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CN-122026700-A - Driving module and method for electric power steering system

CN122026700ACN 122026700 ACN122026700 ACN 122026700ACN-122026700-A

Abstract

The invention discloses a driving module of an electric power steering system, which comprises a micro control unit MCU, a grid driving chip module GDU internal register, a grid driving chip module GDU internal integrated SPI unit, a state machine, a diagnosis unit and three control units, wherein the high-side grid driving module, the high-side comparator module and the low-side grid driving module are integrated in each control unit, the high-side grid driving module is used for receiving instructions of the control units and outputting driving signals to control on and off of high-side MOSFETs corresponding to a three-phase bridge load half-bridge, the low-side grid driving module is used for receiving instructions of the control units and outputting driving signals to control on and off of low-side MOSFETs corresponding to the three-phase bridge load half-bridge, and the high-side comparator module is used for collecting drain-source voltage signals of the high-side MOSFETs and the low-side MOSFETs in the corresponding to the three-phase bridge load half-bridge, comparing with preset thresholds and feeding back to the MCU to provide basis for judging of active or freewheeling MOSFETs.

Inventors

  • Shi Liuli
  • DUAN BINGYING
  • LIU SHUN
  • ZHANG KAILU
  • Jin Fangda

Assignees

  • 博世华域转向系统有限公司

Dates

Publication Date
20260512
Application Date
20260319

Claims (12)

