JPH1132475A - Overvoltage interrupt type power source filtering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power source filtering device for railway car, etc., which can effectively inhibit a load from being damaged or broken due to the overvoltage state of a power source. SOLUTION: A switching transistor Tr2 is provided between the base of a transistor Tr1 and a grownd 12. When an input voltage Vin between input terminals 10 and 12 becomes overvoltage, the transistor Tr1 is cut-off so as to interrupt the power supply to a load by turning on the transistor Tr2. In addition, the input voltage Vin is smoothed, when the voltage Vin is not in an overvoltage state by connecting the output of a low-pass filter LPF to the base of the transistor Tr1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for protecting a load to which DC power is supplied from a power supply of a vehicle such as a railway vehicle, and more particularly, to a load electronic device supplied from such a power supply. The present invention relates to a power supply filter device that protects against noise including overvoltage such as voltage surge or ripple.

[0002]

2. Description of the Related Art Conventionally, in railway vehicles, mainly,
Two power supplies are provided: an AC power supply that supplies three-phase AC power to a power motor and the like, and a DC power supply. The DC power supply is for supplying power to equipment related to the security device, and is composed of a battery charged by the AC power supply in order to secure power supply even in an emergency. Electronic devices related to security devices include broadcasting equipment, emergency lights, automatic train control devices (ATC), and the like.

In such a railway vehicle, the DC power supply line includes various security-related electronic devices connected in parallel between the DC power supply lines, and an AC power supply line (close to the DC power supply line). Surges and ripples may be superimposed due to itself or various devices connected thereto.

Conventionally, a surge absorber or a constant voltage power supply has been used in order to minimize the influence of such surge or ripple on load electronic equipment. The surge absorber is provided in an input stage of a circuit of an electronic device to be supplied with electric power, and when the power exceeds the withstand voltage, it is broken and short-circuited, thereby protecting the other circuits of the electronic device from being applied with an overvoltage. On the other hand, the constant voltage power supply
Provided at the circuit input stage of the load electronic device, when a voltage equal to or higher than a specified value is applied, a power portion equal to or higher than the specified voltage is absorbed by a transistor element or the like in the constant voltage power supply,
This keeps the voltage of the power supplied to the remaining circuits of the electronic device constant.

[0005]

The above-described surge absorber or constant voltage power supply has several problems. That is, in a surge absorber, when a surge absorber element in an electronic device is destroyed by a surge or a ripple having a power resistance or more, the element is short-circuited. As a result, even if the DC power supply recovers from the overvoltage state, the electronic device can no longer be supplied with power, and replacement of the absorber element is required to resume power supply. Further, not only the short circuit of the absorber element but also the heat generated by the short circuit may burn the electronic device circuit. In such a case, the device circuit needs to be repaired. This is not desirable for security-related equipment that is required to operate normally even in an emergency.

Further, in the constant voltage power supply device, the absorption of excess power exceeding a specified voltage is performed by consuming heat as a transistor, so that a large radiator is required depending on the magnitude of surge or ripple. Therefore, there is a problem in that the power supply device itself becomes large, and the cost increases accordingly.

Accordingly, an object of the present invention is to provide a power supply filter device for a vehicle such as a railway vehicle, which can effectively prevent damage or destruction of a load due to an overvoltage state of the power supply.

Another object of the present invention is to provide the above power supply filter device capable of restarting power supply to a load after recovery from an overvoltage state of the power supply.

Still another object of the present invention is to provide the above power supply filter device which can be easily reduced in size.

[0010]

According to the present invention, there are provided first and second input terminals for receiving input power and first and second output terminals for generating output power. The power supply filter device is a) detecting means connected between the first input terminal and the second input terminal, the output means generating a detection signal representing a value of the voltage of the input power between the input terminals. The detection means, comprising:
B) low-pass filter means connected between said first input terminal and said second input terminal, said low-pass filter means having an output for generating a low-pass filter output; A) a first transistor having a first current carrying electrode connected thereto, a control electrode connected to the output of the low pass filter means, and a second current carrying electrode connected to the first output terminal; Switch means having an input connected to the control electrode of the transistor, an output connected to the second input terminal, and a control input, which is turned on or off depending on a control signal received at the control input; E) a switch representing a magnitude relationship between an input connected to the output of the detection means, a value of the detection signal received from the detection means from the detection means, and a threshold value. An output for generating a signal, said control signal comprising: said switch control means for turning on said switch means when said detection signal value is greater than said threshold value. .

