JP5571987B2 - Braking method for brushless DC motor - Google Patents

Description

The present invention relates to a braking method for a brushless DC motor having a braking force control function.

  Conventionally, as a driving device and a braking device for a brushless DC motor, for example, a plurality of arms in which switching elements are connected in series are connected to a power source, and the switching elements of each arm are connected to a motor winding to connect a motor driving circuit. There is a prior art in which the power supply to the motor drive circuit is cut off by a cut-off means (Patent Document 1). In Patent Document 1, when the induced electromotive force exceeds the power supply voltage, the input voltage of the inverter is cut by a semiconductor switch, and the upper arm (or the lower arm) is repeatedly turned on and off by PWM control, whereby the braking force is To control.

  Also, in order to perform regenerative braking of the brushless DC motor when the power is cut off, a power cut-off detection device is provided, and when the power is cut off, all upper arms (or lower arms) are turned on to perform regenerative braking, and then set with a timer There is known a method (Patent Document 2) of winding a tape without slack by a mechanical brake mechanism after a lapse of time.

  On the other hand, an inverter having three high-potential side switching elements and three low-potential side switching elements corresponding to three-phase armature windings, and a control means for controlling the operation of the inverter are provided. A method of performing regenerative braking by providing a charging mode or the like and devising a switching pattern (Patent Document 3) is known.

  In addition, when the brushless DC motor is decelerated, the switch circuit is controlled so as to prevent the drive current from being supplied from the power source to the electric element when the stop command is given, and the rotation direction command is set to a duty corresponding to the braking force. A method of decelerating while switching at a ratio (Patent Document 4) is known.

  Further, a method of obtaining a braking force by rectifying an AC generated voltage by a brushless DC motor by a diode bridge and converting it to a DC voltage, adjusting a voltage of the converted DC voltage by a chopper circuit, and consuming the electric power by a resistor (Patent Document 5) is known.

JP 2006-115558 A JP 2001-157383 A JP-A-11-206179 Japanese Patent Application Laid-Open No. 08-066074 JP 2001-186748 A

However, such a conventional brushless DC motor drive device or brake device has the following problems.
In the technique of Patent Document 1, when the induced voltage of the motor becomes larger than the power supply voltage, the inverter is disconnected from the power supply and regenerative braking is performed. Therefore, the braking control becomes impossible when the induced voltage of the motor is smaller than the power supply voltage. Further, since the capacitor is not connected to the power source of the inverter, the current does not continue during regenerative braking, and a large braking force cannot be generated.
In the technique of Patent Document 2, since regenerative braking is performed with all upper arms (or lower arms) turned on, the braking force cannot be controlled.
In the technique of Patent Document 3, since an initial charging mode is provided and regenerative braking is performed by devising a switching pattern, the conduction ratio of the switching element must be set to a predetermined value, and the braking force is reduced. I can't control it.
The technique of Patent Document 4 is an invention for decelerating a brushless DC motor, and braking force cannot be obtained when the motor output shaft is rotated from the outside.
The technique of Patent Document 5 is a method of obtaining a braking force by adjusting a voltage of a DC voltage obtained by conversion with a chopper circuit and consuming the electric power with a resistor. The brushless DC motor cannot be driven with this device.

The present invention solves the above-mentioned problems of the prior art, enables a brushless DC motor to realize a power running operation and a regenerative operation with a single drive device, and can freely control a braking force and a generated torque, and An object of the present invention is to provide a method for braking a brushless DC motor having a braking force control function that does not cause heat generation because the drive circuit does not have a regenerative resistor.

