CN104373235B - High-pressure common rail piezo actuator drives current control circuit - Google Patents

Abstract

The invention discloses a charging and discharging driving current control circuit of a piezoelectric actuator in a high-voltage common rail system, which includes a charging current modulation circuit, a discharge current inversion processing circuit, and a discharge current modulation circuit. In the charge and discharge current modulation circuit, with the change of charge and discharge current, the connection relationship of the resistance in the current threshold voltage divider circuit is directly affected by the switching device transistor, and the change of the current threshold value is controlled, and the two thresholds are converted to each other. The charge and discharge current modulation circuit outputs PWM signals determined by these two current thresholds. The advantages of the present invention are: the present invention realizes the control of the charge and discharge drive current of the piezoelectric actuator, the drive circuit is simple and easy, and the modulation process of the drive current is completely realized by hardware, which fundamentally ensures the consistency of the current , while occupying less MCU resources.

Description

High voltage common rail piezoelectric actuator driving current control circuit

technical field

The invention relates to piezoelectric actuator drive technology, in particular to a piezoelectric actuator drive current control device for a high-voltage common rail system of a diesel engine.

Background technique

Before the piezoelectric actuator is injected, the energy stored on the piezoelectric actuator is very small, and the voltage of the piezoelectric actuator is very low. When the piezoelectric actuator starts to inject fuel, it is directly charged with 150V voltage. At the initial moment of charging, The current flowing through the piezoelectric actuator will be very large, which may lead to a large acceleration of the piezoelectric actuator’s elongation and deformation. Although this problem can be alleviated by adding a preload, if a piezoelectric actuator is designed to charge Putting the loop drive current control circuit will fundamentally solve this problem. Similarly, if the discharge current is too large, the deformation acceleration of the piezoelectric actuator will also be large due to shortening. It is also necessary to design the discharge current control circuit of the discharge circuit to fundamentally solve this problem, and to ensure the consistency of the charging and discharging current each time.

Piezoelectric crystal driving includes charging and discharging circuit driving, so piezoelectric crystal driving current control is also to control the current of these two driving circuits. At present, the control method for these two currents is basically the current sampling resistor voltage and the set threshold voltage. Comparing the output, and the PWM signal with a fixed frequency duty cycle through a certain logic relationship chopping output to drive the charging and discharging circuit of the piezoelectric actuator to realize the control of the charging and discharging current.

This solution is not a real current closed-loop control, which can easily lead to inconsistent charging and discharging currents. At the same time, the frequency and duty cycle of the PWM signal are not accurate values, and certain requirements are placed on the logical relationship between the PWM signal and the charge and discharge enable signals, which not only brings certain difficulties to software programming, but also wastes MCU resources.

Chinese patent CN101684758A is a piezoelectric high-pressure common rail injection system control unit for a vehicle diesel engine, which relates to a piezoelectric actuator current control method. The means used in the patent for current control and the effect achieved: the charging current of the piezoelectric actuator is determined by the voltage of the current sampling resistor and the PWM signal generated by the frequency division of the CPLD, and the closed-loop control of the charging current is realized. The deficiency and reason of this patent: 1. The duty ratio and frequency of the PWM signal generated by CPLD frequency division is an empirical value set by the individual, and this scheme has certain requirements for the logic timing of the PWM signal and the charging enable signal. The software programming is complex and takes up resources. If this logic sequence is not followed, the charging current waveform will be inconsistent, and the charging time will be different each time. Moreover, the patent does not perform closed-loop control on the discharge current of the piezoelectric crystal. 2. The technical solution determines that the charging and discharging time of the piezoelectric actuator is related to both the set current threshold and the frequency of the PWM signal.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art, to provide a high-voltage common rail piezoelectric actuator drive current control circuit to realize the effective control of the charge and discharge current of the piezoelectric actuator, and to control the piezoelectric actuator The driving current is closed-loop controlled.