With this configuration, when the input power is not in an overvoltage state, the detection signal value is smaller than the threshold value, and therefore, the switch control means for generating the control signal indicating this relationship is controlled by the control signal. By holding the switch OFF, the output of the low-pass filter is continuously supplied to the control electrode of the first transistor to smooth the voltage waveform of the emitter of the first transistor. Thus, power is supplied to the load with the smoothed voltage waveform. On the other hand, when the input power is in an overvoltage state, the detection signal value becomes larger than the threshold value, the switch control means generates the control signal indicating the relationship, and turns on the switch means,
This shorts or grounds the control electrode of the first transistor to the second input terminal. Thereby, the output power is reduced to zero, that is, the power supply to the load is cut off.

According to the present invention, the switch means includes a second terminal having a collector connected to the base of the first transistor, an emitter connected to the second input terminal, and a base receiving the control signal. Transistors. In this case, the switch control means is a first Zener diode having a cathode connected to the output of the detection means and an anode connected to the base of the second transistor, and having a Zener voltage,
The Zener voltage is equal to the base of the second transistor.
The first voltage, wherein the threshold value is determined by an emitter-to-emitter voltage.
A Zener diode.

Further, according to the present invention, the switch means has a) an anode connected to the base of the first transistor, a cathode connected to the second input terminal, and a gate receiving the control signal. A thyristor, b) a normally open switch connected between an anode and a cathode of the thyristor. In this case, the switch control means includes: a) an anode connected to the second input terminal;
A second Zener diode having a cathode and having a Zener voltage defining the threshold value; b) a first input connected to the output of the detection means, and a second input connected to a cathode of the second Zener diode. And a voltage comparator means having an output connected to the gate of the thyristor.

Further, according to the present invention, the low-pass filter means may be a CR filter, and the CR filter may include a) the first input terminal and the output of the low-pass filter means. B) a resistor connected between the output of the low-pass filter means and the second input terminal.

According to the invention, the low-pass filter means is a CR filter.
A) a resistor (R3 ') having one end connected to the first input terminal and the other end; b) an anode connected to the other end of the resistor, and the output of the low-pass filter means. Diode with connected cathode (D1)
And c) a capacitor (C ′) connected between the output of the low-pass filter means and the second input terminal.

Still further, according to the present invention, the detecting means can be a voltage divider connected between the first input terminal and the second input terminal, wherein the voltage divider is
A) a first resistor connected between the first input terminal and the output of the detection means; b) a second resistor connected between the output of the detection means and the second input terminal. Container.

[0017]

Next, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, a case where the present invention is used for a DC power supply of a railway vehicle will be described as an example. The DC power supply of the railway vehicle has, for example, a voltage fluctuation allowable range of 70 to 110 volts. In some cases, the power supply voltage
Surges close to 200 volts may appear and 36
Ripple of 0 Hz (when the AC power supply is 60 Hz) may be superimposed.

FIG. 1 is a circuit diagram showing a power supply filter device A according to one embodiment of the present invention. This device A
This is an automatic return type in which power supply to a load due to an overvoltage state is cut off and power supply is automatically restarted after the overvoltage state disappears. Specifically, the device A includes input terminals 10 and 12 for receiving input power and an output terminal 2 for generating output power.
0,22. The voltage of the input power is indicated by V _in,
Usually 100 volts. The output power voltage is V _out
Which is also typically around 100 volts. The power supply filter device A includes two resistors R1 and R2 connected in series between the input terminals 10 and 12. A resistor R3 and an electrolytic capacitor C are connected in series between the input terminal 10 and the output terminal 22. The junction between resistor R3 and capacitor C is numbered "16".
Indicated by NPN type switching transistor Tr1
Has a collector connected to input terminal 10, an emitter connected to output terminal 20, and a base connected to junction 16. The Tr1 is rated, for example, to have a collector-base voltage V _CBO of 1500 volts and a collector-emitter voltage of 900 volts. Further, the junction 14 is connected to the cathode of the Zener diode ZD1, and its anode is connected to the base of the switching transistor Tr2. Zener diode has a Zener voltage V _Z. The collector of transistor Tr2 is connected to junction 16 or the base of Tr1, and its emitter is connected to input terminal 12.