In order to solve the above problems, the present invention provides a direct current power source for driving a brushless DC motor, a switching element group for turning on and off a current flowing from the direct current power source to the winding of the brushless DC motor, and the switching element group. Capacitors connected in parallel, a switch for disconnecting the DC power supply and the switching element group, the upper arm side of the switching element group for driving the switching element group has several phases, and the lower arm side has one with a power drive circuit, an excitation sequence generator for creating an excitation sequence based on the position information of the brushless DC motor, a PWM signal generator for generating a PWM signal proportional to the command voltage instruction, said excitation sequence The excitation sequence created by the generator and the PWM signal from the PWM signal generator are combined before In the method of driving and braking the brushless DC motor by turning on and off the switching elements of the switching element group, the DC power supply and the switching element group are separated during braking, and the brushless DC motor is separated by the excitation sequence generator. An excitation sequence in a direction opposite to the driving direction of the motor is created, a PWM signal proportional to a braking force instruction is created by the PWM signal generator, and the excitation sequence created by the excitation sequence creator is generated from the PWM signal generator. turning on the switching element of the switching element group of the PWM signal synthesized and, turned off, the induced voltage of the brushless DC motor, a braking force is generated by causing consumed by the brushless DC motor through the switching element group braking Is the method.
Another object of the present invention is to control power running and regenerative operation by an excitation sequence of a brushless DC motor and a PWM signal, and to control a braking force by PWM modulation with upper and lower arms of the switching element group.
Furthermore, the present invention is to provide a rotation direction discriminating circuit for discriminating the rotation direction from the rotor position information of the brushless DC motor, and to create an excitation sequence corresponding to the rotation direction by the excitation sequence generator.

According to the present invention, it is possible to realize the power running operation and the regenerative operation of the brushless DC motor 1 with one drive device. The braking force and generated torque can be freely controlled by the duty ratio of the PWM signal. Since the drive circuit does not have a regenerative resistor, the drive device does not generate heat.
In addition, according to the present invention, the upper and lower arms are turned on / off by PWM modulation, the charge / discharge ratio is changed by changing the duty ratio of the PWM signal, the current is controlled, and the braking force and generated torque can be freely adjusted. Can be controlled.
Furthermore, according to the present invention, since the rotation direction can be determined by the rotation direction determination circuit, an excitation sequence corresponding to the rotation direction can be created.

1 is a block circuit diagram of a brushless DC motor driving device having a braking force control function according to an embodiment of the present invention. FIG. 4 is a main part voltage waveform diagram showing an instruction rotation direction and an excitation sequence by a rotor position detector (Hall IC), (a) is a clockwise (CW) voltage waveform diagram, and (b) is a counterclockwise (CCW) waveform. It is a voltage waveform diagram. When the rotation direction indication is normal rotation and the rotation direction of the rotor is normal rotation, the relationship between the switching command of the UVW phase upper and lower arms generated by the signal synthesizer by the rotor position detector (Hall IC) and the induced voltage of the motor FIG. When the rotation direction instruction is forward rotation and the rotation direction of the rotor is reverse rotation, the relationship between the switching command of the UVW phase upper and lower arms generated by the signal synthesizer by the rotor position detector (Hall IC) and the induced voltage of the motor is shown. It is a waveform diagram. It is a circuit diagram which shows operation | movement description of FIG. It is a circuit diagram which shows operation | movement description of FIG. It is a circuit diagram which shows operation | movement description of FIG. It is a circuit diagram which shows operation | movement description of FIG. It is a block circuit diagram of the brushless DC motor drive device which has a braking force control function in other embodiments of the present invention. It is a block circuit diagram of the brushless DC motor drive device which has a braking force control function in other embodiments of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  In FIG. 1, reference numeral 1 denotes a three-phase brushless DC motor, and reference numeral 2 denotes a rotor encoder that is built in the three-phase brushless DC motor 1 and detects a rotor position of the brushless DC motor 1 using a Hall IC or the like. It is a vessel. Reference numeral 3 denotes a motor driving DC power source for driving the three-phase brushless DC motor 1. The motor driving DC power source 3 is connected to a motor driving power source switch 4 in series so that the motor driving power source 3 is turned on ( ON) and OFF (OFF).

Reference numerals 5 to 10 denote switching elements made of Nch power MOSFETs. These switching elements 5 to 10 are configured by switching elements 5 and 8, switching elements 6 and 9, and switching elements 7 and 10 connected in series, respectively. 3, and a series circuit of these arms 1 to 3 is connected in parallel to each other to constitute a motor drive circuit C.
The switching elements 5, 6 and 7 of the motor driving circuit C constitute the upper arm side main switching elements of the three-phase motor 1, and the gates of the upper arm side main switching elements 5, 6 and 7 are gate driving circuits (driving). Circuit) 11, 12, and 13 are connected to each other, and the upper arm side main switching elements 5, 6, and 7 are turned on (OFF).
The switching elements 8, 9, and 10 of the motor driving circuit C constitute a lower arm side main switching element of a three-phase motor, and a gate driving circuit (driving circuit) is connected to the gates of the lower arm side main switching elements 8, 9, and 10. ) 14, 15, 16 are connected to each other, and the lower arm side main switching elements 8, 9, 10 are turned on (OFF).

