JP3400917B2 - Start control method for commutatorless motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of starting a commutatorless motor by inverter control, and more particularly to a method of using a bootstrap method as a power source for driving a switching element of an upper arm of an inverter circuit.

[0002]

2. Description of the Related Art An example of a drive device for a commutatorless motor is described in Japanese Patent Publication No. 6-46879. FIG. 4 is a circuit diagram showing an example of a drive circuit of a conventional commutatorless motor using an IGBT as a switching element of an impactor, where 1 is a commercial AC power supply, 2 is a converter unit, and 3a to 3c.
Is an upper arm IGBT (Insu
Plated-Gate Bipolar Transistor), 3d to 3f are lower arm IGBTs, 4, 4a to 4c are DC power supplies, and 12 is a non-rectifier motor.

In the figure, an AC voltage supplied from a commercial AC power source 1 is rectified and smoothed by a converter unit 2 to generate a DC voltage. Terminal 2 that outputs this DC voltage
IGBTs 3a to 3f and DC power sources 4, 4a to between a and 2b
An inverter composed of 4c is connected and this DC voltage is supplied.

In this inverter, the I of the upper arm
The collectors of the GBTs 3a, 3b, 3c are converters 2 respectively.
One of the output terminals 2a has the emitters of the lower arm I
It is connected to the collectors of the GBTs 3d, 3e, 3f,
The emitters of these lower arm IGBTs 3d, 3e, 3f are connected to the other output terminal 2b of the converter 2. Also, the connection point of the IGBTs 3a and 3d, the IGBT 3
The connection points of a and 3d and the connection points of IGBTs 3a and 3d are respectively
It forms the output terminal of the inverter , and the commutatorless motor 1
It is connected to two windings of three phases (not shown). further,
DC power supplies 4a, 4b, 4c are connected between the gates and emitters of the upper arm IGBTs 3a, 3b, 3c, respectively, and a common DC power supply 4 supplies a DC voltage to the gates of the lower arm IGBTs 3d, 3e, 3f. ing.

Next, the driving operation of the non-rectifier motor 12 by the inverter will be described with reference to FIG.

A chopper signal is sequentially supplied to the upper arm IGBTs 3a, 3b, 3c by a driving means (not shown) for each T ₀ period, and each ON / OFF operation is performed for each T ₁ period to chop the DC voltage from the converter 2. To do.
At the same time, the lower arm IGBT 3d is connected to the upper arm I
During the on / off period T ₁ of the GBT 3a, the IGB of the lower arm
T3e is of the upper arm IGBT3b of the on / off period T ₁
And the lower arm IGBT3f is the upper arm IGBT3c
The chopper signal is supplied during the on / off period T ₁ of
On / off operations are performed in opposite phases to the upper arm IGBTs 3a, 3b, 3c, respectively. In addition, the upper arm IGBT3a,
Time T ₁ for chopping operation period T ₁ of 3b and 3c
IGBTs 3f, 3d, 3e of the lower arm with a delay of / 2
In this order, the DC voltage is supplied for each T ₁ period, and the ON state is maintained for each T ₁ period.

[0007] Thus, in the period T ₁ which IGBT3a operates on / off, first, the period of T _1/2 of the first half, IGBT3e of the lower arm is turned on, the direct current from the converter 2 above It is chopped by the IGBT 3a of the arm and supplied to the non-commutator electric motor 12, and returns to the converter 2 through the IGBT 3e of the lower arm. IG
T _{1/2 in} the latter half of the T ₁ period during which the BT3a is turned on / off
During the period of time, the lower arm IGBT3f is turned on, and the direct current from the converter 2 is increased by the upper arm IGBT3f.
It is chopped by 3a and supplied to the non-commutator motor 12, and returns to the converter 2 through the IGBT 3f of the lower arm. In period T ₁ in which the following IGBT3b operates on / off, the IGBT3f lower arm in period T ₁ of the first half,
During the latter half of T _1/2 , the lower arm IGBT3d is turned on and the next IGBT3c is turned on / off.
In the T ₁ period during which the off operation is performed, the lower arm IGBT 3d is turned on during the first half T ₁ period and the lower arm IGBT 3e is turned on during the latter half T _1/2 period, and the above operation is repeated.

