CN204733093U - The tri-level switch power amplifier that one-sided brachium pontis frequency multiplication drives - Google Patents

Abstract

The utility model discloses the tri-level switch power amplifier that a kind of one-sided brachium pontis frequency multiplication drives.Its controller is used for converting corresponding switch logic signals to by foreign current Setting signal with from the current feedback signal of current detection circuit, and the actual current value of the solenoid load that current feedback signal and current detection circuit detect is directly proportional; The input of light-coupled isolation and drive circuit is corresponding with the output of controller to be connected, and for future, each way switch logical signal isolation of self-controller is amplified and formed the drive singal of each full-controlled switch device for driving each H-bridge circuit; The output of the control end of each full-controlled switch device of each H-bridge circuit and light-coupled isolation and drive circuit is corresponding to be connected.The utility model is obtaining the low ripple characteristic that tri-level switch power amplifier exports while, improve separately the amplitude of second harmonic component in power amplifier output ripple, produce and there is the stable high frequency small-signal source exported, be integrated with the function in power amplifier and high frequency small-signal source.

Description

The tri-level switch power amplifier that one-sided brachium pontis frequency multiplication drives

Technical field

The utility model relates to a kind of tri-level switch power amplifier, and being applicable to needs high frequency small-signal to inject the occasion realizing sensor-less operation in Mechatronic Systems, such as, be suitable for self-sensing Active Magnetic Bearing.

Background technology

Active Magnetic Bearing has without friction, without the need to lubrication, pollution-free, rotating speed advantages of higher, very fast in field development such as Aero-Space, flywheel energy storage, turbine turbomachinery, high-speed machine tools in recent years.Having in transducer active active magnetic bearing system, in order to the closed loop feedback realizing system controls, must assemble in each degree of freedom of rotor the real-time detection that independently displacement transducer carries out rotor-position signal respectively.The expensive price of displacement transducer makes the cost of system be difficult to reduce, the cost too increase assembling, safeguarding.In addition, the space requirement needed for the displacement sensor of installation position constrains the optimization of electromagnetic bearing size, and transducer is different with the position of actuator also makes control more complicated.

Self-sensing Active Magnetic Bearing is in recent years for solving the problem and the novel electromagnetic bearing proposed.Change and the characteristic of change with rotor-position by utilizing the inductance size of the solenoid of electromagnetic bearing, the function of position transducer is realized while solenoid itself can be made to produce electromagnetic force, thus avoid the use of independent position sensor, the self-sensing realizing Active Magnetic Bearing runs.The main method realizing self-sensing Active Magnetic Bearing at present can be divided into current slope method and high frequency small-signal injection method.Wherein, the dynamic characteristic of current slope method is good, but on System Hardware Requirement high and be subject to current noise impact.The precision of high frequency small-signal injection method is high, good reliability but need extra high frequency small-signal source, utilize the alternative high frequency small-signal source of first harmonic component that in two traditional level PWM close power amplifier output current ripples, amplitude is relatively high, but its overall high ripple characteristics can produce larger loss in electromagnetic bearing, and the amplitude of first harmonic is stable not.The ripple content that tradition three-level pwm close power amplifier exports is significantly lower than two level switch power amplifiers, but in ripple, the amplitude of each harmonic component does not all reach the technical requirement realizing Active Magnetic Bearing self-sensing and run, therefore two traditional level PWM close power amplifiers and traditional three-level pwm close power amplifier all can not be used for self-sensing Active Magnetic Bearing.

Utility model content

The purpose of this utility model is to provide the tri-level switch power amplifier that a kind of one-sided brachium pontis frequency multiplication drives, to overcome all or part of defect of prior art.

Utility model design of the present utility model is: keeping power amplifier to export overall low ripple characteristic while, by improving separately the amplitude of second harmonic component in power amplifier output ripple, produce the high frequency small-signal source of the self-sensing operation that can be used for the Mechatronic Systems such as Active Magnetic Bearing.Thus the self-sensing realizing magnetic bearing while reducing system loss runs, the performance of further raising system, reduction system cost.

For achieving the above object, technical solution adopted in the utility model is: the tri-level switch power amplifier that the utility model one-sided brachium pontis frequency multiplication drives comprises light-coupled isolation and drive circuit, power conversion circuit, current detection circuit and can be used in foreign current Setting signal and the controller converting corresponding switch logic signals from the current feedback signal of current detection circuit to, and the actual current value of the solenoid load that described current feedback signal and current detection circuit detect is directly proportional; Described power conversion circuit comprises H-bridge circuit; The input of light-coupled isolation and drive circuit is corresponding with the output of controller to be connected, and the output of the control end of each full-controlled switch device of described H-bridge circuit and light-coupled isolation and drive circuit is corresponding to be connected.