17, 18, 19 are power supplies for the gate drive circuits of the upper arm side main switching elements 5, 6, 7 of the three-phase motor, and 20 is a gate drive circuit power supply for the lower arm side main switching elements 8, 9, 10 of the three-phase motor. It is a power supply. Between the switching elements 5 and 8 of each of the arms 1 to 3, between the switching elements 6 and 9, and between the switching elements 7 and 10 are output terminals P1, P2 and P3 connected to the motor 1. The output terminal P1 is connected to the U phase of the motor winding of the brushless DC motor 1, the output terminal P2 is connected to the V phase of the motor winding, and the output terminal P3 is connected to the W phase of the motor winding. .
Reference numeral 21 denotes an excitation sequence generator. The rotor position of the brushless DC motor 1 is input from the rotor position detector 2, and an excitation sequence is generated from the rotor position. Reference numeral 22 denotes a signal synthesizer to which an excitation sequence is input from the excitation sequence generator 21. This signal synthesizer 22 turns on / off the main switching element by the excitation sequence and the PWM signal input from the PWM signal generator 23. Create an OFF command.
A smoothing capacitor (hereinafter abbreviated as a braking capacitor) 24 for braking is connected in parallel to the motor driving power supply 3 circuit and the motor driving circuit C. Reference numeral 25 denotes a rotation direction instruction that gives an instruction of the rotation direction to the excitation sequence generator 21.

Next, the operation of the above embodiment will be described.
First, a power running operation (supplying mechanical energy to a load) will be described.
When driving the load of the brushless DC motor 1 by the 120-degree energization method (powering operation), the excitation sequence generator 21 is based on the rotor position information output from the position detector 2 attached to the brushless DC motor 1. Create an excitation sequence.
When the Hall IC is used for the rotor position detector 2, the excitation sequence for the direction indication of the forward rotation and the reverse rotation is as shown in FIG. 2 as in the case of the forward rotation and (a) in the case of the reverse rotation (b). become. The excitation sequence of the U phase, the V phase, and the W phase by the rotor position information of the Hall IC for each phase A, B, C is shown.

  A PWM signal proportional to the command voltage instruction is created by the PWM signal generator 23, and the excitation sequence and the PWM signal are synthesized by the signal synthesizer 22, and an ON / OFF command for each main switching element is created. Upper arm side main switching element driving circuits 11, 12, 13 and the lower arm side receiving power supply from upper arm side main switching element driving circuit power supplies 17, 18, 19 and lower arm side main switching element driving circuit power source 20 The main switching element drive circuits 14, 15, and 16 are operated by the main switching element ON / OFF command synthesized by the signal synthesizer 22, and the upper arm side main switching elements 5, 6, 7 and the lower arm side main switching elements 8, 9. , 10 are turned ON / OFF to drive the brushless DC motor 1.

  At this time, the motor drive power switch 4 is turned ON, and power is supplied from the motor drive power supply 3 to the brushless DC motor 1 through the upper arm side main switching elements 5, 6, 7 and the lower arm side main switching elements 8, 9, 10. I do.

Next, the regenerative operation (absorbing mechanical energy from the load) will be described.
When the brushless DC motor is braked by a 120-degree energization method (regenerative operation), the excitation sequence generator 21 uses the rotor position information output from the position detector 2 attached to the brushless DC motor 1. Create an excitation sequence. The excitation sequence is the same as when driving a load (see FIG. 2).
When braking, a rotation instruction in the direction opposite to the rotation direction of the rotor is given. A PWM signal proportional to the braking force instruction is created by the PWM signal generator 23, and the excitation sequence and the PWM signal are synthesized by the signal synthesizer 22, and an ON / OFF command for each main switching element is created. Upper arm side main switching element driving circuits 11, 12, 13 and the lower arm side receiving power supply from upper arm side main switching element driving circuit power supplies 17, 18, 19 and lower arm side main switching element driving circuit power source 20 The main switching element drive circuits 14, 15, and 16 are operated by the main switching element ON / OFF command synthesized by the signal synthesizer 22, and the upper arm side main switching elements 5, 6, 7 and the lower arm side main switching elements 8, 9. , 10 are turned ON / OFF to drive the brushless DC motor 1.
At this time, the motor drive power switch 4 is turned OFF, and the motor drive power supply 3 is disconnected. The induced voltage of the brushless DC motor 1 is consumed by the brushless DC motor 1 through the upper arm side main switching elements 5, 6, 7 and the lower arm side main switching elements 8, 9, 10 to generate a braking force.

