CN208902298U - A kind of IGBT temperature detection circuit - Google Patents

Abstract

The utility model is specifically related to a kind of IGBT temperature detection circuit, including NTC circuit module, VF conversion module, Fiber isolation transceiver module, CPU acquisition module；NTC circuit module acquisition RN resistance both ends output voltage signal to VF conversion module；The voltage signal received is converted into frequency signal and exported to Fiber isolation transceiver module by the VF conversion module；The Fiber isolation transceiver module transmits a signal to CPU acquisition module；The CPU acquisition module goes out corresponding resistance value at this time by computation of table lookup.The frequency retrieval precision that this method uses is high, also very strong to electromagnetism anti-interference ability, and the precision of NTC sampling also greatly improves, and can reduce the demand of the port ADC, save the resource and cost of system, accuracy is more preferable, also more reliable.

Description

A kind of IGBT temperature detection circuit

Technical field

The present invention relates to temperature sensing circuits, and in particular to a kind of IGBT temperature detection circuit.

Background technique

As the distributed generation resource permeability that new energy is representative is continuously increased, making rapid progress for power electronic technique is used The requirement of family power supply reliability is but being continuously improved；Therefore, with advances in technology, to the temperature protection of the switching devices such as IGBT Propose more strict requirements.Early stage IGBT overheat protector practices well is installed according to module thermal resistance or in Modular surface Temperature sensor, when test point temperature is more than the threshold value of setting, the input pulse signal that software can block IGBT makes IGBT Shutdown is to achieve the purpose that it is made to stop working.And in actual operation, the heat between spreader surface and IGBT module substrate There is biggish inconsistencies during production and assembly for resistance, and the test point for the temperature sensor installed may also be because of the external world Condition rather than the thermal self-restraint stress of radiator, the above reason may result in test point temperature and differ larger with IGBT virtual junction temperature And cause thermal-shutdown circuit work abnormal.The IGBT module enclosed inside of new encapsulating structures some in recent years has temperature sensing (NTC), the stable state shell temperature of module can be effectively detected, and because its temperature sensor (NTC) is encapsulated in inside modules, detection one Cause property is very high, and the junction temperature accuracy detected is also very high.Corresponding this kind of enclosed inside has the IGBT mould of temperature sensor (NTC) Block, it by temperature inversion is analog signal that existing common practice, which is by temperature sensor (NTC), and passes through linear optical coupling isolation After be transferred to logic control part, judge whether its state of temperature is protected by software.Although this method is simple, In the presence of following several disadvantages:

1) due to being isolated using linear optical coupling, and optocoupler linearly interval is narrow, and measurement accuracy is not high, is not suitable for height The temperature detection of precision；2) generally resistance value is used to change into voltage value when sampling, since IGBT often works in forceful electric power magnet ring Border easily causes sampled voltage to be disturbed；3) traditional NTC detection circuit need to generally be sent to CPU, and CPU need to use ADC chip (CPU It is built-in or external) temperature signal is obtained, ADC pin resource is occupied, therefore cause at high cost.

Summary of the invention

1, technical problem to be solved:

In order to solve the above technical problem, the present invention provides a kind of IGBT temperature detection circuits based on frequency measurement.It is logical To the voltage acquisition at the both ends to NTC resistance RN resistance value, and voltage is changed into frequency signal and carries out transmitting trip temperature point of going forward side by side The circuit of analysis.The channel frequency retrieval precision that this method uses is high, and anti-electromagnetic interference capability is strong, and the precision of NTC sampling is high, safety Reliably.

2, technical solution:

A kind of IGBT temperature detection circuit, including NTC circuit module, VF conversion module, Fiber isolation transceiver module, CPU Acquisition module；NTC circuit module acquisition RN resistance both ends output voltage signal to VF conversion module；The VF conversion module The voltage signal received is converted into frequency signal and is exported to Fiber isolation transceiver module；The Fiber isolation receives and dispatches mould Block transmits a signal to CPU acquisition module；The CPU acquisition module goes out corresponding resistance value at this time by computation of table lookup.

The NTC circuit module includes RN resistance, bleeder circuit；The bleeder circuit includes concatenated with RN resistance Two divider resistances R49 and R57；It is converted to after the both end voltage signal input high-precision difference chip I NA105 of the RN resistance The variation of VNTC voltage exports.

The VF conversion module includes chip LM331N；The variation output of the VNTC voltage passes through R52 and C52 composition Low-pass filter circuit is input to chip LM331N, the frequency signal after the LM331N output conversion.