Thus, the upper arm IGBTs 3a-3
The commutatorless electric motor 12 is driven by performing a commutation operation that sequentially switches ON / OFF operations of c and the lower arm IGBTs 3d to 3f.

In order to change the output power of the inverter, the upper arm IGBTs 3a to 3c are turned on / off at high speed in one commutation pattern in this way to chop the output voltage and output current. The lower arm IGBTs 3d to 3f are also the upper arm IGBTs 3a to 3f.
When the IGBTs 3a to 3c are off in synchronization with the on / off of the 3c, the IGBTs 3d to 3d on the lower arm of the same row are turned on.
By performing a chopping operation so that 3f is turned on, the control response of the non-commutator motor 12 is improved.

On the contrary, when such control responsiveness is not required so much, as shown in FIG.
The BTs 3d to 3f may not be involved in the chopping of the output voltage and the output current. In this case, the number of times of switching in the lower arm IGBTs 3d to 3f is reduced, so that the switching loss can be reduced.

Further, when the rotor of the non-commutator motor 12 is a permanent magnet and the rotor magnetic pole position detecting means such as a Hall element is not provided, the commutation pattern of the first commutation does not occur at the time of starting. Even if a current is passed through the stator winding of the commutator motor 12, a large torque cannot be obtained depending on the position of the magnetic pole of the rotor, and it is difficult to rotate the rotor immediately at a high speed. Therefore, in such a case, it is better to perform rotor positioning. This moves the rotor to a predetermined position so that maximum torque is obtained in the next commutation pattern.

By the way, in the conventional example shown in FIG. 4, four DC power supplies are provided.
In order to turn on / off T3a to 3c , since their emitters are independent, it is necessary to apply a DC voltage independently between the respective gates and emitters, and the IGBTs 3d to 3f of the lower arms are Is common, so 1
This is because one DC power source can be shared.

On the other hand, in the inverter having such a structure, there is also a method in which the DC power supply 4 is shared by the upper arm IGBTs 3a to 3c and only one DC power supply is provided. FIG. 7 shows an example of the so-called bootstrap method, in which 5 is a resistor, 6a to 6c are diodes,
Reference numerals 7a to 7c are capacitors, and portions corresponding to those in FIG.

In the figure, the upper arm IGBT3a,
A capacitor 7a is provided between the gate and emitter of each of 3b and 3c.
Are connected to the upper arm IGBTs 3a, 3b, 3
The DC power source 4 is connected to the gates of the respective c's through the diodes 6a, 6b, 6c and the resistor 5.

In this conventional example, the capacitors 7a, 7b,
By charging 7c, the DC power supplies 4a, 4a in FIG.
b, 4c. For example, if the lower arm IGBT 3d is turned on, the DC power supply 4, the resistor 5, the diode 6a, the capacitor 7a and the IG
A closed circuit made up of BT3d is formed, a current flows, and the capacitor 7a is charged to substantially the same voltage as the DC power supply 4.
This charging voltage turns on the upper arm IGBT 3a, and the same applies to the upper arm IGBTs 3b and 3c.

Also in the drive device for such a non-rectifying motor, the inverter operates as shown in FIGS. 5 and 6.

[0017]

By the way, the above-mentioned conventional example has the following problems. That is, when a bootstrap type inverter circuit is used as a power supply for driving the switching element of the upper arm, and the rotor is a permanent magnet and a non-commutator motor without a magnetic pole position detection means such as a Hall element is driven, the lower arm is driven. When the switching element of No. 1 is controlled not to be involved in the chopping of the output voltage and the output current, since the capacitors 7a to 7c of the bootstrap circuit are not charged when the non-rectifier motor is started, the switching element of the upper arm is It cannot be turned on and cannot position or start the rotor.

An object of the present invention is to solve such a problem and to use a bootstrap circuit for the upper arm so that the rotor positioning and the starting at the start of the non-commutator motor can be surely performed. It is intended to provide a starting control method for a commutator motor.