Next, the operation of the motor drive power switch will be described.
If braking is to be performed without disconnecting the motor driving power source 3 by the motor driving power switch 4, a chopper circuit as proposed in [Patent Document 5] described above must be added separately.
In the present invention, in order to simplify the circuit configuration and eliminate the need for a regenerative resistor, the motor driving power source 3 is disconnected by the motor driving power source switch 4 during braking.

Next, the operation of the main switching element drive circuit power supply will be described.
In general, in order to simplify the circuit configuration, a drive circuit for an inverter main switching element at a low voltage uses a charge pump system as proposed in [Patent Document 3], and a Pch FET for the upper arm.
However, the input voltage of the inverter is influenced by the induced voltage and switching of the brushless DC motor and is not determined by the motor drive power switch 4.
Therefore, in the present invention, the upper arm side main switching element driving circuit power source 17, 18, 19 and the lower arm side main switching element driving circuit power source 20 are provided.

Next, the generation of braking force and the operation of the braking capacitor will be described.
As an order of explanation, first, an operation when the braking capacitor 24 is not provided will be described with reference to FIGS.
The brushless DC motor 1 can generate a torque for a power running operation if a current flows in the same phase as the induced voltage. The braking force is generated by applying a current of opposite phase. FIG. 3 shows the relationship between the output signal of the Hall IC, the induced voltage, and the switching signal of each arm.
In FIG. 3, the ON command for each arm is a gray portion. This signal has a waveform in which a PWM signal proportional to the command voltage instruction is created by the PWM signal generator 23 and the excitation sequence and the PWM signal are synthesized by the signal synthesizer 22.

Without the braking capacitor 24, the motor drive power switch 4 is turned OFF. The rotation instruction direction is normal rotation, and the rotation direction of the rotor is normal rotation. The relationship between the switching command of the UVW phase upper and lower arms generated by the signal synthesizer 22 by the rotor position detector (Hall IC) and the induced voltage of the motor In the state 6 in FIG. 3, the relationship between the main switching element of the UV phase and the induced voltage is as shown in FIG.
5 is not connected to the braking capacitor 24 in the block diagram shown in FIG. 1, the motor drive power switch 4 is turned off, the rotation direction instruction is the forward rotation direction, and the rotation direction of the rotor is the forward rotation. When U-phase upper arm element 5 and V-phase lower arm element 9 are ON, U-phase lower arm element 8 and V-phase upper arm element 6 are OFF, U-phase induced voltage is positive, and V-phase induced voltage is negative It is a figure which shows the electric current which flows into the switching element of only UV phase.
As shown in FIG. 5, even if the main switching elements 5 and 9 are ON, there is no current path, and since no current can flow, no braking force can be generated.

Next, the motor drive power switch 4 is turned OFF without the braking capacitor 24. The rotation instruction direction is normal rotation and the rotation direction of the rotor is reverse rotation, and the relationship between the switching command of the UVW phase upper and lower arms generated by the signal synthesizer 22 by the rotor position detector (Hall IC) and the induced voltage of the motor is illustrated. In the state 3 in FIG. 4, the relationship between the main switching element of the UV phase and the induced voltage is as shown in FIG.
6 is not connected to the braking capacitor 24 in the block diagram shown in FIG. 1, the motor drive power switch 4 is turned off, the rotation direction instruction is the forward rotation direction, the rotor rotation direction is the reverse rotation, and U Phase upper arm element 5 and V phase lower arm element 9 are OFF, U phase lower arm element 8 and V phase upper arm element 6 are ON, the induced voltage of U phase is positive, and the induced voltage of V phase is negative It is a figure which shows the electric current which flows into the switching element of only UV phase.

