CN211123210U - Brake resistor short circuit detection circuit - Google Patents
Brake resistor short circuit detection circuit Download PDFInfo
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- CN211123210U CN211123210U CN201921525586.8U CN201921525586U CN211123210U CN 211123210 U CN211123210 U CN 211123210U CN 201921525586 U CN201921525586 U CN 201921525586U CN 211123210 U CN211123210 U CN 211123210U
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Abstract
The embodiment of the utility model discloses braking resistance short circuit detection circuitry for whether the braking resistance on the detection converter short circuit, the converter still includes positive DC bus, burden DC bus, semiconductor power module, drive branch road and the control unit, and braking resistance and semiconductor power module series connection are between positive DC bus and burden DC bus, the control unit is connected to the control end of semiconductor power module through the drive branch road, detection circuitry includes power supply unit, first branch road that discharges, second branch road that discharges and output unit; the first discharging branch circuit is connected to the output end of the power supply unit and pulls down the voltage of the output end of the power supply unit when the semiconductor power module is disconnected; the second discharging branch circuit is connected in series between the output end of the power supply unit and a connection point of the brake resistor and the semiconductor power module; the input end of the output unit is connected to the output end of the power supply unit. The utility model provides a brake resistance detection circuitry simple structure, low price.
Description
Technical Field
The utility model relates to an electron electric power field especially relates to a braking resistance short circuit detection circuitry.
Background
When the motor or other inductive loads driven by the frequency converter are shut down, the motor or other inductive loads are generally stopped by adopting a heat energy consumption braking mode, namely, the kinetic energy of the stopped motor and the magnetic energy in the coil are consumed by a specific energy consumption element, so that the rapid shutdown is realized. However, once the brake resistor is short-circuited, the brake resistor may be damaged or the frequency converter may be burnt, so the frequency converter generally needs to detect whether the brake resistor is short-circuited in real time and protect the frequency converter in real time when the brake resistor is short-circuited.
At present, a current detection method is usually adopted for detecting whether the brake resistor is short-circuited or a professional brake circuit detection chip is adopted for detecting, however, the brake resistor detection method needs an additional power supply, the circuit is relatively complex, the professional brake circuit detection chip is expensive, and selectable suppliers are few.
SUMMERY OF THE UTILITY MODEL
The embodiment of the utility model provides a to above-mentioned when detecting whether short circuit of brake resistance, adopt conventional current detection method to detect the circuit complexity problem that exists and adopt professional brake circuit to detect the chip and detect the problem that the cost of manufacture is high that exists, provide a brake resistance short circuit detection circuitry.
The embodiment of the utility model provides a solve the technical scheme that above-mentioned technical problem adopted and be: the braking resistance short-circuit detection circuit is used for detecting whether a braking resistance on a frequency converter is short-circuited or not, the frequency converter further comprises a positive direct-current bus, a negative direct-current bus, a semiconductor power module, a driving branch circuit and a control unit, the braking resistance and the semiconductor power module are connected between the positive direct-current bus and the negative direct-current bus in series, and the control unit is connected to a control end of the semiconductor power module through the driving branch circuit; the detection circuit comprises a power supply unit, a first discharging branch circuit, a second discharging branch circuit and an output unit; the first discharging branch circuit is connected to the output end of the power supply unit and pulls down the voltage of the output end of the power supply unit when the semiconductor power module is disconnected; the second discharging branch circuit is connected between the output end of the power supply unit and a connection point of the braking resistor and the semiconductor power module in series, and pulls down the voltage of the output end of the power supply unit when the semiconductor power module is conducted and the braking resistor is not short-circuited; the input end of the output unit is connected to the output end of the power supply unit, and a brake resistor short-circuit signal is output when the output end of the power supply unit is at a high level.
Preferably, the first discharging branch comprises a first diode, and an anode of the first diode is connected to the output terminal of the power supply unit, and a cathode of the first diode is connected to the control terminal of the semiconductor power module.
Preferably, the second discharge branch includes a diode group composed of one or more diodes connected in series, and an anode of the diode group is connected to the output terminal of the power supply unit, and a cathode of the diode group is connected to a connection point of the braking resistor and the semiconductor power module.
