JP3214337B2 - Power system voltage detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power system voltage (bus voltage) monitor in a power transmission system.
The present invention relates to a power system voltage detection device that separates a power system voltage (bus voltage) ground potential from an output signal ground potential.

[0002]

2. Description of the Related Art A large number of electronic components are used in equipment mounted on a body that flies in space, such as an artificial satellite and a space shuttle, and almost no equipment can continue operation without power. Therefore, when an operation abnormality of the device occurs, first, it is confirmed whether or not there is an abnormality in the power system. Here, the power system refers to a path from a power generation source by a solar cell to supply to individual power consuming devices (loads) through processes such as stabilization and distribution of power. Monitoring the voltage of this system depends on the power generation capacity of the solar cell,
This monitors the stability of the power, the power distribution function, and the like. In other words, the abnormality in the power system can be identified. In the power system voltage monitoring, the power system voltage (bus voltage) detection signal has a ground potential at a specific position on the system power line. This potential fluctuates based on the transient change of the system load current and the system line impedance. Such a change in the ground potential causes destruction of a circuit for processing a power system voltage (bus voltage) detection signal (hereinafter, referred to as a signal processing circuit) or a reduction in detection accuracy, and is therefore prevented. For this purpose, it is necessary to separate the ground of the power system voltage (bus voltage) detection signal from the ground of the signal processing circuit.

Further, in outer space, the surface irradiated with sunlight is at least + 100 ° C., and the surface not exposed to sunlight is at -10 ° C.
It can be below 0 ° C. This means that the ambient temperature in which the device is used can reach that temperature. Therefore, the operation guarantee temperature range required for the device is wider than that for a device used in a room on the earth equipped with air conditioning equipment.
As typified by superconductivity, the characteristics of electronic components change depending on temperature. An increase in the operation guarantee temperature range of the operation of the device causes a result that the temperature dependency of the electronic component is remarkably exhibited. As a device, it is necessary to minimize the influence of the temperature dependency on the characteristics of the device.
This is because if the detected voltage value of the monitored power system changes, it cannot be determined whether the change is due to a change in the power system voltage itself or a change in the characteristics of the signal processing circuit.

FIG. 8 shows a prior art in which the bus voltage detection signal is pulse-width modulated, transmitted via a photocoupler, and demodulated, thereby separating the bus voltage ground potential and the bus voltage output signal ground potential. FIG. 1 is a schematic diagram of a power system voltage detection device of FIG. 2 is a sawtooth wave generator composed of a constant current source a, a pulse generator b, a transistor c, and a capacitor d, 3 is a comparator, 4 is a bus voltage ground potential, 5 is a bus voltage output signal ground potential, and 6 is a photo. A coupler, 7 is a Zener voltage generating resistor, 8 is a Zener diode, 9 is an output filter (integrating circuit) including a resistor R9 and a capacitor C9, Vin is a bus voltage detection signal,
VD is a sawtooth generator output signal, VP is a comparator output signal, VC is a collector potential of a phototransistor in a photocoupler, and Vout is a bus voltage output signal.

The operation principle of FIG. 8 will be described below. The magnitude relationship between the bus voltage detection signal Vin and the sawtooth wave DD generated by the sawtooth wave generator 2 is compared by the comparator 3, and the output of the comparator 3 is high when Vin> VD and low when Vin <VD. , And Vin is a pulse width modulated signal VP. Here, the maximum value (peak value) of the sawtooth wave VD
Is VDMAX, the minimum value is O, the repetition period is T, and Vin>
Assuming that the time width during which VD is established is THigh, the duty ratio DHi of the high level of the output signal VP of the comparator 3 is high.
gh is given by “Equation 1”.

[0006]

(Equation 1)

The output signal VP of the comparator 3 is separated from the side where the bus voltage ground potential 4 is set to the ground potential by way of the photocoupler 6 to the side where the bus voltage output signal ground potential 5 is set to the ground potential. Is transmitted.
The collector potential VC of the photocoupler 6 is at a high level (off state) when the output signal VP of the comparator 3 is at a high level, and at a low level (on state) when the output signal VP is at a low level. At this time, the bus voltage output signal Vout has an upper limit of a voltage VZ determined by the Zener voltage generating resistor 7 and the Zener diode 8 according to the on / off state of the photocoupler 6, and an output filter (R9) including a resistor R9 and a capacitor C9. Integration circuit) 9
And outputs a voltage that fluctuates depending on the time constant. By setting this time constant sufficiently larger than the repetition period of the output signal VP of the comparator 3, the fluctuation of Vout is suppressed and the output is stabilized. The output signal Vout of the output filter (integrating circuit) 9 is given by "Equation 2".

[0008]

(Equation 2)

FIG. 9 shows changes in signals and voltages of respective parts in the above operation in relation to time. In the above operation, the bus voltage detection signal Vin is pulse width modulated to become the comparator output signal VP, and further demodulated to obtain Vi as shown in "Equation 2".
A bus voltage output signal Vout which is a value proportional to n is obtained.

[0010]

In the power system voltage detection device as described above, as can be seen from "Expression 2", the high-level duty ratio DHigh of the rectangular wave VP which is the output signal of the comparator 3 corresponds to the bus. This is a factor that determines the voltage output signal Vout. This duty ratio is determined by the peak value VDMAX of the sawtooth wave VD. If this value is a constant that is not affected by any external factors, the duty ratio is constant. Therefore, the bus voltage corresponding to the bus voltage detection signal Vin The output signal Vout is uniquely determined. However, in an actual use environment, there is a change in the environmental temperature, and accordingly, the environmental temperature such as a change in the peak value VDMAX of the sawtooth wave VD due to a change in the capacitance of the capacitor d which is a component of the sawtooth wave generator 2. Because there are factors that fluctuate due to changes in
It is impossible to keep the duty ratio constant. This causes a problem that the bus voltage output signal Vout fluctuates even though the bus voltage detection signal Vin is constant.

The present invention has been made to solve such a problem, and a certain bus voltage detection signal V
The bus voltage output signal Vou which is uniquely determined while correcting the variation of the factor affected by the change of the environmental temperature with respect to the in.
The aim is to get t.

