Method and apparatus for driving and controlling synchronous motor using permanent magnets as its field system
First Claim
1. A driving and controlling apparatus for use in a drive unit having a synchronous motor using permanent magnets as its field system which can be excited by a field flux generated by the permanent magnets and a field flux generated by a field current component of a primary current;
- a battery as a source of power; and
power conversion means for converting a discharged power of the battery into alternating current, and then feeding the alternating current as the primary current to the synchronous motor;
said apparatus comprising;
current control means for controlling the primary current of the synchronous motor in accordance with a reference current; and
current condition determination means for determining the reference current in accordance with a voltage of the battery so that the reference current is minimized under predetermined conditions and at least partially cancelling the field flux generated by the permanent magnets with the field flux generated by the field current component so that a counter electromotive force of the synchronous motor does not exceed the voltage of the battery and so that the field flux generated by the field current component has an magnitude corresponding to the voltage of the battery.
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Accused Products
Abstract
A method and an apparatus for driving and controlling a synchronous motor using permanent magnets as its field system are herein disclosed. When a rotational speed of the synchronous motor using the permanent magnets as the field system is more than a base rotational speed, a current condition computing section computes a field weakening reference current in accordance with a battery voltage, a reference torque and a rotational speed. An inverter performs the field weakening control of the the synchronous motor using the permanent magnets as the field system in accordance with the field weakening reference current sent from the current condition computing section to prevent the deterioration of efficiency and the deficiency of output due to the excessive or insufficient field weakening current. The current condition computing section determines optimum reference current by the use of a converged battery voltage, when the battery voltage is converged to a constant value after initial control.
55 Citations
22 Claims
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1. A driving and controlling apparatus for use in a drive unit having a synchronous motor using permanent magnets as its field system which can be excited by a field flux generated by the permanent magnets and a field flux generated by a field current component of a primary current;
- a battery as a source of power; and
power conversion means for converting a discharged power of the battery into alternating current, and then feeding the alternating current as the primary current to the synchronous motor;
said apparatus comprising;current control means for controlling the primary current of the synchronous motor in accordance with a reference current; and current condition determination means for determining the reference current in accordance with a voltage of the battery so that the reference current is minimized under predetermined conditions and at least partially cancelling the field flux generated by the permanent magnets with the field flux generated by the field current component so that a counter electromotive force of the synchronous motor does not exceed the voltage of the battery and so that the field flux generated by the field current component has an magnitude corresponding to the voltage of the battery. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
- a battery as a source of power; and
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18. A method for controlling a drive unit having a synchronous motor using permanent magnets as its field system which can be excited by a field flux generated by the permanent magnet and a field flux generated by a field current component in a primary current;
- a battery as a source of power; and
power conversion means for converting a discharged power of the battery into alternating current, and then feeding the alternating current as the primary current to the synchronous motor;
said method comprising the steps of;judging whether or not the counter electromotive force of the synchronous motor exceeds the voltage of the battery in accordance with the output state of the synchronous motor; determining a reference current so that the field flux generated by the field current component may be fixed to a specific value, when it has been judged that the counter electromotive force does not exceed the voltage of the battery; minimizing the reference current in accordance with the voltage of the battery so that the counter electromotive force of the synchronous motor does not exceed the voltage of the battery and so that the field flux generated by the field current component has a magnitude corresponding to the voltage of the battery, when it has been judged that the counter electromotive force exceeds the voltage of the battery; and controlling the primary current of the synchronous motor in accordance with the reference current to at least partially cancel the field flux generated by permanent magnets with the field flux generated by the field current component.
- a battery as a source of power; and
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19. A method for controlling a drive unit having a synchronous motor using permanent magnets as its field system which can be excited by a field flux generated by the permanent magnets and a field flux generated by a field current component in a primary current;
- a battery as a source of power; and
power conversion means for converting a discharged power of the battery into alternating current, and then feeding the alternating current as the primary current to the synchronous motor;
said method comprising;a first step of judging whether or not either of a reference torque or an output state of the synchronous motor change by as much as a predetermined value or more; a second step of determining an initial reference current in accordance with the reference torque, the output state and a reference minimum voltage based on the voltage of the battery being the reference minimum voltage, when either of the reference torque or the output state of the synchronous motor change by as much as a predetermined value or more; a third step of controlling the primary current of the synchronous motor in accordance with the initial reference current; a fourth step of determining the reference current in accordance with the constant value voltage of the battery so that the counter electromotive force of the synchronous motor does not exceed the voltage of the battery and so that the field flux generated by the field current component has a magnitude corresponding to the voltage of the battery, when the voltage of the battery reaches a constant value after the primary current of the synchronous motor has been controlled in accordance with the initial reference current; and a fifth step of controlling the primary current of the synchronous motor in accordance with the reference current to at least partially cancel the field flux generated by permanent magnets with the field flux generated by the field current component. - View Dependent Claims (20, 21, 22)
- a battery as a source of power; and
Specification