CN208226560U - A kind of electric machine controller and its current foldback circuit - Google Patents
A kind of electric machine controller and its current foldback circuit Download PDFInfo
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- CN208226560U CN208226560U CN201820927136.0U CN201820927136U CN208226560U CN 208226560 U CN208226560 U CN 208226560U CN 201820927136 U CN201820927136 U CN 201820927136U CN 208226560 U CN208226560 U CN 208226560U
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Abstract
The utility model belongs to electrical equipment and field of engineering technology, and in particular to a kind of electric machine controller and its current foldback circuit.It is additionally arranged assignment module and delay circuit in motor controller overcurrent protection circuit, assignment module is located at microprocessor internal, can be with the threshold values of flexibly adjustment overcurrent protection；Delay circuit is used to provide the turn-off time interval of three upper bridge power switch tubes and three lower bridge power switch tubes；Two kinds of measures can be substantially reduced the induced potential of loop of power circuit parasitic inductance, more reliable and effective to solve the problems, such as power switch tube overcurrent damage.
Description
Technical field
The utility model belongs to electrical equipment and field of engineering technology, and in particular to a kind of electric machine controller and its overcurrent are protected
Protection circuit.
Background technique
For general electric machine controller, such as: frequency converter, vehicle control device etc., the power topological loop generallyd use
It is three phase inverter bridge, DC bus-bar voltage inversion is run for three-phase alternating current output voltage with driving motor, at present three-phase inversion
The power switch tube that bridge generally uses is MOSFET (Metal-Oxide-Semiconductor Field-Effect
Transistor) and IGBT (Insulated Gate Bipolar Transistor), the security reliability pair of power switch tube
Key effect is played in the safe operation of electric machine controller.In electric machine controller use process, due to the insulation damages of motor, outside
The reasons such as portion's wiring short circuit can cause electric machine controller output overcurrent, and excessive output currents result in power switching tube generates heat, such as
Switch-off power switching tube will lead to power switch tube and crosses cause thermal damage fruit not in time.
In power switch tube shutdown, the parasitic inductance of loop of power circuit will generate induced potential, the size of induced potential with
The parasitic inductance amount in circuit is directly proportional, directly proportional to the current change quantity in circuit, is inversely proportional with the turn-off time of power switch tube；
The induced potential will be superimposed upon together between the collector and emitter of power switch tube with busbar voltage, so that power switch tube
The voltage at collector and emitter both ends can exceed that power switch tube pressure voltage, lead to power switch tube excessive pressure damages.Generally
, the pressure resistance of MOSFET is related with the temperature of withstanding current capability with itself, and temperature is higher, and pressure resistance is higher, and withstanding current capability is got over
It is low；Temperature is lower, and pressure resistance is lower, and withstanding current capability is higher.
The major way of electric machine controller output overcurrent protection at present is sampled output current signal, and current signal is by electricity
It is sent to overcurrent comparator after the conditioning of road, and is compared output overcurrent signal with preset hardware overcurrent voltage reference, is led to
Over-current signal latches are crossed, latch output is then connected to the enabled of power switch tube gate electrode drive signals buffer
End, simultaneously turns off the six tunnel power switch tube gate electrode drive signals exported by microprocessor, and specific block diagram is shown in attached drawing 1.
The method of motor controller overcurrent protection is the problem is that in electric machine controller operational process, when power returns
Road parasitic inductance is larger, and when the temperature of power module of controller is lower or DC bus-bar voltage is higher, power switch tube occurred
Stream, when switch-off power switching tube, it is possible to causing power switch tube excessive pressure damages.
Based on the above issues, general that power is reduced using the gate pole turn-off speed for reducing power switch tube when overcurrent occurs
The induced potential that parasitic inductance generates when switching tube turns off.But this method needs the dedicated of complicated circuit or higher cost
Gate-drive chip realizes, reliability is poor or higher cost.
Utility model content
The problem of for more reliable effective solution power switch tube overcurrent damage, the utility model proposes a kind of motor controls
Device current foldback circuit processed and the electric machine controller with the current foldback circuit.
The technical solution of the utility model is to provide a kind of motor controller overcurrent protection circuit, and special character exists
In: including current signal sample circuit, current signal conditioning circuit, microprocessor, over-current signal latch, delay circuit, three
Bridge gate electrode drive signals buffer and three-phase inversion unit under bridge gate electrode drive signals buffer, three-phase in phase；
Above-mentioned microprocessor include overcurrent comparator, DAC converter (Digital-to-Analog Converter, below
Abbreviation DAC converter) and assignment module；Above-mentioned assignment module be used for according to the temperature of controller power module, controller it is defeated
Electric current or DC bus-bar voltage set overcurrent voltage reference out；The output end of assignment module is by DAC converter compared with overcurrent
The non-inverting input terminal of device connects；
The output end of above-mentioned current signal sample circuit and the input terminal of current signal conditioning circuit connect；Above-mentioned electric current letter
The output end of number conditioning circuit is connect with the inverting input terminal of overcurrent comparator；The output end and over-current signal of overcurrent comparator are locked
The input terminal of storage connects；The output end of over-current signal latch is slow with bridge gate electrode drive signals on delay circuit and three-phase respectively
The input terminal for rushing bridge gate electrode drive signals buffer under the input terminal or three-phase of device connects, under the output end and three-phase of delay circuit
Bridge gate electrode drive signals buffer input connects on bridge gate electrode drive signals buffer input or three-phase, portal pole on three-phase
Bridge gate electrode drive signals buffer output end is defeated with three-phase inversion unit under the output end and three-phase of driving signal buffer
Enter end connection；Delay between the output signal of the output end of over-current signal latch and the output end output signal of delay circuit
Time should be longer than the time of power switch tube shutdown, while the delay time does not answer too long, otherwise excessive electric current meeting too long yet
Power switch tube is caused to cross cause thermal damage.