Further, the drive singal that light-coupled isolation described in the utility model and drive circuit export is modulated in the mode of variable pulse width the full-controlled switch device on first brachium pontis of each described H-bridge circuit, and the drive singal that described light-coupled isolation and drive circuit export is modulated in the mode of fixed pulse width the full-controlled switch device on second brachium pontis; Full-controlled switch device on second brachium pontis completes a conducting, turn off time cycle of action is that full-controlled switch device on first brachium pontis completes a conducting, turns off the half of the time cycle of action.

Further, controller described in the utility model comprises current control module, pwm signal generation module, rising edge trigger module, square wave generation module and A/D modular converter, described A/D modular converter is for receiving foreign current Setting signal and current feedback signal, the output of A/D modular converter is connected with the input of current control module, the output of current control module is connected with the input of pwm signal generation module, the input of rising edge trigger module is connected with one of them output of pwm signal generation module, the output of rising edge trigger module is connected with the input of square wave generation module, each output of square wave generation module is respectively connected with an input of light-coupled isolation and drive circuit with each output of pwm signal generation module.

Further, current detection circuit described in the utility model comprises current sensor and level shifting circuit, the former limit of current sensor and described solenoid load in series, the secondary of current sensor is connected with the input of level shifting circuit, and the output of level shifting circuit is connected with the input of controller.

Further, the utility model also comprises buffer circuit, and the input of described light-coupled isolation and drive circuit connects through buffer circuit is corresponding with the output of controller.

The tri-level switch power amplifier (below also can referred to as " power amplifier ") that the utility model one-sided brachium pontis frequency multiplication drives is compared with two traditional level switch power amplifiers, its advantage is: by using different switching frequency, multi-form drive singal controls the conducting of the full-controlled switch device on the different brachium pontis of the H-bridge circuit in power amplifier, turn off, selectivity improves the amplitude of the second harmonic component in power amplifier output ripple, while forming the high frequency small-signal source be similar in two level power amplifiers outputs, also achieve the operation of power amplifier three level and export overall ripple content to reduce power amplifier, and then reduce loss, in addition, a brachium pontis in H-bridge circuit is controlled by the switch logic signals of two frequency multiplication square all the time, ensure that the stable output of high frequency small-signal, and the frequency of high frequency small-signal is doubled, control the frequency domain at current component place in exporting away from power amplifier, be also conducive to extraction and the process of signal.The advantage of the utility model power amplifier compared with traditional tri-level switch power amplifier is: be integrated with high frequency small-signal source in power amplifier inside, is beneficial to the complexity simplifying the Mechatronic Systems such as self-sensing Active Magnetic Bearing, improves reliability.

Accompanying drawing explanation

Fig. 1 is the schematic block circuit diagram of the tri-level switch power amplifier that one-sided brachium pontis frequency multiplication of the present utility model drives;

Fig. 2 is the circuit theory diagrams of buffer circuit and light-coupled isolation and drive circuit;

Fig. 3 is the circuit theory diagrams of power conversion circuit and current detection circuit;

Fig. 4 is the voltage current waveform schematic diagram that the switch logic signals that exports of controller in the utility model and power amplifier export.

Embodiment

The tri-level switch power amplifier that the one-sided brachium pontis frequency multiplication of the utility model drives mainly comprises controller 1, light-coupled isolation and drives road 3, power conversion circuit 4 and current detection circuit 5, and power conversion circuit 4 comprises H-bridge circuit 4-1.Wherein, controller 1 can be used in converting corresponding switch logic signals to by foreign current Setting signal with from the current feedback signal of current detection circuit 5, and the actual current value of the solenoid load that current feedback signal and current detection circuit 5 detect is directly proportional.The input of light-coupled isolation and drive circuit 3 is corresponding with the output of controller 1 to be connected, and for future, each way switch logical signal isolation of self-controller 1 is amplified, thus forms the drive singal of each full-controlled switch device for driving H-bridge circuit 4-1; The output of the control end of each full-controlled switch device of H-bridge circuit 4-1 and light-coupled isolation and drive circuit 3 is corresponding to be connected.