[0012]

A power system voltage detecting apparatus according to the present invention includes a differential amplifier having a bus voltage detection signal and a feedback signal as inputs, and outputs the differential amplifier and the sawtooth wave generator. A pulse width modulation signal which is an output of the signal transmission circuit is provided, and a signal transmission circuit for transmitting the output signal of the comparator in a form separated from the bus voltage ground potential is provided. A first demodulation circuit for receiving the bus voltage output signal and demodulating the signal to a signal having a ground potential at the ground potential; providing an output of the first demodulation circuit as a bus voltage output signal; and an output signal of the comparator. A second demodulation circuit for demodulating the pulse width modulated wave into a signal having a bus voltage ground potential as a ground potential is provided.
The output of the second demodulation circuit is used as a feedback signal, and this feedback signal is input to the differential amplifier together with the bus voltage detection signal.

Further, the power system voltage detecting device according to the present invention includes a differential amplifier having a bus voltage detection signal and a feedback signal as inputs, and determines the magnitude relationship between the output of the differential amplifier and the output of the sawtooth wave generator. A comparator for comparing and pulse width modulation is provided, and a first photocoupler connected so as to transmit an output signal of the comparator in a form separated from the bus voltage ground potential is provided, and a photocoupler in the first photocoupler is provided. A first Zener diode is provided in which the collector side of the transistor is connected to the cathode, the emitter side is connected to the anode, the anode side is a bus voltage output signal ground potential, and the positive side output of a power supply having the bus voltage output signal ground potential as a ground potential. A first Zener potential generating resistor connected between the cathode side of the first Zener diode and a first Zener diode is provided. A first output filter which integrates the Zener voltage (integration circuit) is provided, the output signal of the first output filter (integrator circuit) and the bus voltage output signal,
A second photocoupler connected to transmit the output signal of the comparator; a collector of a phototransistor in the second photocoupler connected to a cathode; an emitter connected to an anode; and an anode connected to a bus. A second Zener diode with a voltage ground potential is provided,
A second Zener potential generating resistor connected between the plus side output of the power supply having the bus voltage ground potential as the ground potential and the cathode side of the second Zener diode;
A second output filter (integrating circuit) for integrating the Zener voltage of the second Zener diode is provided, and the output signal of the second output filter (integrating circuit) is used as a feedback signal, and this feedback signal is used together with a bus voltage detection signal. The input is to the differential amplifier.

[0014] A power system voltage detecting apparatus according to the present invention comprises:
A differential amplifier that inputs the bus voltage detection signal and the feedback signal is provided.A comparator that compares the magnitude relationship between the output of the differential amplifier and the output of the sawtooth wave generator and performs pulse width modulation is provided, and is reset on the primary side. A transformer having a winding and a winding on the secondary side for branching a comparator output for a bus voltage output signal and a feedback signal, and connected so as to transmit the comparator output in a form separated from the bus voltage ground potential. The reset winding side of the transformer is connected to the cathode, the anode side is provided with a diode having a bus voltage ground potential, the first current limiting resistor connected to the secondary winding for the bus voltage output signal of the transformer is provided, A first transistor having a first current limiting resistor connected to a base, an emitter having a bus voltage output signal ground potential on the emitter side, and a collector connected to the cathode on the collector side of the first transistor, A first Zener diode connected to the anode is provided, and a first Zener voltage connected between a positive side output of a power supply having a bus voltage output signal ground potential as a ground potential and a cathode side of the first Zener diode. Output filter (integration circuit) that provides a generating resistor and integrates the Zener voltage of the first Zener diode
The output signal of the output filter (integrating circuit) is used as a bus voltage output signal, and further, a second current limiting resistor connected to the secondary winding for the feedback signal of the transformer is provided.
A second transistor having a second current limiting resistor connected to the base and an emitter side having a bus voltage ground potential,
A second Zener diode is provided in which the collector side of the second transistor is connected to the cathode and the emitter side is connected to the anode, and between the positive output of the power supply with the bus voltage ground potential as the ground potential and the cathode of the second Zener diode. And a second output filter (integrating circuit) for integrating the Zener voltage of the second Zener diode, and an output of the second output filter (integrating circuit). Signal as a feedback signal,
This feedback signal is input to the differential amplifier together with the bus voltage detection signal.

Further, the power system voltage detecting apparatus according to the present invention includes a differential amplifier having a bus voltage detection signal and a feedback signal as inputs, and determines the magnitude relationship between the output of the differential amplifier and the output of the sawtooth wave generator. A comparator for comparing and pulse width modulation is provided, and a transformer having a reset winding on the primary side and connected so as to transmit an output signal of the comparator in a form separated from a bus voltage ground potential is provided. A diode having a reset winding connected to the cathode and an anode connected to the bus voltage ground potential is provided, a first current limiting resistor connected to the secondary winding of the transformer is provided, and the first current limiting resistor is used as a base. And a first transistor whose emitter side is set to a bus voltage output signal ground potential. The collector side of the first transistor is connected to the cathode and the emitter side is connected to the ground. A first zener diode connected to the first node, and a first zener voltage generator connected between a plus side output of a power supply having a bus voltage output signal ground potential as a ground potential and a cathode side of the first zener diode. Output filter (integration circuit) that integrates the zener voltage of the first zener diode by providing a resistance for integration
The output signal of the first output filter (integrating circuit) is used as a bus voltage output signal, and a second current limiting resistor connected to the output side of the comparator is provided. Is connected to the base, a second transistor having an emitter side at the bus voltage ground potential is provided, and a third transistor having the collector side connected to the base and the emitter side at the bus voltage ground potential is provided. A third current limiting resistor connected between a positive side output of a power supply having a bus voltage ground potential as a ground potential and a base side of a third transistor, a collector side of the third transistor being a cathode, an emitter being A second Zener diode connected to the anode is provided, and the plus side output of the power supply having the bus voltage ground potential as the ground potential and the second Zener diode are provided. A second Zener voltage generating resistor connected between the cathode side of the diode and a second output filter (integrating circuit) for integrating the Zener voltage of the second Zener diode; The output signal of the (integration circuit) is used as a feedback signal, and this feedback signal is input to the differential amplifier together with the bus voltage detection signal.

