JPH0161022B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a DC power supply device.

Recent technological innovations in the electronics field have been remarkable, and power control technology using power transistors and thyristors has rapidly become more sophisticated. One typical example is the all-electronization of lighting circuits in the lighting field. As a highly efficient lighting method, in response to the need for power saving since oil shocks,
The so-called high-frequency lighting method, which uses an inverter to control lamp lighting at 30KHz to 40KHz, is seen as promising, and companies are currently competing to develop it. As another example, the demand for labor saving and automation has recently become stronger, and the speed control of electric motors has become more generalized using inverters, and active efforts toward automation are being made in the industrial world.

In such a situation, a DC power supply is indispensable, and in particular, an AC/DC conversion circuit that obtains DC from a commercial power supply is an important element in the power control field. By the way, with the recent increase in demand for power control, problems have arisen such as high-frequency interference due to switch-based control, burnout of power factor correction capacitors, reduced efficiency of power company transformers, induction disturbances, etc. Therefore, there is a demand for an AC/DC conversion circuit with less harmonic components, that is, with less input current (voltage) distortion.

Conventionally, a three-phase full-wave rectifier as shown in Figure 1 has been used as an AC/DC conversion circuit when using a three-phase commercial power source to control the speed of an induction motor, high-frequency lighting of a discharge lamp, etc. ing. In this circuit, the second
As shown in the operating state in the figure, there always occurs a period of π/3 during which no input current flows during a half cycle of one phase. In other words, if we focus on the 1st phase of e ₁ , the input current flowing to the e ₁ phase will be the diode D ₁ or
Since it flows only while D ₁ ' is on, t ₀ ~ t ₁ , t ₃
This is because the input current is suspended during the periods from ~ _t4 to _t6 to _t7 . Therefore, this idle period naturally distorts the input current (voltage), resulting in the various problems mentioned above. Furthermore, if power control is performed on the load side using switching using an electronic device such as a thyristor, it goes without saying that the problem will be even greater. In this way, when controlling power using an AC/DC conversion circuit with three-phase full-wave rectification, the distortion of the input current is theoretically large, so it is possible to reduce the distortion and easily obtain smooth DC. There is a need for an AC/DC conversion method that can do this.

Figure 3 shows the basic configuration diagram. 6 is a 3-phase power supply,
1, 2, and 3 are synchronized by the synchronization signal of the synchronization circuit 5,
A high-frequency conversion circuit receives a phase power source as an input and insulates the input and output. 4 is a rectification/smoothing circuit that rectifies and smoothes the high-frequency voltage obtained by serially combining the outputs of the high-frequency conversion circuits 1, 2, and 3.

Figure 4 shows a specific circuit. The high frequency conversion circuits 1, 2, and 3 are push-pull type inverters and have almost the same specifications. The synchronous circuit 5 has a constant output level of 1, 2, 3 using a DC power source as an input power source.
It is a push-pull self-excited inverter similar to
Synchronous bias windings E-ro, Har-ni, and Ho-he for the high-frequency conversion circuit are magnetically coupled and wound around the oscillation inductance. The rectifier/smoothing circuit 4 uses a circuit that is full-wave rectified and then smoothed with a capacitor.

When the power supplies E ₀ and E ₄ are applied to the synchronous circuit 5, self-excited oscillation occurs, and the synchronous bias windings E-ro, Har-ni,
The self-excited oscillation frequency of the synchronous circuit 5 _{is 0.}
A sine wave voltage V _b of (period T ₀ ) is generated as shown in FIG. Now, this V _b is the high frequency conversion circuit 1, 2, 3
When V _b is positive, Q ₁ , Q ₃ , Q ₅ are on, and Q _{2 , Q 4 ,} Q ₆ are off _. , and V _b turns negative, conversely, Q ₁ , Q ₃ , and Q ₅ are off, and Q ₂ ,
Q ₄ and Q ₆ turn on, and therefore the synchronous circuit 5
Transistors Q ₁ , Q ₃ ,
Q ₅ , Q ₂ , Q ₄ , and Q ₆ alternately turn on and off. By performing this operation, the input 3ψ power supply e ₁ ,
When e ₂ and e ₃ are input, each high frequency conversion circuit 1, 2,
The output voltages V ₁ , V ₂ , and V ₃ of 3 are synchronized, as shown in Fig. 5.
The waveforms shown in V ₁ , V ₂ , and V ₃ can be obtained. These peak values V _1-p , V _2-p , and V _3-p are proportional to the absolute values of the instantaneous values of e ₁ , e ₂ , and e ₃ , and when compared with the low frequency of the power supply, It can be obtained as shown in FIG. Therefore, V _put =V ₁ +V ₂ +V ₃ becomes a high frequency voltage having a peak value at a substantially constant level, and has the waveform shown in FIG. This V _put is rectifier smoothing circuit 4
The current is full-wave rectified, smoothed by a capacitor, and converted into smooth direct current.

