CN110943437A - IPM output short circuit protection method - Google Patents
IPM output short circuit protection method Download PDFInfo
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- CN110943437A CN110943437A CN201911302558.4A CN201911302558A CN110943437A CN 110943437 A CN110943437 A CN 110943437A CN 201911302558 A CN201911302558 A CN 201911302558A CN 110943437 A CN110943437 A CN 110943437A
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- 238000000034 method Methods 0.000 title claims abstract description 14
- 238000001514 detection method Methods 0.000 claims abstract description 21
- 238000004804 winding Methods 0.000 claims abstract description 10
- 238000005070 sampling Methods 0.000 description 4
- 230000001960 triggered effect Effects 0.000 description 4
- 230000015556 catabolic process Effects 0.000 description 3
- 230000004044 response Effects 0.000 description 2
- 230000035939 shock Effects 0.000 description 2
- 208000033999 Device damage Diseases 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000002040 relaxant effect Effects 0.000 description 1
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Classifications
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- 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
- H02H7/08—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 dynamo-electric motors
- H02H7/085—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 dynamo-electric motors against excessive load
- H02H7/0854—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 dynamo-electric motors against excessive load responsive to rate of change of current, couple or speed, e.g. anti-kickback protection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
- H02P1/02—Details of starting control
- H02P1/022—Security devices, e.g. correct phase sequencing
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- Engineering & Computer Science (AREA)
- Computer Security & Cryptography (AREA)
- Power Engineering (AREA)
- Protection Of Generators And Motors (AREA)
- Control Of Ac Motors In General (AREA)
Abstract
The invention relates to the field of IPM protection, and discloses an IPM output short-circuit protection method which is used for solving the problems that conventional IPM overcurrent protection only can deal with common overcurrent protection and short-circuit protection cannot be carried out in time. Before the system initializes the motor to start, the MCU sends short circuit detection pulse to the IPM to enable the IPM to energize each phase winding of the motor in turn, the MCU detects the state of an IPM fault output pin, if the IPM fault output pin is detected to be in a fault state, the system stops starting, the MCU displays a fault code on a display device, and if the IPM fault output pin is detected to be in a normal state, the system starts the motor normally. The invention is suitable for IPM output short-circuit protection, can improve IPM short-circuit protection performance, improve system reliability, reduce circuit design difficulty and does not need to increase cost.
Description
Technical Field
The invention relates to the field of IPM (intelligent power module) protection, in particular to an IPM output short-circuit protection method.
Background
Besides a power device (IGBT), the interior of the IPM is also integrated with abundant monitoring and protecting functions, thereby greatly facilitating application and improving system reliability. The IPM protection circuit can realize control voltage under-voltage protection, overheat protection, overcurrent protection and short-circuit protection, and the principles of the overcurrent protection and the short-circuit protection are that when the current flowing through the internal IGBT is monitored to exceed an overcurrent threshold and the duration time exceeds a specified time, the IGBT is turned off to output, and a fault signal is output to the MCU.
Fig. 1 is a typical IPM overcurrent protection circuit, where RS is a current sampling resistor connected between a lower bridge arm output end (LS) of the IPM and ground, the current flowing through RS is an IPM output current, the voltage at the high potential end of RS is proportional to the IPM output current, the IPM output current can be detected by detecting the sampling voltage, and the setting of the overcurrent threshold can be realized by adjusting the resistance of RS. In order to suppress high-frequency interference, the sampled voltage is filtered by a filter circuit consisting of a resistor R1 and a capacitor C1 and then is input into an IPM overcurrent detection pin (OCP) for triggering internal overcurrent hardware protection. When the IPM OCP pin voltage exceeds a specified voltage and the duration exceeds a specified time, the IPM turns off the IGBT output and outputs a fault signal through a fault output pin (FO).
When the IPM is short-circuited at the output (short-circuited motor winding), the current is very large, the short circuit endurance time tsc (short circuit with time) is very small, generally within 5 μ S, and when the short circuit duration exceeds tsc, the IPM is damaged. When designing the protection circuit, the short-circuit protection function is performed only if the total response time Tc of the protection circuit is smaller than the IPM short-circuit tolerant time tsc, where Tc includes the external filter circuit time constant and the drive delay time tscp (short circuit protection time) inside the IPM. Tc in the circuit shown in fig. 1 is t + tscp, where t is the filter time constant. In practical application, tscp can be found from an IPM specification and is a fixed value, generally about 2 muS, so that a filter time constant t becomes an important parameter of a protection circuit, t cannot be designed to be too small or too large, is easy to be interfered by high frequency to generate misoperation, and cannot be triggered to be protected in time when output is short-circuited.