A power system voltage detecting device according to the present invention comprises:
A differential amplifier having a bus voltage detection signal and a feedback signal as inputs is provided, and a comparator for comparing the magnitude relationship between the output of the differential amplifier and the output of the sawtooth wave generator and performing pulse width modulation is provided. A first current limiting resistor connected to a positive side of a power supply having a ground potential is provided, and a first transistor having a first current limiting resistor connected to a collector is provided based on an output side of the comparator, Based on the output side of the comparator, a second transistor having the emitter side of the first transistor connected to the emitter, the collector side having a bus voltage ground potential, and the second transistor connected to the emitter side of the first transistor is provided. One large-capacitance capacitor, a first high-resistance for insulation connected in parallel with the first large-capacity capacitor, and a second large-capacity capacitor connected to the collector of the second transistor. A capacitor is provided, a second high-resistance for insulation is provided in parallel with the second large-capacitance capacitor, and a side of the first large-capacity capacitor that is not connected to the first transistor is a cathode, and a second large-capacity capacitor is provided. A first zener diode having a side not connected to the second transistor connected to the anode, and a first zener diode having the anode side as a bus voltage output signal ground potential, and a first output filter for integrating the zener voltage of the first zener diode (Integration circuit), the output signal of the first output filter (integration circuit) is used as a bus voltage output signal, and the second current limiting resistor is connected to the positive side of a power supply that uses the bus voltage ground potential as a ground potential. A third transistor having a collector connected to a second current limiting resistor based on the output side of the comparator, A fourth transistor having a base connected to the emitter, an emitter connected to the emitter of the third transistor, and a collector connected to the bus voltage ground potential. A second zener diode having a collector connected to the anode, a second output filter (integration circuit) for integrating the zener voltage of the second zener diode, and a second output filter (integration circuit) Is used as a feedback signal, and this feedback signal is input to the differential amplifier together with the bus voltage detection signal.

Further, the power system voltage detecting apparatus according to the present invention includes a differential amplifier having a bus voltage detection signal and a feedback signal as inputs, and determines the magnitude relationship between the output of the differential amplifier and the output of the sawtooth wave generator. A comparator for comparing and pulse width modulation is provided, a first current limiting resistor connected to a positive side of a power supply having a bus voltage ground potential as a ground potential is provided, and a first current limiting resistor is provided based on an output side of the comparator. A first transistor having a limiting resistor connected to a collector, a second transistor having an output side of the comparator as a base, an emitter side of the first transistor connected to an emitter, and a collector side having a bus voltage ground potential. Is provided, a first large-capacity capacitor connected to the emitter side of the first transistor is provided, and a first insulating high resistance connected in parallel with the first large-capacitance capacitor is provided. A second large-capacitance capacitor connected to the collector side of the transistor is provided, a second insulating high resistance connected in parallel with the second large-capacity capacitor is provided, and a first transistor of the first large-capacity capacitor is provided. A first terminating resistor connected between the non-connected side and the side of the second large-capacitance capacitor not connected to the second transistor, and a first integration for integrating a voltage across the first terminating resistor; A first discharging resistor connected in parallel with the capacitor in the first integrating circuit; an output signal of the first integrating circuit as a bus voltage output signal; and a bus voltage ground signal as a ground potential. A second current limiting resistor connected to the positive side of the power supply, and a third transistor having a collector connected to the second current limiting resistor based on the output side of the comparator, A fourth transistor having the emitter side of the third transistor connected to the emitter, the collector side connected to the bus voltage ground potential, and the emitter side of the third transistor and the fourth transistor A second terminating resistor connected between the collector side is provided, a second integrating circuit for integrating a voltage between both ends of the second terminating resistor is provided, and a second terminating resistor connected in parallel with a capacitor in the second integrating circuit is provided. An output signal of the second integrating circuit is provided as a feedback signal, and the feedback signal is input to the differential amplifier together with a bus voltage detection signal.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a block diagram showing Embodiment 1 of the present invention. In FIG. 1, 2, 3, 4, 5, Vin,
VD, VP and Vout are exactly the same as in the conventional device. Reference numeral 1 denotes a differential amplifier having a bus voltage detection signal Vin and a feedback signal VR as inputs, and MT a signal transmission circuit for transmitting a pulse width modulation signal output from the comparator 3 in a form separated from a bus voltage ground potential. , MD1 are signal transmission circuits MT
The first demodulation circuit MD2 demodulates the pulse width modulation signal, which is the output of the comparator 3, into a bus voltage output signal whose ground potential is the ground potential. This is a second demodulation circuit for demodulating a feedback signal whose ground potential becomes the ground potential.

In the power system voltage detecting device configured as described above, the bus voltage detecting signal Vin passes through the differential amplifier 1 together with the feedback signal VR and the output signal VAM of the differential amplifier 1
Output as P. Here, the gain of the differential amplifier 1 is k
Then, the output signal VAMP of this differential amplifier becomes “Equation 3”
Given by

[0020]

(Equation 3)

The magnitude relationship between the differential amplifier output signal VAMP and the sawtooth wave VD generated by the sawtooth wave generator 2 is compared by a comparator 3. The output of the comparator 3 is at a high level when VAMP> VD. When VAMP <VD, the waveform becomes a low-level rectangular wave, and VAMP becomes a pulse width modulated signal VP. At this time, the high-level duty ratio DHigh of VP is equal to the aforementioned "
The output signal VP of the comparator 3 is applied to the bus voltage output signal ground potential 5 in a form separated from the side having the bus voltage ground potential 4 as the ground potential by the signal transmission circuit MT. The signal is transmitted to the first demodulation circuit MD1, which operates as the ground potential.
Is demodulated into a DC signal here and output as a bus voltage output signal Vout. "Equation 4" is established between the signal VAMP before modulation and the signal Vout after demodulation using the undetermined coefficient A.

[0022]

(Equation 4)

On the other hand, the pulse width modulation signal VP output from the comparator 3 is also input to the second demodulation circuit MD2.
The pulse width modulation signal transmitted to the second demodulation circuit MD2 is demodulated into a DC signal here and output as a feedback signal VR. Here, the first demodulation circuit MD1 and the second demodulation circuit MD2
Are exactly the same, the feedback signal VR becomes the same signal as the bus voltage output signal Vout. Therefore, "Equation 5" holds.

[0024]

(Equation 5)

The feedback signal VR is used as the bus voltage detection signal V
The signal is input to the differential amplifier 1 together with in. Thereafter, the above operation is repeated, so that negative feedback is applied. If "VAMP" and "VR" are eliminated from "Equation 3", "Equation 4", and "Equation 5" and arranged, "Equation 6" is established. .

[0026]

(Equation 6)

In Expression 6, if, for example, k = ∞, Expression 7 is satisfied.

[0028]

(Equation 7)

Therefore, from Equation 7, the relationship between the bus voltage detection signal Vin and the bus voltage output signal Vout can be expressed by an expression that does not include the undetermined coefficient A, and Vout is uniquely determined in correspondence with Vin. Is obtained.

