JP2009271039A - Circuit applied to current detection of both voltage ends - Google Patents

Abstract

Provided is a circuit applied to current detection at both voltage ends.
When a sense current is applied to both voltage ends, isolation is performed using a MOS metal oxide semiconductor operational amplifier, so that the circuit is not affected by a leakage current and a voltage error is caused by the leakage. There is no. Also, a fixed reference potential can be provided to the next level amplifier, so that the phase is not delayed and the function of synchronization can be achieved. Furthermore, the function of voltage amplification and replenishment voltage removal is executed using a switch and a capacitor, and finally an accurate detection control voltage can be obtained through an arithmetic circuit. In this way, a simple circuit can be used to realize a complicated circuit function.
[Selection] Figure 2

Description

  The present invention relates to a circuit applied to current detection at both voltage ends, and more particularly to a circuit applied to current detection at both voltage ends, which is a high-voltage high-accuracy current detection circuit applied to a flyback converter.

  As shown in FIG. 1, the traditional current detection method uses the voltage difference detected by the electric resistance Rsen between the two voltage ends, and when dividing the voltage via R11 to R14, the equivalent electric resistances R3 and R4 Affected, leakage current occurs, and an error occurs in V3 and V4 and the actual voltage. Further, the previous error amount is amplified through the ratio magnification of R15 and R16. In addition, at this time, the replenishment voltage of the amplifier is also amplified at the same time, and thus these very large error amounts make the detection control voltage very inaccurate, so that the control accuracy is insufficient, and further, the system malfunctions or becomes unstable. Invite.

  The present invention uses a unit buffer formed by an operational amplifier and has an infinite input electrical resistance when input as a metal oxide semiconductor (MOS), thus achieving current detection at both voltage ends to achieve the purpose of high-precision current detection. The circuit which applies to is provided.

The current detection circuit between the two voltage terminals includes at least two sets of electric resistance and phase synchronization circuits, and each of the two sets of electric resistance and phase synchronization circuits includes at least voltage followers E1 / E2 and two sets of voltage amplification. And a replenishment voltage removal circuit, a subtractor,
The voltage follower E1 / E2 makes the signal to be detected correspond to the electrical resistance, receives the signal accurately, and uses the output as a reference signal as the next level synchronization reference signal,
Each circuit of the two sets of voltage amplification and supplementary voltage removal circuits includes at least operational amplifiers E3 / E4, five switches S1 / S2, and two capacitors C1 / KC1, removes supplementary voltages, and two capacitors. Is the voltage amplification factor,
The subtractor circuit includes at least an operational amplifier E5 and necessary electrical resistances R1-R4 on the subtractor circuit feedback route.

The invention of claim 1 includes at least two sets of electric resistance correspondence and phase synchronization circuits, two sets of voltage amplification and supplemental voltage removal circuits, and a subtractor,
The two sets of electrical resistance correspondence and phase synchronization circuits include at least a voltage follower, and the voltage follower achieves electrical resistance correspondence to a signal to be detected, whereby the signal is accurately received and its output is used as a reference signal. Use it as a synchronization reference signal for the next level,
The two sets of voltage amplification and supplementary voltage removal circuits include at least an operational amplifier, five switches, and two capacitors, remove the supplementary voltage, and set the ratio of the two capacitors as a voltage amplification factor.
The subtractor circuit includes at least an operational amplifier and a necessary electric resistance on the subtractor circuit feedback route, and is a circuit applied to current detection at both voltage ends.
According to a second aspect of the present invention, in the circuit applied to current detection at both voltage ends according to the first aspect, the voltage follower of the electric resistance and phase locked loop circuit can be realized by a single operational amplifier. The circuit is applied to current detection at both voltage ends.
According to a third aspect of the present invention, in the circuit applied to the current detection at both voltage ends according to the second aspect, the operational amplifier of the voltage amplification and supplementary voltage removal circuit is a differential input signal and a single-ended output signal. The circuit is applied to current detection at both voltage ends.
According to a fourth aspect of the present invention, in the circuit applied to the current detection at both voltage ends according to the third aspect, one differential input signal in the operational amplifier of the voltage amplification and supplementary voltage removal circuit is a synchronous reference signal. This circuit is applied to current detection at both voltage ends.
According to a fifth aspect of the present invention, in the circuit applied to the current detection of both voltage ends according to the second aspect, the electrical resistance correspondence / phase synchronization circuit and the voltage amplification / replenishment voltage removal circuit are connected in series. The circuit is applied to current detection at both voltage ends.
According to a sixth aspect of the present invention, in the circuit applied to the current detection of both voltage ends according to the second aspect, the electrical resistance correspondence and phase synchronization circuit and the voltage amplification and supplement voltage removal circuit are combined using a switch and a capacitor. The circuit is applied to current detection at both voltage ends characterized by
The invention according to claim 7 is a circuit applied to current detection at both voltage ends according to claim 1, wherein the current detection circuit is applicable to a DC-DC power supply that outputs a high voltage. The circuit is applied to edge current detection.
The invention of claim 8 is a circuit applied to current detection at both voltage ends according to claim 1, wherein the current detection circuit is applicable to an AC-DC power converter that outputs a high voltage. The circuit is applied to edge current detection.
The invention of claim 9 is a circuit applied to current detection at both voltage ends according to claim 1, wherein the current detection circuit is applicable to a display product such as a field effect display. The circuit is applied to current detection.
According to a tenth aspect of the present invention, in the circuit applied to the current detection at both voltage ends according to the first aspect, the current detection circuit can be applied to a flyback converter. The circuit is applied.

