Summary of the invention
Gather in order to overcome existing linear optical coupling high direct voltage voltage that poor linearity, isolation voltage are not high, the problem of complicated circuit; The present invention provides a kind of voltage isolation Acquisition Circuit, adopts magnetic coupling isolation voltage, realizes that certainty of measurement is high; Fail safe is good; The target that isolation voltage is high, simple in structure, stable and reliable for performance, the isolation Acquisition Circuit when being a kind of high voltage dc bus voltage that is very suitable for measuring on the electric automobile.
The present invention for realizing the technical scheme that its purpose adopts is: a kind of voltage isolation Acquisition Circuit; Comprise the bleeder circuit that the high voltage signal of telecommunication is carried out dividing potential drop; To the voltage collection circuit of gathering after the described bleeder circuit dividing potential drop; The voltage digital signal output that described voltage collection circuit is gathered and with the buffer circuit of described high voltage electric signal isolation; Described buffer circuit is a magnetic coupling buffer circuit, and described magnetic coupling buffer circuit comprises that the first driving inverter and coupling transformer, control switch pipe, second drive inverter, and the output of described voltage digital signal drives the described control switch pipe conducting closure of the reverse promotion of inverter through first; Described control switch pipe is connected with described coupling transformer master limit; Another termination first working power of described coupling transformer master limit, the coupled signal of the secondary of described coupling transformer drives inverter output, another termination second working power of the secondary of described coupling transformer through second.
Further; Above-mentioned voltage isolation Acquisition Circuit is in it is characterized in that: also be connected with in turn at the output of described magnetic coupling buffer circuit the digital signal of described magnetic coupling buffer circuit output is carried out the integrating circuit of analog-converted and the amplifying circuit that the analog signal of conversion is amplified.
Further; Above-mentioned voltage isolation Acquisition Circuit; In it is characterized in that: described integrating circuit comprises four-operational amplifier, and the digital signal of described magnetic coupling buffer circuit output is by the in-phase end input of described four-operational amplifier, and the out-phase end of described four-operational amplifier is through the 13 grounding through resistance; Between the out-phase end of described four-operational amplifier and output, be connected with the 5th electric capacity, the output of described four-operational amplifier is through the 4th capacity earth; The working power of described four-operational amplifier is second working power.
Further, above-mentioned voltage isolation Acquisition Circuit, in it is characterized in that: described amplifying circuit comprises the 3rd operational amplifier and reference voltage and reference voltage bleeder circuit;
The analog signal of the described integrating circuit output of the homophase termination of described the 3rd operational amplifier;
Described reference voltage bleeder circuit comprises the 11 resistance and the 14 resistance that polyphone connects; The other end of reference electrode crimping the 11 resistance; The other end ground connection of the 14 resistance, the end of the 11 resistance and the 14 resistance connecting place connects the out-phase end of described the 3rd operational amplifier through the 12 resistance;
Between the out-phase end of described the 3rd operational amplifier and output, connect by the 15 resistance;
Output at the 3rd operational amplifier also has clamp circuit, and described clamp circuit comprises first diode, and the negative electrode of described first diode connects clamp voltage, and the anode of first diode connects the output of the 3rd operational amplifier;
Output at the 3rd operational amplifier also passes through the 3rd capacity earth;
The working power of the 3rd operational amplifier is second working power.
Further, above-mentioned voltage isolation Acquisition Circuit, in it is characterized in that: described bleeder circuit comprises circuit and the tenth resistance that first resistance, second resistance, the 3rd resistance, the 5th resistance, the 6th resistance, the 7th resistance are formed;
The parallel circuits polyphone of forming with described first resistance, second resistance, the 3rd resistance after described the 5th resistance, the 6th resistance, the 7th resistance parallel connection;
The described high-voltage signal end of another termination of the parallel circuits that described first resistance, second resistance, the 3rd resistance are formed;
Described the tenth resistance of another termination of the parallel circuits that described the 5th resistance, the 6th resistance, the 7th resistance are formed forms the output of described circuit;
The other end ground connection of described the tenth resistance.
Further, above-mentioned voltage isolation Acquisition Circuit, in it is characterized in that: described Acquisition Circuit comprises RC filter circuit, difference balancing circuitry, second filter capacitor and analog to digital conversion circuit;
Described RC filter circuit comprises the 8th resistance and first electric capacity, the output of the described circuit of the described circuit of the 8th resistance first termination, and the 8th resistance is through first capacity earth;
Described difference balancing circuitry comprises the 4th resistance and the 9th resistance; The 4th resistance is connected the positive signal input of the 8th resistance and the first electric capacity junction and analog to digital conversion circuit; The 9th resistance be connected and the negative signal input of analog to digital conversion circuit between;
Described second filter capacitor is connected between the positive and negative signal input part of analog to digital conversion circuit;
Described analog to digital conversion circuit is output as the digital output end of described Acquisition Circuit;
The working power of described analog to digital conversion circuit is first working power.
Compared with present technology the present invention has the following advantages:
1, the present invention adopts magnetic coupling partition method; Independently power supply power supply is all adopted in high-voltage signal and the power supply of low pressure collection terminal; Directly do not connect each other, mutual electrical isolation between Acquisition Circuit digital signal end and the low pressure DSP, therefore; Do not have between high pressure and the low pressure and be electrically connected very big like this stability and the fail safe that has strengthened test macro.
