CN205070950U - Three level switch power amplifier - Google Patents

Abstract

The utility model discloses a three level switch power amplifier, its control regulating circuit include that bridge switch tube drive signal produces the circuit and produces the circuit with lower bridge switch tube drive signal, and the current feedback signal of bearing coil obtains error signal with set signal through the PI regulating circuit on the one hand, and reentrant PWM regulator forms the drive signal who goes up the bridge switch tube, on the one hand obtain error signal with set signal after enlargeing the modulate circuit through the PI regulating circuit, reentrant PWM regulator forms the drive signal of bridge switch tube down, then with drive signal the opening and turn -offing of power tube in pulse modulation circuit and driving isolation circuit direct control power switch bridge circuit to reach control electromagnetic bearing coil current's mesh.

Description

Three Level Switching Power Amplifier

technical field

The utility model belongs to the field of switching power amplifiers, in particular to a three-level switching power amplifier.

Background technique

Traditional mechanical thrust bearings have defects such as friction, wear and the resulting temperature rise, which affect the speed and accuracy of rotating machinery. The magnetic suspension bearing uses magnetic force to suspend the rotor in the air, and then drives the rotor with a rotating motor to rotate around a specific axis. There is no contact between the rotor and the stator, no friction, long service life, no lubrication, and high precision. A new type of high performance bearing.

In the five-degree-of-freedom magnetic suspension bearing control system, the power amplifier is a very important part of the magnetic suspension bearing control system. In the early days, electromagnetic bearing systems mostly used linear power amplifiers. Due to the shortcomings of linear power amplifiers such as low efficiency, relatively large volume, and small power range, nowadays almost all electromagnetic bearing systems use switching power amplifiers with high efficiency and good dynamic characteristics. The earlier switching power amplifiers of magnetic suspension bearings all adopt the current two-level modulation technology, which has the disadvantages of large current ripple and limited dynamic characteristics, while the three-level modulation technology can effectively reduce the current ripple, reduce electromagnetic noise, and at the same time reduce the The copper loss of the coil is reduced, and it is also beneficial to improve the current response speed and control force response speed of the switching power amplifier, thereby improving the overall performance of the system.

The patent document with the Chinese patent authorization number ZL100461627C discloses a control method for a three-level switching power amplifier, including a signal mixing processing circuit, a pulse width modulation circuit, a protection and an optocoupler isolation drive circuit, and processing the signal from the controller to obtain The corresponding voltage signal drives the bridge circuit to control the current of the load. The signal mixing processing circuit of the amplifier is to set the current signal of the inductive load fed back from the electromagnetic coil of the power switch bridge circuit and the voltage adjusted by the quiescent current and add the signal of the PID controller. The output signal is passed through the pulse width bar value. The circuit and the optocoupler isolate the drive circuit and directly drive the power switch tube. The control method uses an inverter to reverse the PID signal to respectively realize the control of the upper and lower switching tubes. The utility model provides a three-level switching power amplifier with a completely different control method from the above-mentioned method.

Utility model content

The purpose of the utility model is to provide a three-level switching power amplifier, which can improve the current response speed and control force response speed of the switching power amplifier.

In order to achieve the above purpose, the technical solution adopted by the utility model is: a three-level switching power amplifier, including a power switch bridge circuit with an upper bridge switch tube and a lower bridge switch tube, and a power switch bridge circuit connected between the two switch tubes. Electromagnetic bearing coil Lm, the driving signals of the upper and lower bridge switch tubes are generated by the switch tube control circuit, the switch tube control circuit includes a pulse modulation circuit, an isolation drive circuit and a control regulation circuit, and the output signal of the control regulation circuit passes through After the pulse modulation circuit and the isolated drive circuit drive the corresponding power switch tube of the power switch bridge circuit, the control regulation circuit is used to process the given signal and the electromagnetic coil current feedback signal of the power switch bridge circuit. The control regulation circuit Including the upper bridge switch tube drive signal generation circuit and the lower bridge switch tube drive signal generation circuit, the upper and lower bridge switch tube drive signal generation circuits both include sequentially connected PI regulators for processing current feedback signals and given signals The circuit and the PWM controller, and the lower bridge switch tube drive signal generation circuit also includes an amplification conditioning circuit for amplifying a given signal, and the amplification conditioning circuit is connected to the given signal input end of the corresponding PI adjustment circuit.

The control and adjustment circuit also includes a signal conditioning circuit for amplifying, filtering and conditioning the current feedback signal.

