JP2673996B2 - Inverter device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to D for DC power conversion.
The present invention relates to an inverter device that constitutes a C-DC converter, particularly to an improvement of a voltage resonance half bridge type, and is used as a power supply device in the fields of communication, home appliances, industrial control equipment and the like.

[0002]

2. Description of the Related Art FIG. 3 shows a circuit configuration of a voltage resonance half-bridge type inverter which has been conventionally used, in which 1 is a DC power supply and 2 and 3 are capacitors for dividing a voltage E ₁ of the DC power supply ₁ into two. 4 is a reactor which constitutes a series resonance circuit together with capacitors 9 and 10, 5 and 6 are switching elements, 7 and 8 are diodes connected in reverse parallel to the switching elements 5 and 6, and 111, 112, 113 and 114 are A diode constituting a single-phase bridge rectification circuit, 12 is a reactor of the filter, 13 is a capacitor of the filter, and 14 is a load. Although the switching elements 5 and 6 are shown as examples of bipolar transistors here, various transistors such as FETs and various thyristors such as GTOs may also be used.

In FIG. 3, capacitors 2 and 3 are generally used.
Has a larger capacity than the capacitors 9 and 10,
The inductance of 12 is selected to be larger than that of the reactor 4. As is well known, this circuit alternately turns on and off the switching elements 5 and 6 so that the middle point of the first arm composed of the capacitors 2 and 3, the switching elements 5 and 6, the diodes 7 and 8, Capacitors 9 and 10
An alternating current output is obtained between the midpoints of the second arms constituted by the
Convert to DC at 4 and supply to load 14.

FIG. 4 shows the waveform of each part of the circuit of FIG. 3, where V ₉ is the voltage of the capacitor 9, I ₁ is the current of the first arm of the capacitors 2 and 3, I ₀ is the current of the load 14, and I ₂ is the current of the capacitor 2.

In FIG. 4, before the time T ₁ , the switching element 5 is on and the switching element 6 is off.
I ₂₃ is capacitor 2 → switching element 5 → diode 111 →
Reactor 12 → (load 14 and capacitor 13) → diode
112 → Reactor 4 → Capacitor 2 flows along the route, storing current energy in reactor 12 and supplying power to load 14.

At time T ₁ , when the current I ₂₃ reaches a predetermined peak value I _P , the switching element 5 is turned off. Then, the current that has been flowing in the switching element 5 up to now is commutated to the capacitor 9, and the voltage V ₉ starts rising. When the voltage V ₉ reaches the voltage E ₁ at the time T ₂ , assuming that the voltage of the capacitor 10 is V ₁₀ , (V ₉ + V ₁₀ = E ₁ )
The voltage V ₁₀ becomes zero. Therefore, if the switching element 6 is turned on at this point, zero voltage switching operation is performed,
Switching loss at the time of turning on can be eliminated.

After time T ₂ , the value of the current I ₂₃ is generally the current I _0.
Because it is smaller, the current I ₀ is: reactor 12 → (load 14 and capacitor 13) → diode
112 (or 114) → diode 113 (or 111) →
The energy is stored in the reactor 12 and is supplied to the load 14 by returning to the reactor 12 route. Since the diodes 112 and 113 or the diodes 114 and 111 are conducting, the AC terminal of the diode bridge is short-circuited.

The current I ₂₃ flows through the route of capacitor 3 → diode 8 → diode 111 → diode 113 → reactor 4 → capacitor 3 in the period of (I ₂₃ > 0), and in the period of (I ₂₃ <0) It flows in the route of 3 → reactor 4 → diode 113 → diode 111 → switching element 6 → capacitor 3.

When the value of the current I ₂₃ becomes larger than the current I _{0 at the} time T ₃ , the operation of the two arms described above on the positive and negative sides is reversed, but the current I ₂₃ is different from the previous route at the time T _1. Taking a similar route, the value of current I ₂₃ peaks at time T ₄ .
When it becomes larger than I _P , the switching element 6 is turned off, and thereafter, the operation similar to that after the time T ₁ is repeated.

[0010]

The above-mentioned operation is the load current.
This is a case where so-called zero voltage switching is performed, in which the switching elements 6 and 5 are turned on when I ₀ is relatively large and the voltages V ₁₀ and V _{9 of} the capacitors ₁₀ and ₉ become zero. It is possible to reduce the switching loss, which is a feature of. However, in the voltage resonance switch shown in the circuit of FIG. 3, when the current I ₀ becomes small, this zero voltage switching cannot be performed, and an excessive current due to a short circuit of the capacitor voltage occurs when the switching element is turned on, which sometimes leads to element destruction, which makes the operation impossible. Become. FIG. 5 shows a waveform in such a case. In FIG. 5, the waveforms at the same locations as in FIG. 4 are shown, but the load current average value of FIG.
This is almost half (19A) in FIG. 5 compared to A).

The operation before time T ₁ in FIG. 5 is similar to that in FIG. 4, but at time T ₂ , the current I ₂₃ , that is, the current of the capacitor 9 of the current I ₂ changes from positive to negative, Since the current of capacitor 9 was small so far, the voltage
V ₉ has not reached voltage E ₁ . The time T _2, after, the voltage V ₉ becomes capacitor 9 current negative begins to descend, the voltage V ₉
Never reaches the voltage E ₁ , ie the voltage V ₁₀ is not zero.

The waveform diagram shown in FIG. 5 shows an example in which the switching element 6 is forcibly turned on at time T ₂ when the voltage V ₉ becomes maximum, that is, the voltage V ₁₀ becomes minimum. At this time, since the voltage remaining in the capacitor 10 is short-circuited, an excessive current causes the switching element 6 and the capacitor 10,
9, the voltage V ₁₀ suddenly changes to zero and the voltage V ₉ suddenly changes to the voltage E ₁ . Since this excessive current adversely affects various circuit components, it cannot be generally operated in such a region, and the conventional circuit cannot be used under a light load.