2, the present invention adopts magnetic coupling partition method, and isolation voltage is higher than light-coupled isolation electric pressure, can realize the 2KV voltage isolation, can satisfy various high tension voltage acquisition applications occasions.
3, the present invention carries out magnetic coupling isolation transmission to the digital signal of serial samples circuit output, does not receive influence of temperature change, isolates than the optocoupler analog signal, and the linearity is higher.
4, the present invention provides a kind of application process flexibly, and to the less demanding occasion of real-time, the digital voltage signal of isolating through the magnetic coupling can directly be read by measuring system, and circuit is simple, and precision is high.Occasion to real-time is had relatively high expectations can be reduced to analog signal with digital voltage signal behind integrating circuit, gather through high-speed dsp ADC module interface, uses flexibly.
Can find out from above summary of the invention and advantage: the method that high-voltage signal Acquisition Circuit provided by the present invention adopts the magnetic coupling to isolate makes the fail safe of system and stability be greatly improved; Circuit design is simple, to different use occasions, adopts different digital signal processing methods, uses flexibly; Once more, do not receive influence of temperature change, it is more accurate to measure.
Below through combining specific embodiment and accompanying drawing that technical scheme of the present invention is carried out comparatively detailed description.
Embodiment
Embodiment 1: present embodiment is the collection buffer circuit of a kind of DC bus-bar voltage to electric automobile when detecting, and schematic block circuit diagram is as shown in Figure 1, comprises resistor voltage divider circuit, Acquisition Circuit, magnetic coupling buffer circuit, integrating circuit and amplifying circuit.
Resistor voltage divider circuit is as shown in Figure 3; Its effect is that the high pressure branch of importing is depressed into the low pressure that satisfies ADC acquisition chip input range; Constitute bleeder circuit by R1, R2, R3, R5, R6, R7, R10 conventional, electric-resistance; In an embodiment; R1=R2=R3=R5=R6=R7, then voltage ratio for
circuit adopt a plurality of resistance also, series system improves the precision of divider resistance, reduces measure error.
Bleeder circuit is depressed into the voltage signal that satisfies low pressure range with dc bus high pressure branch, send Acquisition Circuit through resistance R 8, and analog-signal transitions is digital signal, and is as shown in Figure 3.Wherein R8 constitutes RC filtering with C1 except that metering function is arranged, and its effect can suppress the transient voltage disturbance; R8 output constitutes the difference input with high pressure HV_GND, and R4 and R9 are the difference balance resistance, and differential signal gets into the ADC acquisition channel after C2 filtering, and realization changes bus voltage signal into digital signal that system can discern to be handled.
The high pressure buffer circuit is with isolating through the digital signal of ADC acquisition channel; Though the resistor voltage divider circuit of front is depressed into low-voltage signal with high voltage bus voltage branch; But in some cases; If digital signal directly is connected with voltage measurement system, still can cause damage to the low pressure measurement system, therefore need isolate digital signal.The inner principle of isolation module is as shown in Figure 2, and its inside mainly contains and drives inverter and coupling transformer formation, and supplied with digital signal control switch pipe Q1 conducting after reverse the promotion is closed, and Q1 is connected with coupling transformer master limit, main limit another termination of transformer HV_5V; Digital signal is coupled to secondary and realizes Signal Spacing through main limit; Main limit and secondary are respectively with independently power supply power supply.Main limit is first power supply, and simultaneously also for the ADC of sample circuit provides working power, the secondary power supply is that second working power also provides working power for the operational amplifier in integrating circuit and the amplifying circuit simultaneously.
In the present embodiment; The high voltage dc bus voltage acquisition control system of electric automobile adopts DSP to come the measurement of signal is calculated and monitoring; Consider that the DSP real-time performance is better,, then need the software setting stand-by period if adopt DSP to read the digital signal that the ADC passage is gathered; Like this, with the performance that reduces the DSP real-time.Consider that DSP carries the ADC acquisition channel, therefore, RC integrating circuit of the present invention is that digital signal is reduced to analog signal.The U4 anode is connected with the DATA of magnetic coupling buffer circuit output among Fig. 4.Integrating circuit comprises operational amplifier U4; The digital signal of magnetic coupling buffer circuit output is by the in-phase end input of operational amplifier U4; The out-phase end of four-operational amplifier U4 is through resistance R 13 ground connection; Between the out-phase end of operational amplifier U4 and output, be connected with capacitor C 5, the output of operational amplifier U4 is through capacitor C 4 ground connection; The working power of operational amplifier U4 is second working power.
Amplifying circuit is shown in accompanying drawing 4, and R11 and R14 are composed in series bleeder circuit reference voltage VREF is carried out dividing potential drop, and resistance R 12 of output series connection of this bleeder circuit is connected to the negative terminal of amplifier U3 then, and negative terminal connects R15 to U3 output.Output be connected in series with VCC_3.3 one the protection diode, wherein VCC_3.3 is the DSP power supply, its effect of diode be with U3 output ceiling voltage clamper about 3.3V, with the protection DSP cause burning because of applied signal voltage is too high.ADCINX is connected with DSP ADC passage pin.
In the present embodiment, two working power HV-5V and VCC are isolate each other two independently working powers not altogether.