[0019]

In order to achieve the above object, the present invention turns on at least a switching pattern at the time of rotor positioning in the switching elements of the lower arm when the commutator motor is started. The first switching element of the lower arm, which is connected in series with the switching element of the upper arm, is turned on for a predetermined period, and thereafter, a dead time of a predetermined time period is set so as not to overlap this predetermined period,
The first switching element of the upper arm, which is connected in series with the first switching element of the lower arm, and the second switching element of the lower arm, which is not connected in series with the first switching element, are turned on at the same time to start the start.

First, when the first switching element of the lower arm is turned on, the capacitor of the bootstrap circuit is charged by the first switching element of the upper arm which is connected in series to the first switching element, and the charging voltage is It becomes the DC power supply voltage of the drive circuit of the first switching element of the upper arm, and the first switching element of the upper arm can be turned on.

It is possible that the first switching element of the lower arm is turned off and the first and second switching elements of the lower arm which are connected in series so that the dead time elapses are turned on at the same time. Then, the first switching element of the upper arm and the second switching of the lower arm other than the first switching element of the lower arm connected in series with the first switching element of the upper arm are turned off. Turn on. As a result, the rotor of the commutatorless motor is positioned, and thereafter, the switching elements of the upper arm and the switching elements of the lower arm are on / off controlled in a commutation pattern starting from this state. As a result, the commutatorless motor is started.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a circuit diagram showing an electric motor drive circuit using an embodiment of the start-up control method for a non-rectifier electric motor according to the present invention. 8 is a drive circuit, 9 is a commutation signal output circuit, and 10 is a circuit. The chopper signal output circuits 11a to 11c are AND gates, and the portions corresponding to those in the above drawings are designated by the same reference numerals to omit redundant description.

FIG. 3 is a timing diagram illustrating a motor driving operation of the inverter in the motor drive circuit, T ₁ ~
All T ₆ periods have the same time length (T ₁ = T ₂ = T ₃ = T ₄ = T ₅
= T ₆ = a t _0), and T _5, T _6, T ₄ period is delayed by a time t _0/2 than each T _1, T _2, T ₃ duration.

This embodiment is also based on the bootstrap method similar to the conventional example shown in FIG. 7, and the inverter operates as shown in FIG.

In FIG. 2, the chopper signal output circuit 10
Continuously outputs the chopper signal A and supplies it to the AND gates 11a, 11b and 11c. Commutation signal output circuit 9, the commutation signals B ₁ as the gate signal supplied to the AND gates 11a to period T _1, the gate signal to the next period T ₂
The commutation signal B ₂ as supplied to the AND gates 11b,
Further, in the next T ₃ period, the commutation signal B ₃ as a gate signal is supplied to the AND gate 11c. As a result, the drive circuit 8a receives the chopper signal A from the AND gate 11a during the period T ₁ and turns on / off the IGBT 3a accordingly. In addition, the drive circuit 8b is, T ₂ period,
The chopper signal A is received from the AND gate 11b, and the IGBT 3b is turned on / off in response to this. further,
The drive circuit 8c receives the chopper signal A from the AND gate 11c during the T ₃ period, and turns on / off the IGBT 3c in response thereto.

Further, the commutation signal output circuit 9 outputs the commutation signal C ₁ to T ₂ during the T ₅ period which is the latter half of the T ₁ period and the first half of the T ₂ period.
The commutation signal C ₃ is generated during the T ₆ period, which is the latter half of the period and the first half of the T ₃ period.
, The commutation signal C ₃ is output during the T ₄ period, which is the latter half of the T ₃ period and the _first half of the T ₁ period. The drive circuit 8f is supplied with the commutation signal C ₁ , which keeps the IGBT 3f in the ON state for the period of T ₅ , and the drive circuit 8d is supplied with the commutation signal C ₂ , which causes the IGBT 3d to remain in the T ₆ period. The drive circuit 8e is kept in the ON state, and the commutation signal C ₃ is supplied to the drive circuit 8e, so that the IGBT 3e is kept in the ON state for the period T ₄ .

As described above, by driving the IGBTs 3a to 3f by the drive circuits 8a to 8f, respectively,
As shown in FIG. 3, as IGBT3a~3c the upper arm is repeatedly turned on / off at T _1, T _2, T ₃ periods a respective commutation period, the output voltage to the non-commutator motor 12 and The output current is chopped and the duty ratio of this chopping is made variable so that the output of the inverter can be made variable according to the load (that is, the operating state of the non-rectifier motor 12). Since the IGBTs 3d to 3f receive only commutation signals, they are not involved in chopping.