  The present invention is a high-voltage, high-precision current detection circuit applied to a flyback converter, which can improve the current situation where the detection control voltage in the prior art is inaccurate and the control accuracy is insufficient.

FIG. 2 is a flowchart of the present invention. The high voltage current detection circuit 201 outputs a pair of voltages to the voltage dividing circuit 202. In practice, the counter voltage is about 100 volts or more, and after voltage division through the voltage dividing circuit 202, a voltage received by a pair of analog product circuits can be obtained, and the electric resistance correspondence and phase synchronization circuit 203a, Transmit to 203b.
The circuits 203a and 203b transmit the voltage to the voltage amplification and supplementary voltage removal circuits 204a and 204b after the electrical resistance and phase synchronization, and one of them is a synchronization reference signal having driving capability. Finally, a subtraction operation is directly performed by the arithmetic circuit 205 to obtain an accurate voltage, which can be converted into a highly accurate current.

The electrical resistance and the voltage follower of the phase locked loop are optimally realized by a metal oxide semiconductor operational amplifier.
The operational amplifier of the voltage amplification and supplemental voltage removal circuit is a differential input signal and a single-ended output signal, and one of the differential input signals is a synchronization reference signal for the next level circuit.
The electrical resistance correspondence and phase synchronization circuit and the voltage amplification and supplemental voltage removal circuit are connected in series.

FIG. 3 is a circuit diagram of the present invention.
When the voltage difference detected by the electric resistance Rsen is used and voltage division is performed via R11 to R14, the E2 and E5 input electric resistances are infinite, so the voltage levels of VA and VB are not affected. In addition, the driving capability can be provided, and the reference potential of the operational amplifiers E3 and E4 can be used.
Furthermore, the capacitor C1 and the capacitor KC1 (that is, a K times C1 capacitor?) Are provided with functions of voltage amplification and offset cancellation, and finally an accurate output voltage can be obtained through a subtractor.

The present invention can be applied to a voltage of V1 and V2 of several thousand volts, and the voltage difference V2-V1 detected by Rsen is about several tens of volts, and after being shrunk and reduced by a factor of 1000 through electrical resistances R11 to R14, The voltage difference between the points A and B is as small as several tens of millivolts (the voltage difference is 33 millivolts as shown in FIG. 3). Therefore, the voltage at both points A and B is always very accurate, and other electrical resistances are connected in parallel, so there is no leakage. Therefore, the voltage buffer constituted by the operational amplifiers E2 and E5 is adopted, the achieved electrical resistance correspondence is isolated, and there is no leakage, so that accurate A and B voltage levels can be obtained.
V1 and V2 are time-varying signals obtained by adding a ripple voltage to a DC voltage, and A and B cause a phase delay. Therefore, a fixed voltage level VREF (see FIG. 3, see VREF) through a voltage buffer formed by operational amplifiers E2 and E5. VDIF is equivalent to VA and VB respectively). As a result, the reference points of the operational amplifiers E3 and E4 in the voltage amplification and supplementary voltage removal circuit become the same point, and the phase delay error can be removed and the phase synchronization function can be obtained.

FIG. 4 is an equivalent circuit diagram of the present invention (S1 = 1, S2 = 0). As can be understood by those skilled in the art, at this time, the equivalent circuit is switched, and the capacitor storage charge of the capacitor increase class is increased. Is in a state.
FIG. 5 is an equivalent circuit diagram of the present invention (S1 = 0, S2 = 1). As can be understood by those skilled in the art, the equivalent circuit is a negative feedback route of operational amplifiers E3 and E4. With the capacitors C1 / KC1 and C2 / KC2 above, an operation of K-fold amplification can be performed and an offset cancel operation can be performed.