  As shown in FIG. 6, since the induced voltage of the brushless DC motor 1 is positive, the path through the parasitic diode k of the main switching element 5 and the main switching element 6 and the induced voltage of the brushless DC motor 1 are positive. Thus, there are two possible current paths through the main switching element 8 and the parasitic diode k of the main switching element 9. The current path is indicated by arrows. This current generates a braking force. Therefore, in order to obtain the braking force, an excitation sequence that gives a rotation instruction opposite to the rotation direction of the rotor may be given. However, when the PWM signal is turned off, the main switching elements of all the arms are turned off, so that no current can flow, and the braking torque becomes zero. For this reason, the braking torque is repeatedly turned on and off, and a large braking force cannot be obtained.

Therefore, in the present invention, a braking capacitor 24 is added and the motor drive power switch 4 is turned OFF. The rotation instruction direction is normal rotation and the rotation direction of the rotor is reverse rotation. The relationship between the switching command of the UVW phase upper and lower arms generated by the signal synthesizer 22 by the rotor position detector (Hall IC) 2 and the induced voltage of the motor is In the state 3 in FIG. 4, the relationship between the UV-phase main switching element and the induced voltage is as shown in FIG.
7 turns off the motor drive power source switch 4 shown in FIG. 1 and sets the direction of rotation as the forward rotation direction, the rotation direction of the rotor as the reverse rotation, and the U-phase upper arm element 5 and the V-phase lower arm element 9 are OFF. FIG. 8 is a diagram showing currents flowing through the switching elements of only the UV phase when the U-phase lower arm element 8 and the V-phase upper arm element 6 are ON, the U-phase induced voltage is positive, and the V-phase induced voltage is negative. .
In the current path, the current flows through the path through the parasitic diode of the main switching element 9 through the main switching element 8 from the place where the induced voltage of the brushless DC motor 1 becomes positive, and the charge stored in the braking capacitor 24 is stored in the main switching element 6. Discharged through. This current generates a braking force.

Further, when the PWM signal is turned off, the main switching elements of all the arms are turned off. At this time, the state shown in FIG. 8 is obtained.
8, the motor drive power switch 4 shown in FIG. 1 is turned off, the direction of rotation is set in the forward direction, the rotation direction of the rotor is set in the reverse direction, the U-phase upper and lower arm elements 5 and 8 and the V-phase upper and lower arm elements 6 9 is a diagram illustrating a current that flows through a switching element of only the UV phase when the induced voltage of the U phase is positive and the induced voltage of the V phase is negative.
In FIG. 8, the main switching elements 5, 6, 8, 9 are OFF, but the parasitic diode k of the main switching elements 5, 9 is turned ON and the braking capacitor 24 is charged by the induced voltage generated by the brushless DC motor 1. Therefore, the current is continuous and a braking torque can be generated.

Next, a PWM modulation method will be described.
In driving the brushless DC motor 1, a method of performing modulation by the PWM signal only for the upper arm or the lower arm is generally used.
However, if only the upper arm or the lower arm is subjected to PWM modulation by the method of the present invention, the all-arm OFF period shown in FIG. 8 does not exist, and the braking capacitor 24 cannot be charged. Furthermore, a current flows through the main switching element and the parasitic diode that are turned on, and the braking force cannot be controlled. Therefore, the upper and lower arms are always turned ON / OFF by PWM modulation, the charge / discharge ratio is changed by changing the duty ratio of the PWM signal, the current is controlled, and the braking force is controlled.