The commutatorless motor 12 has a permanent magnet as its rotor and has no rotor magnetic pole position detecting means such as a Hall element.

Next, referring to FIG. 1, an embodiment of a start control method for a non-commutator electric motor according to the present invention in the drive device for the non-commutator electric motor 12 will be described. In the figure, the upper arm IGBTs 3a to 3c and the lower arm IGBTs 3d to 3c are shown.
The sequence of the ON states set with f is shown, and the upper arm IGBTs 3a to 3c perform the chopper operation during the ON period.

This embodiment will be described below by taking the non-commutator motor driving device shown in FIG. 2 as an example.

When the commutatorless electric motor 12 is stopped, no electric charge is stored in the capacitors 7a to 7c, and the IGBTs 3a to 3c cannot be turned on in this state.

Therefore, as shown in FIG. 1, first, during the Ta period, the IGBT 3d is turned on to turn on the DC power supply 4, the resistor 5, and the resistor 5.
A closed circuit composed of the diode 6a, the capacitor 7a, and the IGBT 3d is formed, and a current is passed through this to form the capacitor 7
By charging a, the IGBT 3a is turned on.

Here, after the IGBT 3d is turned on, t
The voltage Vc across the capacitor 7a when [sec] has elapsed
Is Vc = (Vs-Vf-Vce) {1-exp (-t / CR)} [V] (1) where Vs: voltage of DC power supply 4 Vf: forward voltage of diode 6a Vce: IGBT3d Collector / emitter saturation voltage C: capacitance of capacitor 7a R: resistance value of resistor 5

Now, Vs = 15 [V], Vf = 0.7
[V], Vce = 1 [V], C = 0.47 [μF], R =
Assuming 100 [Ω], the Ta period of the above charging is the time constant C
When t = 141 [μsec], which is three times R, is set, the capacitor 7a is charged up to about 95% of the voltage Vs of the DC power supply 4, and the IGBT 3a can be turned on.

I for charging the capacitor 7a in order to position the rotor of the non-commutator motor 12
Following the Ta period in which the GBT 3d is on, the IGBT is
The IGBTs are turned on by turning on the 3a and 3e.
If the ON period of the IGBT 3a takes a little while the 3d is on, a short circuit occurs between the terminals 2a and 2b of the converter 2 and an excessive current flows through these IGBTs 3a and 3d.

In order to prevent this, when the above Ta period in which the IGBT 3d is turned on elapses, all the IGBTs 3
A dead time Tb for turning off a to 3f is provided. Here, the ON / OFF cycles of the IGBTs 3a to 3c are set to 1 to 4
If [μsec], the length tb of this dead time Tb
Is about 10 [μsec], which is longer than this period.

When this dead time Tb elapses, IG
BT3a and IGBT3e are turned on and the commutatorless motor 12
Positioning of the rotor is carried out by passing an electric current through the stator winding of. When the IGBT 3e is turned on, a closed circuit composed of the DC power supply 4, the resistor 5, the diode 6b, the capacitor 7b and the IGBT 3e is formed, and a current flows through the closed circuit to charge the capacitor 7b .

After that, the IGBT 3a is in the ON state for the period Ta in FIG.
By turning on f, the operation shifts to the normal operation shown in FIG. In addition, when the IGBT 3f is turned on, the DC power supply 4, the resistor 5, the diode 6
A closed circuit composed of the capacitor c, the capacitor 7c and the IGBT 3f is formed, and a current flows through the closed circuit to charge the capacitor 7c.

As described above, in this embodiment, at the time of starting, one switching element of the lower arm is first turned on to charge the capacitor connected in series to the switching element, and the dead time Tb for preventing short circuit is passed. After that, by turning each switching element on and off in the same order as in the normal operation, a current flows through the stator winding of the non-commutator motor 12 to position the rotor and The capacitors of the other switching elements of the arm are sequentially charged, and normal operation is started.

