CN204334388U - A Brake Control Circuit of Series Excited Motor - Google Patents

Abstract

The utility model discloses a kind of brake control circuit of series-wound motor, comprise series-wound motor, uncontrollable rectifying part, pulse-width modulation buck chopper power unit and braking circuit, uncontrollable rectifying part comprises 4 diodes, resistance and electric capacity, pulse-width modulation buck chopper power unit comprises controller, first power electric switch device of full-control type and fly-wheel diode, controller comprises digital microcontroller, tension measuring circuit, current measurement circuit, the isolated drive circuit of the first device for power switching and the second device for power switching, braking circuit is the circuit of the second device for power switching and resistant series, braking circuit is in parallel with armature winding.During braking, first control the break-make point duty ratio of the first device for power switching; The terminal voltage of motor is down to and is less than or equal to brake voltage; Control conducting second device for power switching, connect the braking circuit of motor; Record current-limiting resistance electric current and the second excitation winding difference between current close to zero time, cut off the electricity supply, complete braking.

Description

A Brake Control Circuit of Series Excited Motor

technical field

The utility model belongs to the technical field of motor control and relates to a braking control circuit of a series excitation motor.

Background technique

In the traditional technology, since the excitation winding of the series-excited motor is connected in series with the armature winding, if the direction of the electromagnetic torque of the series-excited motor is to be changed to achieve braking, four power electronic switches must be installed in the main circuit of the motor drive to exchange their excitation. The connection terminal between the winding and the armature winding has complex circuit structure and cumbersome control methods.

Utility model content

The purpose of this utility model is to provide a braking control circuit for a series-excited motor, which solves the problem of changing the electromagnetic torque direction of the series-excited motor to achieve braking due to the fact that the field winding of the series-excited motor is connected in series with the armature winding in the prior art. , It is necessary to set four power electronic switches in the main circuit of the motor drive to exchange the connection ends of the excitation winding and the armature winding, the circuit structure is complicated, and the control method is cumbersome.

The technical scheme adopted by the utility model is: a braking control circuit of a series-excited motor, including a series-excited motor, an uncontrollable rectification part, a pulse width modulation step-down chopper power supply part and a braking circuit, the pulse width modulation The step-down chopper power supply part includes a controller, a fully-controlled first power electronic switching device and a freewheeling diode, and the controller includes a digital microcontroller, a voltage measuring circuit, a current measuring circuit, a first power switching device and a second The isolated driving circuit of the second power switching device, the braking circuit is a circuit connected in series with the second power switching device and the current limiting resistor, and the second power switching device is respectively connected to one end of the current limiting resistor and the isolated driving circuit; the second power switch The other end of the device is respectively connected to one end of the armature winding of the series motor and one end of the first excitation winding; the other end of the first excitation winding is respectively connected to one end of the first power switching device, the voltage measurement circuit, and the positive end of the freewheeling diode ; The other end of the current limiting resistor is connected to one end of the armature winding of the other end of the series motor and one end of the second excitation winding through one port of the current measurement circuit; the other end of the second excitation winding passes through another port of the current measurement circuit They are respectively connected to the voltage measurement circuit, the negative terminal of the freewheeling diode, and the uncontrollable rectification part; the output terminals of the voltage measurement circuit and the current measurement circuit are respectively connected to the digital microcontroller; the output terminal of the digital microcontroller is connected to the isolation drive circuit; A power switching device is respectively connected with the isolation drive circuit and the uncontrollable rectification part.

As an improvement of the above technical solution, the uncontrollable rectification part includes a first diode, a second diode, a third diode and a fourth diode, a resistor and a capacitor, and the negative end of the first diode Connected to the AC power supply and connected to the positive end of the third diode; the negative end of the third diode is respectively connected to the negative end of the fourth diode, the negative end of the capacitor, and the other end of the second excitation winding through the current measurement circuit The other end of the diode is connected to the other end; the positive end of the fourth diode is connected to the AC power supply and connected to the negative end of the second diode; the positive end of the first diode and the positive end of the second diode are respectively connected to the resistor One end of the resistor is connected to each other; the other end of the resistor is respectively connected to the positive end of the capacitor and the first power switching device.