FIG. 9 and FIG. 10 show another embodiment of the present invention. The same parts as those in FIG.
FIG. 9 is a block diagram of a method for generating a braking force by determining the rotational direction from the position detector 2.
Explaining the configuration, 1 is a three-phase brushless DC motor (hereinafter abbreviated as a three-phase motor), 2 is a rotor position detector using a rotary encoder, Hall IC, etc., 3 is a motor drive power source, 4 is Motor drive power switch, 5, 6 and 7 are the upper arm side main switching elements (Nch power MOSFET) of the three-phase motor 1, and 8, 9 and 10 are the lower arm side main switching elements (Nch power MOSFET) of the three-phase motor 1 11, 12, 13 are upper arm side main switching element driving circuits of the three-phase motor 1, 14, 15, 16 are lower arm side main switching element driving circuits of the three-phase motor 1, 17, 18, 19 are three phases. Power supply for upper arm side main switching element driving circuit of motor 1, 20 is power supply for lower arm side main switching element driving circuit of three-phase motor 1, 21 is an excitation sequence generator, 22 is a signal synthesizer, 23 PWM signal generator, 24 is a braking capacitor, 25 is a rotation direction instruction, 26 is a rotation direction determination circuit connected between the rotor position detector 2 and the excitation sequence generator 21, and this rotation direction determination circuit 26 is The rotation direction is discriminated from the rotor position information of the rotor position detector 2 and the rotation direction is instructed to the excitation sequence generator 21.

  In FIG. 9, when driving the load of the brushless DC motor 1 by a 120-degree energization method (powering operation), excitation is performed based on the rotor position information output from the position detector 2 attached to the brushless DC motor 1. An excitation sequence is created by the sequence creator 21. A PWM signal proportional to the command voltage instruction is created by the PWM signal generator 23, and the excitation sequence and the PWM signal are synthesized by the signal synthesizer 22, and an ON / OFF command for each main switching element is created. Upper arm side main switching element driving circuits 11, 12, 13 and the lower arm side receiving power supply from upper arm side main switching element driving circuit power supplies 17, 18, 19 and lower arm side main switching element driving circuit power source 20 The main switching element drive circuits 14, 15, 16 are controlled by the main switching element ON / OFF command synthesized by the signal synthesizer 22, and the upper arm side main switching elements 5, 6, 7 and the lower arm side main switching elements 8, 9 , 10 are turned ON / OFF to drive the brushless DC motor 1. At this time, the motor drive power switch 4 is turned ON, and power is supplied from the motor drive power supply 3 to the brushless DC motor 1 through the upper arm side main switching elements 5, 6, 7 and the lower arm side main switching elements 8, 9, 10. Do.

  Subsequently, in FIG. 9, when the load is braked (regenerative operation) on the brushless DCC motor 1 by the 120-degree energization method, the rotation is determined from the rotor position information output from the position detector 2 attached to the brushless DC motor 1. The direction discriminating circuit 26 discriminates the rotation direction, and the excitation sequence generator 21 creates an excitation sequence corresponding to the rotation direction. A PWM signal proportional to the braking force instruction is created by the PWM signal generator 23, and the excitation sequence and the PWM signal are synthesized by the signal synthesizer 22, and an ON / OFF command for each main switching element is created. Upper arm side main switching element driving circuits 11, 12, 13 and the lower arm side receiving power supply from upper arm side main switching element driving circuit power supplies 17, 18, 19 and lower arm side main switching element driving circuit power source 20 The main switching element drive circuits 14, 15, 16 are controlled by the main switching element ON / OFF command synthesized by the signal synthesizer 22, and the upper arm side main switching elements 5, 6, 7 and the lower arm side main switching elements 8, 9 , 10 are turned ON / OFF to drive the brushless DC motor 1. At this time, the motor drive power switch 4 is turned OFF, and the motor drive power supply 3 is disconnected. The induced voltage of the brushless DC motor 1 is consumed by the brushless DC motor 1 through the upper arm side main switching elements 5, 6, 7 and the lower arm side main switching elements 8, 9, 10 to generate a braking force.

FIG. 10 is a block diagram of a method for performing a current control to generate a desired braking force.
Explaining the configuration, 1 is a three-phase brushless DC motor (hereinafter abbreviated as a three-phase motor), 2 is a rotor position detector using a rotary encoder, Hall IC, etc., 3 is a motor drive power source, 4 is Motor drive power switch, 5, 6 and 7 are the upper arm side main switching elements (Nch power MOSFET) of the three-phase motor 1, and 8, 9 and 10 are the lower arm side main switching elements (Nch power) of the three-phase motor 1. MOSFET), 11, 12, and 13 are upper arm side main switching element driving circuits of the three-phase motor 1, 14, 15, and 16 are lower arm side main switching element driving circuits of the three-phase motor 1, and 17, 18, and 19 are 3 The power supply for the upper arm side main switching element drive circuit of the phase motor 1, 20 is the power supply for the lower arm side main switching element drive circuit of the three-phase motor 1, 21 is an excitation sequence generator, 22 is a signal synthesizer, 2 The PWM signal generator 24 is braked capacitor, 25 is the rotation direction instruction, 27 a current detector, 29 a current controller, 30 is a current instruction.