Embodiment 2 FIG. FIG. 2 is a configuration diagram showing a second embodiment of the present invention. In FIG.
4, 5, 6, 7, 8, 9, Vin, VD, VP, VC and Vout are exactly the same as those of the conventional device. Reference numeral 1 denotes a differential amplifier having a bus voltage detection signal Vin and a feedback signal VR as inputs, and 10, 11, 12, and 13 denote 6, 7, 8, 9 respectively.
And is provided for the feedback signal.

In the power system voltage detecting device configured as described above, the bus voltage detecting signal Vin passes through the differential amplifier 1 together with the feedback signal VR and the output signal VAM of the differential amplifier 1
Output as P. Here, the gain of the differential amplifier 1 is k
Then, the output signal VAMP of this differential amplifier is
The magnitude relationship between the differential amplifier output signal VAMP and the sawtooth wave VD generated by the sawtooth wave generator 2 is compared by a comparator of 3, and the output of the comparator 3 is VAMP> V.
A rectangular wave having a high level at D and a low level at VAMP <VD is obtained, and Vin is a pulse width modulated signal VP. At this time, the duty ratio DHigh of the high level of VP is given by the same equation as the above "Equation 1".

The output signal VP of the comparator 3 is separated from the side having the bus voltage ground potential 4 as the ground potential by way of the photocoupler 6 to the side having the bus voltage output signal ground potential 5 as the ground potential. Is transmitted.
The collector potential VC of the photocoupler 6 is at a high level (off state) when the output signal VP of the comparator 3 is at a high level, and at a low level (on state) when the output signal VP is at a low level. At this time, the bus voltage output signal Vout indicates that the photocoupler 6 is on,
In response to turning off, a voltage VZ determined by the Zener voltage generating resistor 7 and the Zener diode 8 is set as an upper limit.
Filter (integrating circuit) composed of a capacitor and a capacitor C9
9 to output a voltage that fluctuates depending on the time constant. By setting this time constant sufficiently larger than the repetition period of the output signal VP of the comparator 3, the fluctuation of Vout is suppressed,
Output is stabilized. Here, Vout is given by "Equation 8".

[0033]

(Equation 8)

FIG. 3 shows changes in signals and voltages of the respective parts in the above operation in accordance with time. next,
The pulse width modulation signal VP output from the comparator 3 is
A bus voltage output signal composed of the photocoupler 10, the Zener voltage generating resistor 11, the Zener diode 12, and the output fill 13 is demodulated by the same circuit as the circuit having the ground potential as the ground potential, and is output as the feedback signal VR. Therefore, the feedback signal VR becomes the bus voltage output signal Vout
And the same signal. Therefore, the above “Equation 5” is established. This feedback signal VR is input to the differential amplifier 1 together with the bus voltage detection signal Vin. Thereafter, the above operation is repeated and negative feedback is applied. Therefore, if VAMP and VR are eliminated and rearranged from "Equation 3", "Equation 5", and "Equation 8", "Equation 9" is established.

[0035]

(Equation 9)

In equation (9), if k = ｋ, for example, the term including the peak value VDMAX of the sawtooth wave VD, which is a variation factor of the bus voltage output signal Vout, is a value sufficiently smaller than 1, so that "Equation 10" holds.

[0037]

(Equation 10)

Therefore, from "Equation 10", since the relationship between the bus voltage detection signal Vin and the bus voltage output signal Vout is given by an expression that does not include a variation factor, Vout uniquely determined in accordance with Vin is determined. Will be obtained.

In the above description, the expression of high or low with respect to the signal or voltage level is a relative concept, and the same effect can be obtained even if the level is inverted.

Embodiment 3 FIG. 4 is a configuration diagram showing a third embodiment of the present invention. In FIG.
4, 5, 6, 7, 8, 9, Vin, VD, VP, VC and Vout are exactly the same as those of the conventional device. Reference numeral 1 denotes a differential amplifier which receives a bus voltage detection signal Vin and a feedback signal VR as inputs, and 11, 12, and 13 are the same as 7, 8, and 9, respectively.
4 is a transformer, 15 is a diode, 16 is a first current limiting resistor, 17 is a first transistor, 18 is a second current limiting resistor, and 19 is a second transistor.

In the power system voltage detection device configured as described above, the bus voltage detection signal Vin passes through the differential amplifier 1 and is output as the output signal VAMP of the differential amplifier 1. The output signal VAMP of the differential amplifier 1 is given by the same equation as in the above "Equation 3". The magnitude relationship between the differential amplifier output signal VAMP and the sawtooth wave VD generated by the sawtooth wave generator 2 is compared by a comparator 3 and the output of the comparator 3 is V
A rectangular wave having a high level when AMP> VD and a low level when VAMP <VD is obtained, and Vin is a pulse width modulated signal V
Becomes P. At this time, the high-level duty ratio D of VP
High is given by the same equation as in the above “Equation 1”.

The output signal VP of the comparator 3 is
The bus voltage output signal is transmitted to the side where the ground potential 5 is used as the bus voltage output signal in a form separated from the side where the bus voltage ground potential 4 is used as the ground potential. A reset winding LR is provided on the primary side of the transformer 14, and the excited energy is used when the output VP of the comparator 3 is at a low level.
Regeneration to the power supply side via 5 prevents the transformer from saturating. Further, the secondary side of the transformer has a first secondary winding LS1 and a second secondary winding LS2.

First, the first secondary winding L of the transformer 14
The output signal VP of the comparator 3 transmitted via S1 drives the first transistor 17 through the first current limiting resistor 16. The collector voltage VC of this transistor 17
Is high level (off state) when VP is high level,
When it is at the low level, it becomes low level (on state). At this time, the bus voltage output signal Vout is the first transistor 1
7, a voltage V determined by a Zener voltage generating resistor 7 and a Zener diode 8 in accordance with the level of the collector potential VC.
With Z as the upper limit, a voltage that varies depending on the time constant of an output filter (integrating circuit) 9 including a resistor R9 and a capacitor C9 is output. This time constant is used as the output signal V of the comparator 3.
By setting it sufficiently larger than the repetition period of P, the fluctuation of Vout is suppressed and the output is stabilized. Here, Vout is given by the above “Equation 8”. In addition, the case where the change of the signal and voltage of each part in the above operation is made to correspond to the time is also the same as FIG.