Compared with the prior art, the utility model has the following advantages: the DC chopper step-down voltage regulating power supply controlled by the pulse width modulation mode is used to supply power for the series excitation motor. When the motor stops, the terminal voltage is first adjusted to an appropriate value, and then Turn on a power electronic switch, and connect a series of current-limiting resistors in parallel to the armature winding of the motor to realize electromagnetic braking; at the same time, measure the current of the second excitation winding of the motor and the current passing through the current-limiting resistor, and calculate the difference between the two , cut off power to the motor when the difference approaches zero. The utility model does not need to exchange the connecting ends of the excitation winding and the armature winding when the series excitation motor is parked and braked, and only controls one power electronic switch to realize the switching of the main circuit during braking.

Description of drawings

Fig. 1 is the circuit schematic diagram of the applied series excitation motor drive system embodiment of the utility model method;

Fig. 2 is a control flow chart of an embodiment of the control method of the present invention for the driving system of a series-excited motor.

In the figure, 11 isolated drive circuit, 2 voltage measurement circuit, 3 digital microcontroller, 4 current measurement circuit, 5 controller, 6 uncontrollable rectification part, 7 braking circuit

M series excitation motor, D1 first diode, D2 second diode, D3 third diode, D4 fourth diode, D freewheeling diode, L1 first excitation winding, L2 second excitation winding,

R1 resistor, R2 current limiting resistor, C capacitor, i1 the current passing through the motor excitation winding, i2 the current passing through the current limiting resistor, V1 the first power switching device, the second power switching device V2 the second power switching device

Detailed ways

The utility model will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Fig. 1, a brake control circuit of a series-excited motor includes a series-excited motor M, an uncontrollable rectification part 6, a pulse width modulation step-down chopper power supply part and a brake circuit 7, and the pulse width modulation step-down The voltage chopper power supply part includes a controller 5, a fully-controlled first power electronic switching device V1 and a freewheeling diode D, and the two ends of the freewheeling diode D supply voltage u. The controller 5 includes a digital microcontroller 3, a voltage measurement Circuit 2, current measuring circuit 4, isolation driving circuit 1 of the first power switching device V1 and the second power switching device V2, the brake circuit 7 is a circuit in series with the second power switching device V2 and the current limiting resistor R2, the first The second power switching device V2 is respectively connected to one end of the current limiting resistor R2 and the isolation drive circuit 1; the other end of the second power switching device V2 is respectively connected to one end of the armature winding of the series-excited motor M and one end of the first excitation winding L1; The other end of an exciting winding L1 is respectively connected to one end of the first power switching device V1, the voltage measurement circuit 2, and the positive end of the freewheeling diode D; The other end of the series-excited motor M is connected to one end of the armature winding and one end of the second excitation winding L2; The negative terminal and the uncontrollable rectification part are connected; the output terminals of the voltage measurement circuit 2 and the current measurement circuit 4 are respectively connected with the digital microcontroller 3; the output terminal of the digital microcontroller 3 is connected with the isolation drive circuit 1; the first power switching device V1 They are respectively connected to the isolated driving circuit 1 and the uncontrollable rectification part.

The uncontrollable rectification part 6 includes a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4, a resistor R1 and a capacitor C, and the cathode of the first diode D1 One end is connected to the AC power supply and connected to the positive end of the third diode D3; the negative end of the third diode D3 is respectively connected to the negative end of the fourth diode D4, the negative end of the capacitor C, and the second excitation winding L2 The other end is connected after another port of the current measuring circuit 4; the positive end of the fourth diode D4 is connected to the AC power supply and connected to the negative end of the second diode D2; the positive end of the first diode D1, the second The anode ends of the two diodes D2 are respectively connected to one end of the resistor R1; the other ends of the resistor R1 are respectively connected to the anode end of the capacitor C and the first power switching device V1.