  In FIG. 10, when a load is driven on the brushless DC motor 1 by a 120-degree energization method (powering operation), excitation is performed based on rotor position information output from the position detector 2 attached to the brushless DC motor 1. An excitation sequence is created by the sequence creator 21. The deviation of the current detected by the command current instruction 30 and the current detector 27 is calculated. The current deviation is input to the current controller 29 to calculate a voltage instruction. A PWM signal proportional to the calculated voltage instruction is generated by the PWM signal generator 23, and the excitation sequence and the PWM signal are synthesized by the signal synthesizer 22, and each of the main switching elements 5, 6, 7, 8, 9, 10 is synthesized. Create an ON / OFF command.

  Upper arm side main switching element driving circuits 11, 12, 13 and the lower arm side receiving power supply from upper arm side main switching element driving circuit power supplies 17, 18, 19 and lower arm side main switching element driving circuit power source 20 The main switching element drive circuits 14, 15, and 16 are operated by the main switching element ON / OFF command synthesized by the signal synthesizer 22, and the upper arm side main switching elements 5, 6, 7 and the lower arm side main switching elements 8, 9. , 10 are turned ON / OFF to drive the brushless DC motor 1. At this time, the motor drive power switch 4 is turned ON, and power is supplied from the motor drive power supply 3 to the brushless DC motor 1 through the upper arm side main switching elements 5, 6, 7 and the lower arm side main switching elements 8, 9, 10. Do.

  Subsequently, in FIG. 10, when the load is braked on the brushless DC motor by the 120-degree energization method (regenerative operation), the rotational direction is determined from the rotor position information output from the position detector 2 attached to the brushless DC motor 1. The circuit 26 discriminates the rotation direction, and the excitation sequence generator 21 generates an excitation sequence corresponding to the rotation direction. The deviation of the current detected by the command current instruction 30 and the current detector 27 is calculated. The current deviation is input to the current controller 29 to calculate a voltage instruction. A PWM signal proportional to the calculated voltage instruction is generated by the PWM signal generator 23, and the excitation sequence and the PWM signal are synthesized by the signal synthesizer 22, and each of the main switching elements 5, 6, 7, 8, 9, 10 is synthesized. Create an ON / OFF command.

  Upper arm side main switching element driving circuits 11, 12, 13 and the lower arm side receiving power supply from upper arm side main switching element driving circuit power supplies 17, 18, 19 and lower arm side main switching element driving circuit power source 20 The main switching element drive circuits 14, 15, and 16 are operated by the main switching element ON / OFF command synthesized by the signal synthesizer 22, and the upper arm side main switching elements 5, 6, 7 and the lower arm side main switching elements 8, 9. , 10 are turned ON / OFF to drive the brushless DC motor 1. At this time, the motor drive power switch 4 is turned OFF, and the motor drive power supply 3 is disconnected. The induced voltage of the brushless DC motor 1 is consumed by the brushless DC motor 1 through the upper arm side main switching elements 5, 6, 7 and the lower arm side main switching elements 8, 9, 10 to generate a braking force.