[0019] The resistors R1 and R2, constitutes a voltage divider VD corresponding to the detecting means, as the junction 14 binary divider output, generating a divided voltage V _d that represents the magnitude of the input voltage V _in I do. When the partial pressure ratio and R _D, which is V _d = R _D V _in.
The resistor R3 and the electrolytic capacitor C constitute a low-pass filter LPF, and the cutoff frequency can be represented by fo = 1 / (2πC · R3). This LPF
Generates its low pass filter output at junction 16. The switching transistor Tr1 has its ON-
ON- of cutoff of power supply to load by OFF switching
Turn OFF. Tr1 is in the ON state.
Functions as a part of the low-pass filter LPF. That is, Tr1 has a configuration in which the base current is controlled by the output of the LPF, and thus functions to multiply the capacity of the capacitor C by _hfe, which is the current amplification factor of the transistor. The cutoff frequency of the low-pass filter LPF is selected to be lower than the above-mentioned ripple frequency of 360 Hz. Also,
The transistor Tr1 is connected to the base-emitter voltage V _BE1 (normally 0.6)
Volts) is output as the emitter voltage, thus providing output power in a smoothed voltage waveform.

The transistor Tr2 is an element corresponding to the above-mentioned switch means. When the base potential is lower than the base-emitter voltage V _BE2 (normally 0.6 volt), the transistor Tr2 is OFF, that is, non-conductive. , LPF and Tr1 cause a low-pass filter operation. On the other hand, when the base potential becomes V _BE2 or more, Tr2 becomes O
N, that is, conduction, grounds the base of Tr1, thereby cutting off the low-pass filter operation and cutting off the power supply to the output terminals 20, 22. Based Zener diode ZD1 and a transistor Tr1 - emitter junction acts as the switch control unit, and the sum of the Zener voltage V _Z and V _BE2, the switching power supply filter apparatus operating threshold V _TH ( Tr2). That is, the threshold value V _TH = V _Z + V _BE2 .

[0021] In power supply filter apparatus A, when the protective voltage is the upper limit value of the input voltage is V _P, partial pressure ratio R _D is,
It is determined so that R _D = V _TH / V _P. The overall operation of the filter device A is as follows. When V _in <V _P , Tr 2 is OFF.
, Causing a low pass filter operation, and V
Tr2 at the time of the _in ≧ V _P is to cut off the power supply to the load is turned ON.

Next, the operation of the power supply filter device A of FIG. 1 will be described more specifically with reference to FIGS.
Note that V _P is set to 120 volts. First, as shown in FIG. 2, if V _in is the first 100 volts, while, for V _in <V _P, a V _d <V _TH, the Tr2 OF
F and Tr1 are in the active area, so that LPF and Tr1
1 operates as a low-pass filter. This operation is called surge S
Voltage of G continues until it exceeds the V _P. When V _P is exceeded, that is, during the portion P1 of the surge SG, V _in ≧ V _P , and at this time, V _d ≧ V _TH , Tr2 is turned on, and Tr1 is cut off, and LPF is cut off. And Tr1 are both cut off to cut off the power supply to the load. V _{out at} this time
The waveform, the relationship between V _in and V _out as can be seen from FIG. 3 showing schematically, V _in drops to rapidly zero after exceeding the V _P. Then, when the V _in is lower than V _P, V
_out rises up to V _P close again. Note that the delay time τ is
This is the delay caused by the low-pass filter.

