GB2587376A - Active bleeder circuit - Google Patents
Active bleeder circuit Download PDFInfo
- Publication number
- GB2587376A GB2587376A GB1913850.2A GB201913850A GB2587376A GB 2587376 A GB2587376 A GB 2587376A GB 201913850 A GB201913850 A GB 201913850A GB 2587376 A GB2587376 A GB 2587376A
- Authority
- GB
- United Kingdom
- Prior art keywords
- bleeder circuit
- voltage
- bleeder
- capacitor
- active
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000003990 capacitor Substances 0.000 claims abstract description 52
- 238000007599 discharging Methods 0.000 claims abstract description 16
- 238000001514 detection method Methods 0.000 claims abstract description 12
- 238000000034 method Methods 0.000 claims description 4
- 230000001960 triggered effect Effects 0.000 claims description 3
- NLZUEZXRPGMBCV-UHFFFAOYSA-N Butylhydroxytoluene Chemical compound CC1=CC(C(C)(C)C)=C(O)C(C(C)(C)C)=C1 NLZUEZXRPGMBCV-UHFFFAOYSA-N 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 7
- 238000001914 filtration Methods 0.000 description 5
- 208000032365 Electromagnetic interference Diseases 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 208000016444 Benign adult familial myoclonic epilepsy Diseases 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 208000016427 familial adult myoclonic epilepsy Diseases 0.000 description 1
- 235000019387 fatty acid methyl ester Nutrition 0.000 description 1
- ZGNITFSDLCMLGI-UHFFFAOYSA-N flubendiamide Chemical compound CC1=CC(C(F)(C(F)(F)F)C(F)(F)F)=CC=C1NC(=O)C1=CC=CC(I)=C1C(=O)NC(C)(C)CS(C)(=O)=O ZGNITFSDLCMLGI-UHFFFAOYSA-N 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000010200 validation analysis Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
- H02H9/041—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage using a short-circuiting device
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
- G05F1/613—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in parallel with the load as final control devices
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/18—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for batteries; for accumulators
Abstract
An active bleeder circuit for discharging voltage in controlled manner is connected by means of an input terminal and an output terminal to a device powered through a switch S, which device has a target capacitor Ctarget coupled between the input terminal and the output terminal. The active bleeder circuit comprises a detection circuit with an operational amplifier (OPAMP), a first resistive divider, a second resistive divider and a bleeder capacitor (figure 4, Cb) and a control circuit comprising a gate resistor and a transistor having a first main electrode, a second main electrode and a control electrode. A bleed load, which may be a resistor, is coupled between the input terminal and the first main electrode of the transistor.
Description
Description
Active Bleeder Circuit The present invention generally relates to an active bleeder circuit for discharging voltage in power supply arrangements.
All power supplies contain filtering capacitors to minimize ripple voltage and only discharge their own capacitors at power off, not caring about what is connected at the output. If external circuits are using additional filtering capacitors, these will not be discharged by the power supply when it is switched off. In circuits with very low leakage current, the voltage can remain present on capacitor's terminals long enough to cause trouble. This problem is fixed in multiple ways by using circuits called bleeders, having the role to actively discharge the capacitors to a safe voltage level.
The simplest bleeder is a resistor or a group of resistors, connected in parallel with filtering capacitors, having a total resistance calculated to ensure a big enough current to discharge the capacitor in a required amount of time, but small enough so the power dissipation is kept to a minimum, while the supply's output is on.
Active bleeders are circuitry designed to discharge the capacitors based on a trigger, since they use larger discharge currents which would seriously affect power supply's performance and dissipate a lot of heat when power is on.
Triggers have multiple forms, relying on: current consumption monitoring, fixed voltage thresholds, ripple voltage, or a combination of them.
The best triggers make advantage of power supply's internal circuitry, were possible. When using industrial power supplies, access to internal circuitry is out of question, being a violation of standards of electric safety, validation, calibration and usage rules. Active bleeders will be therefore connected externally, either at power supply's output or between the output and the circuit.
There are multiple patent documents related to active bleeders published, for example, under US8884537B2 (describing an active bleeder that has a fixed voltage threshold and uses an external trigger), US8723431B2 (in this case, the active bleeder has a fixed voltage threshold), US9210744B2 (the disclosed active bleeder requires access to power supply's internal circuitry and uses ripple voltage as trigger), US9402293B2 (in this case, the solution uses a trigger combination of current consumpTion and requires access to power supply's internal circuitry). Anyway, the published technology is subject for technological improvement.