The utility model also can comprise buffer circuit 2 further, the input of light-coupled isolation and drive circuit 3 is connected through buffer circuit 2 is corresponding with the output of controller 1, thus improves the stability of the switch logic signals that controller 1 exports.

In the utility model, foreign current Setting signal refers to the reference signal of the current value of the decision power amplifier needs output from upper level control appliance; Solenoid load refers to the winding coil for generation of electromagnetic force in electromechanical equipment, as electromagnetic bearing stator winding coil.

Below in conjunction with accompanying drawing, with specific embodiment, the utility model is further described.

In the embodiment shown in fig. 1, the tri-level switch power amplifier that the one-sided brachium pontis frequency multiplication of the utility model drives comprises controller 1, buffer circuit 2, light-coupled isolation and switch driving circuit 3, power conversion circuit 4 and current detection circuit 5.Wherein, power conversion circuit 4 is containing H-bridge circuit 4-1.

Controller 1 receives the given value of current signal i that external equipment provides _refwith the current feedback signal i that current detection circuit 5 exports _mea, wherein, current feedback signal i _meabe that the actual current of current detection circuit 5 to the solenoid L detected (i.e. solenoid load) carries out direct proportion and zoom in or out and obtain the signal that matches with the incoming level of controller 1, make itself and controller 1.

Controller 1 is according to the given value of current signal i received _refwith current feedback signal i _meaproduce corresponding four-way switch logical signal u _g1~ u _g4, and by four-way switch logical signal u _g1~ u _g4send to light-coupled isolation and drive circuit 3 through buffer circuit 2 after output, light-coupled isolation and drive circuit 3 are to the four-way switch logical signal u of input _g1~ u _g4carry out amplifying, isolating, produce the drive singal u of four road full-controlled switch devices _d1~ u _d4and being sent to power conversion circuit 4, four full-controlled switch devices of the H-bridge circuit in power conversion circuit 4 are at drive singal u _d1~ u _d4control under complete corresponding conducting, turn off action, realize the rising of the electric current in the solenoid L of power conversion circuit 4, constant or decline, the actual current value of solenoid L is through the measurement of current detection circuit 5, amplification and generate the current feedback signal i of real-time update _meaand send to controller 1, form a feedback control loop thus.

As a kind of execution mode of the present utility model, controller 1, by monolithic FPGA digital circuit, utilizes the hardware description language programming realization controller functions such as VHDL, Verilog; In addition, controller 1 also can use DSP digitial controller to realize.

As another kind of execution mode of the present utility model, controller 1 also can use the analog circuit that can realize corresponding function.As a kind of concrete example wherein, controller 1 can comprise current control module 1-1, pwm signal generation module 1-2, rising edge trigger module 1-3, square wave generation module 1-4 and A/D modular converter 1-5.Wherein, A/D modular converter 1-5 receives the foreign current Setting signal i from upper level control appliance simultaneously _refwith the current feedback signal i exported by current detection circuit 5 _mea, and this two paths of signals is sampled, keep and A/D conversion and generate the given value of current signal i of digital form _ref(k) and current feedback signal i _meak () is sent to current control module 1-1, wherein k represents current sample time.The input received current Setting signal i of current control module 1-1 _ref(k) and current feedback signal i _mea(k), and according to following formula, calculate control signal u by PI control algolithm:

u(k)＝u(k-1)+(K _p+K _iT)e(k)-K _pe(k-1)

In above formula, the value of the control signal that u (k) is current sample time; U (k-1) is the value of the control signal of a upper sampling instant; K _pand K _ibeing respectively the proportionality coefficient in standard P I control algolithm, integral coefficient, for ensureing system stability, can K being made _p>0, K _i>0, K _pand K _iconcrete value the parameter tuning method of conventional PI control algolithm can be used to obtain; The current track error signal that e (k) is current sample time, e (k)=i _ref(k)-i _mea(k); E (k-1) is the current track error signal of a upper sampling instant.

