JP2586993Y2 - Power supply circuit for semiconductor power converter - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control power supply of a variable speed control device such as an inverter and a servo driver and a main circuit DC voltage detection circuit, and more particularly to a power supply circuit of a semiconductor power conversion device.

[0002]

2. Description of the Related Art In a variable speed controller, detection of a main circuit DC voltage is indispensable from both aspects of control and protection. This DC voltage detection needs to be insulated from the main circuit potential. Currently, there are a method of providing a DC voltage detection circuit using a photocoupler, an insulating amplifier and the like as shown in FIG. 5A, and a method of obtaining a DC voltage detection value from a control power supply output as shown in FIG. 5B. In this method, insulation is provided by a transistor of a control power supply. In FIG. 5, reference numeral 11 denotes a forward converter of an inverter, 12 denotes an inverse converter, and 13 denotes a capacitor of a DC intermediate circuit.

When the system shown in FIG. 5 (b) is adopted, an actual control power supply is constituted, for example, by an RCC (ringing choke converter) system as shown in FIG. In FIG. 6, reference numeral 1 denotes a converter transformer having windings N _P , N _B , N _S1 , N _S2 , and N _S3 , R _G is a starting resistor, Tr ₁ is a switching transistor, R _B is a base resistor, and C _{1 to} C _5. capacitors, D _Z Zener diode, D ₂ to D ₆ are diodes. Diode D ₇ and resistor R are connected in series to the output winding N _S3. Capacitor C ₆ is connected between the resistor R and the common line COM. A diode D ₇ , a resistor R and a capacitor C ₆ shown in the X part of the figure constitute a voltage detection circuit.

[0004] The switching transistor Tr ₁ when the base current ig to flow by application of a DC input voltage V _IN in the circuit configured as above is turned on, then each winding _{N P, N B, N S1} , N S2, N transistor Tr ₁ and induced power _S3 are oN, oFF control is repeated. The power induced in the output winding N _S1 is rectified by the diode D ₄ and the capacitor C ₃ to obtain the output voltage V _{O of the} control power supply.

[0005] Voltage V _NS3 and the detected DC voltage output Vd of the output winding N _S3 is shown as FIG. The RCC switching power supply, the voltage V _OFF during off of the transistor Tr ₁ is used as the power supply output. The voltage V _ON generated when the transistor Tr ₁ is turned on is the input voltage,
That is, it is generated with a magnitude proportional to the main circuit DC voltage.
This V _ON is rectified by a diode D ₇ and passed through a filter of a resistor R and a capacitor C ₆ to obtain a DC voltage detection Vd
Is obtained as a DC value as shown in FIG.

[0006]

When the method shown in FIG. 5A is adopted, a DC voltage detecting circuit using a photocoupler, an insulating amplifier, and the like is separately required, which leads to an increase in cost and a reduction in the size of the apparatus. Hinders When the method shown in FIG. 5B is employed, there is no problem if the control power supply is a normal RCC power supply as shown in FIG. However, low loss, high reliability, and high withstand voltage of the control power supply circuit are required, and the switching transistor of the power supply circuit may be constituted by a high-speed switching element such as an FET. As described above, if the circuit shown in part X in FIG. 6 is used as it is as the DC voltage detection circuit of the power supply circuit using the high-speed switching element, the following problem occurs.

First, the waveforms of the transformer output winding voltage V _NS3 and the DC voltage output Vd are shown in FIG. When the switching element is a MOS-FET, for example, a surge voltage V _Sg is generated at turn-on due to fast switching. This V _Sg is the capacitor C ₆ of the voltage detection circuit X at the _subsequent stage.
Is charged by peak. Therefore, Vd is not the originally desired input voltage proportional portion Vd 'but a higher voltage value. There is no problem if the surge voltage V _Sg is constant within the input voltage range, but since this V _Sg changes depending on the input voltage and the load state of the power supply circuit, linearity which is the most important as a detection output cannot be obtained. .