Preferably, the power supply unit comprises a current-limiting subunit and an energy-storing capacitor, the current-limiting subunit comprises one or more resistors, and the current-limiting subunit and the energy-storing capacitor are connected in series between an external power supply voltage and a reference ground; and the connection point of the current-limiting subunit and the energy-storage capacitor forms the output end of the power supply unit.
Preferably, the output unit includes a first optocoupler and a first level conversion unit, and a primary side anode of the first optocoupler is connected to the output end of the power supply unit; the input end of the first level conversion unit is connected with the secondary side of the first optocoupler, and the output end of the first level conversion unit is connected with the input end of the control unit; and the first level conversion unit outputs a brake resistance short-circuit signal to the control unit when the first optocoupler is switched on.
Preferably, a voltage stabilizing unit composed of a second diode and a voltage stabilizing diode is connected between the positive electrode of the primary side of the first optocoupler and the output end of the power supply unit, the anode of the second diode is connected with the output end of the power supply unit, and the cathode of the second diode is connected with the cathode of the voltage stabilizing diode; and the anode of the voltage stabilizing diode is connected with the input end of the output unit.
Preferably, the detection circuit further includes a filter capacitor, and the filter capacitor is connected in parallel between a primary side positive electrode and a primary side negative electrode of the first optocoupler.
Preferably, the detection circuit further includes a freewheeling diode, an anode of the freewheeling diode is connected to a cathode of the primary side of the first optocoupler, and a cathode of the freewheeling diode is connected to an anode of the primary side of the first optocoupler.
Preferably, the secondary side of the first optocoupler and the input end of the first level conversion unit are connected with a voltage division unit, the voltage division unit comprises a first resistor and a second resistor which are sequentially connected in series, an external power supply voltage is connected to one end of the first resistor, one end of the second resistor is connected with the input end of the first level conversion unit, and the secondary side of the first optocoupler is connected to the connection point of the first resistor and the second resistor.
Preferably, the driving branch comprises a second level conversion unit and a second optical coupler, a primary side input end of the second optical coupler is connected with an output end of the second level conversion unit, and a secondary side output end of the second optical coupler is connected with a control end of the semiconductor power module.
The embodiment of the utility model provides a through when the braking resistance short circuit, power supply unit exports high level signal to output unit, and when the braking resistance is not short circuit, the voltage of drawing down power supply unit's output through first branch road that discharges comes to detect whether short circuit of the braking resistance of converter to output unit output low level signal's method, and circuit structure is simple, and components and parts are few, the low price.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the description of the embodiments of the present invention will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive labor.
Fig. 1 is a schematic structural diagram of a short-circuit detection circuit for a brake resistor according to an embodiment of the present invention;
fig. 2 is a circuit diagram of a short-circuit detection circuit for a brake resistor according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, of the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.
The embodiment of the utility model provides a whether brake resistance short circuit detection circuitry, this circuit is used for detecting the brake resistance on the converter short circuit. As shown in fig. 1, the frequency converter 1 further includes a positive dc bus VBUS +, a negative dc bus VBUS-, a semiconductor power module Q, a driving branch 11, and a control unit 12, wherein the braking resistor R and the semiconductor power module Q are connected in series between the positive dc bus VBUS + and the negative dc bus VBUS-, and the control unit 12 is connected to a control terminal of the semiconductor power module Q via the driving branch 11. The semiconductor power module Q may specifically employ an IGBT (Insulated Gate bipolar transistor).
The braking resistance short circuit detection circuit 2 of the present embodiment includes a power supply unit 21, a first discharging branch 22, a second discharging branch 23, and an output unit 24; the first discharging branch 22 is connected to the output terminal of the power supply unit 21 and pulls down the voltage of the output terminal of the power supply unit 21 when the semiconductor power module Q is turned off; the second discharging branch 23 is connected in series between the output end of the power supply unit 21 and a connection point of the braking resistor R and the semiconductor power module Q, and pulls down the voltage of the output end of the power supply unit 21 when the semiconductor power module Q is turned on and the braking resistor R is not short-circuited; the input terminal of the output unit 24 is connected to the output terminal of the power supply unit 21, and outputs a brake resistance R short-circuit signal when the output terminal of the power supply unit 21 is at a high level.
In order to drive the motor connected to the frequency converter to operate, the voltage between the positive dc bus and the negative dc bus (i.e. the bus voltage) is much greater than the voltage at the output of the power supply unit.