The amplification and conditioning circuit includes an op amp U5A, the inverting input of U5A is used to connect to a given signal through parallel resistors R41 and R42, and the output of U5A is connected to its inverting input through a resistor R43.

The PI adjustment circuit includes an operational amplifier, the non-inverting input terminal of the operational amplifier is used for connecting with a given signal, and the inverting input terminal of the operational amplifier is used for connecting with a current feedback signal.

The PWM regulator adopts a chip with an adjustable duty ratio of 0% to 100%.

The pulse modulation circuit adopts AND gate chip CD4081BM.

The control and adjustment circuit of the three-level switching power amplifier of the utility model includes an upper bridge switch tube drive signal generation circuit and a lower bridge switch tube drive signal generation circuit. signal, and then enters the PWM regulator to form the driving signal of the upper bridge switching tube; on the one hand, the error signal is obtained through the PI regulating circuit with the given signal after the amplification and conditioning circuit, and then enters the PWM regulator to form the driving signal of the lower bridge switching tube. Then, the driving signal directly controls the opening and closing of the power tube in the power switch bridge circuit through the pulse modulation circuit and the driving isolation circuit, so as to achieve the purpose of controlling the coil current of the electromagnetic bearing.

Description of drawings

Fig. 1 is the power switch tube bridge circuit of the utility model three-level switching power amplifier principle structure diagram;

Fig. 2 is the switching tube control circuit of the principle structural diagram of the three-level switching power amplifier of the present invention;

Fig. 3 is a schematic circuit diagram of the generation of the drive signal of the upper bridge switching tube in the control and adjustment circuit;

Fig. 4 is a schematic circuit diagram of the generation of the drive signal of the lower bridge switching tube in the control and regulation circuit;

Fig. 5 is the circuit schematic diagram of the PWM controller of the present utility model;

Fig. 6 is the circuit schematic diagram of the pulse modulation circuit of the present utility model;

Figure 7 is a schematic diagram of the full bridge circuit.

detailed description

Below in conjunction with accompanying drawing and specific embodiment the utility model is further introduced.

As shown in Figure 1, it is the schematic diagram of the embodiment of the three-level switching power amplifier of the present invention. As can be seen from the figure, the amplifier includes a power switch bridge circuit and an electromagnetic bearing coil Lm connected between the two switching tubes. The power switch bridge circuit is a half-bridge main circuit, including the upper bridge switch tube Q1 and the lower bridge switch tube Q2, Q1 and Q2 are MOSFETs or IGBTs, D1 and D2 are power diodes, electrolytic capacitor E1 and non-inductive capacitor C1 are supporting The function of the bus voltage and the peak absorption power tube, Rm is the resistance of the electromagnetic axis coil, the current transformer is connected in series in the loop to sample the inductor current, and its current feedback signal is ILF. The control method of the three-level power amplifier includes the following steps:

(1) When charging, the upper bridge switch tube is turned on and off under the control of the corresponding drive signal, and the lower bridge switch tube Q2 remains on. When both Q1 and Q2 are turned on, Q1, the current transformer , Rm, Lm and Q2 form a charging circuit. When Q1 is turned off and Q2 is turned on, D2, current transformer, Rm, Lm and Q2 form a freewheeling circuit;

(2) When discharging, the switch tube Q2 of the lower bridge is turned on and off under the control of the corresponding drive signal, and the switch tube Q1 of the upper bridge remains in the off state. When Q2 is turned on, D2, the current transformer, Rm, Lm and Q2 form a In the freewheeling circuit, when Q2 is turned off, Lm is in the discharge state, forming a discharge circuit composed of D2, current transformer, Rm, Lm and D1.

In the power switch bridge circuit of this embodiment, the upper and lower switch tube drive signals are generated by the switch tube control circuit, as shown in Figure 2, the switch tube control circuit includes a pulse modulation circuit, an isolation drive circuit and a control regulation circuit, and the control regulation circuit The output signal of the output signal drives the corresponding power switch tube of the power switch bridge circuit after passing through the pulse modulation circuit and the isolation drive circuit. The control regulation circuit is used to process the given signal and the electromagnetic coil current feedback signal of the power switch bridge circuit. The regulating circuit includes an upper bridge switching tube driving signal generating circuit and a lower bridge switching tube driving signal generating circuit, and both the upper and lower bridge switching tube driving signal generating circuits include sequentially connected circuits for processing current feedback signals and given signals. The PI adjustment circuit and the PWM controller, and the lower bridge switch tube drive signal generation circuit also includes an amplification conditioning circuit for amplifying a given signal, and the amplification conditioning circuit is connected to a given signal input end of the corresponding PI adjustment circuit.