The transmitting terminal of the Fiber isolation transceiver module includes optical fiber conversion chip SN75451；The LM331N output Frequency signal is sent into optical fiber head by chip SN75451 and is sent；After the receiving end of Fiber isolation transceiver module receives optical signal It is converted into electric signal.

The electric signal of CPU acquisition module input optical fibre isolation transceiver module receiving end output, is obtained by look-up table The temperature value of specific IGBT.

Further, RN resistance both ends shunt capacitance C53 is filtered in NTC circuit module.

Further, the variation output of the VNTC voltage is input to core by the low-pass filter circuit of R52 and C52 composition 7 feet of piece LM331N, the frequency signal after the 3 feet output conversion of the chip LM331N.

A kind of IGBT temperature detection method, comprising the following steps: step 1: NTC circuit module acquires the temperature letter of IGBT Number it is converted into voltage signal.Step 2: the voltage signal acquired in step 1 is converted into frequency signal by VF conversion module.Step Three: the frequency signal in step 2 is converted into optical signal transmission to receiving end by Fiber isolation transceiver module, and light is believed in receiving end Number it is converted into electric signal.Step 3: the frequency signal of the receiving end transmission of transceiver module is isolated in CPU acquisition module reception optical fiber, The temperature of IGBT at this time is judged according to frequency signal, and control instruction is issued according to frequency signal, is done to control IGBT Temperature protection or temperature display.

Further, judge the temperature of IGBT at this time for look-up table or according to temperature according to frequency signal in step 3 The linear relationship established with the frequency of output is judged.

3, the utility model has the advantages that

(1) this method using being by converting frequency signal for the voltage signal at NTC resistance both ends, believe by the frequency of generation Number generally in several hundred KHZ ranges, and the dominant frequency of common CPU such as FPGA is in 30M, by frequency multiplication can to 100M or more, so It is high using frequency retrieval precision.

(2) frequency signal used in this method is compared to voltage signal, also very strong to electromagnetism anti-interference ability.

(3) since temperature can directly establish linear relationship with the frequency of output, the precision of NTC sampling is also significantly It improves.

(4) since the frequency signal that Fiber isolation transceiver module transmitting terminal issues can be sent directly into I/O port, to subtract The demand for having lacked the port ADC has saved the resource and cost of system.

(5) the NTC detection protection in the present invention is all completed in FPGA device, since FPGA is hardware level equipment, is protected Shield actuation time is shorter, and accuracy is more preferable, also more reliable.

Detailed description of the invention

Fig. 1 is the circuit diagram of NTC circuit module of the invention；

Fig. 2 is the circuit diagram of VF conversion module of the invention；

Fig. 3 is the internal frame diagram of the chip LM331N of VF conversion module of the invention；

Fig. 4 is the structure chart of Fiber isolation transceiver module of the invention；

Fig. 5 is the interface of the input of CPU acquisition module signal frequency and control signal output of embodiment；

Fig. 6 is overall structure figure of the invention.

Specific embodiment

The present invention will be described in detail with reference to the accompanying drawing.

As shown in Fig. 6, a kind of IGBT temperature detection circuit, including NTC circuit module, VF conversion module, Fiber isolation Transceiver module, CPU acquisition module；NTC circuit module acquisition RN resistance both ends output voltage signal to VF conversion module；Institute VF conversion module is stated the voltage signal received is converted into frequency signal and is exported to Fiber isolation transceiver module；The light Fibre isolation transceiver module transmits a signal to CPU acquisition module；The CPU acquisition module calculates corresponding resistance value at this time.

It is as shown in Fig. 1 the circuit diagram of NTC circuit module.The resistance of NTC is RN resistance in figure, at the both ends of RN resistance Series connection divider resistance R49 and R57 is divided.Since NTC changes with the variation of temperature, the voltage at the both ends RN is also with change Change.The voltage NTC1 and NTC2 at the both ends RN are inputted and 3 feet and 2 feet of high-precision difference chip I NA105 respectively；High-precision difference The variation of chip I NA105 output VNTC voltage.

