CN209948997U - Current detection and overcurrent protection circuit of permanent magnet synchronous motor - Google Patents

Abstract

The utility model discloses an interference immunity is stronger, the drive is level and smooth more and make the higher PMSM's of the positioning accuracy who turns into mechanical output current detection and overcurrent protection circuit. The utility model discloses a door driver chip (1), motor (2), U looks power tube, V looks power tube and W looks power tube the S utmost point of U looks power tube, V looks power tube and W looks power tube is provided with first sense resistor (R) respectively₁) A second sensing resistor (R)₂) And a third sense resistor (R)₃) A fourth sensing resistor (R) is respectively connected to the non-common ends of the first sensing resistor, the second sensing resistor and the third sensing resistor_p1) And a fifth sense resistor (R)_p2) And a sixth sense resistor (R)_p3) And the other ends of the fourth sensing resistor, the fifth sensing resistor and the sixth sensing resistor are connected with an input end of a Comparator (CMP). The utility model discloses can be applied to the circuit protection field.

Description

Current detection and overcurrent protection circuit of permanent magnet synchronous motor

Technical Field

The utility model relates to a motor protection field especially relates to a PMSM's current detection and overcurrent protection circuit.

Background

The servo motor plays an important role in the operation control in the industrial automation field, and the control performance requirements of the servo motor are different according to different application occasions. In practical applications, the servo motor has various control modes, such as torque control/current control, speed control, position control, and the like. The detection of the total current plays an important reference role in the calculation of a current loop, overcurrent protection and over-temperature protection.

A permanent magnet synchronous motor is one type of servo motor. As shown in fig. 1, the current detection and overcurrent protection of the current permanent magnet synchronous motor are implemented by three sensing resistors R in the driving circuit₁、R₂And R₃The common terminal is connected with an inductive resistor R in series_sObtained according to kirchhoff's current law, respectively flows through three inductive resistors R₁、R₂And R₃And the sum of the currents flowing through the sense resistor R_sCurrent of (I)_sEqual to the total current I of the whole drive circuit_sumEqual, total voltage V of the drive circuit_sumIs just flowing through the sensing resistor R_sCurrent of (I)_sThe product of the resistance of the resistor is amplified to set the reference voltage as V_refThen, the conditions for the occurrence of the total current over-current protection of the driving circuit are as follows: i is_sum≥V_ref/Rs。

The formula shows that the introduced induction resistor Rs directly becomes a participant of overcurrent protection occurrence conditions, which can bring unstable factors to the driving of the motor and reduce the driving precision, and the scheme can cause that the ground wire layout and the design of the permanent magnet synchronous motor driving plate are not good enough when being realized, the anti-interference capability of the whole driving circuit is not enough, the subsequent motor driving is not smooth enough, and the positioning precision of the final conversion of the motor action into mechanical output cannot be effectively ensured.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that overcome prior art not enough, provide an interference immunity stronger, the drive is more level and smooth and make the higher PMSM's of the positioning accuracy who turns into mechanical output current detection and overcurrent protection circuit.

The utility model adopts the technical proposal that: the utility model comprises a gate driving chip, a motor, a U-phase power tube, a V-phase power tube and a W-phase power tube, the pins of the gate driving chip are respectively connected with the three phases of the motor through the U-phase power tube, the V-phase power tube and the W-phase power tube, the S poles of the U-phase power tube, the V-phase power tube and the W-phase power tube are respectively provided with a first induction resistor, a second induction resistor and a third induction resistor, the common end of the first sensing resistor, the second sensing resistor and the third sensing resistor is connected with the ground in common, a fourth induction resistor, a fifth induction resistor and a sixth induction resistor are respectively connected with the non-common ends of the first induction resistor, the second induction resistor and the third induction resistor, the other ends of the fourth induction resistor, the fifth induction resistor and the sixth induction resistor are connected with the input end of a comparator.

The above solution shows that, because the detection point is reset at the non-common end of the first, second and third sense resistors, after the fourth, fifth and sixth sense resistors are connected, the newly introduced fourth, fifth and sixth sense resistors are connected to the input end of the comparator at the other end, when the resistance values of the three sense resistors are large enough, the current flowing through the fourth, fifth and sixth sense resistors is almost zero, and the power loss therein is almost zero, the influence on the whole driving circuit is avoided while the driving phase current detection function is completed, compared with the prior art, the additional device introduced into the whole driving circuit (such as sense resistor Rs in fig. 1) is reduced, and the integrity of the driving circuit is ensured, the motor driving device does not influence the smoothness of the motor driving during driving, and simultaneously improves the anti-interference capability of the whole circuit.

