DRIVE SYSTEM OF SYNCHRONOUS MOTOR
First Claim
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1. A drive system of a synchronous motor comprising:
- a three-phase synchronous motor;
an inverter connected to the three-phase synchronous motor and constituted of a plurality of switching elements; and
a controller which selects two conducting phases from a three-phase winding of the three-phase synchronous motor and performs conduction control of the inverter in six conduction modes by a pulse width modulation operation,wherein the controller is provided with means of detecting at least one of a terminal potential of a non-conduction phase and a connecting point potential (neutral point potential) of a stator winding of the three-phase synchronous motor, sampling the detected value in synchronization with a conduction pulse of a conduction phase, comparing the sampled value and a reference voltage in terms of level, and sequentially switching the conduction mode in accordance with a result of the level comparison, and the voltage level set as the reference voltage is periodically switched in accordance with the conduction mode.
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Abstract
A drive system of a permanent magnet motor is constituted of a mode switching trigger generator which monitors a state of a permanent magnet motor and issues a mode switching trigger, a conduction mode determining unit which receives the mode switching trigger and switches the mode of the permanent magnet motor, and a PWM generator which outputs a PWM signal to an inverter in accordance with the output of the conduction mode determining unit. The mode switching trigger is generated on condition that the speed electromotive force of the permanent magnet motor exceeds a constant or variable threshold value.
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Citations
10 Claims
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1. A drive system of a synchronous motor comprising:
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a three-phase synchronous motor; an inverter connected to the three-phase synchronous motor and constituted of a plurality of switching elements; and a controller which selects two conducting phases from a three-phase winding of the three-phase synchronous motor and performs conduction control of the inverter in six conduction modes by a pulse width modulation operation, wherein the controller is provided with means of detecting at least one of a terminal potential of a non-conduction phase and a connecting point potential (neutral point potential) of a stator winding of the three-phase synchronous motor, sampling the detected value in synchronization with a conduction pulse of a conduction phase, comparing the sampled value and a reference voltage in terms of level, and sequentially switching the conduction mode in accordance with a result of the level comparison, and the voltage level set as the reference voltage is periodically switched in accordance with the conduction mode. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10)
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2. A drive system of a synchronous motor comprising:
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a three-phase synchronous motor; an inverter connected to the three-phase synchronous motor and constituted of a plurality of switching elements; and a controller which selects two conducting phases from a three-phase winding of the three-phase synchronous motor and performs conduction control of the inverter in six conduction modes by a pulse width modulation operation, wherein the controller is provided with means of detecting at least one of a terminal potential of a non-conduction phase and a connecting point potential (neutral point potential) of a stator winding of the three-phase synchronous motor, sampling the detected value in synchronization with a conduction pulse of a conduction phase, and computing an absolute value of the sampled value and means of comparing the absolute value of the sampled value and a reference voltage in terms of level and sequentially switching the conduction mode in accordance with a result of the level comparison.
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Specification