All external bleeders have drawbacks: - Current monitoring triggers perform well only in a relatively narrow current consumption. Needing to be connected between the output and the powered circuit, they interfere with the latter due to the voltage drops over shunts or electromagnetic interferences; - Triggers based on ripple voltage do not work on regulated, well filtered voltage outputs; - Voltage threshold triggers are unusable in variable voltage output power supplies, causing continuous discharge currents under the threshold, gold performance in a narrow voltage gap above the threshold, and slow reaction time on voltages above the gap.
The technical problem to be solved, in this context, is to design an active device which can be attached at the output of any power supply, does not interfere with the powered circuitry, it is voltage-independent and has no more than two connections.
Therefore, an object of the invention is to solve the deficiencies of the mentioned prior art and to provide an active bleeder circuit for discharging voltage in controlled manner, able to be attached by means of an input terminal and an output terminal to a device powered through a switch, which device has a target capacitor coupled between the input terminal and the output terminal.
This objective is achieved according to the invention by means of the technical characteristics mentioned in the independent claims, namely an active bleeder circuit and an afferent method of discharging voltage.
Further advantageous embodiments are the subject matter of the dependent claims.
The subject-matter of the present invention is an active bleeder circuit comprising a detection circuit with an operational amplifier, a first resistive divider, a second resistive divider and a bleeder capacitor, and a control circuit comprising a gate resistor and a transistor having a first main electrode, a second main electrode and a control electrode, and wherein a bleed load is coupled between the input terminal and the first main electrode of the transistor.
The main advantages of the active bleeder circuit according to invention are: - It follows the power supply voltage without any external adjustments or user intervention; - Low power consumption dictated only by resistor values and operational amplifier's stand-by current; 5-Does not affect neither the power supply, nor external connected circuitry; - Very cheap to produce, components being widely available; - Discharge time and slope shape can be adjusted by simply changing the bleed load; 10-Only two wires to connect.
Another subject-matter of this invention is a method of actively discharging voltage in controlled manner, comprising the following steps: 15-providing a device powered through a switch, comprising a target capacitor coupled between an input terminal and an output terminal, - providing an active bleeder circuit coupled between the input terminal and the output terminal to the powered device, the bleeder circuit comprising a diode, a first resistive voltage divider, a second resistive voltage divider, a bleeder capacitor, an operational amplifier with an inverting input and a non-inverting input, a resistor gate and a transistor with a first main electrode, a second main electrode and a control electrode; - providing a bleed load inserted between the input terminal and the first main electrode of the transistor, whereby when the power supply to the device is switched off, both the bleeder capacitor and the target capacitor begin dis-charging until the voltage over target capacitor drops below a threshold voltage set by the diode and the second voltage divider, the operational amplifier opens the transistor, and target capacitor discharges through bleed load.
The main advantage of this method is versatility, since the active bleeder circuit uses target capacitor's stored energy, powering a circuit which compares the voltage difference between two discharging curves.
Further special features and advantages of the present invention can be taken from the following description of advantageous embodiments by way of the accompanying drawings.
10-Fig. 1 is an exemplary diagram of a prior art arrangement; - Fig. 2 shows how the bleeder circuit is attached in a setup; - Fig. 3 is a simplified representation of the bleeder circuit's internal blocks; - Fig. 4 shows the schematic diagram of an automated test setup, 15 split in sections according to the internal blocks from Fig. 3; - Fig. 5 illustrates a mix of oscilloscope plots performed on the bleeder circuit, showing voltage between nets V+ and V-at power off discharging; 20-Fig. 6 shows modified connections allowing the bleeder circuit to operate as high-voltage capacitor discharger; - Fig. 7 shows an exemplary diagram of the bleeder circuit according to invention, operating as external-triggered bleeder; - Fig. 8 shows an exemplary diagram of the bleeder circuit ac-25 cording to invention, operating as power surge protection.
Referring now to Fig. 1, an exemplary diagram view of a prior art arrangement is shown, comprising a power supply circuit, controlled by a switch S, coupled to a powered device contain-ing a target capacitor Ctarc,t, where by closing the switch S the current flows through a loop created by nodes 1-2-3-4. When the switch S is open, the link between nodes 1 and 4 is broken, and target capacitor CL,"eL cannot be discharged through the power supply circuit.