According to the technical solution provided by the present invention, the high-voltage common rail piezoelectric actuator drive current control circuit includes: a charging current modulation circuit, a discharge current inversion processing circuit, and a discharge current modulation circuit, and the discharge current inversion processing circuit includes Resistors R1, R2 and R3, and the input point of the discharge current inversion processing circuit are connected in series in the charging and discharging circuit of the piezoelectric actuator. The input point is connected to +V power supply through resistor R2 and resistor R1 on the one hand, and connected to Resistor R3 is grounded;

The charging current modulation circuit includes: three resistors R4, R5, and R6 are sequentially connected in series to form a charging current threshold voltage divider circuit, wherein the high-voltage terminal of the resistor R4 is connected to the +V power supply, and the low-voltage terminal of the resistor R6 is grounded; the connection between the resistors R4 and R5 The point voltage is the threshold divided voltage, connected to the inverting terminal of the comparator U18, the same phase terminal of the comparator U18 is connected to the input point of the discharge current inverting processing circuit, the output of the comparator U18 is connected to the base of the transistor Q12 through the resistor R7, so that It works in the on or off state, the emitter of transistor Q12 is grounded, the collector is connected to the connection point of resistors R5 and R6, the output terminal of comparator U18 is pulled up to +V power supply through resistor 21, and connected to the input of NOT gate U20, The output of the non-gate U20 is the charging current modulation PWM signal;

The discharge current modulation circuit includes: three resistors R8, R9, R10 are connected in series in sequence to form a discharge current threshold voltage divider circuit, wherein the high voltage terminal of the resistor R8 is connected to the +V power supply, and the low voltage terminal of the resistor R10 is grounded; the connection between the resistor R8 and R9 The point voltage is the threshold divided voltage, which is connected to the inverting terminal of the comparator U19, and the non-inverting terminal of the comparator U19 is connected to the connection point of resistors R1 and R2, and the output of the comparator U19 is connected to the base of the transistor Q13 through the resistor R11 to make it work In the on or off state, the emitter of transistor Q13 is grounded, the collector is connected to the connection point of resistors R9 and R10, the output terminal of comparator U19 is pulled up to +V power supply through resistor R22, and the output of comparator U19 is the discharge current modulation PWM signal .

In the charging current modulation circuit, as the charging current changes, the connection relationship of the resistor R6 in the charging current threshold voltage divider circuit is directly affected by the switching device transistor Q12, and the change of the current threshold is controlled, and the two thresholds are mutually converted, The charging current modulation circuit outputs a PWM signal determined by these two current thresholds.

In the discharge current modulation circuit, as the discharge current changes, the connection relationship of the resistor R10 in the discharge current threshold voltage divider circuit is directly affected by the switching device transistor Q13, and the change of the current threshold is controlled, and the two thresholds are mutually converted, The discharge current modulation circuit outputs a PWM signal determined by these two current thresholds.

During the discharge process, the output voltage of the sampling resistor R3 is connected to the +V power supply through the series resistors R1 and R2, and the voltage at the connection point of the series resistors R1 and R2 is the discharge current sampling voltage.

Among them, resistors R1, R2, R4, R5, R6, R8, R9, R10 are all precision resistors.

The advantages of the present invention are: the present invention realizes the control of the charging and discharging driving current of the piezoelectric actuator, the driving circuit is simple and easy, and the modulation process of the driving current is completely realized by hardware, which fundamentally ensures the consistency of the current , while occupying less MCU resources.

Description of drawings

Fig. 1 is the schematic circuit diagram of the present invention.

Fig. 2 is a charging and discharging control sequence and a charging and discharging current waveform diagram of the piezoelectric actuator of the present invention.

detailed description

The present invention will be further described below in conjunction with drawings and embodiments.

As shown in FIG. 1 , the charging and discharging drive current control circuit 17 of the piezoelectric actuator in the high-voltage common rail system of the present invention includes three parts: a charging current modulation circuit 14 , a discharge current inversion processing circuit 15 , and a discharge current modulation circuit 16 .

The charging current modulation circuit 14 includes a comparator U18, five resistors R4, R5, R6, R7, R21, a transistor Q12 and a non-gate U20; the connection relationship between each device is described as follows: three resistors R4, R5, R6 is sequentially connected in series to form a charging current threshold voltage divider circuit, in which the high-voltage terminal of resistor R4 is connected to +V power supply, and the low-voltage terminal of resistor R6 is grounded; the voltage at the connection point of resistors R4 and R5 is the threshold voltage divider, which is connected to the counter of comparator U18 Phase terminal, comparator U18 in-phase terminal is connected to the input point of discharge current inversion processing circuit 15, the output of comparator U18 is connected to the base of transistor Q12 through resistor R7, so that it works in the on or off state, and the emitter of transistor Q12 is grounded , the collector is connected to the connection point of resistors R5 and R6, the output terminal of the comparator U18 is pulled up to the +V power supply through the resistor 21, and connected to the input of the non-gate U20, the output of the non-gate U20 is the charging current modulation PWM signal, and the output of the non-gate The piezoelectric actuator charging signal is realized according to a certain logic relationship with other control signals.