The upper portal pole driving signal output end of microprocessor is connect with bridge gate electrode drive signals buffer on three-phase, micro- place
The lower portal pole driving signal output end of reason device is connect with bridge gate electrode drive signals buffer under three-phase.Bridge gate-drive on three-phase
Bridge gate electrode drive signals buffer under signal buffer and three-phase, the two internal structure having the same, while having signal defeated
Enable end out, when output enable end is enabled, closing gate signal output.The power switch tube of three-phase inversion unit is according to gate pole
The high low state of the level of driving signal is switched on or off.
In the program, the model TMS320F28035 of microprocessor includes internal comparator, DAC converter, comparator
Inverting input terminal receive the signal Icur of current signal conditioning circuit output, the non-inverting input terminal of comparator receives DAC module
The input value of output valve AREF, DAC be that software assignment DREF, DREF value can be according to the temperature of controller power module, control
The output electric current or DC bus-bar voltage of device processed adjust (being not limited to these three conditions, designer can flexibly be designed)；
Overcurrent comparator by comparing Icur and AREF value output overcurrent signal OC.Meanwhile the microprocessor also be responsible for generate and it is defeated
Gate electrode drive signals are to gate electrode drive signals buffer out.
The utility model also provides another motor controller overcurrent protection circuit, is characterized in that including electricity
Flow signal sample circuit, current signal conditioning circuit, DAC converter, overcurrent comparator, microprocessor, over-current signal latch,
Bridge gate electrode drive signals buffer and three-phase inversion list under bridge gate electrode drive signals buffer, three-phase on delay circuit, three-phase
Member；
Above-mentioned microprocessor includes assignment module, portal in the upper portal pole driving signal output end and three-phase of microprocessor
The connection of pole driving signal buffer, the lower portal pole driving signal output end and bridge gate electrode drive signals under three-phase of microprocessor are slow
Rush device connection；
Above-mentioned assignment module is used for according to the temperature of controller power module, the output electric current of controller or DC bus electricity
Pressure setting overcurrent voltage reference；The output end of assignment module is connect by DAC converter with the non-inverting input terminal of overcurrent comparator；
The output end of above-mentioned current signal sample circuit and the input terminal of current signal conditioning circuit connect；Above-mentioned electric current letter
The output end of number conditioning circuit is connect with the inverting input terminal of overcurrent comparator；The output end and over-current signal of overcurrent comparator are locked
The input terminal of storage connects；The output end of over-current signal latch is slow with bridge gate electrode drive signals on delay circuit and three-phase respectively
The input terminal for rushing bridge gate electrode drive signals buffer under the input terminal or three-phase of device connects, under the output end and three-phase of delay circuit
Bridge gate electrode drive signals buffer input connects on bridge gate electrode drive signals buffer input or three-phase, portal pole on three-phase
Bridge gate electrode drive signals buffer output end is defeated with three-phase inversion unit under the output end and three-phase of driving signal buffer
Enter end connection.
Microprocessor in the program does not include overcurrent comparator and DAC module, needs to introduce an external overcurrent and compares
The input value of device and DAC module, the same DAC module can flexibly be modified by assignment module.
Further, above-mentioned over-current signal latch includes rest-set flip-flop, rest-set flip-flop include two NAND gate U4A and
U4B, the output end of the set end connection overcurrent comparator of rest-set flip-flop, reset terminal is connected to the output pin of microprocessor, micro-
Processor is responsible for resetting rest-set flip-flop.
The output end of trigger respectively with bridge gate electrode drive signals under bridge gate electrode drive signals buffer on three-phase or three-phase
The enable end of buffer and the input terminal connection of delay circuit；Bridge gate electrode drive signals are slow under the output end and three-phase of delay circuit
Rush the enable end connection of bridge gate electrode drive signals buffer on device or three-phase, bridge gate electrode drive signals buffer and three-phase under three-phase
The output end of upper bridge gate electrode drive signals buffer respectively drives bridge power switch tube and three road bridge power switch tubes under three tunnels.
