used in inverter circuits to which a DC power supply voltage that is more than twice as high as

In the above-mentioned half-bridge type inverter circuit, even in the case of an inverter circuit to which a low DC power supply voltage is input, a boosting means for boosting this DC voltage is inserted,
By inputting the DC voltage boosted by the boosting means to the inverter circuit, the current flowing through the switching element forming the inverter circuit is reduced, the switching element is downsized, and the wiring material is thinned. ing.

In the half-bridge type inverter circuit in which such boosting means is inserted, it is necessary to boost the DC voltage to at least twice the peak value of the AC voltage to be obtained. Such a boost chopper circuit was inserted.

The boost chopper circuit shown in FIG. 5 has a choke coil L ₀ between one end 11 and the other end 12 of the DC power supply 1.
And connecting a series circuit of a switching element T _0, one input terminal 31 of the inverter circuit 3 a series connection point between the choke coil L ₀ and the switching element T ₀ through the diode D ₀ (first capacitor C ₁ ) and the other end 12 of the DC power supply 1 is connected to the other input terminal 32 of the inverter circuit 3 (the other end of the second capacitor C ₂ ). Reference numeral 2 is a ripple absorbing capacitor.

The inverter circuit 3 includes a series connection circuit of the first capacitor C ₁ and the second capacitor C _2, and a series connection circuit of the first switching element T ₁ and the second switching element T _2. Are connected in parallel, and a series connection point of the first capacitor C ₁ and the second capacitor C ₂ and a series connection point of the first switching element T ₁ and the second switching element T ₂ are connected. Is connected to a load 5 via a filter circuit 4 composed of a reactor L ₃ and a capacitor C ₃ to form a half bridge type. Since the inverter circuit 3 and the boost chopper circuit described above are well known, the description of the operation thereof is omitted.

[0007]

In the inverter circuit 3 described above, when the load 5 has an unbalanced component, the voltages applied to the first capacitor C ₁ and the second capacitor C ₂ become unbalanced. However, there is a problem that the output voltage from the side where the voltage becomes small does not reach the peak value.

In order to solve such a problem, conventionally, the first capacitor C ₁ and the second capacitor C ₂ are
The dummy resistors were connected in parallel, and the voltage imbalance was eliminated by balancing the voltage applied to the dummy resistors and the loss due to the dummy resistors, but the loss due to the dummy resistors always occurred. This loss becomes large when the voltage imbalance is large or when the voltage applied to the first capacitor C ₁ and the second capacitor C ₂ is large. Therefore, when used in such an application, the conversion efficiency is lowered. It was a cause and it was not preferable.

[0009]

In order to solve the above problems, the invention according to claim 1 is a direct current power source, and a series connection circuit in which the other end of the first capacitor is connected to one end of the second capacitor, A half-bridge inverter circuit comprising a series connection circuit in which the other end of the first switching element is connected to one end of the second switching element, the series connection point of the first capacitor and the second capacitor. Has a choke coil to which a center tap is connected, and the first winding of the choke coil is connected to the other end of the second capacitor through the first diode and the second winding of the second winding is connected to the second winding. It is connected to one end of the first capacitor via a diode, one end of the DC power supply is connected to the center tap of the choke coil, and the second winding and the second inductor of the choke coil are connected. Third switching element is connected a connection point between the diode and between the other end of the DC power source, before
The voltage applied to the first capacitor and the second capacitor
When the sum voltage with the voltage applied to the capacitor is fixed,
From the AC power supply included in the input current from the DC power supply
Create a PWM control signal to reduce the ripple of
The PWM control signal causes the third switch
And characterized in that controlling the grayed element, thereby, the load 5 is that imbalance voltage increases to be applied to the first and second capacitors have unbalanced components Even if it is considered or if the input voltage of the half-bridge inverter circuit is high and the voltage applied to the first capacitor and the second capacitor is large, the conversion efficiency is not reduced and the first capacitor and the second capacitor are not reduced. Two
The voltage applied to the capacitors can be balanced.

Further, in the invention according to claim 2, a DC power source, a series connection circuit in which the other end of the first capacitor is connected to one end of the second capacitor, and the other end of the first switching element is the second A half-bridge inverter circuit including a series connection circuit connected to one end of a switching element of the first choke, the first center tap being connected to a series connection point of the first capacitor and the second capacitor. A first winding of the choke coil is connected to the other end of the second capacitor via a first diode, and a second winding of the choke coil is connected to the first winding via a second diode. A second tap is provided on the second winding of the choke coil, while being connected to one end of a capacitor, one end of the DC power supply being connected to a first center tap of the choke coil, The third switching element is connected to the second tap and between the other end of the DC power source, the
The voltage applied to the first capacitor and the second capacitor
While keeping the sum voltage with the voltage applied to the sensor constant,
From the AC power supply included in the input current from the DC power supply
Create a PWM control signal to reduce ripple,
This PWM control signal causes the third switching element to
And characterized in that to control the child, thereby, together with the voltage applied to the voltage and the second capacitor being applied to the first capacitor can be balanced, the ratio of the second tap Third by adjusting
The duty ratio of the switching element can be selected.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on its embodiments.