The discharge current inversion processing circuit 15 includes three resistors R1, R2, and R3; the resistors R1, R2 are connected in series, one end of the resistor R1 is connected to the +V power supply, one end of the resistor R2 is connected to the high end of the resistor R3, and the voltage of the series connection point of the resistors R1, R2 is Sample voltage for discharge current.

The discharge current modulation circuit 16 includes a comparator U19, five resistors R8, R9, R10, R11, R22, and a transistor Q13; the connection relationship is described as follows: three resistors R8, R9, R10 are sequentially connected in series to form a discharge current threshold voltage divider circuit , where the high-voltage terminal of resistor R8 is connected to +V power supply, and the low-voltage terminal of resistor R10 is grounded; the voltage at the connection point of resistor R8 and R9 is the threshold divided voltage, which is connected to the inverting terminal of comparator U19, and the non-inverting terminal of comparator U19 is connected to the resistor The connection point of R1 and R2, the output of the comparator U19 is connected to the base of the transistor Q13 through the resistor R11, so that it works in the on or off state, the emitter of the transistor Q13 is grounded, and the collector is connected to the connection point of the resistors R9 and R10. The output of the comparator U19 is connected to the +V power supply through the pull-up resistor R22, the output discharge current of the comparator U19 modulates the PWM signal, and realizes the discharge signal of the piezoelectric actuator according to a certain logic relationship with other control signals.

The present invention designs a charging and discharging current modulation circuit for a piezoelectric actuator, which is completely implemented by a hardware circuit. Two charging current thresholds are set in the circuit, and the charging current thresholds are mutually converted between the two values, so that the charging current modulation output is at The setting between the two thresholds is shown in FIG. 2 . The charging current modulation output, the charging enable signal and the charging voltage feedback signal jointly drive the charging circuit according to a certain logical relationship. The modulation output of the discharge current is similar to the charge current, and two discharge current thresholds are set in the discharge current modulation circuit.

The output of the charging current threshold comparator U18 controls the switching state of the transistor Q12, and the transistor Q12 is in an on or off state, and is constantly switched between the two states. When the transistor Q12 is cut off, the total resistance connected in series by the resistors R5 and R6 divides the voltage of the power supply, and the current threshold increases; when the transistor Q12 is turned on, the connection point of the resistors R5 and R6 is forced to be grounded, and the resistor R5 divides the voltage of the power supply. The current threshold becomes smaller. The comparator U18 modulates and outputs a corresponding PWM signal according to the set threshold, further controlling the charging process of the piezoelectric actuator.

Piezoelectric actuator charging is the process of storing energy, and discharging is just the opposite, which is the process of releasing energy. Therefore, the directions of charging and discharging currents are completely opposite. For the voltage of the current sampling resistor, the sampling voltage is a positive voltage during the charging process, and the sampling voltage during the discharging process is positive. The sampling voltage is a negative voltage, so in order to simplify the discharge process, the sampling voltage conditioning circuit superimposes a positive voltage on the voltage through the superposition principle, and converts the sampling voltage into an easy-to-handle positive voltage by adjusting the size of the voltage dividing resistor.

After the discharge current sampling voltage is inverted, the larger the sampling output voltage is, the smaller the discharge current is, and the smaller the sampling output voltage is, the larger the discharge current is, just opposite to the charging current sampling output. Although the working principle of the modulation output of the discharge current comparator is basically similar to that of the charging process, the output of the charge current threshold comparator needs to be processed by an inverter and then combined with other related signals to control the entire charging process according to a certain logic.

In the present invention, the output of the charge and discharge current threshold comparator controls the working state of the corresponding transistor, and the turn-on or cut-off of the transistor determines the magnitude of the charge and discharge current threshold.

The working mode of the present invention is introduced in detail below.

