Control method for bidirectional quasi-Z-source inversion type motor driving system

Abstract

The invention relates to a control method for a bidirectional quasi-Z-source inversion type motor driving system. The control method comprises the following steps of collecting the voltage of a capacitor C2 and the current of a permanent magnet synchronous motor; obtaining voltage components of a d axis and a q axis; obtaining a direct-connection duty ratio; carrying out an SVPWM (space vector pulse width modulation) algorithm by inserting the direct-connection duty ratio according to the voltage components of the d axis and the q axis and the direct-through duty ratio to obtain six paths of PWM control signals for controlling the on and off of three-phase bridge arms of a three-phase bridge type inverter; and carrying out logic calculation on the six paths of PWM control signals to output a PWM control signal for controlling the on and off of an IGBT switch tube S7. Compared with the prior art, the average direct-connection duty ratio and the capacitor voltage closed loop control closed loop policy are added to the conventional SVPWM control method, so that the direct current side voltage has the voltage boosting capability; and on the basis, the power switch S7 which is complementary with the direct-connection state is further designed, so that the bidirectional flow of energy can be realized.

Description

technical field [0001] The invention relates to the field of automobile motor and control technology, in particular to a control method of a bidirectional quasi-Z source inverter motor drive system. Background technique [0002] In the traditional electric drive system, the inverter is a voltage type inverter, which has the following disadvantages: [0003] 1. The bus voltage of the voltage-type inverter is the output voltage of the battery, which is limited by the battery voltage. When the car is climbing and accelerating, the voltage will drop when the battery is insufficient, resulting in insufficient output power of the motor. In order to improve Due to the soft characteristics of battery output, a non-isolated BOOST circuit is usually added to the output end of the battery in fuel cell vehicles and electric commercial vehicles. After the BOOST circuit increases the voltage, it is supplied to the three-phase bridge inverter to drive the motor. The level DC / DC inverter i...

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Problems solved by technology

[0003] 1. The bus voltage of the voltage-type inverter is the output voltage of the battery, which is limited by the battery voltage. When the car is climbing and accelerating, the voltage will drop when the battery is insufficient, resulting in insufficient output power of the motor. In order to improve Due to the soft characteristics of battery output, in fuel cell vehicles and electric commercial vehicles, a non-isolated BOOST circuit is usually added to the output end of the battery. After the BOOST circuit increases the voltage, it supplies the three-phase bridge inverter to drive the motor. The first-stage DC / DC inverter is a two-stage circuit, and the transmission efficiency of the system as a whole is low after two-stage conversion

[0004] 2. The upper and lower bridge arms of the traditional voltage-type inverter cannot be turned on at the same time, and the dead time needs to be increased. However, the existence of the dead time will distort the output voltage and current, increase the torque ripple of the system, and increase the electromagnetic force of the system. Noise affects the comfort and reliability of the electric drive system

The circuit structure of this patented inverter is applied to the field of photovoltaic parallel grid. When the light load or the Z source inductance is small, it will appear in an abnormal working state and cannot overcome the influence caused by the intermittent current, and the control method adopts Open-loop control, applied in the field of automotive electric drive technology, cannot achieve the purpose of high-speed speed control

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