In this case, Vin _in the overvoltage state is applied to the collector of Tr1, but Tr1 does not generate heat due to cutoff. At this time, the power in the overvoltage state is supplied to the resistor R
1, consumed in R2, R3. Also, each element in the device A is not destroyed if the breakdown voltage is equal to or higher than the surge voltage. The same applies to the next part P2 of the surge SG. Note that the low-pass filter operation hardly works between the surge portions P1 and P2 for a short time equal to or higher than the cutoff frequency of the filter. After the surge portion P2 is again low-pass filter operation and the feeding operation is restored becomes V _in <V _P. This effectively protects the load electronics from surges, i.e., transient overvoltages, and provides power to the load when the overvoltage condition is restored, without having to replace or repair elements in the device A. Restart automatically.

Next, a ripple RP1 having a relatively small amplitude is used.
Appears at the power supply voltage, the voltage at that time is the protection voltage V
_Since it is smaller than _P , the LPF and Tr1 smooth the ripple by the low-pass filter operation, and supply the power with minimized noise to the load. Next, relatively when large ripple RP2 amplitude appeared to the power supply voltage, performs a cutoff of the power supply only during the portion P3, P4 of the voltage at that time is the protection voltage V _P above, and in other portions,
Perform a low pass filter operation to minimize power supply noise as much as possible.

As described above, the power supply filter device A shown in FIG. 1 effectively protects electronic devices and the like related to security devices in a railway vehicle so that their operation can be ensured even in an emergency, and To minimize the effect of power supply noise.

Next, a power supply filter device B according to another embodiment of the present invention will be described with reference to FIG. This power supply filter device B is of a manual recovery type that can manually restart the power supply after the power supply is cut off and the overvoltage state disappears. It should be noted that, in the following, only the parts of the apparatus B that are different from the apparatus A of FIG. 1 will be described. As shown, device B replaces Tr2 of device A with:
A thyristor SCR and a return switch SW are provided.
The anode of the thyristor is connected to the junction 16, that is, the base of Tr 1, and its cathode is connected to the input terminal 12. The thyristor SCR is in the OFF state when the gate voltage is lower than the gate trigger voltage of the SCR, and turns ON when the gate voltage is equal to or higher than the gate trigger voltage. The return switch SW is a normally open switch connected between the anode and the cathode of the SCR, and when turned on manually, reduces the anode current of the SCR and turns off the SCR.

Further, the apparatus B is composed of ZD1 and Tr1 of the apparatus A.
Voltage comparator C instead of the base-emitter junction of
MP, a Zener diode ZD2, and two resistors R
4, R5. The non-inverting input of the voltage comparator is connected to junction 14 and the inverting input is connected to the cathode of ZD2. The anode of ZD2 is connected to the input terminal 12. ZD2 is Zener voltage V _Z of the same value as V _Z 'has, in the device B, the Zener voltage V _Z'
Is the switching threshold value V _TH 'of the filter device operation.
Becomes The output of the voltage comparator is connected to the input terminal 12 via resistors R4 and R5 connected in series. The junction 18 between these resistors is connected to the gate of the thyristor. When the _{V in <V P, V d} <V TH '(=
V _Z ′), so that the voltage comparator CMP generates a low output of, for example, zero volts. This zero volt is S
It is lower than the gate trigger voltage of CR. On the other hand, when V _in ≧ V _P , V _d ≧ V _TH ′, so that the voltage comparator CMP
Generates a high level output. The voltage at the junction 18 at the time of this high level voltage determines the voltage dividing ratio by the resistors R4 and R5 so as to be higher than the gate trigger voltage of the SCR.

Next, the overall operation of the power supply filter device B will be described. When V _in <V _P , the thyristor S
CR is OFF, and at this time, O
As in the FF state, the LPF and Tr1 perform a low-pass filter operation. When V _in ≧ V _P , the thyristor is turned on, and the power supply to the load is cut off in the same manner as when Tr 2 of device A is turned on. However, in the apparatus B of FIG. 4, even if the overvoltage state is recovered, the thyristor SCR
Remain ON, so that the power supply is not automatically restored. Power supply /
In order to restart the low-pass filter operation, the operator needs to turn on the return switch. After turning ON, the above operation is repeated.