Current control module 1-1 sends the control signal u (k) of current sample time to pwm signal generation module 1-2, and it is T that pwm signal generation module 1-2 produces the cycle _sthe switch logic signals (be called for short " PWM switch logic signals ") of pulse-width modulation (PWM) form.At a switch periods T _sin, switch logic signals u _g1the conducting state of high level corresponding full-controlled switch device T1, u _g1the off state of low level then corresponding T1, the duration of full-controlled switch device T1 conducting state is expressed as T _on, then the duty ratio of PWM switch logic signals is α=T _on/ T _s, and 0≤α≤1.The first via PWM switch logic signals u that pwm signal generation module 1-2 exports _g1duty cycle alpha be directly proportional to the size of u (k), the second road PWM switch logic signals u _g2with u _g1become complementary relationship, if i.e.: u _g1for high level, then u _g2for low level; If u _g1for low level, then u _g2for high level.U _g2duty ratio equal (1-α).The two-way PWM switch logic signals u that pwm signal generation module 1-2 exports _g1and u _g2signal isolation is carried out and the corresponding drive singal u becoming the full-controlled switch device T1 on the brachium pontis 1 of the H-bridge circuit in power conversion circuit respectively after amplifying successively through buffer circuit 2, light-coupled isolation and drive circuit 3 _d1, full-controlled switch device T2 drive singal u _d2, drive singal u _d1and u _d2be sent to power conversion circuit 4 respectively, so by the conducting that controls full-controlled switch device T1 and T2, turn off the discharge and recharge realizing solenoid L (load), thus improve, maintain or reduce the output current of power amplifier.

Meanwhile, rising edge trigger module 1-3 receiving key logical signal u _g1and detect u _g1rising edge, generate and send synchronous triggering signal to square wave generation module 1-4, as the enabling signal of square wave generation module 1-4.Correspondingly, square wave generation module 1-4 generates the switch logic signals u of the square of two line state complementations _g3and u _g4, the special PWM switch logic signals that duty ratio is 0.5 can be regarded as, but u _g3and u _g4switch periods be u _g1and u _g2half, i.e. T _s/ 2.Switch logic signals u _g3and u _g4realize signal isolation successively through buffer circuit, light-coupled isolation and drive circuit and after amplifying, become the drive singal u of the full-controlled switch device T3 on the brachium pontis 2 in H-bridge circuit 4-1 accordingly _d3with the drive singal u of full-controlled switch device T4 _d4.

As shown in Figure 2, as a kind of execution mode of the present utility model, buffer circuit 2 is made up of eight NAND gate U1 ~ U8, and light-coupled isolation and drive circuit 3 are made up of four optocoupler U9 ~ U12.Controller 1 produces and sends switch logic signals u _g1to the input of the NAND gate U1 in buffer circuit 2, U1 and U2 connects, and the output of U2 is connected to the input of the optocoupler U9 of light-coupled isolation and drive circuit 3, the drive singal u of the full-controlled switch device T1 in H-bridge circuit 4-1 _d1by optocoupler U ₉export.In like manner, the switch logic signals u of controller 1 output _g2, u _g3and u _g4the drive singal u of full-controlled switch device T2, T3, T4 is generated through buffer circuit 2 and light-coupled isolation and drive circuit 3 _d2, u _d3, u _d4process be similar to the T1 drive singal u of full-controlled switch device _d1generative process, do not repeat them here.

As shown in Figure 3, power conversion circuit 4 comprises H-bridge circuit.In Fig. 3, H-bridge circuit 4-1 is U by four full-controlled switch device T1, T2, T3, T4 and voltage _dcdC bus power supply composition, wherein full-controlled switch device T1 and T2 forms the connection mid point of brachium pontis 1, T1 and T2 is a point, and one end of a point connection solenoid L (i.e. load), the voltage at this point place is u _a; The connection mid point that full-controlled switch device T3 and T4 forms brachium pontis 2, T3 and T4 is b point, and b point connects the other end of solenoid L, and the voltage at b point place is u _b, therefore voltage (i.e. load voltage) u at solenoid L two ends _ab=u _a-u _b; The control end of full-controlled switch device T1 receives the drive singal u of the optocoupler U9 output in light-coupled isolation and drive circuit 3 _d1, the control end of full-controlled switch device T2 receives the drive singal u of the optocoupler U10 output in light-coupled isolation and drive circuit 3 _d2, the control end of full-controlled switch device T3 receives the drive singal u of the optocoupler U11 output in light-coupled isolation and drive circuit 3 _d3, the control end of full-controlled switch device T4 receives the drive singal u of the optocoupler U12 output in light-coupled isolation and drive circuit 3 _d4.

As shown in Figure 3, current detection circuit 5 comprises current sensor 5-1 and level shifting circuit 5-2.Wherein, level shifting circuit 5-2 is by integrated operational amplifier U13 and resistance R ₁, R ₂, R ₃the proportional amplifier of composition.Connect with the solenoid L of power conversion circuit 4 in the former limit of current sensor 5-1; The secondary of current sensor 5-1 exports the voltage signal be directly proportional to the actual current size in solenoid L, and this voltage signal is through resistance R ₁be sent to integrated operational amplifier U ₁₃positive input terminal carry out level conversion, thus by integrated operational amplifier U ₁₃generate the current feedback signal i matched with the incoming level of controller 1 _meaand send to controller 1.

