Output circuit and brushless motor using the same

Claim 2

A brushless motor comprising: a permanent magnet rotor multipole-magnetized; armature windings of plural phases and connected at one ends in common; a position detector for detecting the rotational positions of said rotor and armature windings; pairs of push-pull output transistors connected to phases of said aramture windings and equal in phase number to said phases of said armature windings; first current detecting means for detecting currents flowing in said armature windings; a first amplifier for amplifying a difference between the output signal of said first current detecting means and a switching means which switches the output of said first amplifier corresponding to the output of said position detector so that the exciting phase of each of said armature windings is energized by one of said pair of output transistors; a second current detecting means which outputs a signal corresponding to the base current of said one transistor; a second amplifier for amplifying a difference between the output signals of said first and second detecting means; and a second position signal switching means which energizes the exciting phases of said armature windings by the other of said pair of output transistors, whereby said second amplifier controls the conductive state of the other transistor so as to keep a constant ratio of the base current of said one transistor to a current flowing in said first current detecting means, thereby generating a torque corresponding to a torque command input.

Claim 3

A brushless motor according to claim 1, wherein said second current detecting means employs a current mirror and a resistance, and said first amplifier employs a differential amplifier of current output type, so that the current output of said differential amplifier is distributed by said current mirror to said first position signal switching means and resistance, thereby using a voltage across both ends of said second current detecting means as the output of said second current detecting means.

Claim 4

A brushless motor according to claim 1, wherein said first position signal switching means is of a current output type, an emitter follower transistor is interposed between said first position signal switching means and the base of said output transistor, and a resistance is interposed as a second current detecting means into the collector circuit of said emitter follower transistor, so a voltage across both ends of said resistance is used as the output of said second current detecting means.

Claim 5

A brushless motor comprising: a multipole-magnetized permanent magnet rotor; armature windings of plural phases and connected at one ends in common; a position detector for detecting the rotational positions of said rotor and armature windings; pairs of push pull output transistors connected to said phases of said armature windings and equal in phase number to said phases respectively; a first current detection resistance which detects the sum of emitter currents of one transistor group of said pairs of output transistors; a voltage dividing means for dividing a voltage detected by said first current detection resistance; a first amplifier for amplifying a difference between the output signal of said voltage dividing means and a motor torque command input; a first position signal switching means which switches the output of said first amplifier corresponding to the output of said position detector so as to energize the exciting phase of said armature windings by said one transistor group at said pairs of output transistors; a second current detection resistance which generates a voltage corresponding to the base current of said one transistor group; a second amplifier which amplifies a difference between said detected voltages by said first and second current detection resistances; and second position signal switching means which switches the output of said second amplifier corresponding to the output of said position detector so as to energize the exciting phase of said armature windings by the other transistor group of said pairs of output transistors, said second amplifier controlling the conductive state of said other transistor groups so that a ratio of the base current of said one transistor group to a current flowing in said first current detection resistance is kept at a constant value K and a dividing ratio of said voltage dividing means is defined as K/(1-K), thereby generating a torque corresponding to said torque command input.

Claim 6

A brushless motor comprising: a multipole-magnetized permanent magnet rotor; armature windings of plural phases and connected at one ends in common; a position detector for detecting the rotational positions of said rotor and armature windings; pairs of push pull output transistors connected to said phases of said armature windings and equal in phase number to said phases respectively; a first current detection resistance which detects the sum of emitter currents of one transistor group of said pairs of output transistors; a voltage dividing means for dividing a voltage detected by said first current detection resistance; a first amplifier for amplifying a difference between the output signal of said voltage dividing means and a motor torque command input; a first position signal switching means which switches the output of said first amplifier corresponding to the output of said position detector so as to energize the exciting phase of said armature windings by said one transistor group at said pairs of output transistors; a second current detection resistance which generates a voltage corresponding to the base current of said one transistor group; a second amplifier which amplifies a difference between said detected voltages by said first and second current detection resistances; and second position signal switching means which switches the output of said second amplifier corresponding to the output of said position detector so as to energize the exciting phase of said armature windings by the other transistor group of said pairs of output transistors, said second amplifier controlling the conductive state of said other transistor groups so that a ratio of the base current of said one transistor group to a current flowing in said first current detection resistance is kept at a constant value K and a dividing ratio of said voltage dividing means is defined as K/(1-K), thereby generating a torque corresponding to said torque command input.