As described above, according to the brushless DC motor driving apparatus having the braking force control function according to the above embodiment, the effects listed below can be obtained.
By combining the excitation sequence created by the excitation sequence creation device 21 and the PWM signal from the PWM signal generator 23, the switching elements of the switching element groups 5 to 10 constituting the inverter circuit C are turned on and off to make the brushless. The DC motor is driven, and the DC power source and the switching element group are disconnected at the time of braking, and the induced voltage of the brushless DC motor 1 is consumed by the brushless DC motor 1 through the switching element groups 5 to 10. Since the power is generated, the brushless DC motor 1 can realize the power running operation and the regenerative operation with a single drive device, and the braking force and the generated torque can be freely controlled by the duty ratio of the PWM signal. Further, since the drive circuit does not have a regenerative resistor, the drive device does not generate heat.
Moreover, as the drive circuit power supplies 17 to 20, the number of phases can be reduced because the number of phases on the upper arm side of the switching element groups 5 to 10 is one and the number of lower arm sides is one.
Furthermore, the power running and regenerative operations are controlled by the excitation sequence of the brushless DC motor 1 and the PWM signal, and the upper and lower arms of the switching element groups 5 to 10 control the braking force by PWM modulation. Can be turned on and off, and the charge / discharge ratio can be changed by changing the duty ratio of the PWM signal, the current can be controlled, and the braking force and generated torque can be controlled freely.
Further, a rotation direction discriminating circuit 26 for discriminating the rotation direction from the rotor position information of the brushless DC motor 1 is provided, and an excitation sequence corresponding to the rotation direction is generated by the excitation sequence generator 21. Therefore, an excitation sequence corresponding to the rotation direction. Can be created.
Further, a current detector 27 is interposed between the DC power source 3 and the switching element groups 5 to 10, and the deviation between the current detected by the current detector 27 and the current instruction is calculated, and the current deviation is calculated as the current deviation. A voltage instruction is calculated by inputting to the controller 29, and the calculated voltage instruction is input to the PWM signal generator 23 to create a PWM signal. Therefore, the voltage instruction input to the PWM signal generator 23 by the current controller 29 Can be calculated. Therefore, an accurate voltage instruction can be input to the PWM signal generator 23.

  The present invention is not limited to the above embodiment. For example, the motor uses the three-phase brushless DC motor 1, but it may be other than three phases, or may be a single phase or three or more phases. Further, the switching elements 5 to 10 constituting the inverter circuit C are not limited to the Nch power MOSFET, and other semiconductor elements such as a transistor and a thyristor can also be used. Further, as the gate drive circuits 11 to 16, any circuit can be used as long as the switching elements 5 to 10 can be turned ON / OFF. Needless to say, the present invention can be appropriately modified.

DESCRIPTION OF SYMBOLS 1 3 phase brushless DC motor 2 Rotor position detector 3 Motor drive (direct current) power supply 4 Motor drive power switch 5-10 Switching element 11-16 Gate drive circuit (drive circuit)
17 to 20 Power supply for gate drive circuit 21 Excitation sequence generator 22 Signal generator 23 PWM signal generator 24 Braking capacitor 25 Direction of rotation direction 26 Direction of rotation determination circuit 27 Current detector 29 Current controller

Claims (3)

A direct current power source for driving a brushless DC motor;
A switching element group for turning on and off a current flowing from the DC power source to the winding of the brushless DC motor;
A capacitor connected in parallel with the group of switching elements;
A switch that disconnects the DC power supply and the switching element group;
A drive circuit power source in which the upper arm side of the switching element group for driving the switching element group has several phases and the lower arm side has one ;
An excitation sequence generator for generating an excitation sequence based on the position information of the brushless DC motor;
A PWM signal generator that generates a PWM signal proportional to the command voltage indication;
With
In the method of driving and braking the brushless DC motor by combining the excitation sequence created by the excitation sequence creator and the PWM signal from the PWM signal generator to turn on and off the switching elements of the switching element group ,
During braking, disconnect the DC power supply and the switching element group,
The excitation sequence generator creates an excitation sequence in the direction opposite to the driving direction of the brushless DC motor,
Create a PWM signal proportional to the braking force instruction with the PWM signal generator,
Turn on and off the switching elements of the switching element group by synthesizing the excitation sequence created by the excitation sequence creator and the PWM signal from the PWM signal generator,
A braking force is generated by causing the brushless DC motor to consume the induced voltage of the brushless DC motor through the switching element group.
Braking method for brushless DC motor. Powering, brushless DC motor according to claim 1, the regenerative operation is controlled by the excitation sequence and the PWM signal of the brushless DC motor, and characterized by the control of the braking force by the PWM modulation in the upper and lower arms of the switching element group Braking method. The rotation direction detection circuit for determining the direction of rotation from the rotor position information of the brushless DC motor is provided, the excitation sequence matching the rotational direction according to claim 1 or 2, characterized in that created by the excitation sequence generator Braking method for brushless DC motor.

Images