As shown in Figure 4, when the tri-level switch power amplifier that one-sided brachium pontis frequency multiplication of the present utility model drives is in rising, constant and decline three operating states to the electric current that solenoid L exports, the voltage of four-way switch logical signal and solenoid L, the waveform of current signal are respectively as the T of first, second, and third in Fig. 4 _sshown in each signal waveform in time period (order from left to right by Fig. 4).Below in conjunction with Fig. 4, the three-level control principle strategy that the one-sided brachium pontis frequency multiplication adopted the utility model drives and output characteristic are described.In Fig. 4, subgraph (a)-(h) is followed successively by the switch logic signals u that controller 1 exports _g1waveform, switch logic signals u _g2waveform, switch logic signals u _g3waveform and switch logic signals u _g4waveform, the voltage u at a point place in brachium pontis 1 _awaveform, the voltage u at b point place in brachium pontis 2 _bwaveform, be added in the voltage u at solenoid L two ends _abthe waveform of (i.e. load voltage), the current i of solenoid L _lwith the current average of solenoid L waveform.Wherein, the switch logic signals u that pwm signal generation module 1-2 produces is set _g1and u _g2switch periods be T _s, and u _g1and u _g2for high and low level is complementary, namely both can not be high level simultaneously or be low level.The switch logic signals u that square wave generation module 1-4 produces is set _g3and u _g4switch periods be T _s/ 2, and u _g3and u _g4also be that high and low level is complementary.As switch logic signals u _g1during for high level, switch logic signals u _g1carry out isolating through buffer circuit 2 and light-coupled isolation and drive circuit 3 successively, amplify after generate drive singal u _d1, drive singal u _d1drive the full-controlled switch device T1 conducting on the brachium pontis 1 of H-bridge circuit 4-1; Due to switch logic signals u _g2with u _g1complementation, therefore full-controlled switch device T2 turns off, the now voltage u of a point _aequal DC bus-bar voltage U _dc; In like manner, as switch logic signals u _g1during for low level, full-controlled switch device T1 turns off, T2 conducting, now the voltage u of a point _aequal zero.By adjustment switch logic signals u _g1in high level time account for the ratio (i.e. duty cycle alpha=T of whole switch periods _on/ T _s, 0≤α≤1), a switch periods T can be controlled _sthe u of interior a point voltage _amean value 0 to U _dcscope in change.Similar, as switch logic signals u _g3during for high level, switch logic signals u _g3carry out isolating through buffer circuit 2 and light-coupled isolation and drive circuit 3 successively, amplify after generate drive singal u _d3, drive singal u _d3drive the full-controlled switch device T3 conducting on the brachium pontis 2 of H-bridge circuit 4-1, due to switch logic signals u _g4with u _g3complementation, therefore full-controlled switch device T4 turns off, the now voltage u of b point _bequal DC bus-bar voltage U _dc; In like manner, as switch logic signals u _g3during for low level, full-controlled switch device T3 turns off, T4 conducting, now b point voltage u _bequal zero.Due to the switch logic signals u of square _g3, u _g4high level, low level time equal, namely duty ratio is 0.5, therefore the average voltage of b point in a switch periods be always U _dc/ 2.

With first of Fig. 4 T _swaveform in time period is that example is specifically described:

At front 1/4T _sin time period, make the switch logic signals u that controller 1 exports _g1for high level, u _g2for low level, then full-controlled switch device T ₁conducting, T ₂turn off, the voltage u at a point place _aequal DC bus supply voltage U _dc; Make switch logic signals u _g3for low level, u _g4for high level, then full-controlled switch device T3 turns off, T4 conducting, the voltage u at b point place _bequal 0, therefore be added in the voltage u at solenoid L two ends _ab=u _a-u _b=U _dc-0=U _dc>0, now DC bus power supply is to solenoid L quick charge, makes the current i of solenoid L _lrapid rising.

At 1/4T _s-1/2T _sin time period, make the switch logic signals u that controller 1 exports _g1for high level, u _g2for low level, then full-controlled switch device T1 conducting, T2 turns off, and is added in the voltage u at brachium pontis 1 mid point a place _a=U _dc; Make switch logic signals u _g3for high level, u _g4for low level, then full-controlled switch device T3 conducting, T4 turns off, the voltage u at b point place _b=U _dc, therefore be added in the voltage u at solenoid L two ends _ab=u _a-u _b=U _dc-U _dc=0, now there is not energy exchange between DC bus power supply and solenoid L, make the current i of solenoid L _lalmost constant, be freewheeling state.

