Research On Speed Sensorless System Of Vehicle Air Conditioning Compressor

At present,most automotive air-conditioning compressor control systems use Permanent Magnet Synchronous Motor(PMSM)motors as the power source.Because of their corresponding rapid,large power density,mature control algorithms and excellent performance,they have been widely used.Taking the vector control system of permanent magnet synchronous motor as the system control frame,and using the relevant observation algorithm to replace the traditional position sensor when reading the rotor phase information,the closed-loop control of the position sensorless control system is completed,because the photoelectric encoder and resolver are not used.Equivalent position detection devices,thus avoiding a series of problems such as increasing system cost,reducing system reliability,and having a large impact on volume.Instead,the current and voltage signals during motor operation are used to estimate the rotor phase of the motor.The field of automotive air-conditioning compressors with stringent requirements has a wide range of applications.As a relatively mature control theory,sliding mode variable structure control is widely used in rotor position observation of permanent magnet synchronous motors.However,due to its poor observation effect at low speeds,it cannot be extended to the full speed domain of the control system.Therefore,for the problem of zero-degree and low-speed starting,the I / F starting algorithm based on vector current closed-loop control is studied.The virtual coordinate system is used to simulate the rotation of the motor,and the current component of the given coordinate on the actual coordinate axis is used to generate the electromagnetic torque drive.The motor obtains the initial speed.Aiming at the problem of inaccurate virtual angle tracking of the algorithm,an improved I / F starting algorithm based on the characteristic of "torque-power angle self-balancing" is proposed,and the switching methods between the two phase observation algorithms and sliding mode observer are described.For the chattering problem that is prone to occur in traditional sliding mode observers,an improved method for the switching function of the sliding mode variable structure algorithm is studied.The saturation switching function is used instead of the switching switching function,and the sinusoidal curve is used to further optimize the back-EMF observation at the boundary layer.The problem of switching chattering has been proved by simulation and experiment.Aiming at the difficulty of adjusting the parameters of the current inner loop PI regulator of traditional vector control,starting from the theory of the current loop control theory,a parameter optimization theory of the current loop PI regulator based on a series of motor parameters such as stator resistance is proposed.Also in the Similink model Feasibility verification was carried out in simulation and actual bench experiment.Using Infineon TC212 single-chip microcomputer to build a hardware control platform,and wrote the corresponding control program,the algorithm and optimization of the proposed algorithm are implemented,and finally successfully realized the schematic diagram of the sensorless vector control system of permanent magnet synchronous motor,PCB drawing,console rack system construction and related performance tests and proved the feasibility of the proposed algorithm and various improvements.