On the other hand, the output signal VP of the comparator 3 transmitted via the second secondary winding LS2 on the secondary side of the transformer 14
Is the second current limiting resistor 18, the second transistor 1
9, a second Zener voltage generating resistor 11, a second Zener diode 12, and a second output filter (integrating circuit) 13. The output is passed through a circuit. The output signal ground potential 5 is set to be the same as the circuit that sets the ground potential, and this output signal is the same as the bus voltage output signal Vout. This signal is input to the differential amplifier 1 together with the bus voltage detection signal Vin as a feedback signal VR. With such a configuration, the negative feedback is applied to the bus voltage detection signal Vin, so that the above-mentioned “Equation 9” and “Equation 10” are satisfied. As a result, the bus voltage detection signal Vin and the bus The relationship of the voltage output signal Vout is given by an equation that does not include a variation factor, and Vout uniquely determined in correspondence with Vin is obtained.

In the above description, the expression of high or low with respect to the signal or voltage level is a relative concept, and the same effect can be obtained even if the level is inverted.

Embodiment 4 FIG. FIG. 5 is a configuration diagram showing a fourth embodiment of the present invention. In FIG.
4, 5, 7, 8, 9, Vin, VD, VP, VC and Vou
t is exactly the same as the conventional device. 1 is a differential amplifier having a bus voltage detection signal Vin and a feedback signal VR as inputs.
1, 12, 13 are the same as 7, 8, 9 respectively, 15 is a diode, 16 is a first current limiting resistor, 17 is a first transistor, 20 is a transformer, 21 is a second current limiting resistor, and 22 is The second transistor, 23 is a third current limiting resistor, and 24 is a third transistor.

In the power system voltage detecting device configured as described above, the bus voltage detecting signal Vin passes through the differential amplifier 1 and is output as the output signal VAMP of the differential amplifier 1. This differential amplifier output signal VAMP and the sawtooth wave generator 2
The magnitude relationship with the sawtooth wave VD generated in the above is compared by the comparator 3, and the output of the comparator 3 is at a high level when VAMP> VD.
A rectangular wave having a low level when AMP <VD is obtained, and Vin becomes a pulse width modulated signal VP. At this time, the duty ratio DHigh of the high level of VP is given by the same equation as the above "Equation 1".

The output signal VP of the comparator 3 is
Through 0, the bus voltage output signal is transmitted to the side having the ground potential 5 as the ground potential in a form separated from the side having the bus voltage ground potential 4 as the ground potential. A reset winding LR is provided on the primary side of the transformer 20, and the energy excited when the output VP of the comparator 3 is at a low level and the diode 1 when the output VP is at a high level.
Regeneration to the power supply side via 5 prevents the transformer from saturating. The output signal VP of the comparator 3 transmitted via the secondary winding LS of the transformer drives the first transistor 17 through the first current limiting resistor 16. The collector voltage VC of this transistor is at a high level (off state) when VP is at a high level, and at a low level (on state) when VP is at a low level. At this time, the bus voltage output signal Vout is equal to the collector potential V of the first transistor 17.
A voltage fluctuating depending on a time constant of an output filter (integrating circuit) 9 including a resistor R9 and a capacitor C9 with an upper limit of a voltage VZ determined by the Zener voltage generating resistor 7 and the Zener diode 8 according to the level of C. Is output. By making this time constant sufficiently larger than the repetition period of the output signal VP of the comparator 3, the fluctuation of Vout is suppressed and the output is stabilized. Here, Vout is the above “Equation 8”.
Given by In addition, signals of each part in the above operation,
The case where the change in the voltage is made to correspond to the time is the same as that in FIG.

Further, the output signal VP of the comparator 3 is
The second transistor 2 through the second current limiting resistor 21
2 is driven. The collector potential of the second transistor 22 is low (transistor 22 on) when the output signal VP of the comparator 3 is high and high (transistor 22 off) when the output signal VP is low. Therefore,
The transistor 22 simulates the operation of the transformer 20. In this manner, the output signal VP of the comparator 3 transmitted through the transistor 22 includes the third current limiting resistor 23, the third transistor 24, the second Zener voltage generating resistor 11, and the second Zener voltage generating resistor 11. The signal is output through a circuit composed of a diode 12 and a second output filter (integrating circuit) 13. The circuit configuration here is the same as that of the circuit using the bus voltage output signal ground potential 5 as the ground potential. This output signal is the same as the bus voltage output signal Vout. This signal is the feedback signal V
R is input to the differential amplifier 1 together with the bus voltage detection signal Vin. With such a configuration, the negative feedback is applied to the bus voltage detection signal Vin, so that the above-mentioned “Equation 9” and “Equation 10” are satisfied. As a result, the bus voltage detection signal Vin and the bus The relationship of the voltage output signal Vout is given by an equation that does not include a variation factor, and Vout uniquely determined in correspondence with Vin is obtained.

In the above description, the expression of high or low with respect to the signal or voltage level is a relative concept, and the same effect can be obtained even if the level is inverted.

Embodiment 5 FIG. FIG. 6 is a configuration diagram showing a fifth embodiment of the present invention. In FIG.
4, 5, 8, 9, Vin, VD, VP and Vout are the same as those of the conventional device. 1 is a differential amplifier which receives a bus voltage detection signal Vin and a feedback signal VR as inputs, 12 and 13 are the same as 8, 9 respectively, 25 is a first current limiting resistor, 26 is a first transistor, and 27 is a second transistor. Transistor, 28
Is a first large capacity capacitor, 29 is a second large capacity capacitor, 30 is a first insulating high resistance, 31 is a second insulating high resistance, 32 is a second current limiting resistance, 33 is a third current limiting resistance. The transistor 34 is a fourth transistor.

In the power system voltage detection device configured as described above, the bus voltage detection signal Vin passes through the differential amplifier 1 and is output as the output signal VAMP of the differential amplifier 1. The output signal VAMP of the differential amplifier 1 is given by the same equation as in the above "Equation 3". The magnitude relationship between the differential amplifier output signal VAMP and the sawtooth wave VD generated by the sawtooth wave generator 2 is compared by a comparator 3, and the output of the comparator 3 is VAM
It becomes a rectangular wave which becomes high level when P> VD and becomes low level when VAMP <VD, and Vin is a pulse width modulated signal VP.
Becomes At this time, the high-level duty ratio DHi of VP
gh is given by the same formula as the above “Equation 1”.