Fig. 2 shows an active bleeder circuit, according to the invention, in a setup that introduces an additional current path through additional nodes 5 and 6, discharging target capacitor Otargot in a loop 2-5-6-3.
Fig. 3 is a simplified representation of the bleeder circuit's internal blocks, namely a detection circuit, a control element and a discharge load. Detection circuit senses when a capaci-tance voltage begin to decrease, sending a signal expressed as voltage, V", to a control element which connects a discharge load in parallel with target capacitor Ctargot.
Fig. 4 shows the complete bleeder circuit diagram, according to invention, split in sections corresponding to the internal blocks from Fig. 3. Between an input terminal of the bleeder circuit and an output terminal of the bleeder circuit there is a difference of potential referenced as an output signal of bleeder circuit, expressed as voltage and named target voltage Vtarget. Also, a detected signal is expressed as voltage V", as well as the output signal of detection circuit, V".
The control element comprises a transistor T and a resistor gate R""Le. A first main electrode of transistor T is coupled through a bleed load (illustrated here as a resistor without reference) to the input terminal of the bleeder circuit, so that the bleed load allows a control electrode current to be delivered to the control electrode of transistor T; a second main electrode of transistor T is coupled to the output ter-minal of the bleeder circuit, while an output of transistor T is coupled via gate resistor Rcat, to the output terminal of the bleeder circuit. Also, the output of transistor T is coupled to an output of an operational amplifier from the detection circuit. The detection circuit further comprises a diode D coupled to the input terminal of the bleeder circuit, two resistor circuits connected in parallel, a first resistor circuit with two resistors, R1 and R, arranged as a first divider and coupled between the input terminal and the output terminal of the bleeder circuit, and a second resistor circuit with two resistors, R2 and R, also arranged as a second divider and connected in series with diode D between the input terminal and the output terminal of the bleeder circuit. Resistor R1 is coupled to the inverting input of operational amplifier OMAMP, while resistor R2 is coupled to the non-inverting input of operational amplifier CRAMP. A bleeder capacitor Gs and filtering capacitors Cfthat filter possible voltage spikes caused by external electromagnetic interferences are also connected in parallel with the two resistor circuits.
By this arrangement, the detection circuit charges bleeder capacitor 01, from target capacitor Otargot through diode D. Since bleeder capacitor Cb served as energy reserve for bleeder circuit while discharging target capacitor Ctargot, diode D ensures that own voltage Vownwill not decrease along with target voltage Vtargot at power off. In this case, the trigger relies on the fact that target capacitor Ct,r,,t will discharge faster than bleeder capacitor ot, and target voltage VL"eLwill become lower than own voltage V"-When power supply switches its output off, both capacitors Do and Ctargot begin discharging until the voltage over target capacitor Ctargc, drops below a threshold voltage set by diode D and the second voltage divider, R/R2. In that moment, the operational amplifier OPAMP's output opens the transistor T, and target capacitor Ctarget discharges through bleed load. Gate resistor Rm,t, keeps transistor T blocked until the voltage exceeding bleeder capacitor CI, is sufficient to power the operational amplifier OPAMP, avoiding power-on currenT surges.
The solution is to calculate the capacitance of bleeder capacitor Cb in such a way that the voltage over target capacitor Ctargct drops below the threshold while bleeder capacitor CI, still has the energy required to power the operational ampli-fier °FAME' for long enough to activate transistor T. In Fig. 5 it is shown voltage between nets V+ and V-at power off discharging, in three combination: - powered device connected, bleeder disconnected -the slowest 10 rate of discharge; - powered device connected, bleeder connected -the fastest rate of discharge; - powered device disconnected, bleeder disconnected -the rate of discharging is moderated.
Possible alternative embodiments according to invention, but serving different operating functions, are illustrated in Fig. 6, 7 and 8. Fig. 6 shows an embodiment allowing the bleeder circuit to operate as high-voltage capacitor discharger, hay-ing a voltage regulator inserted between diode D and operational amplifier OMAMP. Fig. 7 shows an exemplary diagram of the bleeder circuit according to invention, operating as external-triggered bleeder, whereas the embodiment of bleeder circuit with modified connections from Fig. 8 operates as power surge protection.
However, while certain embodiments of the present invention have been described in detail, those familiar with the art to which this invention relates will recognize various alterna-tive designs and embodiments for practicing the invention as defined by the following claims.