  1. 1. An electric power steering system drive module, comprising: The micro-control unit MCU (10), the grid driving chip module GDU (20) and the three-phase bridge load half-bridge (30), wherein three-phase bridge load half-bridges (30) are arranged and form a three-phase bridge structure, and each three-phase bridge load half-bridge (30) comprises a high-side MOSFET (Q1) and a low-side MOSFET (Q2); The micro control unit MCU (10) configures an internal register of the grid driving chip module GDU (20) through an SPI interface, acquires a state feedback signal, and transmits a MOSFET switch control instruction through a IHx _ N, ILx signal after operation processing; The grid driving chip module GDU (20) is internally integrated with an SPI unit, a state machine, a diagnostic unit (40) and three control units (50); The SPI unit, the state machine and the diagnosis unit (40) are used for realizing SPI data interaction with the MCU (10), distributing driving instructions to each control unit (50) and diagnosing the working state of the module; the three control units (50) are in one-to-one correspondence with the three-phase bridge load half-bridges (30), and a high-side gate driving module (60), a high-speed comparator module (80) and a low-side gate driving module (70) are integrated in each control unit (50); The high-side grid driving module (60) is used for receiving an instruction of the control unit (50) and outputting a driving signal to control the high-side MOSFET (Q1) of the corresponding three-phase bridge load half bridge (30) to be turned on and off; The low-side grid driving module (70) is used for receiving an instruction of the control unit (50) and outputting a driving signal to control the on and off of a low-side MOSFET (Q2) of a corresponding three-phase bridge load half-bridge (30); The high-speed comparator module (80) is used for collecting drain-source voltage signals of the high-side MOSFET (Q1) and the low-side MOSFET (Q2) in the corresponding three-phase bridge load half-bridge (30), comparing the drain-source voltage signals with a preset threshold value, and feeding back the drain-source voltage signals to the MCU (10) to provide a basis for judging the active or follow current MOSFET.
  2. 2. The electric power steering system driving module according to claim 1, wherein the high-speed comparator module (80) collects drain-source voltages (VDHVShx) of the high-side MOSFET (Q1) through the comparator (1) (CF 1), collects drain-source voltages (VShxGND) of the low-side MOSFET (Q2) through the comparator (2) (CF 2), and compares the collected voltage values with a high-voltage threshold (VSHH) and a low-voltage threshold (VSHL), respectively.
  3. 3. The electric power steering system driving module as set forth in claim 1, wherein the high-side gate driving module (60) comprises a first chip resistor (R1), a MOS1 (Q01), a second chip resistor (R2), a MOS2 (Q02) first resistor (R1) with one end connected to the SPI unit and the state machine and diagnosis unit (40), another end connected to the MOS1 (Q01) first end, a MOS1 (Q01) second end connected to the CP2 port of the gate driving chip module GDU (20), a MOS1 (Q01) third end connected to the high-side driving port (GHx) of the gate driving chip module GDU (20), a second resistor (R2) with one end connected to the SPI unit and the state machine and diagnosis unit (40), another end connected to the MOS2 (Q02) first end, a MOS2 (Q02) second end connected to the MOS1 (Q01) third end, and a MOS2 (Q02) third end connected to the high-side sampling port (SHx) of the gate driving chip module GDU (20).
  4. 4. The electric power steering system driving module as set forth in claim 1, wherein the low-side gate driving module (70) comprises a third chip resistor (R3), a MOS3 (Q03), a fourth chip resistor (R4), a MOS4 (Q04), one end of the third chip resistor (R3) is connected with the SPI unit, the state machine and the diagnostic unit (40), the other end is connected with the first end of the MOS3 (Q03), the second end of the MOS3 (Q03) is connected with the CP1 port of the GDU (20), the third end of the MOS3 (Q03) is connected with the low-side driving port (GLx) of the GDU (20), the one end of the fourth chip resistor (R4) is connected with the SPI unit, the state machine and the diagnostic unit (40), the other end is connected with the first end of the MOS4 (Q04), the second end of the MOS4 (Q04) is connected with the third end of the MOS3 (Q03), and the third end of the MOS4 (Q04) is connected with the low-side sampling port (SLx) of the GDU (20).
  5. 5. The electric power steering system driving module according to claim 1, wherein the MCU (10) realizes data interaction with the gate driving chip module GDU (20) through an SCK clock line, an SDI master-slave line, an SDO master-slave line and a CS chip select line of an SPI interface, and sends a switch state instruction of a three-phase bridge high-low side MOSFET to the gate driving chip module GDU (20) through a IHx _ N, ILx signal.
  6. 6. The electric power steering system driving module as set forth in claim 1, wherein the three-phase bridge load half-bridge (30) is replaced by a six-phase bridge load half-bridge, the number of control units (50) of the gate driving chip module GDU (20) is correspondingly increased, the structure and driving method of each control unit are consistent with those of the three-phase bridge, and the adaptation is realized by matching with internal register parameters of the gate driving chip module GDU (20) through an SPI interface of the MCU (10).
