A pulse width modulation method, wherein the method is applied to a three-phase converter, and comprises: obtaining initial three-phase modulation waves and a converter modulation degree; calculating a common-mode-component change-rate adjustment coefficient based on preset modulation parameters and the converter modulation degree, wherein the preset modulation parameters comprise a preset maximum modulation degree, a preset minimum modulation degree, a preset minimum common-mode-component change rate between a positive clamping state and a negative clamping state, a preset difference between a maximum common-mode-component change rate and a minimum common-mode-component change rate between a positive clamping state and a negative clamping state, and a modulation curvature parameter of the three-phase converter; calculating a modulation wave set corresponding to the initial three-phase modulation waves based on a preset maximum modulation-wave amplitude-limiting value, a preset minimum modulation-wave amplitude-limiting value, the initial three-phase modulation waves, and the common-mode-component change-rate adjustment coefficient, and selecting a modulation wave having a minimum absolute value from the modulation wave set as a common-mode modulation wave; and superposing the common-mode modulation wave onto each initial three-phase modulation wave to obtain output three-phase modulation waves, wherein the calculating a common-mode-component change-rate adjustment coefficient based on preset modulation parameters and the converter modulation degree comprises: obtaining the preset maximum modulation degree M max, the preset minimum modulation degree M min, the preset minimum common-mode-component change rate K b between a positive clamping state and a negative clamping state, the preset difference K a between a maximum common-mode-component change rate and a minimum common-mode-component change rate between a positive clamping state and a negative clamping state, and the modulation curvature parameter N of the three-phase converter, wherein N is greater than 0; and substituting M max, M min, K b, K a, N, and the converter modulation degree M into a formula K = K a × M − M min M max − M min N + K b to calculate the common-mode-component change-rate adjustment coefficient K. obtaining initial three-phase modulation waves and a converter modulation degree; calculating a common-mode-component change-rate adjustment coefficient based on preset modulation parameters and the converter modulation degree, wherein the preset modulation parameters comprise a preset maximum modulation degree, a preset minimum modulation degree, a preset minimum common-mode-component change rate between a positive clamping state and a negative clamping state, a preset difference between a maximum common-mode-component change rate and a minimum common-mode-component change rate between a positive clamping state and a negative clamping state, and a modulation curvature parameter of the three-phase converter; calculating a modulation wave set corresponding to the initial three-phase modulation waves based on a preset maximum modulation-wave amplitude-limiting value, a preset minimum modulation-wave amplitude-limiting value, the initial three-phase modulation waves, and the common-mode-component change-rate adjustment coefficient, and selecting a modulation wave having a minimum absolute value from the modulation wave set as a common-mode modulation wave; and superposing the common-mode modulation wave onto each initial three-phase modulation wave to obtain output three-phase modulation waves, wherein the calculating a common-mode-component change-rate adjustment coefficient based on preset modulation parameters and the converter modulation degree comprises: obtaining the preset maximum modulation degree M max, the preset minimum modulation degree M min, the preset minimum common-mode-component change rate K b between a positive clamping state and a negative clamping state, the preset difference K a between a maximum common-mode-component change rate and a minimum common-mode-component change rate between a positive clamping state and a negative clamping state, and the modulation curvature parameter N of the three-phase converter, wherein N is greater than 0; and substituting M max, M min, K b, K a, N, and the converter modulation degree M into a formula K = K a × M − M min M max − M min N + K b to calculate the common-mode-component change-rate adjustment coefficient K. obtaining the preset maximum modulation degree M max, the preset minimum modulation degree M min, the preset minimum common-mode-component change rate K b between a positive clamping state and a negative clamping state, the preset difference K a between a maximum common-mode-component change rate and a minimum common-mode-component change rate between a positive clamping state and a negative clamping state, and the modulation curvature parameter N of the three-phase converter, wherein N is greater than 0; and substituting M max, M min, K b, K a, N, and the converter modulation degree M into a formula K = K a × M − M min M max − M min N + K b to calculate the common-mode-component change-rate adjustment coefficient K.