In FIG. 6, when a DC input voltage V _IN is applied, a base voltage ig flows to the switching transistor Tr ₁ through the starting resistor _RG , and the transistor T 1
r ₁ turns on. The starting resistor _RG has such a role, and is indispensable for the operation principle. 400V
In a system inverter, V _IN = about 600 V (400 V
× 2 ^1/2 = 565 V, 440 × 2 ^1/2 = 622 V), which is 700 to 800 V during regeneration due to sudden deceleration or the like, and V _IN rises to about 1000 to 1200 V during output ground fault protection. Starting resistor Rg can not in excessively high resistance in consideration of such start-up voltage set value of h _FE (current amplification factor) and a power supply circuit of the transistor Tr _1. Generally, the starting voltage of the power supply circuit of the inverter device is required to be 50% or less of the rated input voltage. That is, about 250VDC @ 400 x 0.9 (10% down) for 400V inverter
× 0.5 (50%) × 2 ^1/2 (DC) = about 255 (VD
C) It is required to start the power supply circuit in (1). For this reason, at present, a resistance value of 100 to 150 KΩ and a rated power value of about 8 W or more are required as the starting resistance Rg. Therefore, there is a disadvantage that the size of the printed circuit board is increased.

[0009] Since the base resistance R _B is in consideration of variations of h _FE of the transistor Tr _1, must be so flown sufficient base current I _B minimum input voltage V _{IN (MIN)} also, the base resistance R _B Currently requires about 4 W of rated power. However, this voltage V _B of the base winding N _B
Depends on the design. However, since V _IN is also higher and higher, the more an V _B it is necessary to increase the power capacity of the base resistance R _B, Thus the printed circuit board becomes large, tricky, especially 400V system.

The present invention has been made in view of the above points, and has as its object to detect a detection voltage proportional to an input voltage without being affected by a surge voltage even when a high-speed switching element such as a field effect transistor is used. It is another object of the present invention to provide a power supply circuit of a semiconductor power conversion device that can obtain a small power supply capacity of a starting resistance and a base resistance and can downsize a printed circuit board.

[0011]

SUMMARY OF THE INVENTION The present invention has a main circuit DC intermediate voltage of a semiconductor power converter as an input voltage, and has a base winding wound in reverse polarity to the main winding, and an output winding. A converter transformer, a switching element connected in series to a main winding of the converter transformer, and a voltage divided by a starting resistor and a voltage induced in a base winding are used as power supplies, and an oscillation pulse is supplied to a control terminal of the switching element. Regulator control IC that supplies power
A filter having a cutoff frequency lower than the oscillation frequency of a surge voltage generated when the switching element is turned on, and integrating a voltage induced in an output winding of the converter transformer; and a rectifier for rectifying an output voltage of the filter. And an element.

[0012]

[Function] Main circuit DC intermediate voltage V _{IN of} semiconductor power converter
Is applied, and the voltage reaches the activation start voltage of the switching regulator control IC, the IC starts oscillating. The input voltage at which this oscillation starts is determined by the starting resistance. I for switching regulator control
The switching element is turned on by the oscillation output pulse of C,
When the OFF control is performed, power is supplied to the output winding and a voltage induced in the base winding is supplied to the IC as a power supply V _CC .

[0013] The voltage induced in the output winding of the converter transformer is integrated by a filter, and the integrated output of the filter is rectified by a rectifying element, thereby detecting the main circuit DC voltage.

The surge voltage generated by the high-speed switching of the switching element is removed because the cutoff frequency of the filter is lower than the oscillation frequency of the surge voltage. Therefore, no error occurs due to the surge voltage,
A detection voltage proportional to the input voltage is obtained.