Further, above-mentioned delay circuit is RC filter circuit, including resistance R20 and capacitor C20, U4A output end with
One end of resistance R20 connects, and portal pole is driven on bridge gate electrode drive signals buffer or three-phase under the other end and three-phase of resistance R20
The enable end connection of dynamic signal buffer；The high-voltage end of capacitor C20 is connect with the other end of resistance R20, the low-pressure end of capacitor C20
Ground connection.
Further, above-mentioned current signal sampling circuit samples export electric current, including current Hall sensor and signal are adopted
Sample circuit, the effect of current Hall sensor are will to export electric current to be converted to voltage signal and realize electrical isolation, signal sampling
Circuit includes an operational amplifier, and output end connect composition voltage follower circuit with inverting input terminal, realizes circuit
Impedance matching and the driving capability for enhancing signal.
Current signal sample circuit specifically includes current Hall sensor and signal sample circuit；
Above-mentioned signal sample circuit includes R1C1 filter circuit, operational amplifier U1A；
The input terminal of R1C1 filter circuit and the output end of current Hall sensor connect, the output end of R1C1 filter circuit
It is connect with the non-inverting input terminal of operational amplifier U1A, the inverting input terminal and operational amplifier U1A of operational amplifier U1A exports
End is connected, and operational amplifier U1A output end connects resistance R4, and the other end of resistance R4 is connected to the reverse phase of operational amplifier U2A
Input terminal.
Further, it is unidirectional electricity that above-mentioned current signal conditioning circuit, which is used to sample obtained bidirectional current signal condition,
Signal is flowed, and is sent to overcurrent comparator after partial pressure and filtering.
Further, above-mentioned current signal conditioning circuit includes power supply VCC, the first partial pressure and filter circuit, operation amplifier
Device U1B, resistance R4, operational amplifier U2A, diode D1, operational amplifier U2B, the partial pressure of resistance R5 and second and filter circuit；
Power supply VCC is connected to the non-inverting input terminal of operational amplifier U1B, operation amplifier by the first partial pressure with filter circuit
The inverting input terminal of device U1B is connected with the output end of operational amplifier U1B, the output end and operation amplifier of operational amplifier U1B
The non-inverting input terminal of device U2A connects；
The anode of the output end connection diode D1 of operational amplifier U2A, the cathode of diode D1 are connected by resistance R5
To the inverting input terminal of U2A, inverting input terminal is connected to the output end of operational amplifier U1A by resistance R4；
The non-inverting input terminal of operational amplifier U2B is connect with the cathode of diode D1, the anti-phase input of operational amplifier U2B
End is connected with the output end of operational amplifier U2B；The output end of operational amplifier U2B is connect with the second partial pressure with filter circuit.
Further, above-mentioned first partial pressure and filter circuit include resistance R2, resistance R3 and capacitor C2, the resistance R2's
One end is connect with the output end of power supply VCC, the high-voltage end and operational amplifier of the other end and resistance R3, capacitor C2 of resistance R2
The non-inverting input terminal of U1B connects, the low-pressure end ground connection of resistance R3 and capacitor C2；
Above-mentioned second partial pressure and filter circuit include resistance R6, resistance R7, resistance R8 and capacitor C3, one end of resistance R6 with
The output end of operational amplifier U2B connects, and the other end of resistance R6 is connect with one end of resistance R7, resistance R8, and resistance R8's is another
The high-voltage end of one termination capacitor C3 exports Icur signal, the low-pressure end of another termination capacitor C3 of resistance R7.
The utility model also provides a kind of electric machine controller, is characterized in that including above-mentioned current foldback circuit.
The beneficial effects of the utility model are:
1, the utility model proposes motor controller overcurrent protection circuit be additionally arranged assignment module and delay circuit, assignment
Module is located at microprocessor internal, and designer can be with the threshold values of flexibly adjustment overcurrent protection；Delay circuit is for providing three
The turn-off time interval of a upper bridge power switch tube and three lower bridge power switch tubes；Two kinds of measures can be substantially reduced power
The induced potential of circuit parasitic inductance, thus the possibility of power switch tube excessive pressure damages caused by greatly reducing because of overcurrent
Property；
2, the threshold values of the utility model motor controller overcurrent protection can according to electric machine controller temperature of power module height,
The conditions such as DC bus-bar voltage size are flexibly modified by assignment module.When microprocessor detects controller power module temperature
Spend lower, when DC bus-bar voltage is higher, corresponding power switch tube pressure resistance is lower, and passing through software assignment module reduces controller
Overcurrent protection threshold values, when overcurrent turn-off function switching tube occurs for controller, cut-off current is smaller, the induced potential that parasitic inductance generates
Lower, which is superimposed upon between the collector and emitter of power switch tube together with busbar voltage, power switch tube
The voltage at collector and emitter both ends is relatively low, is no more than power switch tube pressure resistance, thus caused by greatly reducing because of overcurrent
A possibility that power switch tube excessive pressure damages；
3, after the utility model electric machine controller detects that overcurrent occurs, the order of switch-off power switching tube is to turn off first
Three upper bridge power switch tubes turn off three lower bridge power switch tubes after delay；Either it is first turned off three lower bridge power
Switching tube after delay, turns off three upper bridge power switch tubes, rather than simultaneously turns off six power switch tubes, can reduce back
The induced potential that road parasitic inductance generates achievees the purpose that the voltage stress that reduction power switch tube is born in overcurrent turn-off function,
Circuit is simple, and cost is relatively low；
4, using the current signal processing circuit, the bidirectional current signal condition that sampling is obtained is unidirectional current signal,
It is sent to the inside of microprocessor, so that over-current signal can be realized in DAC and comparator resource of microprocessor internal
The purpose of output, cost is relatively low.