At 1/2T _s-3/4T _sin time period, make the switch logic signals u that controller 1 exports _g1for high level, u _g2for low level, then full-controlled switch device T1 conducting, T2 turns off, and is added in the voltage u at brachium pontis 1 mid point a place _a=U _dc; Make switch logic signals u _g3for low level, u _g4for high level, then full-controlled switch device T3 turns off, T4 conducting, the voltage u at b point place _b=0, therefore the voltage u being added in solenoid L two ends _ab=u _a-u _b=U _dc-0=U _dc, now DC bus power supply is to solenoid L quick charge, makes the coil current i of solenoid L _lrapid rising.

For last 1/4T _stime period, wherein, at front T _on-3/4T _sin time period, make the switch logic signals u that controller 1 exports _g1for high level, u _g2for low level, then full-controlled switch device T1 conducting, T2 turns off, and is added in the voltage u at brachium pontis 1 mid point a place _a=U _dc; Make switch logic signals u _g3for high level, u _g4for low level, then full-controlled switch device T3 conducting, T4 turns off, the voltage u at b point place _b=0, therefore the voltage u being added in solenoid L two ends _ab=u _a-u _b=U _dc-U _dc=0, now there is not energy exchange between DC bus power supply and solenoid L, make the current i in solenoid L _lalmost constant, be freewheeling state.In the end T _s-T _onin time period, make the switch logic signals u that controller 1 exports _g1for low level, u _g2for low level, then full-controlled switch device T1 turns off, T2 conducting, is added in the voltage u at the mid point a place of brachium pontis 1 _a=0; Make switch logic signals u _g3for high level, u _g4for low level, then full-controlled switch device T3 conducting, T4 turns off, the voltage u at b point place _b=U _dc, therefore be added in the voltage u at solenoid L two ends _ab=u _a-u _b=0-U _dc=-U _dc, now solenoid L is to DC bus power supply feedback energy, the current i of solenoid L _lrapid reduction.

Due to first T at Fig. 4 _sin time period, be added in the voltage u at solenoid L two ends _ab=U _dctime be longer than u _ab=-U _dctime, the therefore voltage u at solenoid L two ends _abat this T _smean value in time period is greater than zero, the current average of solenoid rise.

From analyzing above, by controlling four-way switch logical signal u _g1, u _g2, u _g3and u _g4low and high level change, and then control turn-on and turn-off time of four full-controlled switch devices T1, T2, T3 and T4 of H-bridge circuit, the voltage u at solenoid L two ends can be realized _abthree kinds of level states, i.e.+U _dc, 0 and-U _dc, make the utility model be a kind of tri-level switch power amplifier.

In above-mentioned analysis, only for switch logic signals u _g1a particular value of duty cycle alpha discuss.In fact, if meet 0.5< α≤1, the current i of solenoid L _lmean value be propradation, and α is larger, electric current rises faster, obtains maximum climbing speed when α=1.

In like manner, can second, third T in analysis chart 4 _sthe situation of change of the voltage of switch logic signals, solenoid L, the current signal of solenoid L in time period.Wherein, at second T _sin time period, switch logic signals u _g1duty cycle alpha=0.5, therefore the current average of solenoid L keep stable.At the 3rd T _sin time period, switch logic signals u _g1duty ratio 0≤α <0.5, therefore the current i of solenoid L _lmean value for decline state, α is less, and electric current declines faster, obtains maximum fall off rate when α=0.

In order to the high frequency small-signal source comprised in the tri-level switch power amplifier that one-sided brachium pontis frequency multiplication of the present utility model drives is described, below with T _sfor the cycle, set up the voltage u at solenoid L two ends _abfourier series model:

If

$u_a\left(t\right)=a_{01}+\underset{n=1}{\overset{\mathrm{\&infin;}}{\&Sigma;}}\&lsqb;a_{n1}cos\left({\mathrm{n\&omega;}}_{s}t\right)+b_{n1}sin\left({\mathrm{n\&omega;}}_{s}t\right)\&rsqb;$