Claim 7

A brushless motor comprising: a multipole-magnetized permanent magnet rotor; aramture windings of plural phases and connected at one ends in common; a position detector for detecting the rotational positions of said rotor and armature windings; pairs of push pull output transistor connected to said phases of said armature windings and equal in phase number to said phases respectively; a first current detecting means for detecting currents flowing in said armature windings; a control means; a first amplifier which amplifies through said control means a difference between the output signal of said first current detecting means and a motor torque command input; a first position signal switching means which switches the output of said first amplifier corresponding to an output of said position detector so as to energize the exciting phase of said armature windings by said one transistor group at said pairs of output transistors; a second current detecting means which outputs a signal corresponding to the base current at said one transistor group; a second amplifier which amplifies a difference between the output signals of said first and second current detecting means; a second position signal switching means which switches an output of said second amplifier corresponding to the output of said position detector so as to energize the exciting phase of said aramture windings by the other of said transistor groups at said pairs of output transistors; a third current detecting means which ouputs a signal corresponding to the base current of said other transistor group, and a third amplifier which amplifies a difference between the output signals of said first and third current detecting means, whereby said second amplifier controls the conductive state of said other transistor group so as to keep a constant ratio of the base current of said one transistor group to a current flowing in said first current detecting means and in a case where a ratio of the base current of said other transistor gorup to said current flowing in said first current detecting means becomes the predetermined value, the output signal of said third differential amplifier controls said control means to limit the currents in said armature windings, thereby generating a torque corresponding to said torque command signal.

Claim 8

A brushless motor comprising: a multipole-magnetized permanent magnet rotor; aramture windings of plural phases and connected at one ends in common; a position detector for detecting the rotational positions of said rotor and armature windings; pairs of push pull output transistor connected to said phases of said armature windings and equal in phase number to said phases respectively; a first current detecting means for detecting currents flowing in said armature windings; a control means; a first amplifier which amplifies through said control means a difference between the output signal of said first current detecting means and a motor torque command input; a first position signal switching means which switches the output of said first amplifier corresponding to an output of said position detector so as to energize the exciting phase of said armature windings by said one transistor group at said pairs of output transistors; a second current detecting means which outputs a signal corresponding to the base current at said one transistor group; a second amplifier which amplifies a difference between the output signals of said first and second current detecting means; a second position signal switching means which switches an output of said second amplifier corresponding to the output of said position detector so as to energize the exciting phase of said aramture windings by the other of said transistor groups at said pairs of output transistors; a third current detecting means which ouputs a signal corresponding to the base current of said other transistor group, and a third amplifier which amplifies a difference between the output signals of said first and third current detecting means, whereby said second amplifier controls the conductive state of said other transistor group so as to keep a constant ratio of the base current of said one transistor group to a current flowing in said first current detecting means and in a case where a ratio of the base current of said other transistor gorup to said current flowing in said first current detecting means becomes the predetermined value, the output signal of said third differential amplifier controls said control means to limit the currents in said armature windings, thereby generating a torque corresponding to said torque command signal.

Claim 9

A brushless motor according to claim 5, wherein a first current mirror and a first resistance are used for said second current detecting means, and a differential amplifier of current output type is used for said first amplifier, said current output being distributed by said first current mirror into said first position signal switching means and first resistance, so that a voltage across both ends of said first resistance is used for the output of said second current detecting means.

Claim 10

A brushless motor according to claim 5, wherein said third current detecting means employs a second current mirror and a second resistance and said second amplifier employs a differential amplifier of current output type, said current output being distributed by said second current mirror into said second position signal switching means and second resistance, thereby using a voltage across both ends of said second resistance for the output of said third current detecting means.

Claim 11

A brushless motor according to claim 5, wherein said control means provides a third resistance and a transistor, one end of said third resistance is used for an input terminal for the torque command input signal, and the other end of the same is connected to said first amplifier and to the collector of said transistor directly or through a fourth resistance to thereby form an output terminal, the base of said transistor forming a control terminal for controlling the limited amount.

Claim 12

A brushless motor according to claim 5, wherein said third amplifier amplifies a difference between the output signal of a fourth current detecting means for detecting currents in said armature windings and the output signal of said third current detecting means.

Claim 13

A brushless motor according to claim 5, wherein a low-pass filter is interposed between said third amplifier and said control means.

Claim 14

A brushless motor comprising a multipole-magnetized permanent magnet rotor; aramture windings of plural phases; a position detector for detecting the rotational positions of said rotor and armature windings; output transistor groups comprising transistors equal in number to said phases and for applying currents onto said aramture windings; a first current detecting means for detecting currents in said armature windings; a first amplifier which amplifies a difference between the output signal of said first current detecting means and a torque command input signal; a position signal switching means which switches an output of said first amplifier corresponding to the output of said position detector so as to energize the exciting phase of said armature windings by said output transistor groups; a second current detecting means which outputs a signal corresponding to the base current of said output transistor group; a second amplifier which amplifies a difference between the output signals of said first and second detecting means; and a switching mode power supply for feeding power to said armature windings, whereby the output of said second amplifier controls an output voltage of said switching mode power supply to thereby keep a constant ratio of a current flowing in said first current detecting means to the base current of said output transistor group.