At the same time, the circuit of the combined operational amplifier E3, E4 for voltage amplification and replenishment voltage removal using switches and capacitors amplifies the voltage of tens of millivolts to several volts (VSC1 = 1.1 volts, VSC2 = 4.4 volts), Further, a subtractor circuit constituted by an operational amplifier E1 is entered, a differential voltage (VOUT2 = 3.3 volts as shown in FIG. 4) is computed and calculated, and an analog conversion digital circuit or the like is entered for processing. Since both the points A and B are accurate voltages, the voltages at both points are still accurate voltages through the circuits of the operational amplifiers E3 and E4. Finally, after passing through the subtractor constituted by the operational amplifier E1, an accurate voltage difference is obtained, and the system performance can be optimized by precise control.
The present invention can be applied to a DC-DC (push-pull, etc.) power supply or AC-DC power converter that outputs a high voltage, and all of these high-accuracy current detection circuits can be employed. At the same time, the detection circuit can be applied as a product to a display product such as a field effect launch display or a consumer electronic product having a power source change.

1 is a schematic diagram of an embodiment of a known technique. 3 is a flowchart of the present invention. It is the Example schematic of this invention. It is the Example schematic of this invention. It is the Example schematic of this invention.

Explanation of symbols

E1, E2, E3, E4, E5 operational amplifier
R1, R2, R3, R4 Electric resistance
R11, R12, R13, R14 Electrical resistance
R16, R17, R18 Electric resistance
Rsen electrical resistance
C1, KC1, C2, KC2 capacitors
201 High voltage current detection circuit
202 voltage divider circuit
203a, 203b Electrical resistance and phase synchronization circuit
204a, 204b Voltage amplification and supplement voltage removal circuit
205 Arithmetic circuit

Claims (10)

Including at least two sets of electrical resistance and phase synchronization circuits, including two sets of voltage amplification and supplemental voltage removal circuits, a subtractor,
The two sets of electrical resistance correspondence and phase synchronization circuits include at least a voltage follower, and the voltage follower achieves electrical resistance correspondence to a signal to be detected, whereby the signal is accurately received and its output is used as a reference signal. Use it as a synchronization reference signal for the next level,
The two sets of voltage amplification and supplementary voltage removal circuits include at least an operational amplifier, five switches, and two capacitors, remove the supplementary voltage, and set the ratio of the two capacitors as a voltage amplification factor.
The subtractor circuit includes at least an operational amplifier and a necessary electric resistance on the subtractor circuit feedback route.   2. A circuit applied to current detection at both voltage ends according to claim 1, wherein the voltage follower of said electric resistance correspondence and phase locked loop circuit can be realized by one operational amplifier. Application circuit.   3. The circuit applied to current detection at both voltage ends according to claim 2, wherein the operational amplifier of the voltage amplification and supplemental voltage removal circuit is a differential input signal and a single-ended output signal. Circuit applied to current detection.   4. A circuit applied to current detection at both voltage ends according to claim 3, wherein one differential input signal of the operational amplifier of said voltage amplification and supplementary voltage removal circuit is a synchronous reference signal. Circuit applied to edge current detection.   3. A circuit applied to current detection at both voltage ends according to claim 2, wherein the electric resistance correspondence and phase synchronization circuit and the voltage amplification and supplementary voltage removal circuit are connected in series. Application circuit.   3. A circuit applied to current detection at both voltage terminals according to claim 2, wherein said electric resistance correspondence and phase synchronization circuit and said voltage amplification and supplement voltage removal circuit are combined using a switch and a capacitor. This circuit is applied to current detection.   2. A circuit applied to current detection at both voltage ends according to claim 1, wherein the current detection circuit is applicable to a DC-DC power supply that outputs a high voltage. circuit.   2. A circuit applied to current detection at both voltage ends according to claim 1, wherein the current detection circuit is applicable to an AC-DC power converter that outputs a high voltage, and is applied to current detection at both voltage ends. circuit.   2. The circuit applied to current detection at both voltage ends according to claim 1, wherein the current detection circuit is applicable to a display product such as a field effect emission display.   2. The circuit applied to current detection at both voltage ends according to claim 1, wherein the current detection circuit is applicable to a flyback converter.

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