First, the output signal VP of the comparator 3 is divided into a first transistor 26 to which a first current limiting resistor 25 for limiting the collector current is connected and a second transistor 26 whose collector side is a bus voltage ground potential. The push-pull circuit constituted by the transistor 27 is driven, and the output signal of this circuit is used as the output signal of the bus voltage output signal ground potential 5 via the large-capacitance capacitors 28 and 29 and the insulating high-resistances 30 and 31.
To the grounding side. In response to the transmitted signal, the bus voltage output signal Vout fluctuates depending on the time constant of the output filter (integration circuit) 9 including the resistor R9 and the capacitor C9, with the upper limit being the voltage VZ determined by the Zener diode 8. Voltage. This time constant is calculated by the comparator 3
By making the output signal VP sufficiently larger than the repetition period of the output signal VP, the fluctuation of the bus voltage output signal Vout is suppressed and the output is stabilized. Here, Vout is represented by the above-mentioned “Equation 8”.

Next, the output signal VP of the comparator 3 is
Second current limiting resistor 32 for limiting the collector current
Drives the push-pull circuit composed of the third transistor 33 connected to the third transistor 33 and the fourth transistor 34 whose collector side is the bus voltage ground potential, and outputs a signal from the push-pull circuit. The Zener diode 12 and the output filter (integrating circuit) 13 and output through the circuit. Since the output signal VP of the comparator 3 is processed by such a circuit configuration, the signal output from the output filter (integrating circuit) 13 becomes the same as the bus voltage output signal Vout. The same signal as the bus voltage output signal Vout output from the output filter (integrating circuit) 13 is input to the differential amplifier 1 together with the bus voltage detection signal Vin as a feedback signal VR. With such a configuration, negative feedback is applied to the bus voltage detection signal Vin, and the above-described “Equation 9” and “Equation 10” are satisfied. As a result, the bus voltage detection signal Vin and the bus voltage The relationship of the output signal Vout is given by an equation that does not include a variation factor, and V is uniquely determined in correspondence with Vin.
out will be obtained.

In the above description, the expression of high or low with respect to the signal or voltage level is a relative concept, and a similar effect can be obtained even if the level is inverted.

Embodiment 6 FIG. In the fifth embodiment, the first and second large-capacitance capacitors 2 are used in order to separate the side on which the bus voltage ground potential 4 is the ground potential and the side on which the bus voltage output signal ground potential 5 is the ground potential.
8 and 29 and high insulating resistors 30 and 31 are provided, and a zener diode 8, a resistor R9 and a capacitor C
Although an output filter (integrating circuit) 9 made up of the first and second large-capacitance capacitors 9 and 9 is provided as in the embodiment shown in FIG. 35, a first integrating circuit 36 for integrating the voltage between both ends thereof, a first discharging resistor 37 for discharging the capacitor in the first integrating circuit, and a third discharging resistor 37 for the feedback signal. , A push-pull circuit constituted by fourth transistors 33 and 34, an output voltage of this circuit is terminated by a second terminating resistor 38, and a second integrating circuit 39 for integrating the voltage between both ends is provided with a second integrating circuit 39. The same effect can be obtained by providing the second discharging resistor 40 for discharging the capacitor in the integrating circuit.

[0057]

According to the present invention, a differential amplifier having a bus voltage detection signal and a feedback signal as inputs is provided, and the difference between the output of the differential amplifier and the output of the sawtooth wave generator is compared to determine the pulse width. A comparator for modulating the signal; a signal transmission circuit for transmitting a pulse width-modulated comparator output signal in a form separated from a bus voltage ground potential; and a bus voltage output for receiving a pulse width modulation signal output from the signal transmission circuit. A first demodulation circuit that demodulates the signal to a signal whose ground potential is the ground potential; a configuration in which the output of the first demodulation circuit is a bus voltage output signal; and a pulse width modulation signal that is a comparator output signal By providing a second demodulation circuit for demodulating the bus voltage ground potential to a signal that becomes the ground potential, by making this second demodulation circuit and the first demodulation circuit the same configuration,
The output of the second demodulation circuit is made the same as the bus voltage output signal that is the output of the first demodulation circuit, and this output is input to the differential amplifier together with the bus voltage detection signal as a feedback signal, and negative feedback is performed. Since the bus voltage detection signal is subjected to negative feedback according to the fluctuation of the bus voltage output signal, the relationship between the bus voltage detection signal and the bus voltage output signal becomes independent of the fluctuation factor. There is an effect that a bus voltage output signal uniquely determined according to the bus voltage detection signal can be obtained.

Further, according to the present invention, since the circuit subsequent to the photocoupler is configured to be the same, the feedback signal is the same as the bus voltage output signal, and this feedback signal is differentially output together with the bus voltage detection signal. Since the configuration is such that negative feedback is input to the amplifier and negative feedback is applied to the bus voltage detection signal according to the variation of the bus voltage output signal, the variation appearing in the bus voltage output signal is corrected, as a result,
The relationship between the bus voltage detection signal and the bus voltage output signal is independent of the variation factor, and there is an effect that a bus voltage output signal uniquely determined corresponding to the bus voltage detection signal is obtained.

According to the present invention, since the circuit downstream of the secondary side of the transformer is configured to be the same, the feedback signal becomes the same signal as the bus voltage output signal. Since the negative feedback is applied to the dynamic amplifier, negative feedback is applied to the bus voltage detection signal in accordance with the fluctuation of the bus voltage output signal, and the fluctuation that appears in the bus voltage output signal is corrected. As a result, the relationship between the bus voltage detection signal and the bus voltage output signal is independent of the variation factor, and the bus voltage output signal uniquely determined in correspondence with the bus voltage detection signal is obtained.

Further, according to the present invention, since the second transistor performs the same operation as the signal transmission operation of the transformer, the circuit operation at the subsequent stage from the comparator output side is the same. Therefore, the feedback signal becomes the same signal as the bus voltage output signal, and this feedback signal is input to the differential amplifier together with the bus voltage detection signal to apply a negative feedback, so that the bus voltage detection signal includes the bus voltage output signal. Negative feedback is applied according to the fluctuation, and the fluctuation that appears in the bus voltage output signal is corrected. As a result, the relationship between the bus voltage detection signal and the bus voltage output signal becomes independent of the fluctuation factor, There is an effect that a bus voltage output signal uniquely determined according to the voltage detection signal can be obtained.

Further, according to the present invention, since the secondary winding of the transformer provided for the feedback signal is not required, the size, weight and cost of the transformer can be reduced. This has the effect of reducing size, weight, and cost.