FIG. 1 is a circuit diagram of a half-bridge type inverter circuit according to a first embodiment of the present invention.

The half-bridge type inverter circuit shown in FIG. 1 is characterized by a DC power supply 1 and a series connection circuit in which the other end of the _first switching element T ₁ is connected to one end of the second switching element T ₂ . which has a series circuit connected to the first end of the capacitor C ₁ to the second end of the capacitor C _2, the center to a series connection point of the first capacitor C ₁ and the second capacitor C ₂ The choke coil L has a tap connected to it, and the first winding L ₁ of the choke coil L has the second diode via the first diode D ₁ .
Is connected to the other end of the capacitor C ₂ and the second winding L ₂ is connected to one end of the first capacitor C ₁ via the second diode D _2, and one end 11 of the DC power supply 1 is connected to the choke. The second winding L ₂ of the choke coil L and the second diode D are connected to the center tap of the coil L.
That is, the third switching element T ₃ is connected between the connection point with ₂ and the other end 12 of the DC power supply 1. 2
Is a ripple absorbing capacitor.

In the above-mentioned half-bridge type inverter circuit, the input voltage, that is, the sum voltage V _{C of the} voltage V _C1 applied to the first capacitor C ₁ and the voltage V _C2 applied to the second capacitor C _2. Is detected, and the error voltage obtained by error-amplifying this with a voltage reference value is compared with a triangular wave to create a PWM control signal, so that the sum voltage V _C becomes constant. T ₃ can be controlled, the sum voltage V _C is detected, and an error voltage obtained by error-amplifying the sum voltage V _C with the current reference value is smoothed to obtain a current target value. If the PWM control signal is created by comparing the error voltage obtained by amplifying the error between the input currents of the half-bridge type inverter circuit with the triangular wave, the ripple of the AC power supply contained in the input current is reduced.
It is possible to control the switching element T ₃ of.

Next, the operation of the above half bridge type inverter circuit will be described.

(Operation Mode 1) This operation mode 1 is the third
This is the case when the switching element T _{3 of} is on. That is, when the third switching element T ₃ is turned on, the one end 11 of the DC power supply 1 → the second winding L ₂ of the choke coil L →
A current flows through the path of the third switching element T ₃ → the other end 12 of the DC power supply 1 to accumulate energy in the choke coil L.

(Operation mode 2) This operation mode 2 is the third
This is the case when the switching element T _{3 of} is off. That is, when the third switching element T ₃ is turned off, the energy stored in the choke coil L in the operation mode 1 is released, but the voltage V _C1 applied to the first capacitor C ₁ and the second Voltage V _C2 applied to capacitor C ₂
The route of release is different depending on the magnitude relationship.

That is, the first winding L of the choke coil L
_If the number of turns of ₁ = the number of turns of the second winding L ₂ of the choke coil L, then in the case of V _C1 > V _C2 , the connection point between the first winding L ₁ of the choke coil L and the first diode D ₁ The potential becomes lower than the potential at the other end of the second capacitor C ₂ (potential on the anode side of the first diode D ₁ ) and becomes the first diode D 1.
_{Since 1} is forward biased, the first winding L ₁ of the choke coil L → the second capacitor C ₂ → the first diode D ₁
→ A current flows in the path of the first winding L _{1 of} the choke coil L, and the energy of the choke coil L is transferred to the second capacitor C ₂ . At this time, the potential at the connection point between the second winding L ₂ of the choke coil L and the second diode D ₂ becomes lower than the potential at one end of the first capacitor C ₁ and the second diode D ₂ is reverse biased. Choke coil L
No current flows in the path of the second winding L ₂ → the second diode D ₂ → the first capacitor C ₁ → the second winding L ₂ of the choke coil L.

Similarly, when V _C1 <V _C2 , the potential at the connection point between the second winding L ₂ of the choke coil L and the second diode D ₂ is the potential at one end of the first capacitor C ₁ (the first Second diode D ₂ (cathode side potential) of the second
Since the diode D ₂ is forward biased, the second winding of the choke coil L L ₂ → second diode D ₂ → first capacitor C ₁ → second winding L ₂ consisting path current of the choke coil L Flows and the energy of the choke coil L is transferred to the first capacitor C ₁ . At this time, the potential at the connection point between the first winding L ₁ of the choke coil L and the first diode D ₁ is higher than the potential at the other end of the second capacitor C ₂ , and the first diode D ₁ is reversed. Since it is biased, the first winding L ₁ of the choke coil L → the second capacitor C ₂
→ First diode D ₁ → No current flows in the path of the first winding L ₁ of the choke coil L.