Therefore, when starting a non-commutator motor whose rotor is a permanent magnet and does not have a rotor magnetic pole position detecting means such as a Hall element, in order to secure a driving voltage for the switching element of the upper arm, Even when the bootstrap method is used and the switching element of the lower arm is controlled not to be involved in the chopping of the output voltage and the output current, the rotor can be positioned and a reliable start can be achieved.

In the above embodiment, the IGBT is used as the switching element, but the invention is not limited to the IGBT, and if the current can be turned on / off like a bipolar transistor, a MOSFET, a thyristor or the like. , Whatever.

[0043]

As described above, according to the present invention,
When a bootstrap method is used as a power source for driving a switching element in an inverter circuit and a rotor is a permanent magnet and a non-commutator motor without a magnetic pole position detecting means such as a Hall element is driven, the lower arm is driven. Even when the switching element is controlled not to participate in the chopping of the output voltage and the output current, the rotor can be surely positioned and started at the time of starting the commutatorless motor.

[Brief description of drawings]

FIG. 1 is a timing diagram showing an embodiment of a start control method for a commutatorless motor according to the present invention.

FIG. 2 is a circuit diagram showing an example of a drive device for a non-commutator motor using the method for starting a non-commutator motor according to the present invention.

FIG. 3 is a timing chart showing the operation of the non-commutator motor shown in FIG. 2 after the drive device is started.

FIG. 4 is a diagram showing a conventional example of a drive device for an electric motor.

5 is a timing chart showing an operation example of the driving apparatus shown in FIG.

FIG. 6 is a diagram showing timings showing another operation example of the drive device shown in FIG.

FIG. 7 is a circuit diagram showing a conventional example of a drive device for an electric motor by an inverter using a bootstrap method.

[Explanation of symbols]

2 Converter section 3a to 3f IGBT 4 DC power supply 5 resistance 6a to 6c diode 7a to 7c capacitors 8a-8f drive circuit 9 Commutation signal output circuit 10 Chopper signal output circuit 11a-11c AND gate 12 Non-commutator motor

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-194156 (JP, A) JP-A-5-137349 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02P 6/18 H02P 6/20

Claims (5)

(57) [Claims] 1. A series circuit of an upper arm switching element and a lower arm switching element for supplying a current to each winding of the non-commutator motor is provided by the number of windings of the non-rectifier motor. A power element unit to which a DC power supply voltage is applied from a converter to each of the series circuits, a commutation signal output circuit that outputs a commutation signal, a chopper signal output circuit that outputs a chopper signal, the commutation signal and the chopper A drive circuit using a bootstrap circuit for turning on / off the switching elements of the upper arm in a predetermined order for a predetermined time, and the commutation signal is supplied. A drive circuit for setting the switching elements of the lower arm in an ON state for a predetermined time in a predetermined order, and At the start of the commutator motor, in the first period, the lower arm of the rotor of Brushless DC electric motor of the switching element
Turn on a specific one for positioning
The upper arm connected in series to the switching element
Of the switching elements of the upper arm and the switching elements of the lower arm that are in the ON-enabled state and are connected in series with the switching element that has been turned ON during the second period. A start-up control method for a commutatorless motor, characterized in that one of the switching elements different from the selected switching element is turned on. 2. The start-up control method for a commutatorless motor according to claim 1, wherein switching of the lower arm that is turned on in the first period is performed between the first period and the second period. A start-up control method for a non-commutator motor, comprising a third period in which an element and a switching element of the upper arm connected in series thereto are simultaneously turned off for a predetermined time. 3. The start-up control method for a non-commutator motor according to claim 1 or 2, wherein the rotor of the non-commutator motor is a permanent magnet and has no magnetic pole position detecting means for the rotor. A starting control method for a commutatorless motor, which is an electric motor. 4. The start-up control method for a commutatorless motor according to claim 1, 2 or 3, wherein the time length of the first period is used in the drive circuit of the switching element of the upper arm. A start-up control method for a non-rectifier motor, which is characterized by being longer than the charging time constant of the circuit. 5. The start-up control method for a non-rectifier motor according to claim 2, 3 or 4, wherein the time length of the third period is longer than the switching time of the switching element. Start control method for slave motor.