Claim 15

A brushless motor comprising a multipole-magnetized permanent magnet rotor; aramture windings of plural phases; a position detector for detecting the rotational positions of said rotor and armature windings; output transistor groups comprising transistors equal in number to said phases and for applying currents onto said aramture windings; a first current detecting means for detecting currents in said armature windings; a first amplifier which amplifies a difference between the output signal of said first current detecting means and a torque command input signal; a position signal switching means which switches an output of said first amplifier corresponding to the output of said position detector so as to energize the exciting phase of said armature windings by said output transistor groups; a second current detecting means which outputs a signal corresponding to the base current of said output transistor group; a second amplifier which amplifies a difference between the output signals of said first and second detecting means; and a switching mode power supply for feeding power to said armature windings, whereby the output of said second amplifier controls an output voltage of said switching mode power supply to thereby keep a constant ratio of a current flowing in said first current detecting means to the base current of said output transistor group.

Claim 16

A brushless motor according to claim 11, wherein a current mirror and a resistance are used for said second current detecting means and a differential amplifier of current output type is used for said first amplifier, said current output being distributed by said current mirror into said position signal switching means and resistance, so that a voltage across both ends of said resistance is used as the output of said second current detecting means.

Claim 17

A brushless motor according to claim 11, wherein a low-pass filter is interposed between said second amplifier and said switching mode power supply.

Claim 18

A brushless motor comprising: a multipole-magnetized permanent magnet rotor; aramture windings of plural phases and connected at the ends in common; a phase detector for detecting the rotational positions of said rotor and armature windings; pairs of push pull output transistors connected to phases of said armature windings and equal in phase number to said phases respectively; a switching mode power supply of variable output voltage and interposed in series with the current passage of each of said armature windings; a first current detecting means for detecting currents in said aramture windings; a first amplifier which amplifies a difference between the output signal of said first current detecting means and a motor torque command input signal; a first position signal switching means which switches the output of said first amplifier corresponding to the output of said position detector so as to energize the exciting phase of said armature windings by said one transistor group at said pairs of output transistors; a second current detecting means which outputs a signal corresponding to the base current of said one transistor group; a second amplifier which amplifies a difference between the output signals of said first and second current detecting means; a second position signal switching means which switches the output of said second amplifier correpsonding to the output of said position detector so as to energize the exciting phase of said armature windings by said other transistor group at said pairs of output transistors; a third current detecting means which outputs a signal corresponding to the base current at said other transistor group, and a third amplifier which amplifies a difference between the output signals of said first and third current detecting means, whereby said second amplifier controls the conductive state of said other transistor gorup to keep a constant ratio of the base current at said one transistor group to a current flowing in said first current detecting means, and the output signal of said third amplifier controls an output voltage of said switching mode power source so as to keep a constant ratio of the base current of said other transistor group to a current flowing in said first current detecting means, thereby generating a torque corresponding to said torque command input signal.

Claim 19

A brushless motor comprising: a multipole-magnetized permanent magnet rotor; aramture windings of plural phases and connected at the ends in common; a phase detector for detecting the rotational positions of said rotor and armature windings; pairs of push pull output transistors connected to phases of said armature windings and equal in phase number to said phases respectively; a switching mode power supply of variable output voltage and interposed in series with the current passage of each of said armature windings; a first current detecting means for detecting currents in said aramture windings; a first amplifier which amplifies a difference between the output signal of said first current detecting means and a motor torque command input signal; a first position signal switching means which switches the output of said first amplifier corresponding to the output of said position detector so as to energize the exciting phase of said armature windings by said one transistor group at said pairs of output transistors; a second current detecting means which outputs a signal corresponding to the base current of said one transistor group; a second amplifier which amplifies a difference between the output signals of said first and second current detecting means; a second position signal switching means which switches the output of said second amplifier correpsonding to the output of said position detector so as to energize the exciting phase of said armature windings by said other transistor group at said pairs of output transistors; a third current detecting means which outputs a signal corresponding to the base current at said other transistor group, and a third amplifier which amplifies a difference between the output signals of said first and third current detecting means, whereby said second amplifier controls the conductive state of said other transistor gorup to keep a constant ratio of the base current at said one transistor group to a current flowing in said first current detecting means, and the output signal of said third amplifier controls an output voltage of said switching mode power source so as to keep a constant ratio of the base current of said other transistor group to a current flowing in said first current detecting means, thereby generating a torque corresponding to said torque command input signal.

Claim 20

A brushless motor according to claim 14, wherein a first current mirror and a first resistance are used for said second current detecting means and a differential amplifier of current output type is used for said first amplifier, said current output being distributed by said first current mirror into said first position signal switching means and first resistance, so that a voltage across both ends of said first resistance is used as the output of said second current detecting means.

Claim 21

A brushless motor according to claim 14, wherein a second current mirror and a second resistance are used for said third current detecting means and a differential amplifier of current output type is used for said second amplifier, said current output being distributed by said second current mirror into said second position signal switching means and second resistance so that a voltage across both ends of said second current detecting means is used for said third current detecting means.

Claim 22

A bruhsless motor according to claim 14, wherein said switching mode power supply is provided with a power supply terminal, an output end and a control terminal, thereby outputting a voltage corresponding to the output voltage of said third amplifier applied to said control terminal.