This power supply filter device B is suitable for the case where the power supply should be restarted after the power supply is cut off and the cause of the overvoltage state is clarified. For example, it is advantageous when the cause of the overvoltage condition is to be investigated or when the overvoltage condition needs to be removed or repaired. In contrast, the power supply filter device A of FIG.
Is suitable when power supply should be resumed immediately regardless of the cause of the overvoltage condition.

Next, a power supply filter device C according to another embodiment of the present invention will be described with reference to FIG. In addition,
Since the circuit of the device C is almost the same as that of the device A of FIG. 1, FIG. 5 shows a portion different from the circuit of FIG. 1, and the same symbols are used for the same elements in FIG. , And similar elements have a '
Is attached. As can be seen, a feature of the device C is that the low-pass filter LPF 'comprises a diode D1 between its resistor R3' and the capacitor C '. The diode D1 has an anode connected to one end of the resistor R3 'and the collector of the transistor Tr2, and a cathode connected to the base of the transistor Tr1 and one end of the capacitor C'.

With this circuit configuration, when Tr2 is turned on and turned on, the diode D1 prevents the charge charged in the capacitor C 'from discharging through Tr2 and discharges through the base of Tr1. As a result, the Tr1 does not immediately shut off after the turn-on of the Tr2, and the base current is supplied by the current discharged from the capacitor, so that the Tr1 keeps the conduction state for a certain time depending on the discharge time constant. Therefore, the output voltage V _out
As shown schematically in FIG. 6, not immediately become zero as shown in FIG. 3 when V _in exceeds V _P, gradually decreases. When the discharge current decreases to a value at which Tr1 cannot be maintained in the conductive state, Tr1 is cut off and the output voltage _Vout becomes zero.
Again, by V _in is lower than V _P, when the Tr2 is turned off, as shown in FIG. 6, V _out is returned to the vicinity again V _P.

The power supply filter device C that performs a gradual cutoff is suitable for a case in which a surge is terminated in a short time even if a surge occurs, or a case where it is desirable to minimize the interruption of power supply due to the occurrence of a surge. . In such a case, by appropriately selecting the discharge time constant of the capacitor C ′ according to the duration of the surge, it is possible to supply power with less interruption. Furthermore, excessive power consumption by Tr1 is
Since only when a surge occurs, the heat generation is much smaller than that of a constant voltage power supply.

In the power supply filter device according to the embodiment of the present invention described above, the following changes are possible.
For example, an NPN transistor can be replaced with a PNP transistor. Second, the power supply filter device of the present invention can be similarly applied to a vehicle other than a railway vehicle when there is the same problem as described above. Third, have been described divider as an example of detecting means, as long as it can generate a signal representative of the V _in, can be changed to other circuits.

[0034]

According to the power supply filter device of the present invention described above, when an overvoltage state of the power supply voltage occurs, power is supplied to the load without damaging or destroying elements in the filter device or the load electronic device. Can be shut off. In addition, since power supply interruption does not accompany element damage or destruction,
After the overvoltage state disappears, the power supply to the load can be automatically or manually resumed as necessary. Furthermore,
Since the transistor in the filter device consumes little or no excess power to cope with the overvoltage condition, a large radiator required in the case of the conventional constant voltage power supply device is unnecessary, In addition, since the electrolytic capacitor can have a small capacity, it is easy to reduce the size of the device. Further, if the voltage divider VD is used, the power supply filter device according to the present invention can be obtained simply by changing the voltage division ratio _RD .
DC power batteries with different rated voltages (for railway cars,
For example, there are three types: 100 volts, 24 volts, and 12 volts).

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a power supply filter device A according to one embodiment of the present invention.

[2] using the operation of the power supply filter apparatus A of FIG. 1 more in detail described, waveform diagram of the input voltage V _in.

Figure 3 is a timing diagram showing the relationship between the input voltage V _in and the output voltage V _out of _the power supply filter apparatus A of FIG.

FIG. 4 is a circuit diagram showing a power supply filter device B according to another embodiment of the present invention.