Detailed description of the invention
Fig. 1 is that motor controller overcurrent protects electrical block diagram in the prior art；
Fig. 2 is the motor controller overcurrent protection electrical block diagram of embodiment one in the utility model；
Fig. 3 is the current sampling circuit and signal conditioning circuit diagram of embodiment one in the utility model；
Fig. 4 is the microprocessor of embodiment one and gate-drive buffer circuits schematic diagram in the utility model；
Fig. 5 is the three-phase inversion element circuit schematic diagram of embodiment one in the utility model；
Fig. 6 is the motor controller overcurrent protection electrical block diagram of embodiment two in the utility model.
Specific embodiment
The content of the utility model in order to facilitate understanding makees into one the utility model below in conjunction with drawings and examples
The detailed description of step, the following examples illustrate the utility model, but is not intended to limit the scope of the present invention.
Embodiment one
Figure it is seen that the present embodiment current signal sample circuit acquisition output electric current, current signal conditioning circuit will
The collected bidirectional current signal condition of current signal sample circuit is unidirectional current signal, and is sent to after partial pressure and filtering
Microprocessor.Microprocessor includes overcurrent comparator, assignment module and DAC, and assignment module is same by DAC and overcurrent comparator
The connection of phase input terminal, the input value that the non-inverting input terminal of overcurrent comparator receives the output valve AREF, DAC of DAC module is assignment
Module assignment DREF, DREF value can be adjusted according to the temperature or DC bus-bar voltage of controller power module (be not limited to this two
A condition, designer can flexibly be designed, such as can also adjust DREF value according to the output electric current of controller)；It crosses
The inverting input terminal for flowing comparator receives the Icur signal after current signal conditioning circuit improves.Overcurrent comparator passes through ratio
Value output overcurrent signal OC compared with Icur and AREF.Microprocessor is also responsible for producing and exporting gate electrode drive signals to gate-drive
Signal buffer, including export upper bridge gate electrode drive signals and the supreme bridge gate electrode drive signals buffer of lower bridge gate electrode drive signals
With lower bridge gate electrode drive signals buffer.Over-current signal OC is input to over-current signal latch by overcurrent comparator, is believed overcurrent
It number is latched, prevents repeatedly the generation of overcurrent, it is slow to be connected to bridge gate electrode drive signals on three-phase by Latch output signal 1OE
Bridge gate electrode drive signals buffer under device or three-phase is rushed, 1OE is connected to delay circuit simultaneously, and delay circuit output signal 2OE connects
It is connected under three-phase bridge gate electrode drive signals buffer on bridge gate electrode drive signals buffer or three-phase.Bridge gate-drive is believed under three-phase
Bridge gate electrode drive signals buffer receives the output of over-current signal latch or the output of delay circuit on number buffer or three-phase,
When output enable end is enabled, gate signal output is closed.The power switch tube of three-phase inversion unit is according to gate electrode drive signals
The high low state of level be switched on or off.
From figure 3, it can be seen that current sampling circuit and signal conditioning circuit in the present embodiment, current sampling circuit includes electricity
Flow Hall sensor and signal sample circuit, the effect of current Hall sensor is will to export electric current to be converted to voltage signal and real
Existing electrical isolation, signal sample circuit include an operational amplifier, output end connect with inverting input terminal form voltage with
With device circuit, realizes the impedance matching of circuit and enhance the driving capability of signal.Signal conditioning circuit includes two operation amplifiers
Device, bleeder circuit and filter circuit；It is that will sample obtained bidirectional current signal condition be unidirectional current signal, and is passed through that it, which is acted on,
It crosses partial pressure and is sent to the internal comparator of microprocessor after filtering.
Current sampling circuit and current signal conditioning circuit working principle are as follows:
Resistance R1 receives current sampling signal, and in the present embodiment, when motor operates normally, current signal is peak-to-peak value range
For 0-5V, bias is the signal of 2.5V, and 0V corresponds to negative sense output maximum current, and 5V indicates positive output maximum current, passes through
After resistance R1, capacitor C1 filtering, the non-inverting input terminal of operational amplifier U1A is connected to (using double operation amplifiers in the present embodiment
Device device, model are TL3472ID), the inverting input terminal of operational amplifier U1A is connected with its output end, forms voltage follower
Circuit plays impedance matching and improves the jamproof ability of signal, and output end connects resistance R4, and the other end of resistance R4 is connected to
The inverting input terminal of operational amplifier U2A.