List of reference signs 1, 2, 3, 4, 5 Nodes C., Bleeder capacitor Of Filtering capacitor Ctarget Target capacitor Diode Transistor R Dividing resistor Ri First resistor of detection circuit R2 Second resistor of detection circuit Rgato Gate resistor °RAMP Operational amplifier V"_ Detected signal, expressed as voltage Vout Output signal of detection circuit, expressed as voltage Vtargct Output signal of bleeder circuit, expressed as voltage
Claims (10)
- Patent claims 1. An active bleeder circuit for discharging voltage in controlled manner, able to be attached by means of an input ter-5 minal and an output terminal to a device powered through a switch, which device has a target capacitor coupled between the input terminal and the output terminal, the active bleeder circuit further comprising a detection circuit with an operational amplifier, a first resistive divider, a second resis10 tive divider and a bleeder capacitor, and a control circuit comprising a gate resistor and a transistor having a first main electrode, a second main electrode and a control electrode, wherein a bleed load is coupled between the input terminal and 15 the first main electrode of the transistor.
- 2. Active bleeder circuit according to claim 1, wherein the bleed load is a resistor.
- 3. Active bleeder circuit according to claim 1, wherein the first resistive divider of the bleeder circuit is coupled to the inverting input of the operational amplifier, and the second resistive divider of the bleeder circuit is connected to the non-inverting input of the operational amplifier.
- 4. Active bleeder circuit according to claim 1, wherein an external trigger signal is received via the first resistive divider.
- 5. Active bleeder circuit according to claim 3, wherein a voltage regulator is coupled between the diode and the bleeder capacitor of the bleeder circuit.II
- 6. Active bleeder circuit according to claim 1, wherein the first resistive divider of the bleeder circuit is coupled to the non-inverting input of the operational amplifier, and the second resistive divider of the bleeder circuit is connected to the inverting input of the operational amplifier.
- 7. Method of actively discharging voltage in controlled man-ner, comprising the following steps: - providing a device powered through a switch, comprising a target capacitor coupled between an input terminal and an output terminal, - providing an active bleeder circuit coupled between the input terminal and the output terminal to the powered device, the bleeder circuit comprising a diode, a first resistive voltage divider, a second resistive voltage divider, a bleeder capacitor, an opera7_ional amplifier with an inverting input and a non-inverting input, a resistor gate and a transistor with a first main electrode, a second main electrode and a control electrode; providing a bleed load inserted between the input terminal and the first main electrode of the transistor, whereby when the power supply to the device is switched off, both the bleeder capacitor and the target capacitor begin discharging until the voltage over target capacitor drops below a threshold voltage set by the diode and the second voltage divider, the operational amplifier opens the transistor, and target capacitor discharges through bleed load.
- 8. Use of the device according to claim 4 as an externally 30 triggered active discharge circuit.
- 9. Use of the device according to claim 5 as high-voltage discharger.
- 10. Use of the device according to claim 6 as a power surge protection circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1913850.2A GB2587376B (en) | 2019-09-26 | 2019-09-26 | Active bleeder circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1913850.2A GB2587376B (en) | 2019-09-26 | 2019-09-26 | Active bleeder circuit |
Publications (4)
| Publication Number | Publication Date |
|---|---|
| GB201913850D0 GB201913850D0 (en) | 2019-11-13 |
| GB2587376A true GB2587376A (en) | 2021-03-31 |
| GB2587376A8 GB2587376A8 (en) | 2021-05-12 |
| GB2587376B GB2587376B (en) | 2021-09-22 |
Family
ID=68538922
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1913850.2A Active GB2587376B (en) | 2019-09-26 | 2019-09-26 | Active bleeder circuit |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2587376B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113852171A (en) * | 2021-11-30 | 2021-12-28 | 深圳市爱图仕影像器材有限公司 | Circuit for controlling electric quantity discharge and electronic equipment |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07337007A (en) * | 1994-06-07 | 1995-12-22 | Japan Radio Co Ltd | Dc voltage supply circuit |
-
2019
- 2019-09-26 GB GB1913850.2A patent/GB2587376B/en active Active
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07337007A (en) * | 1994-06-07 | 1995-12-22 | Japan Radio Co Ltd | Dc voltage supply circuit |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113852171A (en) * | 2021-11-30 | 2021-12-28 | 深圳市爱图仕影像器材有限公司 | Circuit for controlling electric quantity discharge and electronic equipment |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2587376A8 (en) | 2021-05-12 |
| GB2587376B (en) | 2021-09-22 |
| GB201913850D0 (en) | 2019-11-13 |
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