According to the present invention, since the circuit operation at the subsequent stage from the comparator output side is configured to be the same, the feedback signal becomes the same signal as the bus voltage output signal, and this feedback signal is compared with the bus voltage detection signal. Since the negative feedback is applied to the dynamic amplifier, negative feedback is applied to the bus voltage detection signal in accordance with the fluctuation of the bus voltage output signal, and the fluctuation that appears in the bus voltage output signal is corrected. As a result, the relationship between the bus voltage detection signal and the bus voltage output signal is independent of the variation factor, and the bus voltage output signal uniquely determined in correspondence with the bus voltage detection signal is obtained.

Further, according to the present invention, since the circuit operation at the subsequent stage from the comparator output side is the same, the feedback signal becomes the same signal as the bus voltage output signal, and this feedback signal is used as the bus voltage detection signal. With the differential amplifier and negative feedback, the bus voltage detection signal is subject to negative feedback according to the fluctuation of the bus voltage output signal.
The fluctuation appearing in the bus voltage output signal is corrected, and as a result, the relationship between the bus voltage detection signal and the bus voltage output signal becomes independent of the fluctuation factor, and is uniquely determined according to the bus voltage detection signal. There is an effect that a voltage output signal can be obtained.

Further, in the present invention, since the latter stage of the large-capacity capacitor is terminated with a resistor, the large-capacity capacitor can be reduced in size, and as a result, the device itself can be reduced in size and weight.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing Embodiment 1 of a power system voltage detection device according to the present invention.

FIG. 2 is a configuration diagram showing Embodiment 2 of a power system voltage detection device according to the present invention.

FIG. 3 is a time chart showing an operation state of each unit in a power system voltage detection device according to a second embodiment of the present invention;

FIG. 4 is a configuration diagram showing Embodiment 3 of a power system voltage detection device according to the present invention.

FIG. 5 is a configuration diagram showing Embodiment 4 of a power system voltage detection device according to the present invention.

FIG. 6 is a configuration diagram showing Embodiment 5 of a power system voltage detection device according to the present invention.

FIG. 7 is a configuration diagram showing Embodiment 6 of a power system voltage detection device according to the present invention.

FIG. 8 is a configuration diagram showing a conventional power system voltage detection device.

FIG. 9 is a time chart showing an operation state of each unit of the conventional power system voltage detection device.

[Explanation of symbols]

1 differential amplifier, 2 sawtooth generator, 3 comparator, 4
Bus voltage ground potential, 5 bus voltage output signal ground potential, 6 first photocoupler, 7 first zener voltage generating resistor, 8 first zener diode, 9
1st output filter (integration circuit), 10 2nd photocoupler, 11 2nd Zener voltage generation resistance, 12
2nd Zener diode, 13 2nd output filter (integration circuit), 14 transformer, 15 diode, 1
6 first current limiting resistor, 17 first transistor, 1
8 second current limiting resistor, 19 second transistor,
Reference Signs List 20 transformer, 21 second current limiting resistor, 22 second transistor, 23 third current limiting resistor, 24 third transistor, 25 first current limiting resistor, 26
First transistor, 27 Second transistor, 28
First large-capacitance capacitor, 29 second large-capacity capacitor, 30 first high-resistance for insulation, 31 second high-resistance for insulation, 32 second current-limiting resistance, 33 third transistor, 34 fourth Transistor, 35 discharge resistor first termination resistor, 36 first integration circuit, 37 first discharge resistor, 38 second termination resistor, 39 second integration circuit, 40 second discharge resistor, a constant current source, b pulse generator, c transistor, d capacitor, R9
Resistance, C9 capacitor, LR reset winding, L
S1 transformer 14 first secondary winding, LS2 transformer 14 second secondary winding, LS transformer 20 secondary winding, Vin bus voltage detection signal, VAMP differential amplifier output signal, VD sawtooth Output signal of wave generator, output signal of VP comparator, collector potential of VC (photo) transistor, Vout bus voltage output signal.

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Toshio Gouchi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Corporation (56) References JP-A-51-100767 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) G01R 19/165

Claims (6)