Power supply VCC passes through resistance R2, and the non-inverting input terminal of operational amplifier U1B, the both ends resistance R3 are connected to after R3 partial pressure
Shunt capacitance C2, capacitor C2 play the role of signal filtering, and the inverting input terminal of operational amplifier U1B is connected with its output end,
Voltage follower circuit is formed, the output signal VREF of operational amplifier U1B is connected to the homophase input of operational amplifier U2A
End, VREF voltage value is equal with the bias voltage 2.5V of current signal, such as generates the bias voltage of 2.5V simultaneously using other circuits
Without departing from the protection scope of the utility model (it is also able to achieve the function for example, by using special voltage reference chip, such as uses base
In the voltage reference circuit of device TL431).The non-inverting input terminal of operational amplifier U2A connects bias voltage VREF, operation amplifier
The anode of the output end connection diode D1 of device U2A, the cathode of diode D1 are connected to operational amplifier U2A's by resistance R5
The value of inverting input terminal, resistance R4 is equal with the value of resistance R5.When current signal voltage value is lower than bias voltage VREF value, fortune
It calculates amplifier U2A and exports high level, diode D1 forward conduction, resistance R4, R5, operational amplifier U2A, diode D1 composition is instead
Phase Proportion amplifier, input current signal voltage 0-2.5V, corresponding output signal voltage 5-2.5V.When current signal voltage value is high
When bias voltage VREF value, operational amplifier U2A exports low level, and diode D1 is not turned on, input current signal voltage
2.5-5V equal with output signal voltage；The output of diode D1 while the non-inverting input terminal for being connected to operational amplifier U2B, fortune
The inverting input terminal for calculating amplifier U2B is connected with its output end, forms voltage follower circuit, the output of operational amplifier U2B
Signal passes through resistance R6, and R7 partial pressure is sent into microprocessor after capacitor C3 filtering by resistance R8.By current sampling circuit and
After signal conditioning circuit, the input current signal of 0-5V is improved into the output voltage signal of 2.5-5V, is only needed in microprocessor
One comparator reduces the demand to microprocessor internal comparator resource it may determine that whether overcurrent occurs.
Fig. 4 is the microprocessor and gate-drive buffer circuits schematic diagram of the present embodiment, the model of microprocessor
TMS320F28035, internal includes hardware overcurrent comparator, and DAC module does not surpass according to external comparator and DAC module
The protection scope of the utility model out, the output signal Icur of the inverting input terminal receiving signal reason circuit of overcurrent comparator,
Non-inverting input terminal receives the output valve of DAC module, and the input value of DAC module can flexibly be modified by assignment module.
In the present embodiment, the assignment module in microprocessor adjusts the input of DAC module according to the temperature of current controller
Value, when power switch tube temperature is lower, the decline of power switch tube proof voltage ability reduces overcurrent protection threshold values；Specifically, this
In embodiment, controller temperature of power module at 0~-40 DEG C, overcurrent protection threshold values from 100% linear decline to 50%, when
Temperature of power module is lower, when overcurrent occurs, can turn off power switch tube under lesser output electric current, to reduce because of parasitism
The size of induced potential caused by inductance, the voltage at power switch tube both ends when reducing shutdown, probability of damage reduce.
The comparator output overcurrent level signal OC of microprocessor, in the present embodiment, OC is that low level indicates that overcurrent occurs,
Two NAND gates U4A and U4B form rest-set flip-flop, and set end connects OC signal, and the output that reset terminal is connected to microprocessor is drawn
Foot；After OC signal is set low, rest-set flip-flop latches over-current signal, prevents repeatedly the generation of overcurrent；When the disappearance of overcurrent condition, OC signal
Height is set, microprocessor is according to Conditional reset rest-set flip-flop.
The model of upper bridge gate electrode drive signals buffer U3A and lower bridge gate electrode drive signals buffer U3B is
Output end can be set to high-impedance state for enhancing gate signal driving capability, and by enable end OE by SN74HCT244NSR,
Gate electrode drive signals for switch-off power switching tube.Upper bridge gate electrode drive signals buffer U3A receives microprocessor output
Three road bridge driving signals, lower bridge gate electrode drive signals buffer U3B receive bridge driving signal under three tunnels that microprocessor exports.
The output signal 1OE of rest-set flip-flop is connected to the enable end of bridge gate electrode drive signals buffer U3A, signal 2OE
It is connected to the enable end of lower bridge gate electrode drive signals buffer U3B.After overcurrent occurs, the output signal 1OE of rest-set flip-flop is first
The driving output of three road bridges is blocked, for signal 1OE after delay, signal 2OE then blocks bridge driving output under three tunnels.This implementation
In example, in order to reduce cost, delay is provided using RC filter circuit and (it is practical without departing from this to provide delay according to other modes
Novel protection scope)；In the present embodiment, resistance R20 and capacitor C20 form delay circuit, and signal 1OE and signal 2OE's prolongs
When the time be slightly larger than power switch tube turn-off time.