In the fuel injection process of the piezoelectric high-pressure common rail system, the piezoelectric actuator includes two processes of charging and discharging. When the electronic control unit sends out the fuel injection enable signal, the piezoelectric actuator starts charging, and after a certain charging time, it reaches its set charging voltage, and the charging process ends. As shown in Figure 1, M1 is the charging circuit switch tube of the piezoelectric actuator, M3 is the low-end strobe switch tube of the piezoelectric actuator, the charging process transistors M1 and M3 are active at the same time, +HIGH_V passes through M1, current-limiting inductors L, M3 1. Resistor R3 charges the piezoelectric actuator C23, and the voltage of the piezoelectric actuator C23 gradually rises. When the charging voltage is reached, the actuator voltage feedback circuit is invalid, and the piezoelectric actuator charging circuit is disabled, and the transistor M1 is turned off to complete the charging process. During the fuel injection process, the low-side strobe transistor M3 remains on, and the voltage of the piezoelectric actuator C23 maintains the charging voltage value. When the fuel injection ends, the piezoelectric actuator C23 releases the charging voltage. M2 is the switch tube of the discharge circuit of the piezoelectric actuator. During the discharge process, M2 is turned on, and the voltage of the piezoelectric actuator C23 is released through the circuit composed of the current-limiting inductor L, transistor M2, resistor R3 and transistor M3. The voltage of the piezoelectric actuator C23 Gradually decrease, when the set discharge voltage is reached, the voltage feedback loop is invalid, the piezoelectric actuator discharge loop is disabled, the transistor M2 is turned off, and the discharge process ends.

In order to ensure the fast response of the piezoelectric actuator, the voltage of the piezoelectric actuator C23 needs to be quickly charged to its set voltage, so the vehicle power supply needs to be boosted to a high voltage of +HIGH_V through a DC/DC Boost circuit. Around 150V.

When the diesel engine starts fuel injection, the MCU sends a charging enable signal, the charging voltage and current of the piezoelectric actuator C23 are zero, the charging voltage feedback comparator outputs a high level, and the comparator U18 in the charging current modulation circuit 14 outputs a low level, Transistor Q12 is cut off, and resistors R4, R5, and R6 are connected in series to form a voltage divider circuit with +V power supply (such as +5V). The series resistance of two resistors R5 and R6 divides the total series resistance, and the inverting phase of comparator U18 The voltage at the input terminal is the divided voltage, forming the charging current threshold 1. The current feedback comparator U18 outputs a low level and is inverted by the NOT gate U20, and the MCU charging enable signal and the charging voltage feedback signal are processed by a certain logic to enable the charging circuit power device M1, and the +HIGH_V high voltage passes through the diode D1, the limiter The flow inductance L charges the piezoelectric actuator C23, and the charging voltage and current of the piezoelectric actuator C23 gradually rise. When the charging current reaches its set threshold 1, the current modulation comparator U18 outputs a high level, and the transistor Q12 is turned on, so that The series connection point of resistors R5 and R6 is grounded, both ends of resistor R6 are grounded and short-circuited, resistors R4 and R5 are connected in series with +V power supply to form a voltage divider circuit, and the voltage at the inverting input terminal of comparator U18 becomes the divided voltage, forming The charging current threshold 2, obviously, the charging current threshold 2 is smaller than the charging current threshold 1. The current feedback comparator U18 outputs a high level and is inverted by the NOT gate U20, and after a certain logic processing with the MCU charging enable signal and the voltage feedback signal, the power device M1 of the charging circuit is turned off, and the reverse electromotive force in the current-limiting inductor L passes through The body diode of the power device M2 in the discharge circuit continues to charge the piezoelectric actuator C23, and the charging current of the piezoelectric actuator C23 gradually decreases. When it drops to the set current threshold 2, the current modulation comparator U18 of the charging circuit outputs a low voltage level, the transistor Q12 is cut off, the voltage of the inverting input terminal of the comparator U18 becomes the charging current threshold 1 again, the charging power device M1 is turned on again, and the +HIGH_V high voltage continues to charge the piezoelectric actuator C23, and the current gradually increases. When it reaches the set charging current threshold 1 again, the inverting input voltage of the current modulation comparator U18 becomes the charging current threshold 2 again, the charging power device M1 is turned off, and the back electromotive force of the current-limiting inductance L passes through the body diode of M2 to the piezoelectric The actuator C23 continues to charge, the charging current gradually decreases, and so on, until the charging voltage of the piezoelectric actuator C23 reaches its set voltage threshold, the voltage feedback circuit outputs a low level, and the power device M1 of the charging circuit is completely turned off. The charging process of actuator C23 is completed. The resistors R4, R5, and R6 in the charging current threshold voltage divider circuit are precision resistors to ensure the consistency of the charging current threshold.