If the outputs of the high frequency conversion circuits 1, 2, and 3 are combined in series in this way, each output will be supplied to the load without any pauses, and therefore there will be no pause period for the input current as in the case of full-wave rectification. Distortion etc. can be made extremely small.

FIG. 8 shows one embodiment of the present invention. Circuit blocks 1, 2, and 3 within the dashed line frame are high frequency conversion circuits.
The circuit specifications are almost the same except for the power supply section. All of them are push-pull type inverters, and only the synchronous circuit 5 constitutes a self-excited inverter.
In other words, the oscillating voltage generated in the oscillation windings n ₁ and n ₂ and the capacitor C ₀ flows to the bases of the transistors Q ₁ and Q _2.
This is because the induced voltage of _Vd is fed back. Therefore, when the DC power sources E ₀ and E ₁ are turned on, the synchronous circuit 5 self-oscillates and generates a sinusoidal high-frequency voltage _V a between the windings A and B, C and D, and E and H, respectively. , V _b ,
V _c occurs in the same direction as V _cp . These V _a , V _b ,
Since V _c is applied across the base resistances of the switch transistors of high frequency conversion circuits 1, 2, and 3, V _cp
is positive (V _a , V _b , V _c are positive), the transistor
Q ₄ , Q ₆ , and Q ₈ are turned on, and Q ₃ , Q ₅ , and Q ₇ are forced to turn off. Conversely, when V _cp is negative, Q ₃ ,
Q ₅ , Q ₇ turn on, Q ₄ , Q ₆ , Q ₈ turn off, and high frequency conversion circuits 1, 2, and 3 are forced to switch in synchronization with the self-excited vibration period of synchronous circuit 5. As a result, synchronous oscillating voltage is generated in the output transformers T ₁ , T ₂ , and T ₃ .

Now, if we use a commercial power supply with an input voltage of 3ψ, each line voltage e ₁ , e ₂ , e ₃ is 2π/3 as shown in Figure 6.
The phases are shifted one by one, and the high frequency conversion circuits 1, 2,
The primary winding voltages V ₁ , V ₂ , and V ₃ of the output transformer No. 3 have waveforms whose envelopes are shifted by 2π/3 as shown in FIG. Therefore, if the output windings of _the output transformers T ₁ , T ₂ , and T ₃ are insulated and separated as shown in FIG. ₁₁ and V ₁₂ voltages.
This size is determined by the number of windings on the secondary side, and if they have the same specifications, V ₁₁ and V ₁₂ will be approximately the same value,
Compared to a single output type with no separate secondary side,
V ₁₁ has an amplitude waveform of approximately 1/2. Therefore, in Figure 2
As shown in Figure 7, V _put is also smooth and 1/2 compared to the single output type, and if rectified and smoothed, the smoothed DC voltage V _D1 becomes 1/2, and the two can be used independently as smoothed DC power supplies. It becomes possible.

Since the present invention is configured as described above, it is possible to provide an independent DC power source to each load (for example, an inverter), and it is possible to individually control the power source of the load. In addition, it becomes easy to supply DC to equipment that requires isolation, which often causes malfunctions due to noise between equipment. Furthermore, it has effects such as low input distortion.

[Brief explanation of drawings]

Figure 1 is a conventional DC power supply, Figure 2 is an operational diagram, Figure 3 is a basic block diagram of the DC power supply, Figure 4 is a concrete circuit, and Figure 5 is V _b , V ₁ , V _{2 .} ，
V ₃ , FIG. 6 e ₁ , V ₁ , e ₂ , V ₂ , e ₃ , V ₃ , FIG. 7 is an explanatory diagram of the operation, and FIG. 8 shows an embodiment of the present invention. 1, 2, 3... High frequency conversion circuit, 4... Rectifying and smoothing circuit, 5... Synchronous circuit, 6... AC power supply, T ₁
~ _T3 ...Oscillation transformer, _Q1 ~ _Q8 ...Transistor, _E0 , _E1 ...DC power supply.

Claims (1)

[Claims] 1. Three sets, each inputting a 3-phase power supply and each line voltage of the above power supply, having almost the same circuit specifications, isolated input and output, and a plurality of n outputs, and each output being isolated from each other. Extract one output of the high frequency conversion circuit and the high frequency conversion circuit from each set,
A DC power supply device comprising n sets of full-wave rectification/smoothing circuits that perform full-wave rectification and smoothing after series synthesis, and a synchronization circuit that operates the high-frequency conversion circuit in synchronization.