In the following, taking a semiconductor power module as an IGBT as an example, the working principle of the braking resistor short-circuit detection circuit is as follows:
when the control unit 12 sends a driving signal to control the IGBT to be turned on, the brake resistor R starts to operate. Under normal conditions (that is, under the condition that the braking resistor R is short-circuited), the IGBT operates in a saturation state, at this time, the voltage between the collector and the emitter of the IGBT is small, the second discharging branch 23 pulls the voltage of the output end of the power supply unit 21 low, at this time, the output unit 24 detects a low level, and the output unit 24 does not output a short-circuit signal of the braking resistor R.
When the IGBT is turned on, if the brake resistor R is short-circuited, the collector of the IGBT is directly connected to the positive dc bus VBUS +, and at this time, a short-circuit current on the positive dc bus VBUS + will directly flow through the IGBT, and since the short-circuit current is too large, the IGBT is converted from a saturation state to a desaturation state, and a voltage on the collector of the IGBT is equal to a bus voltage, so that the second discharging branch 23 cannot pull down the voltage at the output end of the power supply unit 21, and at this time, the output unit 24 detects that the output end of the power supply unit 21 is at a high level, and outputs a short-circuit signal of the brake resistor.
When the control unit 12 sends a driving signal to control the IGBT to turn off, the braking resistor R does not work, and the control terminal of the IGBT is at a low level. The first discharging branch 22 between the control terminal of the IGBT and the output terminal of the power supply unit 21 pulls down the voltage at the output terminal of the power supply unit 21 from the high level to the low level, so as to avoid that the output unit 24 makes a misjudgment (i.e., the output unit 24 mistakes the power supply voltage of the power supply unit 21 as a high level signal) to send a short-circuit signal of the brake resistor R. That is to say, the embodiment of the utility model provides a when semiconductor power module does not switch on, draw down the voltage of the output of power supply unit 21 through first branch road 22 that discharges, make detection circuitry 2 not effective in effect, circuit structure is simple, and components and parts are few, the low price.
Specifically, as shown in fig. 2, the first discharge branch 22 may include a first diode D1, an anode of the first diode D1 is connected to the output terminal of the power supply unit 21, and a cathode of the first diode D1 is connected to the control terminal of the semiconductor power module Q. When the semiconductor power module Q is in the off state, the control terminal of the semiconductor power module Q is at a low potential, and the voltage at the output terminal of the power supply unit 21 can be pulled down by the first diode D1.
The second discharge branch 23 may include a diode group including one or more diodes connected in series, and an anode of the diode group is connected to the output terminal of the power supply unit 21, and a cathode of the diode group is connected to a connection point of the braking resistor R and the semiconductor power module Q. The diode group can pull down the voltage at the output terminal of the power supply unit 21 when the semiconductor power module Q is turned on and the brake resistor R is not short-circuited. In addition, the diode group can prevent the bus current from flowing into the circuit when the brake resistor R is short-circuited, thereby protecting the circuit.
The power supply unit 21 may include a current limiting subunit 211 and an energy storage capacitor C0, the current limiting subunit 211 includes one or more resistors, the current limiting subunit 211 and the energy storage capacitor C0 are connected in series between the external power supply voltage L + and the ground VBUS-, and a connection point of the current limiting subunit 211 and the energy storage capacitor C0 constitutes an output terminal of the power supply unit 21, the current limiting subunit 211 may limit a current flowing into the output unit 24 to prevent the current from being excessively large to damage the output unit 24, and the output unit 24 is powered by the energy storage capacitor C0 when the output terminal voltage of the power supply unit 21 is pulled low.
The output unit 24 may include a first optocoupler U1 and a first level shift unit U2, and a primary side anode of the first optocoupler U1 is connected to the output terminal of the power supply unit 21; the input end of the first level conversion unit U2 is connected with the secondary side of the first optocoupler U1, and the output end of the first level conversion unit U2 is connected with the input end of the control unit 12; when the first optocoupler U1 is turned on, the first level shift unit U2 outputs a brake resistor R short-circuit signal to the control unit 12.