  7. 7. An electric power steering system driving method implemented based on the electric power steering system driving module according to any one of claims 1, comprising the steps of: S1, an MCU (10) sends a switch state instruction to a gate driving chip module GDU (20) through an SPI interface, and after the gate driving chip module GDU (20) receives the instruction, a high-speed comparator module (80) collects drain-source voltages of a high-side MOSFET (Q1) and a low-side MOSFET (Q2); S2, the high-speed comparator module (80) compares the acquired drain-source voltage with a high-voltage threshold (VSHH) and a low-voltage threshold (VSHL) respectively, the comparison result is fed back to the MCU (10) through SPI, and the MCU (10) judges an active MOSFET and a free-wheeling MOSFET, wherein the active MOSFET is an MOSFET for controlling the phase voltage slope, and the free-wheeling MOSFET is an MOSFET which only participates in free-wheeling and does not control the phase voltage slope; S3, the grid driving chip module GDU (20) adjusts driving current parameters according to the judging result of the MCU (10).
  8. 8. The method for driving an electric power steering system according to claim 7, wherein in step S2, the judgment rules of the active MOSFET and the freewheel MOSFET are as follows: 1) If the phase voltage VShx > the high-voltage threshold (VSHH) and the high-side MOSFET (Q1) is to be turned on, the low-side MOSFET (Q2) is an active MOSFET and the high-side MOSFET (Q1) is a freewheel MOSFET; 2) If the phase voltage VShx < low-voltage threshold (VSHL) and the low-side MOSFET (Q2) is to be turned on, the high-side MOSFET (Q1) is an active MOSFET and the low-side MOSFET (Q2) is a freewheeling MOSFET; 3) If the high voltage threshold (VSHH) VSHL < the phase voltage VShx < the low voltage threshold (VSHL), then the next MOSFET to be turned on is the active MOSFET.
  9. 9. The method according to claim 7, wherein in the step S3, the turning-on process of the active MOSFET is divided into four phases: a) A precharge stage, in which the gate driving chip module GDU (20) outputs a current I1 for a time T1 to precharge the gate and source of the active MOSFET, so that the voltage of the gate and source reaches a turn-on threshold (Vth); b) A miller platform rising stage, in which the grid driving chip module GDU (20) outputs a current I2, the charging is continued until the grid source voltage reaches a miller platform voltage Vplat for a period of time T2, until the phase voltage (VShx) reaches a low-voltage threshold Value (VSHL), and if the phase voltage (VShx) reaches a high-voltage threshold Value (VSHH) in the stage, the step c) is skipped to directly enter the step d); c) A Miller charging stage, in which the grid driving chip module GDU (20) outputs a current I3 for a time T3, and the Miller platform voltage Vplat is maintained until the phase voltage (VShx) reaches a high-voltage threshold (VSHH), and the dv/dt slope is controlled; d) In the hold charging stage, the gate driving chip module GDU (20) firstly charges the output current I4 to the end of the blanking time and the filtering time set by software, and then switches to continuously supply power for the hold current I5.
  10. 10. The method for driving an electric power steering system according to claim 7, wherein in the step S3, the turning-off process of the freewheel MOSFET is divided into three phases: e) The pre-discharge stage, namely outputting a discharge current I6 by a grid driving chip module GDU (20) for a time T7, pre-discharging the grid and the source of the follow current MOSFET to reduce the voltage of the grid and the source to VGS_PDT; f) The continuous discharge stage, namely the grid driving chip module GDU (20) outputs a discharge current I5 to continuously discharge in a timeout period T8T7 set by software; g) And in the current switching stage, when the rising edge of the PWM signal of the active MOSFET is triggered, the grid driving chip module GDU (20) outputs current I8, and after the T4 period of the active MOSFET is ended and the time lasts for T16, the current is switched to be continuously kept by the bleeder current I5.
  11. 11. The method according to claim 7, wherein in the step S3, the turning-off process of the active MOSFET is divided into four phases: h) The pre-discharge stage, namely outputting a discharge current I6 by a grid driving chip module GDU (20) for a time T7, pre-discharging the grid and the source of the active MOSFET to reduce the voltage of the grid and the source to VGS_PDT; i) The Miller platform maintaining stage comprises the steps that a grid driving chip module GDU (20) outputs a release current I9, so that the grid source voltage keeps the Miller platform voltage Vplat until the phase voltage (VShx) reaches a high-voltage threshold (VSHH) and then continues for T10 time until the phase voltage (VShx) reaches a low-voltage threshold (VSHL), and the di/dt slope is controlled at the stage; j) The Miller voltage discharging stage, namely the grid driving chip module GDU (20) outputs a release current I11 to enable the voltage of the grid source electrode to be reduced to 0V until the Miller voltage discharging stage is finished, and the dv/dt slope is controlled at the stage; k) In the subsequent discharging stage, the grid driving chip module GDU (20) outputs the discharge current I12 until the rising edge of the PWM signal of the freewheeling MOSFET is triggered, the current is switched to the discharge current I8, and after the time T16 is over, the current is switched to the discharge current I5 to be continuously maintained.
  12. 12. The method for driving an electric power steering system according to claim 7, wherein in the step S3, the turning-on process of the freewheel MOSFET is divided into two phases: l) a precharge stage, wherein the grid driving chip module GDU (20) outputs a current I1 for T1 time to precharge the grid and source electrodes of the freewheeling MOSFET so as to enable the voltage of the grid and source electrodes to reach a conduction threshold (Vth); m) a keep charging stage, namely the output current I11 of the grid driving chip module GDU (20) is continuously charged, and the switch is made to keep supplying power to the current I5 after the blanking time and the filtering time set by software are finished.