In the two stages of the charging process, the charging current flows to the ground through the current-limiting inductor L, the piezoelectric actuator C23, and the current sampling resistor R3. The charging current is sampled directly from the sampling resistor R3, and the larger the charging current, the sampling voltage The larger is also, the relationship between the two is proportional. During the discharge process, the energy stored in the piezoelectric actuator C23 flows to the negative terminal of the piezoelectric actuator through the current-limiting inductance L and the sampling resistor R3, forming a release circuit, and the direction of the discharge current of the piezoelectric actuator C23 is just opposite to the charging current , if the discharge current is directly sampled from the sampling resistor R3, the sampling voltage is negative level, so the piezoelectric actuator drive current control device must have a negative power supply processing circuit, so in the circuit design, the sampled discharge voltage of the resistor R3 and The +V power supply voltage is superimposed through resistors R1 and R2. The voltage at the series connection point of resistors R1 and R2 is the discharge current sampling output, and the larger the discharge current is, the smaller the sampling output is. Precision resistors are used for resistors R1 and R2.

When the fuel injection of the piezoelectric actuator C23 ends, the piezoelectric actuator C23 starts to discharge. Since the sampling of the discharge current of the piezoelectric actuator C23 is different from the sampling of the charging current, the discharge current modulation circuit 16 and the charging current modulation circuit 14 are also different. . The discharge current sampling output is connected to the non-inverting input terminal of the comparator U19, and the connection point of the series resistors R8 and R9 in the discharge current threshold voltage divider circuit is connected to the inverting input terminal of the comparator U19. When the MCU sends a discharge enable signal, although the piezoelectric The discharge current of the actuator C23 is zero, but the discharge current sampling voltage is greater than the threshold voltage, the comparator U19 outputs a high level, and the transistor Q13 is turned on. In the discharge current threshold voltage divider circuit composed of resistors R8, R9, and R10, the resistors R9, The series connection point of R10 is grounded, the two ends of the resistor R10 are short-circuited to the ground, the +V power supply and the resistors R8 and R9 form a threshold voltage divider circuit to form a discharge current threshold 3, because the comparator U19 outputs a high level and the discharge current does not reach the set value The threshold value is 3, the three signals drive the discharge power device M2 after certain logic processing, and the energy stored in the piezoelectric actuator C23 forms a discharge circuit through the current-limiting inductance L, power tube M2, and sampling resistor R3; the discharge current gradually increases , the discharge current sampling output gradually decreases. When the discharge current reaches its set threshold 3, the comparator U19 outputs a low level, and the transistor Q13 is cut off. The series resistance composed of resistors R9 and R10 divides the voltage of the +V power supply to form a discharge The current threshold is 4. Obviously, the discharge current threshold 3 is smaller than the threshold 4. The comparator U19 outputs a low level. After a certain logical relationship is processed, the discharge power device M2 is turned off, and the energy stored in the current-limiting inductor L is transferred to the DC/DC through the body diode of M1. The boost circuit capacitor is charged, and the discharge current gradually decreases. When the discharge current reaches its set threshold 4, the comparator U19 outputs a high level, and the discharge power device M2 is turned on again, and the discharge current threshold becomes threshold 3 again. The actuator continues to discharge through M2; the discharge current gradually increases. When it reaches the set threshold 3, the comparator U19 outputs a low level again, and the discharge power device M2 is turned off, and the discharge current sampling voltage becomes the threshold 4 again, and M2 is turned off. The piezoelectric actuator C23 charges the DC/DC Boost capacitor through the current-limiting inductance L, and the current gradually decreases; in this way, the energy stored in the piezoelectric actuator C23 becomes less and less, and the voltage decreases accordingly. When the discharge voltage reaches The threshold is set, the discharge voltage comparator outputs a low level to completely shut down the entire discharge process, and the discharge process of the piezoelectric actuator is completed. In the above discharge current threshold voltage divider circuit, the resistors R8, R9 and R10 are precision resistors to ensure the consistency of the discharge current threshold.

As can be seen above, the present invention has the following characteristics:

1. The current PWM modulation signal is completely realized by hardware, which is simple and reliable, and the driving current has good consistency.

2. The charging and discharging current thresholds determine the average current during the charging and discharging time, so the charging and discharging time of the piezoelectric actuator is only determined by these two thresholds.