[0013]

The reason for not performing the zero voltage switching waveform example of FIG. 5 SUMMARY OF THE INVENTION may, from time T ₁ to time T ₁ ', the current I ₂₃ flows in the route described above, in this route Has a large value because the current decays slowly because it includes the reactor 12 having a relatively large inductance, but after time T ₁ ′, (I ₂₃ <I ₀ ),
The route of I ₂₃ is switched to the route shown in the route in the period of (I ₂₃ > I ₀ ) after the time T ₂ described above, and the inductance in the circuit becomes a small value only for the reactor 4, so that the current flows rapidly. Decays to zero at time T ₂ . The current I ₂₃ between the time T ₁ ′ and the time T ₂ is accordingly the capacitor 9
Since the current of is small, the voltage V ₉ does not reach the voltage E ₁ and zero voltage switching cannot be performed.

In view of these points, the voltage V ₉
The route of current I ₂₃ until the voltage E ₁ is reached at time T ₁
Therefore, the route at time T ₁ ′ is maintained, a large current is maintained without attenuating the capacitor 9 current, and zero voltage switching is performed.

[0015]

The route of the current I ₂₃ is switched after the time T ₁ ′ in FIG. 5 because the diode 111 and the diode 111 are switched in the route of the current I _0.
This is because 114 or both of the diodes 112 and 113 become conductive, and the AC terminals of the single-phase bridge composed of the diodes 111 to 114 are short-circuited. In order to avoid such a short-circuited state, the diodes 111 to 114 are replaced with switching element bridges, and the switching elements are selectively turned on. Hereinafter, the present invention will be described in detail with reference to the drawings.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the construction of an essential part of an embodiment of the present invention represented in a manner similar to FIG. 3, in which 151 to 154 are switching elements replacing the diodes 111 to 114 in FIG. 3, and 16 is a load voltage. Is a diode for preventing the reverse voltage from being applied to the switching elements 151-154. In the figure,
The same reference numerals as those in FIG. 3 indicate parts having the same functions. FIG. 2 shows the waveform of each part of the circuit of FIG. 1, and the same reference numerals as those in FIGS. 4 and 5 show the waveforms at the same points.

Before time T ₁ , the same operation as in FIGS. 4 and 5 is performed, and at time T ₁ , the switching element 5 is also operated.
Is off. After the time T ₁ , until the time T ₂ when the voltage V ₉ reaches the voltage E ₁ , the switching elements 151 and 152 are turned on, but the switching elements 153 and 154 are kept off. Therefore, from time T ₁ to time T ₂ are without switching the route of the current I _23, current I ₂₃ is kept relatively large value. Therefore, the current of the capacitor 9 also keeps a large value, and even under the condition that the voltage V ₉ does not reach the voltage E ₁ in the circuit of FIG. 3, the voltage E ₁ can be reached by the circuit configuration of FIG. It is possible.

[0018] In Figure 2 the load current average value even though is more slightly lower than FIG. 5 (17A), the voltage V ₉ time
It can be seen that the voltage reaches E ₁ at T ₂ and zero voltage switching is performed. From time T ₂ to time T ₄ , all the switching elements 151 to 154 are turned on and the same operation as the circuit in FIG. 3 is performed, but from time T ₄ to time T ₅ , the operation from time T ₁ to time T ₂ Symmetrically with the switching elements 151 and 152 being turned off and the switching elements 153 and 154 being turned on, the voltage V
_{By making 10} reach the voltage E ₁ , the zero voltage switching of the switching element 5 is possible.

[0019]

As described in detail above, by constructing the conventional voltage resonance half-bridge type inverter as shown in FIG. 1, the zero voltage switch can be performed even in the light load region, and the range of use is expanded. It becomes possible to do.
By the way, in the waveform diagrams shown in FIGS. 4, 5 and 2, the circuit time constants are 100 μH for reactor 12, 0.5 μF for capacitors 9 and 10, and 10 μH for reactor 4.
When the voltage of the DC power supply 1 is 100V and the voltage to the load 14 is 50V, the zero voltage switching cannot be performed in the circuit of FIG.
It was confirmed by simulation that the load current can be used up to 10 A by using the circuit.

[0020]

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a main part configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing waveforms at various points in the circuit of FIG.

FIG. 3 is a circuit diagram of a known voltage resonant half-bridge type inverter.

FIG. 4 is a diagram showing waveforms at various points in the circuit shown in FIG. 3;

FIG. 5 is a waveform chart of each part shown for explaining the problems of the conventional technique.

[0021]

[Explanation of symbols]

 1 DC power supply 2 Capacitor 3 Capacitor 4 Reactor 5 Switching element 6 Switching element 9 Capacitor 10 Capacitor 111 Diode 112 Diode 113 Diode 114 Diode 12 Reactor 13 Capacitor 14 Load 151 Switching element 152 Switching element 153 Switching element 154 Switching element

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H02M 7/5387 9181-5H H02M 7/5387 A

Claims (1)

(57) [Claims] 1. A first arm composed of a series connection body of two capacitors at both ends of a DC power supply, and a second arm in which a parallel connection body of a switching element, an anti-parallel diode and a capacitor are connected in series. A reactor and an AC terminal of a single-phase bridge rectifier circuit composed of four switching elements are connected in series between the midpoints of the first arm and the second arm, and between the DC terminals of the rectifier circuit. Two of the four switching elements are connected so as not to short-circuit the DC terminal of the rectifier circuit while the load is connected and the two switching elements forming the second arm are both in the off state.
An inverter device characterized by selectively turning on an individual piece.