Further, the U-phase power tube includes a first field effect tube and a second field effect tube respectively connected to the high-low level pins of the gate driver chip, the S-pole of the first field effect tube and the D-pole of the second field effect tube are connected to the U of the motor, the first sense resistor is connected to the S-pole of the second field effect tube, the V-phase power tube includes a third field effect tube and a fourth field effect tube respectively connected to the high-low level pins of the gate driver chip, the S-pole of the third field effect tube and the D-pole of the fourth field effect tube are connected to the V of the motor, the second sense resistor is connected to the S-pole of the fourth field effect tube, the W-phase power tube includes a fifth field effect tube and a sixth field effect tube respectively connected to the high-low level pins of the gate driver chip, the S-pole of the fifth field effect tube and the D-pole of the sixth field effect tube are connected to the W of the motor, and the third induction resistor is connected with the S pole of the sixth field effect transistor.

According to the scheme, the six field effect tubes are utilized to form the three-phase power tube part of the motor, so that the driving stability and reliability are ensured, and the electrode driving is smoother.

Drawings

FIG. 1 is a schematic diagram of a drive circuit for a prior art permanent magnet synchronous motor;

fig. 2 is a schematic circuit diagram of the present invention.

Detailed Description

As shown in FIG. 2, the circuit of the utility model comprises a gate driving chip 1, a motor 2, a U-phase power tube, a V-phase power tube and a W-phase power tube, the pin of the gate driving chip 1 is respectively passed through the U-phase power tube the V-phase power tube with the W-phase power tube with the three-phase connection of the motor 2 the S poles of the U-phase power tube, the V-phase power tube and the W-phase power tube are respectively provided with a first induction resistor R₁A second sensing resistor R₂And a third sense resistor R₃The first induction resistor R₁The second induction resistor R₂And the third sense resistor R₃Is connected to the common terminal of the first sense resistor R₁The second induction resistor R₂And the third sense resistor R₃Are respectively connected with a fourth induction resistor R_p1A fifth sense resistor R_p2And a sixth sense resistor R_p3Said fourth sense resistor R_p1The fifth induction resistor R_p2And the sixth sense resistor R_p3And the other ends thereof are connected to the input terminal of the comparator CMP. The other input terminal of the comparator CMP inputs a reference voltage V_ref。

The U-phase power tube comprises a first field effect tube 3 and a second field effect tube 4 which are respectively connected with high and low level pins of the gate driving chip 1, the S pole of the first field effect tube 3, the D pole of the second field effect tube 4 and the U of the motor 2 are connected, and the first induction resistor R₁The V-phase power tube comprises a third field effect tube 5 and a fourth field effect tube 6 which are respectively connected with high and low level pins of the gate driving chip 1, the S pole of the third field effect tube 5, the D pole of the fourth field effect tube 6 and the V pole of the motor 2 are connected, and the second induction resistor R is connected with the S pole of the second field effect tube 4₂The W-phase power tube comprises a fifth field effect tube 7 and a sixth field effect tube 8 which are respectively connected with the high-low level pins of the gate driving chip 1, the S pole of the fifth field effect tube 7, the D pole of the sixth field effect tube 8 and the W of the motor 2 are connected, and the third induction resistor R is connected with the S pole of the fourth field effect tube 6₃And is connected with the S pole of the sixth field effect transistor 8.

In FIG. 2, a first sense resistor R is provided₁The current flowing is I₁Fourth sense resistor R_p1And a first sensing resistor R₁Is at a point where non-ground terminals are connected, has a voltage of V₁(ii) a Setting a second induction resistor R₂The current flowing is I₂Fifth sense resistor R_p2And a second sensing resistor R₂Is at a point where non-ground terminals are connected, has a voltage of V₂(ii) a Setting a third induction resistor R₃The current flowing is I₃The sixth sense resistor R_p3And a third sense resistor R₃Is at a point where non-ground terminals are connected, has a voltage of V₃(ii) a Setting a fourth induction resistor R_p1The fifth induction resistor R_p2And the sixth sense resistor R_p3The voltage of one terminal connected to the input terminal of the comparator CMP is V_sumCurrent is set to I_sumThen there is

