Nvh control method of tandem motor system

A noise vibration and harshness (NVH) control method of a tandem motor system, comprising a motor I and a motor II, rotor shafts of the two motors being connected to each other to form a tandem motor, wherein rotors of the motor I and the motor II are staggered with each other at an angle of Δθ when being installed, such that a resultant cogging torque of the tandem motor varies with Δθ, wherein the maximum value of Δθ, Δθmax, is determined by the number of stator slots Z and the number of rotor pole pairs Pn, of a motor, as shown in the following formula:

• Δ
• ⁢
• θ
• max
• =
• P
• n
• Z
• ·
• 360
• when an amplitude of the resultant cogging torque varies with Δθ, there exists an optimal Δθopt within a range of [0, Δθmax], at which the amplitude of the resultant cogging torque of the tandem motor is minimal;
• as shown in the figure, an angle of Δθopt is an optimal misaligned installation angle for the rotors of the motor I and the motor II;
• and a method for optimizing Δθ through a controller is as follows:
• S1, installing the tandem motor on a test bench;
• S2, dividing Δθmax into N equal parts, denoted as
• Δ
• ⁢
• θ
• i
• =
• Δ
• ⁢
• θ
• i
• -
• 1
• +
• (
• i
• -
• 1
• )
• ·
• Δ
• ⁢
• θ
• max
• N
• ,
• wherein i=1, 2, . . . , N+1, and Δθ0=0;
• S3, first setting i=1, and calculating a misalignment angle Δθ1 (i=1) between the rotors of the motor I and the motor II when i=1;
• S4, starting the tandem motor and waiting until a rotational speed of the tandem motor is stable;
• S5, measuring and recording the resultant cogging torque of the tandem motor under the stable rotational speed state;
• S6, stopping the motor and setting i=i+1;
• S7, determining whether i is equal to N+1, if so, proceeding to the next step S8, and if not, returning to S3 and recalculating the misalignment angle Δθi based on a new value of i;
• and
• S8, conducting a final analysis on a measured result to obtain the optimal Δθopt.