The output signal DRV-UP, DRV-VP, DRV-WP of upper bridge gate electrode drive signals buffer U3A passes through gate-drive electricity
Road (not shown) respectively drives three road bridge power switch tubes, and corresponding gate signal is UP, VP, WP；Lower bridge gate-drive letter
The output signal DRV-UN, DRV-VN, DRV-WN of number buffer U3B respectively drives three tunnels by gate drive circuit (not shown)
Lower bridge power switch tube, corresponding gate signal are UN, VN, WN.
Fig. 5 is the three-phase inversion element circuit schematic diagram of the present embodiment, and power switch tube uses power MOSFET tube, direct current
Bus has a Support Capacitor, six (group) power MOSFET tube Q1, Q2, Q3, Q4, Q5, and Q6 is connected into the structure of three phase inverter bridge, supports
There are loop of power circuit parasitic inductance Lk1 and Lk2 between capacitor and three phase inverter bridge, in universal three phase inverter bridge loop structure,
Parasitic inductance Lk1 and Lk2 are the main parasitic inductance of loop of power circuit, and the induced potential generated can be expressed from the next: Vlk=
(Lk1+Lk2) * Δ i/ Δ t, Δ i indicate that current changing rate when power switch tube shutdown in parasitic inductance, Δ t indicate that power is opened
The turn-off time for closing pipe it can be concluded that, reduces parasitic inductance amount or reduces current changing rate or increase power and open from above formula
The turn-off time for closing pipe can reduce induced potential, reach the voltage at power switch tube both ends when reducing switch-off power switching tube,
Reduce the purpose of power switch tube excessive pressure damages probability.Be in the utility model by reduce parasitic inductance current changing rate with
Reduce induced potential.
It is practical using this when following analysis U phase exports generation short circuit (it is identical that other are mutually shorted analytic process) overcurrent with V phase
Bridge power switch tube separates the course of work and beneficial effect of time delayed turn-off above and below novel middle three-phase.
In the present embodiment, if Q1 and Q4 is opened simultaneously, (the power switch tube opening state in the present embodiment is power switch
The situation of both end voltage stress maximum when pipe cut-off current, other opening states can similarly be analyzed by the analysis
Conclusion), short circuit current circuit is the circuit S1 as shown in the figure, and bus capacitor is positive --- outside parasitic inductance Lk1--- switching tube Q1---
Portion's short-circuit line --- switching tube Q4--- parasitic inductance Lk2--- bus capacitor cathode；Under the action of busbar voltage, on short-circuit line
Electric current Isc rapid increase, until reaching overcurrent threshold values, circuit switch-off power switching tube；In the present embodiment, three road portal poles
Driving turns off first, power switch tube Q1 shutdown, and short circuit current circuit is the circuit S2 as shown in the figure, and the outside switching tube Q2--- is short
Electric current on route --- switching tube Q4, parasitic inductance Lk1 and Lk2 is within the turn-off time of power switch tube Q1, from short circuit current
Isc is reduced to 0, then the induced potential generated on parasitic inductance Lk1 and Lk2: Vlk=(Lk1+Lk2) * Isc/ Δ t, the electricity of inducting
Barrier layer is added in the both ends of power switch tube Q1.After delay, external short circuit line current is Isc1, and more smaller than Isc value (value is big
It is small related with delay time and S2 loop reactances), bridge gate-drive seals wave under three-phase, lower bridge power switch tube Q2 and Q4 shutdown,
Short circuit current circuit is the circuit S3 as shown in the figure, bus capacitor cathode --- two pole of parasitic inductance Lk2--- switching tube Q2 inverse parallel
Pipe --- external short circuit line --- switching tube Q3 anti-paralleled diode --- parasitic inductance Lk1--- bus capacitor anode；Parasitic inductance
Electric current on Lk1 and Lk2 is within the turn-off time of power switch tube Q2, and it is Isc1 that short circuit current increases from 0, then parasitic inductance
The induced potential generated on Lk1 and Lk2: Vlk=(Lk1+Lk2) * Isc1/ Δ t, the induced potential are superimposed upon power switch tube Q4
Both ends.
It can be obtained from the above analysis, the maximum induced potential generated on parasitic inductance Lk1 and Lk2 is Vlk=(Lk1+Lk2) *
Isc/ Δ t, if six power switch tubes are not simultaneously turned off, in the pass of power switch tube using the method in the utility model
In disconnected time Δ t, the current changing rate in parasitic inductance is 2*Isc, and the maximum induced potential of generation is Vlk=(Lk1+Lk2) *
2*Isc/ Δ t, the induced potential than the method for the utility model is big, is superimposed upon power switch tube both ends, increases power switch
The probability of pipe excessive pressure damages.
A phase current sampling, two-phase or three-phase current sampling and overcurrent protection are only listed in the present embodiment only to be needed to repeat to make
It can be realized with the circuit in the utility model.