Such as the circuit diagram that attached drawing 2 is VF conversion module.The variable signal input R52 and C52 composition of above-mentioned VNTC voltage Low-pass filter circuit is then input to chip LM331N.It is as shown in Fig. 3 the internal frame diagram of chip LM331N.Due to NTC with The variation of temperature and change, divider come out voltage also with variation.LM331 chip passes through the differential signal of 6 feet and 7 feet Adopt into.Can be seen from figure 3: if 7 foot signals are higher, voltage comparator will be higher, and voltage comparator will trigger list Stable state timer.The output of timer may turn on rate-adaptive pacemaker transistor and switched current source, the time cycle of unlatching be t= 1.1RtCt.Within the period, the electric current i flowed out from switched current source will be provided within the unit time charge Q of fixed quantity= I*t, these charge storages are in capacitor CL.This will be such that Vx increases, and more than V1.In the end cycle of timing, electric current I can quilt Shutdown, timer also can be by reset itself.When no electric current is flowed into from the 1st foot, capacitor CL is gradually discharged by RL, until VX It is reduced to the level of V1.At this moment, triggering timer is started next cycle work by comparator.Electric current follows strictly when flowing into CL IAVE=i*(1.1*RtCt) * f；When electric current flows out CL, Vx:RL=VDS:RL is followed strictly.If VLS is doubled, frequency is also doubled To maintain balance.Therefore even if a simple voltage-frequency converter can also be provided in very wide frequency range input voltage with The precise proportions corresponding relationship of frequency.

Such as the structure chart of the Fiber isolation transceiver module of the invention of attached drawing 4.The output signal of VF conversion module is sent into optical fiber Transceiver insulation module.Optical fiber transceiving isolation module changes into optical signal using electric signal, completes telecommunication by optical fiber, behind Electric signal is changed by optical signal again.As shown in Figure 3.Specific as follows: VF output signal is sent by data DATA foot, is passed through 75451 logic chips push triode to be sent into optical fiber head, and receiving end passes through optical fiber again and changes into electric signal.

It as shown in Fig. 5, is CPC using the connection jaws of EMP1270T144C chip input and the interface of output control signal Schematic diagram.The wherein frequency that the receiving end of connection jaws IGBTA, IBGTB, IGBTC input optical fibre transceiver insulation module transmits Rate signal；The signal value of connection jaws output control IGBT realizes IGBT overheat protector to complete shutdown PWM driving.Wherein CPC can acquire optical output signal by the I/O port of DSP or FPGA, it is not limited to the chip in figure.

In conclusion the present invention uses the detection method of detection IGBT temperature to change into voltage, voltage using temperature for IGBT The signal of changeable frequency is changed by circuit (being not limited to certain specific chips), frequency signal is sent into height after optical signal isolation Fast signal processor (being not limited to the CPU such as CPLD FPGA) passes through the available specific IGBT temperature value of look-up table.According to reality Border is required to be IGBT overheat protector or temperature display.Although the present invention has been described by way of example and in terms of the preferred embodiments, it Be not it is for the purpose of limiting the invention, it is any to be familiar with this those skilled in the art, without departing from the spirit and scope of the invention, from when can It makes various changes or retouches, therefore protection scope of the present invention should be defined with claims hereof protection scope and be It is quasi-.

Claims (3)

1. a kind of IGBT temperature detection circuit, it is characterised in that: including NTC circuit module, VF conversion module, Fiber isolation transmitting-receiving Module, CPU acquisition module；NTC circuit module acquisition RN resistance both ends output voltage signal to VF conversion module；The VF The voltage signal received is converted into frequency signal and exported to Fiber isolation transceiver module by conversion module；The optical fiber every CPU acquisition module is transmitted a signal to from transceiver module；The CPU acquisition module goes out corresponding resistance at this time by computation of table lookup Value；

The NTC circuit module includes RN resistance, bleeder circuit；The bleeder circuit includes concatenated two with RN resistance Divider resistance R49 and R57；VNTC is converted to after the both end voltage signal input high-precision difference chip I NA105 of the RN resistance The variation of voltage exports；

The VF conversion module includes chip LM331N；The low pass that the variation output of the VNTC voltage passes through R52 and C52 composition Filter circuit is input to chip LM331N, the frequency signal after the LM331N output conversion；

The transmitting terminal of the Fiber isolation transceiver module includes optical fiber conversion chip SN75451；The frequency of the LM331N output Signal is sent into optical fiber head by chip SN75451 and is sent；It is converted after receiving optical signal the receiving end of Fiber isolation transceiver module At electric signal；

The electric signal of CPU acquisition module input optical fibre isolation transceiver module receiving end output, is obtained specifically by look-up table IGBT temperature value.

2. a kind of IGBT temperature detection circuit according to claim 1, it is characterised in that: in NTC circuit module RN resistance both ends shunt capacitance C53 is filtered.

3. a kind of IGBT temperature detection circuit according to claim 1, it is characterised in that: the variation of the VNTC voltage Output is input to 7 feet of chip LM331N by the low-pass filter circuit of R52 and C52 composition, and 3 feet of the chip LM331N are defeated Frequency signal after converting out.