The base winding the power supply voltage V _CC is also input voltage rises for the main winding and the polarity are wound in opposite kept constant. Therefore, the voltage value of the output pulse of the IC becomes constant, and the power capacity of the base resistor connected to the control terminal of the switching element can be small. As a result, the reliability of the device is improved and the size of the printed circuit board can be reduced. In addition, since the switching regulator control IC is used, the starting resistance current becomes small,
As a result, the power capacity of the starting resistor can be small, and the printed circuit board can be downsized.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the same parts as those in FIG. 6 are denoted by the same reference numerals. A switching element, for example, a field effect transistor FE, is connected to the main winding N _P of the converter transformer 1.
T (MOS-FET) is connected in series. R _G1 ,
R _G2 is a starting resistor for dividing the input voltage (main circuit DC voltage) V _IN . Start between the resistors R _G1, R _G2 is connected to one end of the base winding N _B through the Zener diode D _Z and the diode D ₂ of the illustrated polarity. The common connection point of the Zener diode D _Z and the diode D ₂ and the base winding N
Between the other end of _B are connected to the capacitor C _2. Starting resistor R _G1, R common connection point and the base winding N switching regulator control for IC14 is between the other end of the _B of _G2 are connected. The output side of this IC 14 is a base resistor R
It is connected to the gate of the FET via _B. Power each induced in the plurality of output winding of the converter transformer 1 are respectively rectified by the diode D ₄ to D _n and the capacitor C ₄ -C _n, it is supplied as the control power source or driver power supply. Incidentally base winding N _B are wound in opposite polarity to the main winding N _P.

The voltage detection circuit (X ') is configured as follows. By connecting a resistor R and a rectifier diode D to the output winding N _S3 of the converter transformer 1 in series, and a capacitor C to the common connection point of the resistors R and the rectifier diode D, a capacitor C _O is the cathode of the rectifier diode D Connected. The cut-off frequency of the filter comprising the resistor R and the capacitor C is the field-effect transistor F
It is selected to be lower than the oscillation frequency of the surge voltage V _Sg when the ET is turned on.

D _1a and D _1b are diodes, and C _1a and C _1b are capacitors. The input voltage V of the circuit of FIG.
_IN uses a DC intermediate voltage of the main circuit of the inverter shown in FIG. In FIG. 1B, reference numeral 11 denotes a forward conversion unit, 12 denotes an inverse conversion unit, and 13 denotes a capacitor.

In the circuit configured as described above, when the input voltage V _IN is applied, the voltage divided by the starting resistors R _G1 and R _G2 is supplied to the switching regulator control IC 14. The starting current ig at this time is extremely small. When the power supply voltage V _{CC of the} IC 14 reaches the startup start voltage V _CCS , a pulse is output from the OUT terminal at an oscillation frequency set by a resistor and a capacitor externally connected to the IC. The power supply voltage V _{CC at} this time is V _CC = R _g2 · V
_IN / (R _g1 + R _g2 ) = V _CCS . Therefore, the input voltage V _{IN at} which oscillation starts can be set by the starting resistors R _g1 and R _g2 .

The field effect transistor FET is the IC1
4 on the oscillation pulses output, is off-controlled, the capacitor C ₂ and conducts the diode D ₂ when off is supplied as a power supply voltage V _CC to the switching regulator control for IC14 is charged. Zener diode D
_Z operates for voltage value adjustment. Since the power supply voltage V _CC is supplied every time the IC 14 oscillates, the oscillation continues and power is obtained on the output winding side. Since base winding N _B are wound in the opposite direction to the main winding N _P, the input voltage V _IN
The power supply voltage V _CC does not continue to increase with the rise, but is controlled to a constant value. Therefore, the voltage value of the output pulse of the IC 14 is also constant. This makes it possible to reduce the power capacity of the base resistance R _B.

V _NS3 (voltage of output winding N _S3 ), Vd (output voltage of voltage detection circuit X), Vd
₁ (RC filter output voltage) is shown as in FIG.
As can be seen from FIG. 2, since the cut-off frequency of the RC filter is lower than the oscillation frequency of the surge voltage V _Sg generated when the FET is turned on, the filter output voltage waveform Vd ₁ is V
_The waveform has _Sg removed. However, if the cut-off frequency of the RC filter is too low, a desired output cannot be obtained as shown by the broken line in FIG. 2. Therefore, the cut-off frequency is selected so as not to be too low.