The power switch bridge circuit of this embodiment is a half-bridge main circuit, including an upper bridge switch tube Q1 and a lower bridge switch tube Q2, Q1 and Q2 are MOSFETs or IGBTs, D1 and D2 are power diodes, electrolytic capacitor E1 and a non-inductive capacitor C1 is the function of supporting the bus voltage and absorbing the peak of the power tube, Rm is the resistance of the electromagnetic axis coil, Lm is the inductance of the electromagnetic bearing coil, the current transformer is connected in series in the loop to sample the inductor current, and its current feedback signal is ILF.

The G pole of Q1 is connected to the drive signal DRV1_G through the resistor R11. A series branch of the resistor R10 and the diode D11 is connected in parallel at both ends of R11. The S pole of Q1 is connected to the drive signal DRV1_E, and the resistor R12 is connected between the G pole and the S pole. ; The G pole of Q2 is connected to the drive signal DRV2_G through the resistor R21, and the series branch of the resistor R20 and the diode D5 is connected in parallel at both ends of R21, and the S pole of Q2 is connected to the drive signal DRV2_E, and a resistor is connected between the G pole and the S pole R22.

The control and adjustment circuit also includes a signal conditioning circuit for amplifying, filtering and conditioning the current feedback signal.

The generation of the drive signal G1 of the upper bridge switching tube in the control and regulation circuit is shown in Figure 3. The current feedback signal ILF is amplified, filtered and conditioned to obtain the signal IFA. IFA is connected to the inverting input terminal of U4A precision operational amplifier OPA2277U through resistor R32, and the signal IGA conditioned by the given signal IG is connected to the non-inverting input terminal of U4A precision operational amplifier through resistor R33 and capacitor C32, and the given and feedback are adjusted by PI The circuit obtains the error signal EO1, and the PI parameter is determined by the capacitor C33, the resistor R34, and the capacitor C34, and is also affected by the feedforward capacitor C32.

EO1 enters the error signal input terminal of the PWM regulator, and the duty cycle of the chip used by the PWM regulator can be adjusted from 0% to 100%. The utility model example uses UC3843, and the duty cycle of the output square wave of UC3843 is adjusted by the error signal .

The generation of the drive signal G2 of the lower bridge switching tube in the control and adjustment circuit is shown in Figure 4. The signal IGB is obtained after conditioning the given signal IG, and the amplification and conditioning circuit composed of the resistor R41, resistor R42, resistor R43 and operational amplifier U5A is used to realize the given signal. The amplification of the specific magnification of the fixed signal IGB is lifted. In this embodiment, the amplification of 1.01 times is preferred. The inverting input terminal of U5A is used to connect to the IGB through the parallel circuit formed by the resistor R41 and the resistor R42, and its non-inverting input terminal is connected to the ground through the resistor R44. The output terminal of U5A is connected to its inverting input terminal through the resistor R43; the output signal is filtered by the filter resistor R45 and the filter capacitor C41, and then connected to the non-phase of the PI adjustment circuit U6A precision operational amplifier OPA2277U through the op amp U5B through the resistor R51 and capacitor C51 At the input terminal, the conditioned feedback signal IFB is connected to the inverting input terminal of the U6A precision operational amplifier through the resistor R52, and the given signal and the feedback signal are obtained through the PI adjustment circuit to obtain the error signal EO2, and the PI parameters are determined by the capacitor C52, the resistor R53, and the capacitor C53 decision, and is affected by the feed-forward capacitor C51.

As shown in Figure 5, the signal EOX (where X is 1 or 2, that is, EO1 and EO2) output from the PI adjustment circuit enters the first pin of the error signal input pin of the PWM regulator UC3843BN, and its operating frequency is controlled by the fourth pin The external resistor RT and capacitor CT are determined. The third pin is the signal after the current divider, which is used to compare the error signal with it to generate a duty cycle change. The sixth pin is the output pin for driving the square wave. The duty ratio of the chip used by the PWM regulator can be adjusted from 0% to 100%, and the duty ratio of the output square wave of UC3843BN is adjusted through the error signal.