According to the above operation modes, V _C1 > V
Since in the case of _C2 energy of the choke coil L is transferred to the second capacitor C _2, the voltage V _C2 of the second voltage V _C2 of the capacitor C ₂ is applied to the second capacitor C ₂ rises first it is possible to balance the voltage V _C1 applied to the first capacitor C _1, in the case of V _C1 <V _C2 because energy of the choke coil L is transferred to the first capacitor C _1, the first capacitor C ₁ voltage V _C1 can be balanced with the voltage V _C2 applied to the first voltage V _C1 applied to the capacitor C ₁ to the second capacitor C ₂ rises.

FIG. 2 is a circuit diagram of a half-bridge type inverter circuit according to the second embodiment of the present invention.

The feature of the embodiment shown in FIG. 2 is that the embodiment shown in FIG. 1 has the number of turns of the first winding L ₁ of the choke coil L = the number of turns of the second winding L ₂ of the choke coil L. On the other hand, the connection point between the first winding L ₁ and the second winding L ₂ of the choke coil L is the first center tap, and the second winding L ₂ of the choke coil L is the second tap. Is provided, and the third switching element T ₃ is connected to this second tap.

According to the above-described second embodiment, the third
When the switching element T _{3 of the third} switching element T ₃ is turned on, energy is accumulated in the choke coil L and the third switching element T 3
_{When 3} is turned off, the energy of the choke coil L is transferred to the lower voltage capacitor, so that the voltage V _C1 of the first capacitor and the voltage V _C2 of the second capacitor can be balanced.

Further, in addition to the above-described respective embodiments, one end and the other end of the DC power supply may be reversed to have a configuration as shown in FIGS.

[0025]

As described above, according to the present invention, in the half-bridge type inverter circuit, the load 5 has an unbalanced component and the voltage imbalance applied to the first capacitor and the second capacitor is large. Even if the input voltage is high and the voltage applied to the first capacitor and the second capacitor is high, the first capacitor and the second capacitor are not deteriorated in conversion efficiency. Since the voltage applied to the circuit can be balanced, it largely contributes to the expansion of applications of the half-bridge type inverter circuit.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a half-bridge type inverter circuit according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of a half-bridge type inverter circuit according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram of a modified example of the half-bridge type inverter circuit according to the embodiment of FIG.

FIG. 4 is a circuit diagram of a modified example of the half-bridge type inverter circuit according to the embodiment of FIG.

FIG. 5 is a circuit diagram of a conventional half-bridge type inverter circuit.

[Explanation of symbols]

1 DC power supply 2 capacitors 3 inverter circuit 4 Filter circuit 5 load

Claims (2)

(57) [Claims] 1. A DC power supply, a series connection circuit in which the other end of the first capacitor is connected to one end of a second capacitor, and the other end of the first switching element is connected to one end of the second switching element. A half-bridge inverter circuit including a series connection circuit, comprising a choke coil having a center tap connected to a series connection point of the first capacitor and the second capacitor, and a first choke coil of the choke coil. A winding is connected to the other end of the second capacitor via a first diode, and a second winding is connected to one end of the first capacitor via a second diode. One end is connected to the center tap of the choke coil, and a third switching element is provided between a connection point between the second winding of the choke coil and the second diode and the other end of the DC power supply. Is connected to the first element.
The voltage applied to the capacitor and the second capacitor
The sum of the applied voltage and the direct current
Ripple from AC power supply included in input current from power supply
Create a PWM control signal to reduce the
Control the third switching element by the M control signal
A half-bridge type inverter circuit characterized in that 2. A DC power supply, a series connection circuit in which the other end of the first capacitor is connected to one end of a second capacitor, and the other end of the first switching element is connected to one end of the second switching element. A half-bridge inverter circuit including a series connection circuit, comprising a choke coil having a first center tap connected to a series connection point of the first capacitor and the second capacitor. Has a first winding connected to the other end of the second capacitor through a first diode and a second winding connected to a second winding.
Is connected to one end of the first capacitor via the diode, one end of the DC power supply is connected to the first center tap of the choke coil, and the second tap is connected to the second winding of the choke coil. Is provided, and a third switching element is connected between the second tap and the other end of the DC power supply, and is applied to the first capacitor.
Sum of voltage and voltage applied to the second capacitor
While keeping the pressure constant, the input current from the DC power supply
P to reduce the ripple from the included AC power supply
Create a WM control signal and use this PWM control signal to
A half-bridge type inverter circuit characterized by controlling a third switching element .