The IPM output short-circuit current is much larger than the rated current, so the short-circuit withstand time tsc is much smaller than the over-current withstand time toc. When a protection circuit is designed, if referring to tsc, a filter time constant t needs to be designed to be very small, generally 2-3 muS is needed, and thus frequent false protection can occur due to interference in a complex electromagnetic environment. Therefore, in practical applications, the filter time constant t is designed to be larger under the condition that the overcurrent tolerance time toc is satisfied, so that the IPM internal hardware protection can be effectively triggered in the case of overcurrent and the error protection caused by high-frequency interference can be effectively avoided. However, this design has a serious problem: the response time of the protection circuit exceeds the short-circuit tolerant time tsc when the IPM works normally, and short-circuit protection cannot be performed, namely, the IPM has not yet been triggered to have damage by internal hardware protection when the IPM outputs short circuit. While IPM output short circuits (caused by short circuits in the machine windings or other causes) are a small probability event, the consequences are severe once they occur and without effective protection measures.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the IPM output short-circuit protection method is provided for solving the problems that the conventional IPM overcurrent protection can only deal with the common overcurrent protection and cannot carry out the short-circuit protection in time.
The technical scheme adopted by the invention for solving the technical problems is as follows: before a system initializes a motor to start, an MCU sends a short-circuit detection pulse to the IPM to enable the IPM to energize each phase winding of the motor in turn, the MCU detects the state of an IPM fault output pin, if the IPM fault output pin is detected to be in a fault state, the system stops starting, the MCU displays a fault code on a display device, and if the IPM fault output pin is detected to be in a normal state, the system starts the motor normally.
Further, when the MCU sends the short detection pulse to the IPM, the PFC circuit is in an off state.
Further, the MCU controls the pulse width to be more than or equal to the IPM internal driving delay time.
The invention has the beneficial effects that:
1. the invention advances the IPM output short circuit detection and protection time from the normal working period to the system initialization period, changes the passive detection protection into the active detection protection, and improves the detection reliability. During the normal working period of the frequency converter, various motors and power devices can generate high-frequency and high-energy interference, and the detection and the triggering of a protection circuit are seriously influenced; and during system initialization, interference signals are weak, and the detection and triggering reliability of a protection circuit is high.
2. The invention can effectively reduce thermal shock to the IPM by carrying out short circuit detection and protection when the PFC circuit is in a closed state. The power device damage mechanism can be basically attributed to thermal breakdown in addition to overvoltage breakdown. Excessive IPM internal temperatures cause degradation of the internal leads and package housing, and, in the worst case, permanent failure or explosion. During system initialization, PFC is closed, IPM working voltage is much lower than that when PFC is opened during system normal working, and IPM internal bridge arm on-resistance can be regarded as a fixed value, and according to a formula W-V2The method has the advantages that the heat productivity can be greatly reduced by the scheme of short circuit detection when the PFC circuit is in a closed state, and thermal shock to the IPM can be effectively reduced.
3. The mode of actively sending the short-circuit detection pulse can reliably detect the output short-circuit fault while relaxing the time constant of the filter circuit. Because the IPM short-circuit current is too large, which results in a small short-circuit withstand time tsc, if short-circuit protection is implemented by using the existing method, the time constant of the filter circuit needs to be designed to be very small (the short-circuit withstand time tsc minus the driving delay time tscp is 2-3 μ S), and the protection circuit is susceptible to noise interference to generate error protection, so that the time constant of the filter circuit is designed to be large (generally 10 μ S) in actual use, which causes that the existing scheme can only implement ordinary over-current protection but cannot implement short-circuit protection. The invention actively sends the short circuit detection pulse, and can reliably trigger the IPM internal hardware protection circuit as long as the short circuit detection pulse width is ensured to be more than or equal to the drive delay time tscp, and is irrelevant to the time constant of the filter.
In summary, the invention improves the IPM short circuit protection performance, improves the system reliability, reduces the circuit design difficulty, and does not need to increase the cost.
Drawings
FIG. 1 illustrates an exemplary IPM overcurrent protection circuit;
FIG. 2 is a flow chart of the IPM output short circuit protection method of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the following examples and accompanying drawings.
As shown in fig. 2, the IPM output short-circuit protection method of the present invention comprises the following steps:
the first step is as follows: and initializing the MCU on the system.
In the step, the MCU completes chip hardware initialization, detection and initialization of peripheral sensors, PFC control parameter initialization and IPM control parameter initialization, and sets an I/O port, connected with an IPM FO pin, of the MCU to be in a falling edge trigger interrupt input mode, so that the MCU can process the IPM at the first time when the IPM outputs a fault signal.
The second step is that: before the PFC is turned on and the motor is not started, the MCU sends a short-circuit detection pulse to the IPM, the pulse width is slightly larger than the internal drive delay time tscp of the IPM, and the IPM is enabled to energize each phase winding of the motor in turn.