In this case, the detection output is actually IC,
Since noise is superimposed on a power supply such as an IC because the signal is processed by an operational amplifier or the like, an error occurs there. In practical use of the above circuit, it is necessary to suppress noise appearing in the power supply output by a common mode filter constituted by an inductance L and a capacitor C as shown in FIG. 3 or a CR absorber as shown in FIG.

The switching regulator control IC 14 is currently commercially available from semiconductor manufacturers. In the embodiment, the switching element is MO
Although the S-FET is used, the invention is not limited to this, and another switching element such as a transistor may be used.

[0024]

As described above, according to the present invention, a switching element is generated by an oscillation output pulse of a switching regulator control IC using a voltage induced in a base winding wound in a direction opposite to a main winding as a power supply. And the cut-off frequency of the filter that integrates the output winding voltage is selected to be lower than the oscillation frequency of the surge voltage generated when the switching element is turned on. Is obtained.

(1) Even if a high-speed switching element such as an FET is used, a desired DC voltage can be detected without being affected by a surge voltage generated when the element is turned on. Moreover, the voltage detection circuit can be constituted only by the RC filter, the rectifying diode and the capacitor. Therefore, a complicated DC voltage detection circuit using a photocoupler, an insulating amplifier, or the like becomes unnecessary, and the device can be reduced in size and cost.

(2) The control power supply can be configured to have low loss and high withstand voltage.

(3) Since the starting current ig is extremely small, the power capacity of the starting resistor can be reduced. Therefore, the size of the printed circuit board can be reduced and the reliability can be improved.

(4) "The printed circuit board becomes large",
In some cases, the control power of the 400 V inverter was obtained from the main power supply via a transformer in view of the fact that "high reliability cannot be obtained". However, if the present invention is applied, the transformer and the rectifier circuit can be eliminated. Therefore, the size of the entire apparatus can be reduced.

[0029] (5) the base winding the power supply voltage V _CC is also input voltage rises for the main winding and the polarity are wound in opposite kept constant. Therefore, the voltage value of the output pulse of the IC becomes constant, and the power capacity of the base resistor connected to the control terminal of the switching element can be small. As a result, the reliability of the device is improved and the size of the printed circuit board can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a voltage waveform chart for explaining the operation of the embodiment.

FIG. 3 is a circuit diagram showing another embodiment of the present invention.

FIG. 4 is a circuit diagram showing another embodiment of the present invention.

FIG. 5 is a circuit diagram showing a conventional DC voltage detection method.

FIG. 6 is a circuit diagram showing an example of a conventional control power supply circuit.

FIG. 7 is a voltage waveform diagram for explaining a conventional voltage detection method.

FIG. 8 is a voltage waveform diagram for explaining a problem when a high-speed switching element is used.

[Explanation of symbols]

1 ... transformer 11 ... rectifier unit 12 ... inverse transform unit _{13, C, C 0 ~C n} , C 1a, C 1b ... capacitor D ... rectifying diode _{D 2 ~D n, D 1a,} D 1b ... diode D _Z ... Zener diode FET: Field effect transistor R _G1 , R _G2 , Start-up resistor R _B : Base resistor 14: Switching regulator control IC X ': Voltage detection circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H02M 3/00-3/44

Claims (1)

(57) [Scope of request for utility model registration] 1. A converter transformer having a main circuit DC intermediate voltage of a semiconductor power converter as an input voltage, a base winding wound in a polarity opposite to that of a main winding, and an output winding; A switching element connected in series to the main winding, and a switching regulator control IC for supplying an oscillation pulse to a control terminal of the switching element, using the voltage divided by the starting resistor and the voltage induced in the base winding as a power supply. A filter having a cutoff frequency lower than the oscillation frequency of the surge voltage generated when the switching element is turned on, and integrating a voltage induced in an output winding of the converter transformer; and a rectifier for rectifying an output voltage of the filter. A power supply circuit for a semiconductor power conversion device, comprising: an element;