| 摘要 |
<p>First and second inverters are each controlled based on pulse width modulation using a carrier signal. In order to decrease the noise caused by the first inverter and the second inverter, a frequency (f1) of a carrier signal of the first inverter and a frequency (f2) of a carrier signal of the second inverter are controlled. The frequency (f1) of the carrier signal of the first inverter is changed periodically or randomly within a first preset frequency range (420) as time elapses. The frequency (f2) of the carrier signal of the second inverter is changed periodically or randomly within a second preset frequency range (430) to avoid overlapping the first frequency range (420).</p> |