Description

Driving module and method for electric power steering system Technical Field The invention relates to the field of automobiles, in particular to a current-type pre-drive-based driving module for an electric power steering system. Background In the field of electric power steering systems, synchronous motor MOSFET power driving modules reaching ASILD grades are mostly of voltage driving type, and the on and off speeds of MOSFETs are adjusted through external driving grid resistors so as to optimize switching loss and waveform quality and improve motor control efficiency and EMI characteristics. Because parasitic inductance and stray capacitance exist in the wiring and the loop of the MOSFET on the PCB, voltage and current are rapidly changed in the switching process of the MOSFET, voltage and current peaks can be generated under the interaction of the capacitance and the inductance, and the EMI characteristics are deteriorated. To reduce dv/dt and di/dt, the MOSFET turn-on speed needs to be reduced, and at the same time, the turn-off speed needs to be increased to reduce EMI, so that the turn-on driving circuit needs to be separated from the turn-off bleeding circuit, a gate driving resistor Ron is usually arranged in the turn-on circuit, a turn-off resistor Roff with smaller resistance is arranged in the turn-off circuit, and a diode Doff is connected in series. The three-phase bridge circuit needs to be additionally provided with 18 devices, the number of the devices of the six-phase motor is increased by times, the layout area is greatly increased, when the loads of different torque motors are replaced, the resistance values of Ron and Roff are required to be independently adjusted, the hardware circuit design cannot be locked, the purchase of the resistors with different resistance values and the long plate making period are realized, the production cost and the period are increased, and meanwhile, the production takt and the circuit integration level are reduced due to the increase of peripheral devices. Disclosure of Invention In the summary section, a series of simplified form concepts are introduced that are all prior art simplifications in the section, which are described in further detail in the detailed description section. The summary of the invention is not intended to define the key features and essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. Aiming at the defects of the prior art, the invention aims to provide an electric power steering system driving module and a method which can flexibly regulate and control a switch according to the working state of a MOSFET without increasing electric elements and production cost. In order to solve the above technical problems, the driving module of an electric power steering system provided by the present invention includes: The micro-control unit MCU 10, the grid driving chip module GDU 20 and the three-phase bridge load half-bridge 30, wherein three-phase bridge load half-bridges 30 are arranged and form a three-phase bridge structure, and each three-phase bridge load half-bridge 30 comprises a high-side MOSFET Q1 and a low-side MOSFET Q2; The micro control unit MCU 10 is a control core of a driving circuit, configures an internal register of the grid driving chip module GDU 20 through an SPI interface, acquires a state feedback signal, and transmits a MOSFET switch control instruction through a IHx _ N, ILx signal after operation processing; The gate driving chip module GDU 20 is a driving execution and signal acquisition core, and is internally integrated with an SPI unit, a state machine, a diagnosis unit 40 and three control units 50; The SPI unit and state machine and diagnostic unit 40 is a communication and control core of the gate driver chip module GDU 20, and is configured to implement SPI data interaction with the MCU 10, distribute driving instructions to the control units 50, and diagnose the working state of the modules; The three control units 50 are in one-to-one correspondence with the three-phase bridge load half-bridges 30, each control unit 50 is a phase-level driving core, and a high-side gate driving module 60, a high-speed comparator module 80 and a low-side gate driving module 70 are integrated inside; the high-side gate driving module 60 is configured to receive the instruction of the control unit 50 and output a driving signal to control the high-side MOSFET Q1 of the corresponding three-phase bridge load half-bridge 30 to be turned on and off; the low-side gate driving module 70 is configured to receive the instruction of the control unit 50 and output a driving signal to control the on and off of the low-side MOSFET Q2 of the corresponding three-phase bridge load half-bridge 30; the high-speed comparator module 80 is configured to collect drain-source voltage signals corresponding to the high-side MOSFET Q1 and the low-side MOSFE