$u_b\left(t\right)=a_{02}+\underset{n=1}{\overset{\mathrm{\&infin;}}{\&Sigma;}}\&lsqb;a_{n2}cos\left({\mathrm{n\&omega;}}_{s}t\right)+b_{n2}sin\left({\mathrm{n\&omega;}}_{s}t\right)\&rsqb;$

u _ab＝u _a(t)-u _b(t)

In above formula, t represents current time, a ₀₁for u _ain the amplitude of DC component, a _n1for u _ain the amplitude of the n-th subharmonic cosine component, b _n1for u _ain the amplitude of the n-th subharmonic sinusoidal component, a ₀₂for u _bthe amplitude of the DC component comprised, a _n2for u _bin the amplitude of the n-th subharmonic cosine component, b _n2for u _bin the amplitude of the n-th subharmonic sinusoidal component, ω _sfor switching angle frequency, ω _s=2 π/T _s.

Only consider second harmonic, namely get n≤2, according to Fig. 4 (e) and Fig. 4 (f), and in conjunction with the conventional decomposition algorithm of Fourier decomposition, can be calculated:

$u_a\left(t\right)={\mathrm{aU}}_{dc}+\frac{2U_{dc}}{\mathrm{\&pi;}}\sin \left(\mathrm{\&pi;}\mathrm{\&alpha;}\right)\sin \left({\mathrm{\&omega;}}_{s}t\right)-\frac{U_{dc}}{\mathrm{\&pi;}}\sin \left(2\mathrm{\&pi;}\mathrm{\&alpha;}\right)\cos \left(2{\mathrm{\&omega;}}_{s}t\right)$ ①

$u_b\left(t\right)=\frac{U_{dc}}{2}-\frac{U_{dc}}{\mathrm{\&pi;}}sin\left(2{\mathrm{\&omega;}}_{s}t\right)$ ②

$\begin{array}{c}{u}_{ab}\left(t\right)=(a-0.5)U_{dc}+\frac{2U_{dc}}{\mathrm{\&pi;}}\sin \left(\mathrm{\&pi;}\mathrm{\&alpha;}\right)\sin \left({\mathrm{\&omega;}}_{s}t\right)\\ -\frac{U_{dc}}{\mathrm{\&pi;}}\sin \left(2\mathrm{\&pi;}\mathrm{\&alpha;}\right)\cos \left(2{\mathrm{\&omega;}}_{s}t\right)-\frac{2U_{dc}}{\mathrm{\&pi;}}\sin \left(2{\mathrm{\&omega;}}_{s}t\right)\end{array}$ ③

With above formula 1. to formula 3. in, α=T _on/ T _sfor switch logic signals u _g1duty ratio, U _dcfor the magnitude of voltage of DC bus power supply; Formula is 3. in formula, and the Section 1 on the right side of equal sign is DC component, and Section 2 is first harmonic component, and the 3rd, Section 4 is respectively cosine term and the sine term of second harmonic component.As can be seen from formula 1. to formula 3., the amplitude of first harmonic component changes with the change of duty ratio, particularly when α can disappear completely close to ripple amplitude when 0 or 1, therefore stable not as high frequency small-signal source.

Further by u _abt the second harmonic cosine in (), sinusoidal component synthesize the second harmonic component u that can be shown below ₂t (), this formula is the output expression formula in high frequency small-signal source.

$\begin{array}{c}{u}_2\left(t\right)=-\frac{U_{dc}}{\mathrm{\&pi;}}\sin \left(2\mathrm{\&pi;}\mathrm{\&alpha;}\right)\cos \left(2{\mathrm{\&omega;}}_{s}t\right)-\frac{U_{dc}}{\mathrm{\&pi;}}\sin \left(2{\mathrm{\&omega;}}_{s}t\right)\\ =\frac{U_{dc}}{\mathrm{\&pi;}}\sqrt{\mathrm{1+}{\sin }^2\left(2\mathrm{\&pi;}\mathrm{\&alpha;}\right)}\cos (2{\mathrm{\&omega;}}_{s}t-\mathrm{\&theta;})\end{array}$

Wherein, phase angle theta=-arctan (sin (2 π α)).

As can be seen from the output expression formula in above high frequency small-signal source, the output of second harmonic component exists all the time, namely the output frequency f=2 ω in high frequency small-signal source _s/ 2 π=2/T _s.Thus, (frequency is 2/T to realize second harmonic in power amplifier output ripple _s) raising of component amplitude, create and there is the stable high frequency small-signal source exported.