As shown in Figure 2, the DC chopper step-down voltage-regulated power supply controlled by the pulse width modulation method supplies power to the series-excited motor M. When parking and braking, firstly control the duty ratio of the on-off point of the first power switching device V1; After the terminal voltage of the motor drops to less than or equal to the braking voltage; control the conduction of the second power switch device V2, turn on the braking circuit of the motor, and realize braking; when the difference between the measured current i2 and i1 is close to zero, cut off the power supply, Braking is done.

Example:

Set the chopping control period of the PWM step-down chopper power supply as Tp. The controller uses 3Tp time to control the on-off point duty ratio of the first power switching device V1, that is, and measures to confirm that the terminal voltage of the motor drops to less than or equal to the braking voltage; the controller uses Tp time to turn on the second power switching device V2 , and then measure the current i2 and i1 in each Tp time, and calculate the difference; when the measured difference is close to zero, the controller cuts off the power supply with Tp time.

The utility model does not need to exchange the connecting ends of the excitation winding and the armature winding when the series excitation motor is parked and braked, and only controls one power electronic switch to realize the switching of the main circuit during braking.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the utility model without limitation. Although the utility model has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the utility model can be Modifications or equivalent replacements of the new technical solutions without departing from the spirit and scope of the technical solutions of the utility model shall be covered by the claims of the utility model.

Claims (2)

1. the brake control circuit of a series-wound motor, it is characterized in that, comprise series-wound motor (M), uncontrollable rectifying part (6), pulse-width modulation buck chopper power unit and braking circuit (7), described pulse-width modulation buck chopper power unit comprises controller (5), first power electric switch device (V1) of full-control type and fly-wheel diode (D), described controller (5) comprises digital microcontroller (3), tension measuring circuit (2), current measurement circuit (4), the isolated drive circuit (1) of the first device for power switching (V1) and the second device for power switching (V2), described braking circuit (7) is the circuit that the second device for power switching (V2) and current-limiting resistance (R2) are connected, second device for power switching (V2) respectively with one end of current-limiting resistance (R2), isolated drive circuit (1) is connected, the other end of the second device for power switching (V2) is connected with one end armature winding of series-wound motor (M), the first excitation winding (L1) one end respectively, the other end of the first excitation winding (L1) is connected with the positive terminal of one end of the first device for power switching (V1), tension measuring circuit (2), fly-wheel diode (D) respectively, the other end of current-limiting resistance (R2) is connected with the other end armature winding of series-wound motor (M), the second excitation winding (L2) one end more respectively through the Single port of current measurement circuit (4), the other end of the second excitation winding (L2) is connected with tension measuring circuit (2), the negative pole end of fly-wheel diode (D), uncontrollable rectifying part respectively behind the another port of current measurement circuit (4), tension measuring circuit (2), current measurement circuit (4) output are connected with digital microcontroller (3) respectively, the output of digital microcontroller (3) is connected with isolated drive circuit (1), first device for power switching (V1) is connected with isolated drive circuit (1), uncontrollable rectifying part respectively.

2. the brake control circuit of a kind of series-wound motor according to claim 1, it is characterized in that, described uncontrollable rectifying part (6) comprises the first diode (D1), the second diode (D2), the 3rd diode (D3) and the 4th diode (D4), resistance (R1) and electric capacity (C), and the negative pole one termination AC power of the first diode (D1) is also connected in positive pole one end of the 3rd diode (D3); Negative pole one end of 3rd diode (D3) is connected behind the another port of current measurement circuit (4) with negative pole one end of the 4th diode (D4), negative pole one end of electric capacity (C), the other end of the second excitation winding (L2) respectively; The positive pole one termination AC power of the 4th diode (D4) is also connected with negative pole one end of the second diode (D2); Positive pole one end of first diode (D1), positive pole one end of the second diode (D2) are connected with one end of resistance (R1) respectively; The other end of resistance (R1) is connected with positive pole one end of electric capacity (C), the first device for power switching (V1) respectively.