FIG. 5 is a circuit diagram showing a power supply filter device C according to another embodiment of the present invention, showing only a portion different from the device A of FIG. 1;

Figure 6 is a timing diagram showing the relationship between the input voltage V _in and the output voltage V _out of the apparatus of FIG.

[Description of Reference Numerals] 10, 12: a pair of input terminals 14, 16, 18: junction 20, 22: a pair of output terminals VD: voltage divider LPF, LPF ': low-pass filter V _in: input voltage V _out: Output voltage V _d : Divided output V _TH , V _TH ': Threshold value V _Z , V _Z ': Zener voltage V _P : Protection voltage

Claims (8)

[Claims] A power supply filter device (A) having first and second input terminals (10, 12) receiving input power and first and second output terminals (20, 22) generating output power. B) wherein a) the first input terminal (10) and the second input terminal (1
2) which has an output (14) for generating a detection signal (V _d ) representing the value of the voltage of the input power between the input terminals. B) a low-pass filter connected between the first input terminal and the second input terminal, the low-pass filter having an output for generating a low-pass filter output; C) a first having a first current carrying electrode connected to the first input terminal, a control electrode connected to the output of the low pass filter means, and a second current carrying electrode connected to the first output terminal. D) switch means having an input connected to the control electrode of the first transistor, an output connected to the second input terminal, and a control input, wherein the control received by the control input is Depends on the signal E) the switch means (Tr2; SCR, SW), which is turned on or off, and e) an input connected to the output of the detection means, a value of the detection signal received from the detection means from the detection means and a threshold. (V _TH ; V _TH ′), and an output for generating a control signal indicating a magnitude relationship with (V _TH ; V _TH ′), wherein the control signal is output when the detection signal value is larger than the threshold value. A power supply filter device comprising the switch control means (ZD1, Tr2; CMP, ZD2, R4, R5) for turning on the switch means. 2. The apparatus of claim 1, wherein said switch means comprises: a collector connected to a base of said first transistor;
A second transistor (Tr) having an emitter connected to the second input terminal and a base receiving the control signal;
2) A power supply filter device comprising: 3. The apparatus according to claim 2, wherein said switch control means has a cathode connected to said output of said detection means, and an anode connected to a base of said second transistor,
And a first zener diode having a zener voltage (V _Z), the Zener voltage, the second transistor base - defining said threshold out with emitter voltage (V _BE2), first the Zener diode (ZD1),
And a power supply filter device. 4. The apparatus according to claim 1, wherein said switch means comprises: a) an anode connected to the base of said first transistor, a cathode connected to said second input terminal, and said control signal. A thyristor (SCR) having a receiving gate; and b) a normally open switch (SW) connected between an anode and a cathode of the thyristor. 5. The device according to claim 4, wherein said switch control means comprises: a) a Zener having an anode connected to said second input terminal, and a cathode, and defining said threshold value. second Zener diode having a voltage (V _Z ') (ZD
2), b) a voltage comparison having a first input connected to the output of the detection means, a second input connected to the cathode of the second Zener diode, and an output connected to the gate of the thyristor. (CMP, R4, R5). 6. The apparatus according to claim 1, wherein said low-pass filter means is a CR filter, and said CR filter comprises: a) said first input terminal and said low-pass filter means; A resistor (R3) connected between the output and the second output;
A power supply filter device, comprising: a capacitor (C) connected between the input terminal and the input terminal. 7. The apparatus according to claim 1, wherein the low-pass filter means is a CR filter, the CR filter comprising: a) one end connected to the first input terminal; A resistor (R3 ') having the other end; b) a diode (D1) having an anode connected to the other end of the resistor, and a cathode connected to the output of the low-pass filter means; The output of the low-pass filter means and the second
A power supply filter device comprising: a capacitor (C ′) connected between the power supply filter and an input terminal. 8. The apparatus according to claim 1, wherein said detecting means is a voltage divider (VD) connected between said first input terminal and said second input terminal. A) a first resistor (R1) connected between the first input terminal and the output of the detecting means; b) the output of the detecting means and the second input terminal; A power supply filter device, comprising: a second resistor (R2) connected between the two.