When the semiconductor power module Q is turned on and the brake resistor R is shorted, the output end of the power supply unit 21 is at a high level and is greater than the turn-on voltage of the first optocoupler U1, the first optocoupler U1 is turned on and outputs a high level to the first level conversion unit U2, and the first level conversion unit U2 converts the high level output by the first optocoupler U1 into a TT L level signal (a transistor-transistor logic level signal), that is, a brake resistor R short-circuit signal, and outputs the signal to the control unit 12, so that the control unit 12 performs a corresponding protection measure according to the signal, for example, cuts off the power supply of the inverter.
When the semiconductor power module Q is turned on and the brake resistor R is not short-circuited or the semiconductor power module Q is turned off, the output terminal of the power supply unit 21 is at a low level and is lower than the turn-on voltage of the first optocoupler U1, and the first optocoupler U1 is turned off and does not output a signal.
In order to keep the voltage of the primary side of the first optocoupler U1 stable and avoid the erroneous conduction of the first optocoupler U1 caused by the unstable voltage, a voltage stabilizing unit 25 composed of a second diode D2 and a voltage stabilizing diode DZ is connected between the positive electrode of the primary side of the first optocoupler U1 and the output end of the power supply unit 21, the anode of the second diode D2 is connected with the output end of the power supply unit 21, and the cathode of the second diode D2 is connected with the cathode of the voltage stabilizing diode DZ; the anode of the zener diode DZ is connected to the input terminal of the output unit 24.
The brake resistor detection circuit further comprises a filter capacitor C1, and the filter capacitor C1 is connected in parallel between the primary positive electrode and the primary negative electrode of the first optocoupler U1 to filter ripple interference.
The brake resistor detection circuit further comprises a freewheeling diode DF, the anode of the freewheeling diode DF is connected with the cathode of the primary side of the first optocoupler U1, the cathode of the freewheeling diode DF is connected with the anode of the primary side of the first optocoupler U1, and the freewheeling diode DF mainly plays a freewheeling role.
A voltage division unit can be further connected between the secondary side of the first optical coupler U1 and the input end of the first level conversion unit U2, the voltage division unit comprises a first resistor R1 and a second resistor R2 which are sequentially connected in series, one end of the first resistor R1 is connected with an external power supply voltage (+5V), one end of the second resistor R2 is connected with the input end of the first level conversion unit U2, and the secondary side of the first optical coupler U1 is connected to the connection point of the first resistor R1 and the second resistor R2.
In the braking resistance detection circuit, the driving branch 11 may include a second level conversion unit U11 and a second optical coupler U12, a primary input end of the second optical coupler U12 is connected to an output end of the second level conversion unit U12, and a secondary output end is connected to a control end of the semiconductor power module Q, the control unit 12 sends a driving signal to the second level conversion unit U11 according to an operation instruction of the motor, and the second level conversion unit U11 converts the driving signal into a TT L level signal and outputs the TT L level signal to the second optical coupler U12, so that the second optical coupler U12 drives the semiconductor power module Q to be turned on according to the driving signal.
The above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.
Claims (10)
1. A braking resistance short circuit detection circuit is used for detecting whether a braking resistance on a frequency converter is short-circuited or not, the frequency converter further comprises a positive direct current bus, a negative direct current bus, a semiconductor power module, a driving branch circuit and a control unit, the braking resistance and the semiconductor power module are connected between the positive direct current bus and the negative direct current bus in series, and the control unit is connected to a control end of the semiconductor power module through the driving branch circuit; the detection circuit is characterized by comprising a power supply unit, a first discharging branch circuit, a second discharging branch circuit and an output unit; the first discharging branch circuit is connected to the output end of the power supply unit and pulls down the voltage of the output end of the power supply unit when the semiconductor power module is disconnected; the second discharging branch circuit is connected between the output end of the power supply unit and a connection point of the braking resistor and the semiconductor power module in series, and pulls down the voltage of the output end of the power supply unit when the semiconductor power module is conducted and the braking resistor is not short-circuited; the input end of the output unit is connected to the output end of the power supply unit, and a brake resistor short-circuit signal is output when the output end of the power supply unit is at a high level.
2. The braking resistance short-circuit detection circuit according to claim 1, wherein the first discharge branch includes a first diode, and an anode of the first diode is connected to the output terminal of the power supply unit, and a cathode of the first diode is connected to the control terminal of the semiconductor power module.