(57) [Claims] A differential amplifier having a bus voltage detection signal and a feedback signal as inputs, a comparator for comparing a magnitude relationship between an output of the differential amplifier and an output of a sawtooth wave generator and performing pulse width modulation; A signal transmission circuit for transmitting an output signal of the comparator in a form separated from a bus voltage ground potential, and a bus voltage output receiving a pulse width modulation signal output from the signal transmission circuit and having a bus voltage output signal ground potential of a ground potential A first demodulation circuit that demodulates the signal into a signal; a pulse width modulation signal that is an output signal of the comparator; A power system voltage detection device comprising: a second demodulation circuit for inputting to an amplifier. 2. A differential amplifier having a bus voltage detection signal and a feedback signal as inputs, a comparator for comparing a magnitude relationship between an output of the differential amplifier and an output of a sawtooth wave generator and performing pulse width modulation, A first photocoupler connected to transmit the output signal of the comparator in a form separated from the bus voltage ground potential, a collector side of a phototransistor in the first photocoupler is connected to a cathode, and an emitter side is connected to an anode. A first zener diode having an anode side as a bus voltage output signal ground potential, a positive side output of a power supply having a bus voltage output signal ground potential as a ground potential, and a cathode connected to the first zener diode. The first Zener potential generating resistor and the Zener voltage of the first Zener diode are integrated to form a bus voltage output signal. A first output filter followed by
A second photocoupler connected to transmit an output signal of the comparator, a collector side of a phototransistor in the second photocoupler connected to a cathode, an emitter side connected to an anode, and an anode side connected to a bus voltage ground. A second Zener diode to be a potential, a second Zener potential generating resistor connected between a positive side output of a power supply having a bus voltage ground potential as a ground potential and a cathode side of the second Zener diode, A second output filter for integrating the Zener voltage of the second Zener diode and inputting the integrated signal as a feedback signal to the differential amplifier. . 3. A differential amplifier having a bus voltage detection signal and a feedback signal as inputs, a comparator for comparing the magnitude relationship between the output of the differential amplifier and the output of the sawtooth wave generator and performing pulse width modulation, And a winding for branching a pulse width modulation signal, which is the output of the comparator, to a bus voltage output signal and a feedback signal on the secondary side, and further comprising a bus voltage for outputting the output signal of the comparator. A transformer connected so as to be transmitted in a form separated from the ground potential; a diode having a reset winding side of the transformer connected to a cathode and an anode side having a bus voltage ground potential; and a diode for a bus voltage output signal of the transformer. A first current limiting resistor connected to the next winding, a first transistor having the first current limiting resistor connected to the base, and having the emitter side as a bus voltage output signal ground potential; A first Zener diode in which the collector side of the first transistor is connected to the cathode and the emitter side is connected to the anode, a plus side output of a power supply having a bus voltage output signal ground potential as a ground potential, and the first Zener diode. A first Zener voltage generating resistor connected between the cathode sides, a first output filter connected to integrate a Zener voltage of the first Zener diode into a bus voltage output signal, and A second current limiting resistor connected to the feedback signal secondary winding of the transformer, the second current limiting resistor is connected to the base, a second transistor whose emitter side is a bus voltage ground potential, A second Zener diode having the collector side connected to the cathode and the emitter side connected to the anode, and a bus voltage; A second Zener voltage generating resistor connected between the plus side output of a power supply having a land potential as a ground potential and the cathode side of the second Zener diode, and a Zener voltage of the second Zener diode integrated. And a second output filter for inputting the integrated signal as a feedback signal to the differential amplifier. 4. A differential amplifier having a bus voltage detection signal and a feedback signal as inputs, a comparator for comparing the magnitude relationship between the output of the differential amplifier and the output of the sawtooth wave generator and performing pulse width modulation, And a transformer connected to transmit the output signal of the comparator in a form separated from the bus voltage ground potential, and a reset winding side of the transformer connected to a cathode and an anode side. A bus voltage ground potential, a first current limiting resistor connected to a secondary winding of the transformer, and the first current limiting resistor connected to a base, and an emitter connected to a bus voltage output signal ground. A first transistor having a potential, a first Zener diode having a collector connected to the cathode on the collector side, and an emitter connected to the anode, and a bus. A first zener voltage generating resistor connected between a positive output of a power supply having a voltage output signal ground potential as a ground potential and a cathode side of the first zener diode, and a zener voltage of the first zener diode A first output filter connected to integrate the second current limiting resistor to a bus voltage output signal, a second current limiting resistor connected to the output side of the comparator, and a second current limiting resistor based on the first output filter. A second transistor connected to a bus voltage ground potential on the emitter side, a third transistor connected to the base on the collector side of the second transistor and having the emitter side as a bus voltage ground potential, and a bus voltage ground potential A third current limiting resistor connected between the plus side output of a power supply having a ground potential and the base side of the third transistor, A second Zener diode in which the collector side of the three transistors is connected to the cathode and the emitter side is connected to the anode, and between the plus side output of the power supply with the bus voltage ground potential as the ground potential and the cathode side of the second Zener diode. A connected second Zener voltage generating resistor and a second output filter that integrates the Zener voltage of the second Zener diode and inputs the integrated signal as a feedback signal to the differential amplifier. A power system voltage detection device, comprising: 5. A differential amplifier having a bus voltage detection signal and a feedback signal as inputs, a comparator for comparing a magnitude relationship between an output of the differential amplifier and an output of a sawtooth wave generator and performing pulse width modulation, and a bus. A first current limiting resistor connected to the positive side of a power supply having a voltage ground potential as a ground potential, and a first transistor having the output side of the comparator connected to a base and the first current limiting resistor connected to a collector An output side of the comparator is connected to a base, an emitter side of the first transistor is connected to an emitter, a collector side is connected to a bus voltage ground potential, and a second transistor is connected to an emitter side of the first transistor. A first large-capacitance capacitor, a first insulating high-resistance connected in parallel to the first large-capacitance capacitor, and a second high-resistance connected to the collector of the second transistor. A second large-capacitance capacitor, a second insulating high-resistance connected in parallel to the second large-capacity capacitor, and a side of the first large-capacity capacitor that is not connected to the first transistor is a cathode; A side of the second large capacity capacitor that is not connected to the second transistor is connected to the anode, a first Zener diode having the anode side as a bus voltage output signal ground potential, and integrating a Zener voltage of the first Zener diode. A first output filter connected to be a bus voltage output signal, a second current limiting resistor connected to a positive side of a power supply having a bus voltage ground potential as a ground potential, and an output side of the comparator. A third transistor having the second current limiting resistor connected to the collector at the base, and the third transistor having the output side of the comparator at the base. A fourth transistor in which the emitter side of the transistor is connected to the emitter and the collector side is a bus voltage ground potential, and a second transistor in which the emitter side of the third transistor is connected to the cathode and the collector side of the fourth transistor is connected to the anode And a second output filter that integrates a Zener voltage of the second Zener diode and inputs the integrated signal as a feedback signal to the differential amplifier. System voltage detector. 6. A differential amplifier having a bus voltage detection signal and a feedback signal as inputs, a comparator for comparing a magnitude relationship between an output of the differential amplifier and an output of a sawtooth wave generator and performing pulse width modulation, and a bus. A first current limiting resistor connected to the positive side of a power supply having a voltage ground potential as a ground potential, and a first transistor having the output side of the comparator connected to a base and the first current limiting resistor connected to a collector An output side of the comparator is connected to a base, an emitter side of the first transistor is connected to an emitter, a collector side is connected to a bus voltage ground potential, and a second transistor is connected to an emitter side of the first transistor. A first large-capacitance capacitor, a first insulating high-resistance connected in parallel to the first large-capacitance capacitor, and a second high-resistance connected to the collector of the second transistor. A second large-capacitance capacitor, a second insulating high-resistance connected in parallel with the second large-capacity capacitor, a side of the first large-capacity capacitor not connected to the first transistor, and A first terminating resistor connected between the side of the large-capacitance capacitor not connected to the second transistor, and a terminal connected to integrate the voltage across the first terminating resistor into a bus voltage output signal. A first integrating circuit, a first discharging resistor connected in parallel to a capacitor in the first integrating circuit, and a second connected to a positive side of a power supply having a bus voltage ground potential as a ground potential. A current limiting resistor, the output side of the comparator is a base, the third transistor the second current limiting resistor is connected to a collector, and the output side of the comparator is a base, the third transistor Emitter Is connected to the emitter, a fourth transistor whose collector side is a bus voltage ground potential, a second terminating resistor connected between the emitter side of the third transistor and the collector side of the fourth transistor, A second integration circuit that integrates the voltage between both ends of the second terminating resistor and inputs the integrated signal as a feedback signal to the differential amplifier, and a capacitor in the second integration circuit in parallel. A power system voltage detecting device, comprising: a second discharging resistor connected thereto.