Embodiment two
From fig. 6, it can be seen that the present embodiment is not what is different from the first embodiment is that the microprocessor of the present embodiment includes overcurrent
Comparator, the microprocessor in the embodiment are only responsible for producing and exporting gate electrode drive signals to gate electrode drive signals buffer.
It therefore, further include an external overcurrent comparator and DAC module in the embodiment, the input value of the same DAC module can pass through
Assignment module in microprocessor is flexibly modified.
Assignment module is set according to the adjustment of the temperature of controller power module, the output electric current of controller or DC bus-bar voltage
Determine overcurrent voltage reference；The output end of assignment module is connect by DAC converter with the non-inverting input terminal of overcurrent comparator；Electric current
The output end of signal sample circuit and the input terminal of current signal conditioning circuit connect；The output end of current signal conditioning circuit with
The inverting input terminal of overcurrent comparator connects；The output end of overcurrent comparator is connect with the input terminal of over-current signal latch.
Embodiment of above is merely to illustrate the utility model, and is not limitation of the utility model, the utility model
In one or more methods or circuit belong to the protection scope of the utility model；Ordinary skill people in relation to technical field
Member can also make a variety of changes and modification in the case where not departing from the spirit and scope of the utility model, therefore all etc.
Same technical solution also belongs to the scope of the utility model, and the scope of patent protection of the utility model should be defined by the claims.
Claims (10)
1. a kind of motor controller overcurrent protects circuit, it is characterised in that: improved including current signal sample circuit, current signal
Circuit, microprocessor, over-current signal latch, delay circuit, portal pole under bridge gate electrode drive signals buffer, three-phase on three-phase
Driving signal buffer and three-phase inversion unit；
The microprocessor includes overcurrent comparator, DAC converter and assignment module；The assignment module is used for according to controller
The temperature of power module, the output electric current of controller or DC bus-bar voltage set overcurrent voltage reference；The output of assignment module
End is connect by DAC converter with the non-inverting input terminal of overcurrent comparator；
The output end of the current signal sample circuit and the input terminal of current signal conditioning circuit connect；The current signal tune
The output end of reason circuit is connect with the inverting input terminal of overcurrent comparator；The output end and over-current signal latch of overcurrent comparator
Input terminal connection；The output end of over-current signal latch respectively with bridge gate electrode drive signals buffer on delay circuit and three-phase
Input terminal or three-phase under bridge gate electrode drive signals buffer input terminal connection, portal under the output end and three-phase of delay circuit
Bridge gate electrode drive signals buffer input connects on pole driving signal buffer input or three-phase, bridge gate-drive on three-phase
Input terminal of the bridge gate electrode drive signals buffer output end with three-phase inversion unit under the output end and three-phase of signal buffer
Connection；
The upper portal pole driving signal output end of microprocessor is connect with bridge gate electrode drive signals buffer on three-phase, microprocessor
Lower portal pole driving signal output end connect with bridge gate electrode drive signals buffer under three-phase.
2. a kind of motor controller overcurrent protects circuit, it is characterised in that: improved including current signal sample circuit, current signal
Circuit, DAC converter, overcurrent comparator, microprocessor, over-current signal latch, delay circuit, bridge gate-drive letter on three-phase
Bridge gate electrode drive signals buffer and three-phase inversion unit under number buffer, three-phase；
The microprocessor includes assignment module, and portal pole is driven in the upper portal pole driving signal output end and three-phase of microprocessor
Dynamic signal buffer connection, lower portal pole driving signal output end and the bridge gate electrode drive signals buffer under three-phase of microprocessor
Connection；
The assignment module according to the temperature of controller power module, the output electric current of controller or DC bus-bar voltage for setting
Determine overcurrent voltage reference；The output end of assignment module is connect by DAC converter with the non-inverting input terminal of overcurrent comparator；
The output end of the current signal sample circuit and the input terminal of current signal conditioning circuit connect；The current signal tune
The output end of reason circuit is connect with the inverting input terminal of overcurrent comparator；The output end and over-current signal latch of overcurrent comparator
Input terminal connection；The output end of over-current signal latch respectively with bridge gate electrode drive signals buffer on delay circuit and three-phase
Input terminal or three-phase under bridge gate electrode drive signals buffer input terminal connection, portal under the output end and three-phase of delay circuit
Bridge gate electrode drive signals buffer input connects on pole driving signal buffer input or three-phase, bridge gate-drive on three-phase
Input terminal of the bridge gate electrode drive signals buffer output end with three-phase inversion unit under the output end and three-phase of signal buffer
Connection.
3. motor controller overcurrent according to claim 1 or 2 protects circuit, it is characterised in that:
The over-current signal latch includes rest-set flip-flop, and rest-set flip-flop includes two NAND gates U4A and U4B, rest-set flip-flop
Set end connects the output end of overcurrent comparator, and reset terminal is connected to the output pin of microprocessor；
The output end of trigger is buffered with bridge gate electrode drive signals under bridge gate electrode drive signals buffer on three-phase or three-phase respectively
The enable end of device and the input terminal connection of delay circuit；Bridge gate electrode drive signals buffer under the output end and three-phase of delay circuit
Or on three-phase bridge gate electrode drive signals buffer enable end connection, bridge on bridge gate electrode drive signals buffer and three-phase under three-phase
The output end of gate electrode drive signals buffer respectively drives bridge power switch tube and three road bridge power switch tubes under three tunnels.
