The invention discloses a two-level circuit board for achieving
permanent magnet synchronous motor frequency conversion soft start and grid-connected control. The two-level circuit board comprises a
voltage-current sampling module and a motor conversion position sampling module, wherein the
voltage-current sampling module and the motor conversion position sampling module are used for respectively acquiring
grid voltage, motor current and
motor speed, used for converting the parameters into digital signals, used for transmitting the signals to a DSP (
Digital Signal Processor), transmitting 6 paths of PWM (
Pulse Width Modulation) electric signals through synergistic treatment of the DSP and FPGA (
Field Programmable Gate Array), and used for driving 6 IGBTs (Insulated Gate Bipolar Transistors) of a
voltage type two-level frequency converter to be powered on and off so as to achieve soft start of a
permanent magnet synchronous motor; meanwhile, the DSP compares the
grid voltage which is sampled in real time with three-phase voltage output from the frequency converter; and when a
synchronous switching condition is met, the DSP transmits a switching
control signal and feeds into a
relay driving module to ignite the solenoid of a three-phase
alternating current contactor, achieve on-off of the three-phase
alternating current contactor, and finally achieve
synchronous switching of
frequency conversion of the
permanent magnet synchronous motor to grid-connected frequency current
impact. The problems of soft start of the permanent
magnet synchronous motor and large current
impact when switching from
frequency conversion to working frequency of the permanent
magnet synchronous motor can be solved.