If the motor has a winding short circuit, a higher voltage can be generated on the sampling resistor RS when the corresponding winding is electrified, the voltage enters the IPM OCP pin after passing through the filtering wave, an IPM internal hardware protection circuit is triggered, and a fault signal is output to the MCU through the FO pin.
The third step: the MCU detects IPM FO pin status. And if the FO pin is detected to be in a fault state, the system stops starting, and the MCU displays a fault code through the display device. If the FO pin is detected to be in a normal state, the next step is continued.
The fourth step: the system starts the motor normally to make the motor start to work normally.
Taking a certain model of IPM for driving a dc fan as an example, the overcurrent rated operating current is 5A, the rated operating voltage is 400V, the overcurrent withstand time toc is 25 μ S, the short circuit withstand time is 5 μ S, and the internal driving delay time is 2 μ S, so that the filter time constant should be less than 3 μ S to perform short circuit protection when designing a protection circuit. However, in practical use, in order to reduce high-frequency interference, the filter parameters are: R1K, C10 nF, and time constant t R C10 μ S, which exceeds the short circuit withstand time 5 μ S, meaning that the circuit does not function as a short circuit protection. The method adopted by the invention is that after the system is electrified and the MCU is initialized, when the PFC is not opened and the motor is not started, the MCU sends a short-circuit detection pulse to the IPM, the pulse width is 3.5 muS, and the pulse interval is 16.5 muS, so that the IPM alternately energizes each phase winding of the motor, if a certain winding of the motor is short-circuited, the current flowing through the IPM is increased sharply, and simultaneously a higher voltage pulse is generated on a sampling resistor RS, the voltage pulse is filtered and then sent to an IPM overcurrent protection detection pin and triggers an IPM internal hardware protection circuit, and the IPM shuts off all IGBT outputs and outputs a low level at a fault output pin. And after the MCU detects the fault signal output by the IPM, the system is immediately stopped to continue starting, and the fault code is displayed through the display device. According to the method, a pulse IPM is input on a short-circuit phase, and then a fault signal can be output by an FO pin.
Claims (3)
1. Before a system initializes a motor to start, an MCU sends a short-circuit detection pulse to the IPM to enable the IPM to energize each phase winding of the motor in turn, the MCU detects the state of an IPM fault output pin, if the IPM fault output pin is detected to be in a fault state, the system stops starting, the MCU displays a fault code on a display device, and if the IPM fault output pin is detected to be in a normal state, the system starts the motor normally.
2. The IPM output short-circuit protection method of claim 1, wherein the PFC circuit is in an off state when the MCU sends a short-circuit detection pulse to the IPM.
3. The IPM output short-circuit protection method of claim 1, wherein the MCU controls the pulse width to be equal to or greater than the IPM internal driving delay time.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911302558.4A CN110943437A (en) | 2019-12-17 | 2019-12-17 | IPM output short circuit protection method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911302558.4A CN110943437A (en) | 2019-12-17 | 2019-12-17 | IPM output short circuit protection method |
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| CN110943437A true CN110943437A (en) | 2020-03-31 |
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| CN201911302558.4A Pending CN110943437A (en) | 2019-12-17 | 2019-12-17 | IPM output short circuit protection method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112034384A (en) * | 2020-08-05 | 2020-12-04 | 苏州汇川联合动力系统有限公司 | Method, device and computer-readable storage medium for identifying short circuit of motor system |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008029060A (en) * | 2006-07-18 | 2008-02-07 | Mitsubishi Electric Corp | Semiconductor device |
| CN103683202A (en) * | 2012-09-20 | 2014-03-26 | 博世力士乐(西安)电子传动与控制有限公司 | Device and method for detecting output earth short circuit condition of frequency converter |
| CN109038476A (en) * | 2018-08-08 | 2018-12-18 | 杭州先途电子有限公司 | A kind of current foldback circuit and controller |
-
2019
- 2019-12-17 CN CN201911302558.4A patent/CN110943437A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008029060A (en) * | 2006-07-18 | 2008-02-07 | Mitsubishi Electric Corp | Semiconductor device |
| CN103683202A (en) * | 2012-09-20 | 2014-03-26 | 博世力士乐(西安)电子传动与控制有限公司 | Device and method for detecting output earth short circuit condition of frequency converter |
| CN109038476A (en) * | 2018-08-08 | 2018-12-18 | 杭州先途电子有限公司 | A kind of current foldback circuit and controller |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112034384A (en) * | 2020-08-05 | 2020-12-04 | 苏州汇川联合动力系统有限公司 | Method, device and computer-readable storage medium for identifying short circuit of motor system |
| CN112034384B (en) * | 2020-08-05 | 2023-12-26 | 苏州汇川联合动力系统股份有限公司 | Method, apparatus and computer readable storage medium for identifying motor system short circuit |
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Application publication date: 20200331 |
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