3. The brake resistor short detection circuit according to claim 1, wherein the second discharge branch includes a diode group composed of one or more diodes connected in series, and an anode of the diode group is connected to an output terminal of the power supply unit, and a cathode of the diode group is connected to a connection point of the brake resistor and the semiconductor power module.
4. The brake resistance short circuit detection circuit according to claim 1, wherein the power supply unit includes a current limiting subunit and an energy storage capacitor, the current limiting subunit includes one or more resistors, and the current limiting subunit and the energy storage capacitor are connected in series between an external supply voltage and a reference ground; and the connection point of the current-limiting subunit and the energy-storage capacitor forms the output end of the power supply unit.
5. The brake resistor short-circuit detection circuit according to claim 1, wherein the output unit comprises a first optocoupler and a first level conversion unit, and a primary side anode of the first optocoupler is connected to the output terminal of the power supply unit; the input end of the first level conversion unit is connected with the secondary side of the first optocoupler, and the output end of the first level conversion unit is connected with the input end of the control unit; and the first level conversion unit outputs a brake resistance short-circuit signal to the control unit when the first optocoupler is switched on.
6. The braking resistance short-circuit detection circuit according to claim 5, wherein a voltage stabilization unit composed of a second diode and a voltage stabilization diode is connected between the positive electrode of the primary side of the first optocoupler and the output end of the power supply unit, the anode of the second diode is connected with the output end of the power supply unit, and the cathode of the second diode is connected with the cathode of the voltage stabilization diode; and the anode of the voltage stabilizing diode is connected with the input end of the output unit.
7. The brake resistor short detection circuit of claim 5, wherein the detection circuit further comprises a filter capacitor connected in parallel between the primary side positive electrode and the primary side negative electrode of the first optocoupler.
8. The brake resistor short detection circuit according to claim 5, wherein the detection circuit further comprises a freewheeling diode, and wherein an anode of the freewheeling diode is connected to a negative primary side of the first optocoupler and a cathode of the freewheeling diode is connected to a positive primary side of the first optocoupler.
9. The braking resistance short-circuit detection circuit according to claim 5, wherein a voltage division unit is connected between the secondary side of the first optocoupler and the input end of the first level conversion unit, the voltage division unit comprises a first resistor and a second resistor which are sequentially connected in series, one end of the first resistor is connected with an external power supply voltage, one end of the second resistor is connected with the input end of the first level conversion unit, and the secondary side of the first optocoupler is connected with a connection point of the first resistor and the second resistor.
10. The braking resistance short-circuit detection circuit according to claim 1, wherein the driving branch comprises a second level conversion unit and a second optocoupler, a primary side input end of the second optocoupler is connected with an output end of the second level conversion unit, and a secondary side output end of the second optocoupler is connected with a control end of the semiconductor power module.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921525586.8U CN211123210U (en) | 2019-09-12 | 2019-09-12 | Brake resistor short circuit detection circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921525586.8U CN211123210U (en) | 2019-09-12 | 2019-09-12 | Brake resistor short circuit detection circuit |
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| CN211123210U true CN211123210U (en) | 2020-07-28 |
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| CN201921525586.8U Active CN211123210U (en) | 2019-09-12 | 2019-09-12 | Brake resistor short circuit detection circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112285537A (en) * | 2020-10-28 | 2021-01-29 | 南京科远驱动技术有限公司 | Circuit and method for self-diagnosis of main circuit of frequency converter |
| CN112986857A (en) * | 2021-01-25 | 2021-06-18 | 中国电子科技集团公司第二十九研究所 | Circuit and method for detecting and identifying short-circuit fault of positioning capacitor bank through single port |
-
2019
- 2019-09-12 CN CN201921525586.8U patent/CN211123210U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112285537A (en) * | 2020-10-28 | 2021-01-29 | 南京科远驱动技术有限公司 | Circuit and method for self-diagnosis of main circuit of frequency converter |
| CN112986857A (en) * | 2021-01-25 | 2021-06-18 | 中国电子科技集团公司第二十九研究所 | Circuit and method for detecting and identifying short-circuit fault of positioning capacitor bank through single port |
| CN112986857B (en) * | 2021-01-25 | 2023-04-25 | 中国电子科技集团公司第二十九研究所 | Circuit and method for detecting and identifying and positioning short-circuit fault of capacitor bank through single port |
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