V₁=I₁*R₁......................... (1)

V₂=I₂*R₂......................... (2)

V₃=I₃*R₃......................... (3)

According to kirchhoff's current law, at V_sumThat point, there is:

(V₁-V_sum)/R_p1= (V_sum-V₂)/ R_p2+ (V_sum-V₃)/R_p3………..(4)

let R_p1=R_p2=R_p3=R_pIt is possible to obtain:

V_sum= (V₁+V₂+V₃)/3…………………………………….. (5)。

if R is_pRelative to the first induction resistor R₁A second sensing resistor R₂And a third sense resistor R₃All are infinite, then three parallel-like resistors R flow_p1、R_p2And R_p3The current of the power tube is ignored, and the driving current of the power tube can be considered to be equal to the first sensing resistor R₁A second sensing resistor R₂And a third sense resistor R₃The sum of the drive currents of the three resistors if: r₁=R₂=R₃And is provided with R₁=R₂=R₃=R_StThe total current of the driving circuit can be obtained by combining the formulas (1), (2), (3) and (5):

I_sum=（I₁+I₂+I₃）=3*V_sum/ R_St………… ……………….(6)

conditions under which total current over-current protection of the drive circuit occurs:

I_sum≥3*V_ref/ R_St…………………………………………(7)。

according to the above formula, the circuit of the present invention can detect the current of the PMSM and determine the overcurrent without involving the external induction of the fourth inductive resistor R_p1The fifth induction resistor R_p2And the sixth sense resistor R_p3When current detection is carried out, voltage drop of the driving efficiency tube cannot be shunted, power loss cannot be generated, and detection does not need to be carried out by introducing a fourth induction resistor R_p1A fifth sense resistor R_p2And a sixth sense resistor R_p3The drive circuit is used as a part of the whole drive circuit, thereby avoiding the influence of the introduced part used as detection on the original drive circuit, ensuring the anti-interference capability of the whole drive circuit and the smoothness of motor drive, and ensuring the positioning precision finally converted into mechanical output.

Claims (2)

1. A current detection and overcurrent protection circuit of a permanent magnet synchronous motor comprises a gate drive chip (1), a motor (2), a U-phase power tube, a V-phase power tube and a W-phase power tube, wherein pins of the gate drive chip (1) are respectively connected with three phases of the motor (2) through the U-phase power tube, the V-phase power tube and the W-phase power tube, and S poles of the U-phase power tube, the V-phase power tube and the W-phase power tube are respectively provided with a first induction resistor (R)₁) A second sensing resistor (R)₂) And a third sense resistor (R)₃) Said first sensing resistor (R)₁) The second induction resistor (R)₂) And the third induction resistance (R)₃) Is characterized in that: at the first induction resistance (R)₁) The second induction resistor (R)₂) And the third induction resistance (R)₃) Are respectively connected with a fourth induction resistor (R)_p1) And a fifth sense resistor (R)_p2) And a sixth sense resistor (R)_p3) Said fourth sense resistor (R)_p1) The fifth induction resistor (R)_p2) And the sixth sense resistor (R)_p3) And the other end of each is connected to an input terminal of a Comparator (CMP).

2. The current detection and overcurrent protection circuit of a permanent magnet synchronous motor according to claim 1, characterized in that: the U-phase power tube comprises a first field effect tube (3) and a second field effect tube (4) which are respectively connected with high and low level pins of the gate driving chip (1), the S pole of the first field effect tube (3) is connected with the D pole of the second field effect tube (4) and the U of the motor (2), and the first induction resistor (R)₁) The V-phase power tube comprises a third field effect tube (5) and a fourth field effect tube (6) which are respectively connected with high and low level pins of the gate driving chip (1), the S pole of the third field effect tube (5), the D pole of the fourth field effect tube (6) and the V pole of the motor (2) are connected, and the second induction resistor (R) is connected with the S pole of the second field effect tube (4)₂) The W-phase power tube comprises a fifth field effect tube (7) and a sixth field effect tube (8) which are respectively connected with high and low level pins of the gate driving chip (1), the S pole of the fifth field effect tube (7), the D pole of the sixth field effect tube (8) and the W of the motor (2) are connected, and the third induction resistor (R) is connected with the S pole of the fourth field effect tube (6)₃) Is connected with the S pole of the sixth field effect transistor (8).

Images