Therefore the control principle of the utility model in conjunction with traditional three-level pwm close power amplifier and the service requirement of self-sensing Active Magnetic Bearing, making controller 1 produce switch periods is respectively T _sthe switch logic signals u of complementation of two-way PWM form _g1, u _g2be T with switch periods _sthe switch logic signals u of the complementation of the two-way square of/2 _g3, u _g4.By ensureing under the prerequisite that signal sequence is synchronous, by u _g1, u _g2and u _g3, u _g4isolation drives the full-controlled switch device on the different brachium pontis of H-bridge circuit respectively after amplifying, design while maintenance power amplifier exports low ripple characteristic, provide frequency to be 2/T _shigh frequency small-signal export novel tri-level switch power amplifier, thus tri-level switch power amplifier and high frequency small-signal source are integrated, be conducive to the complexity simplifying the Mechatronic Systems that self-sensing Active Magnetic Bearing etc. needs high frequency small-signal to inject, improve its reliability.

Claims (8)

1. the tri-level switch power amplifier of an one-sided brachium pontis frequency multiplication driving, it is characterized in that: comprise light-coupled isolation and drive circuit (3), power conversion circuit (4), current detection circuit (5) and can be used in foreign current Setting signal and the controller (1) converting corresponding switch logic signals from the current feedback signal of current detection circuit (5) to, described current feedback signal is directly proportional to the actual current value of the solenoid load that current detection circuit (5) detects; Described power conversion circuit (4) comprises H-bridge circuit (4-1); The input of light-coupled isolation and drive circuit (3) is corresponding with the output of controller (1) to be connected, and the output of the control end of each full-controlled switch device of described H-bridge circuit (4-1) and light-coupled isolation and drive circuit (3) is corresponding to be connected.

2. tri-level switch power amplifier according to claim 1, is characterized in that:

The drive singal that described light-coupled isolation and drive circuit (3) export is modulated in the mode of variable pulse width the full-controlled switch device on first brachium pontis of each described H-bridge circuit (4-1), and the drive singal that described light-coupled isolation and drive circuit (3) export is modulated in the mode of fixed pulse width the full-controlled switch device on second brachium pontis; Full-controlled switch device on second brachium pontis completes a conducting, turn off time cycle of action is that full-controlled switch device on first brachium pontis completes a conducting, turns off the half of the time cycle of action.

3. tri-level switch power amplifier according to claim 1 and 2, it is characterized in that: described controller (1) comprises current control module (1-1), pwm signal generation module (1-2), rising edge trigger module (1-3), square wave generation module (1-4) and A/D modular converter (1-5), described A/D modular converter (1-5) is for receiving foreign current Setting signal and current feedback signal, the output of A/D modular converter (1-5) is connected with the input of current control module (1-1), the output of current control module (1-1) is connected with the input of pwm signal generation module (1-2), the input of rising edge trigger module (1-3) is connected with one of them output of pwm signal generation module (1-2), the output of rising edge trigger module (1-3) is connected with the input of square wave generation module (1-4), each output of square wave generation module (1-4) is respectively connected with an input of light-coupled isolation and drive circuit (3) with each output of pwm signal generation module (1-2).

4. tri-level switch power amplifier according to claim 1 and 2, is characterized in that:

Described current detection circuit (5) comprises current sensor (5-1) and level shifting circuit (5-2), the former limit of current sensor (5-1) and described solenoid load in series, the secondary of current sensor (5-1) is connected with the input of level shifting circuit (5-2), and the output of level shifting circuit (5-2) is connected with the input of controller (1).

5. tri-level switch power amplifier according to claim 3, is characterized in that:

Described current detection circuit (5) comprises current sensor (5-1) and level shifting circuit (5-2), the former limit of current sensor (5-1) and described solenoid load in series, the secondary of current sensor (5-1) is connected with the input of level shifting circuit (5-2), and the output of level shifting circuit (5-2) is connected with the input of controller (1).

6. the tri-level switch power amplifier according to claim 1,2 or 5, it is characterized in that: also comprise buffer circuit (2), the input of described light-coupled isolation and drive circuit (3) connects through buffer circuit (2) is corresponding with the output of controller (1).

7. tri-level switch power amplifier according to claim 3, is characterized in that: also comprise buffer circuit (2), and the input of described light-coupled isolation and drive circuit (3) connects through buffer circuit (2) is corresponding with the output of controller (1).

8. tri-level switch power amplifier according to claim 4, is characterized in that: also comprise buffer circuit (2), and the input of described light-coupled isolation and drive circuit (3) connects through buffer circuit (2) is corresponding with the output of controller (1).