As shown in Figure 6, the pulse modulation circuit uses an AND gate chip CD4081BM, and the drive signal GX (X is 1 or 2) enters the input pins 1 and 2 of the AND gate U2XA, and at the same time pins 1 and 2 are short-circuited, and The output pin 3 of the gate is connected to the input pin 5 of the AND gate U2XB, the fault signal level OFF is connected to the input pin 6 of U2XB, and the output pin 4 of the U2XB AND gate is the DRVX signal, and the X mentioned above is 1 or 2 .

The drive signals G1 and G2 are obtained by the pulse modulation circuit and the isolation drive circuit to obtain DRV1_G, DRV1_E and DRV2_G, DRV2_E, respectively to directly drive the power switch tubes Q1 and Q2 in the main circuit of the half bridge to turn on and off, so as to control the electromagnetic bearing coil current the goal of.

The working principle and process of the control method of the three-level switching power amplifier of the present invention are as follows: Since the given signal IGB has a 1/100 rise, when charging, the power switch tube Q1 performs a duty cycle under the control of the PWM controller UC3843 Changing on and off; at this time, the control power switch tube Q2 remains on under the control of the PWM controller UC3843BN, thus realizing the charging state of Q1, current transformer, Rm, Lm and Q2 or D2, current transformer, The freewheeling state of Rm, Lm and Q2; when discharging, the power switch tube Q2 is turned on and off under the control of the PWM controller UC3843BN, and the signal IGA is the same as the given signal and IG amplitude, then The power switch tube Q1 is always in the off state, thus realizing the freewheeling state of D2, current transformer, Rm, Lm and Q2 or the discharging state of D2, current transformer, Rm, Lm and D1.

The power switch bridge circuit of this embodiment is a half-bridge main circuit, and of course a full-bridge circuit can also be used, as shown in Figure 7, including four power transistors Q1-Q4, wherein Q1 and Q3 are upper-bridge power transistors , Q2, Q4 are power tubes of the lower bridge, and its control principle is the same as that of the full bridge circuit.

The above embodiments are only used to help understand the core idea of the utility model, and cannot limit the utility model with this. For those skilled in the art, any modification or equivalent replacement of the utility model according to the idea of the utility model shall be carried out in specific implementation. Any changes done in the manner and scope of application should be included in the protection scope of the present utility model.

Claims (6)

1. a tri-level switch power amplifier, comprise the power switch bridge circuit with switch on the bridge pipe and bridge switch pipe and the electromagnetic bearing coil Lm be connected between two switching tubes, it is characterized in that, on described, the drive singal of bridge switch pipe is produced by switch controlled circuit, this switch controlled circuit comprises pulse modulated circuit, isolated drive circuit and regulating and controlling circuit, the output signal of described regulating and controlling circuit passes through pulse modulated circuit, the corresponding power switch pipe of isolated drive circuit rear drive power switch bridge circuit, described regulating and controlling circuit is used for the solenoid current feedback signal of Setting signal and power switch bridge circuit to process, this regulating and controlling circuit comprises switch on the bridge pipe drive signal generation circuit and bridge switch pipe drive signal generation circuit, on, bridge switch pipe drive signal generation circuit include connect in turn for PI regulating circuit that current feedback signal and Setting signal are carried out processing and PWM controller, and bridge switch pipe drive signal generation circuit also comprises the amplification modulate circuit for carrying out Setting signal to amplify process, this amplification modulate circuit is connected to the Setting signal input of corresponding PI regulating circuit.

2. tri-level switch power amplifier according to claim 1, is characterized in that: described regulating and controlling circuit also comprises for amplifying current feedback signal, the signal conditioning circuit of filtering and conditioning.

3. tri-level switch power amplifier according to claim 1 and 2, it is characterized in that: described amplification modulate circuit comprises amplifier U5A, the inverting input of U5A is used for being connected with Setting signal with resistance R42 by the resistance R41 of parallel connection, and the output of U5A is connected with its inverting input by resistance R43.

4. tri-level switch power amplifier according to claim 3, is characterized in that: described PI regulating circuit comprises an amplifier, and the in-phase input end of amplifier is for connecting Setting signal, and its inverting input is used for being connected with current feedback signal.

5. tri-level switch power amplifier according to claim 1, is characterized in that: the chip that described pwm modulator adopts duty ratio 0% ~ 100% adjustable.

6. tri-level switch power amplifier according to claim 1, is characterized in that: described pulse modulated circuit adopts and door chip CD4081BM.