Claims (7)

1. high-pressure common rail piezo actuator drives current control circuit, it is characterized in that, including: charging current modulation circuit (14), the anti-phase processing circuit of discharge current (15), discharge current modulation circuit (16), the anti-phase processing circuit of described discharge current (15) includes resistance R1, R2 and R3, the input point of the anti-phase processing circuit of discharge current (15) is connected in the charge and discharge loop of piezo actuator, on the one hand described input point connects+V power supply through resistance R2 and resistance R1, on the other hand through resistance R3 ground connection；

Described charging current modulation circuit (14) including: three resistance R4, R5, R6 are sequentially connected in series charging current threshold value bleeder circuit, wherein the high pressure termination+V power supply of resistance R4, the low-pressure end ground connection of resistance R6；The junction point voltage of resistance R4 Yu R5 is threshold value branch pressure voltage, access the end of oppisite phase of comparator U18, the input point of the comparator U18 homophase termination anti-phase processing circuit of discharge current (15), the output of comparator U18 is connected with transistor Q12 base stage through resistance R7, it is made to be operated on or off state, transistor Q12 grounded emitter, the junction point of colelctor electrode connecting resistance R5 and R6, the outfan of comparator U18 is pulled to+V power supply through resistance 21, and connect the input of not gate U20, not gate U20 output i.e. charging current modulation (PWM) signal；

Described discharge current modulation circuit (16) including: three resistance R8, R9, R10 are sequentially connected in series discharging current threshold bleeder circuit, wherein the high pressure termination+V power supply of resistance R8, the low-pressure end ground connection of resistance R10；The junction point voltage of resistance R8 Yu R9 is threshold value branch pressure voltage, access the end of oppisite phase of comparator U19, the junction point of comparator U19 in-phase end connecting resistance R1 and R2, the output of comparator U19 is connected with transistor Q13 base stage through resistance R11, it is made to be operated on or off state, transistor Q13 grounded emitter, the junction point of colelctor electrode connecting resistance R9 and R10, comparator U19 outfan is pulled to+V power supply through resistance R22, the output of comparator U19 i.e. discharge current modulation (PWM) signal.

2. high-pressure common rail piezo actuator drives current control circuit as claimed in claim 1, it is characterized in that, in described charging current modulation circuit (14), change along with charging current, resistance R6 annexation in charging current threshold value bleeder circuit is directly affected by switching device transistor Q12, controlling the change of current threshold size, and two threshold values are mutually changed, charging current modulation circuit (14) exports the pwm signal determined by the two current threshold；

In the charging current threshold value bleeder circuit of described resistance R4, R5, R6 composition, resistance R4, R5, the R6 being connected in series forms bleeder circuit with+V power supply, the series resistance of two resistance R5, R6 carries out dividing potential drop to total series resistance, the anti-phase input terminal voltage of comparator U18 is this branch pressure voltage, forms first charging current threshold value in said two threshold value；

Resistance R4, R5 series connection forms bleeder circuit with+V power supply, and the anti-phase input terminal voltage of comparator U18 becomes this branch pressure voltage, forms second charging current threshold value in said two threshold value.

3. high-pressure common rail piezo actuator drives current control circuit as claimed in claim 1, it is characterized in that, in described discharge current modulation circuit (16), change along with discharge current, resistance R10 annexation in discharging current threshold bleeder circuit is directly affected by switching device transistor Q13, controlling the change of current threshold size, and two threshold values are mutually changed, discharge current modulation circuit (16) exports the pwm signal determined by the two current threshold；

In the discharging current threshold bleeder circuit of described resistance R8, R9, R10 composition, resistance R9, R10 are connected in series a ground connection, resistance R10 two ends shorted to earth ,+V power supply and resistance R8, R9 form threshold value bleeder circuit, form first discharging current threshold in said two threshold value；

Series resistance right+V power supply the dividing potential drop of resistance R9, R10 composition, forms second discharging current threshold in said two threshold value.

4. high-pressure common rail piezo actuator drives current control circuit as claimed in claim 1, it is characterized in that, in discharge process, the output voltage of sampling resistor R3 is concatenated resistance R1, R2 and is connected to+V power supply, and series resistance R1, the junction point voltage of R2 are discharge current sampled voltage.

5. high-pressure common rail piezo actuator drives current control circuit as claimed in claim 1, it is characterized in that, in the anti-phase processing circuit of described discharge current (15), resistance R1, R2 use precision resistance.

6. high-pressure common rail piezo actuator drives current control circuit as claimed in claim 1, it is characterized in that, in described charging current modulation circuit (14), resistance R4, R5, R6 use precision resistance.

7. high-pressure common rail piezo actuator drives current control circuit as claimed in claim 1, it is characterized in that, in described discharge current modulation circuit (16), resistance R8, R9, R10 use precision resistance.