4. motor controller overcurrent according to claim 3 protects circuit, it is characterised in that:
The delay circuit is RC filter circuit, including resistance R20 and capacitor C20, U4A output end and resistance R20 one end
Connection, bridge gate electrode drive signals buffer on bridge gate electrode drive signals buffer or three-phase under the other end and three-phase of resistance R20
Enable end connection；The high-voltage end of capacitor C20 is connect with the other end of resistance R20, the low-pressure end ground connection of capacitor C20.
5. motor controller overcurrent according to claim 4 protects circuit, it is characterised in that: the current signal sampling electricity
Road includes current Hall sensor and signal sample circuit；
The signal sample circuit includes R1C1 filter circuit and operational amplifier U1A；
The input terminal of R1C1 filter circuit and the output end of current Hall sensor connect, the output end and fortune of R1C1 filter circuit
Calculate the non-inverting input terminal connection of amplifier U1A, inverting input terminal and the operational amplifier U1A output end phase of operational amplifier U1A
Even, operational amplifier U1A output end connects resistance R4, and the other end of resistance R4 is connected to the anti-phase input of operational amplifier U2A
End.
6. motor controller overcurrent according to claim 1 or 2 protects circuit, it is characterised in that: the current signal tune
It is unidirectional current signal that reason circuit, which is used to sample obtained bidirectional current signal condition, and is sent to after partial pressure and filtering
Flow comparator.
7. motor controller overcurrent according to claim 6 protects circuit, it is characterised in that: the current signal conditioning electricity
Road include power supply VCC, first partial pressure with filter circuit, operational amplifier U1B, resistance R4, operational amplifier U2A, diode D1,
Operational amplifier U2B, resistance R5 and the second partial pressure and filter circuit；
Power supply VCC is connected to the non-inverting input terminal of operational amplifier U1B, operational amplifier by the first partial pressure with filter circuit
The inverting input terminal of U1B is connected with its output end, the output end of operational amplifier U1B and the homophase input of operational amplifier U2A
End connection；
The anode of the output end connection diode D1 of operational amplifier U2A, the cathode of diode D1 are connected to U2A by resistance R5
Inverting input terminal, inverting input terminal is connected to the output end of operational amplifier U1A by resistance R4；
The non-inverting input terminal of operational amplifier U2B is connect with the cathode of diode D1, the inverting input terminal of operational amplifier U2B with
The output end of operational amplifier U2B is connected；The output end of operational amplifier U2B is connect with the second partial pressure with filter circuit；
The value of resistance R5 is equal with the value of resistance R4.
8. motor controller overcurrent according to claim 7 protects circuit, it is characterised in that: first partial pressure and filtering
Circuit includes that resistance R2, resistance R3 and capacitor C2, one end of the resistance R2 are connect with the output end of power supply VCC, resistance R2's
The other end is connect with the non-inverting input terminal of resistance R3, the high-voltage end of capacitor C2 and operational amplifier U1B, resistance R3 and capacitor C2's
Low-pressure end ground connection；
Second partial pressure and filter circuit include resistance R6, resistance R7, resistance R8 and capacitor C3, one end of the resistance R6 with
The output end of operational amplifier U2B connects, and the other end of resistance R6 is connect with one end of resistance R7, resistance R8, and resistance R8's is another
The high-voltage end of one termination capacitor C3 exports Icur signal, the low-pressure end of another termination capacitor C3 of resistance R7.
9. motor controller overcurrent according to claim 1 protects circuit, it is characterised in that: the model of the microprocessor
For TMS320F28035.
10. a kind of electric machine controller, it is characterised in that: including any current foldback circuit of claim 1-9.
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| CN201820927136.0U CN208226560U (en) | 2018-06-14 | 2018-06-14 | A kind of electric machine controller and its current foldback circuit |
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| CN201820927136.0U CN208226560U (en) | 2018-06-14 | 2018-06-14 | A kind of electric machine controller and its current foldback circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108599111A (en) * | 2018-06-14 | 2018-09-28 | 谢红普 | A kind of electric machine controller and its current foldback circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108599111A (en) * | 2018-06-14 | 2018-09-28 | 谢红普 | A kind of electric machine controller and its current foldback circuit |
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Effective date of registration: 20191015 Address after: 710000 3 / F, auxiliary building, Oukai entrepreneurial Town, No. 25, development avenue, Xiliu Street office, Xi'an high tech Zone, Shaanxi Province Patentee after: Xi'an Haige Electrical Technology Co., Ltd. Address before: 710077 Xionghua Science Park Complex Building, 72 Jinye Road, Yanta District, Xi'an City, Shaanxi Province, 3rd Floor Patentee before: Xie Hong Pu |