1、Dead-time Compensation of SVPWM Based on DSP TMS320F2812 for PMSMSong Xuelei*, Wen Xuhui, Guo Xinhua, and Zhao FengInstitute of Electrical Engineering, Chinese Academy of Sciences, Beijing, P.R.ChinaE-mail: songxlAbstractThe dead-time effect in a three-phase voltage source inverter can result in vol
2、tage losses, current waveform distortion and torque pulsation. In order to improve the current waveform and decrease the torque pulsation, this paper proposes a dead-time compensation method of SVPWM. This method divides the i - i plane into six sectors and compensates the dead-time of SVPWM accordi
3、ng to the sector number of stator current vector determined by the - and -axis components of the stator current vector in the two-phase static reference frame. In addition, this method can be implemented entirely through software without any extra hardware. Finally experiments based on DSP TMS320F28
4、12 are established and made, and the experiment results indicate that the proposed method is correct and feasible.Index Terms-dead-time compensation,SVPWM,PMSM,TMS320F2812I. INTRODUCTIONBecause the permanent magnet synchronous machine (PMSM) has a lot of advantages such as high power density, high e
5、fficiency, high torque to inertia ratio, high reliability, et al1,therefore, the PMSM driving system have been widely used in many application fields, especially in hybrid electric vehicles (HEV) in recentyears2-6. In the PMSM driving system, the three-phase voltage source inverter is usually adopte
6、d and the IGBT and MOSFET are also used because of their fast switchingfrequency. For the three-phase voltage source inverter, in order to avoid the short circuit of the dc link occurring when the two switch devices of the same phase are turned on simultaneously, the dead-time is usually inserted in
7、 the gate driving switch signals. During the duration of the dead-time, both of the two switch device of the same phase are turned off. The existing of the dead-time will lead to a series of dead-time effect problems such as voltage losses, current waveform distortion and torque pulsation, especiall
8、y under the condition of small current or low speed.SVPWM (Space Vector Pulse Width Modulation) is a popular modulation method for three-phase voltage source inverter in motor driving system. In order to improve the current waveform of motors and decrease the torque pulsation of motors, several dead
9、-time compensation methods of SVPWM have been researched and used in the motor driving system7-11. Most of the compensation methods are based on the theory of average voltage deviation. In this paper, a novel dead-time compensation method of SVPWM, which is also based on the theory of average voltag
10、e deviation, is proposed. This method divides the i - i plane into six sectors and compensates the deadtime of SVPWM according to the stator current vector angle determined by the - and - axis components of the stator current vector in the - reference frame. In addition, this method can be implement
11、ed entirely through software without any extra hardware design. Finally experiments are made on the PMSM driving platform based on DSP TMS320F2812 to test and verify the proposed compensation method.II. DEAD-TIME COMPENSATION METHODFig.1 shows the topology diagram of the PMSM driving system whose in
12、vert unit adopts the three-phase voltage source inverter. In Fig.1, Q1, Q2, Q3, Q4, Q5 and Q6 are six IGBTs of the three-phase voltage source inverter, and D1, D2, D3, D4, D5 and D6 are their reverse parallel diodes respectively. In addition, the driving switch signals g1, g2, g3, g4, g5 and g6 are
13、provided by the control unit of the driving system.Define the phase currents ia, ib and ic are positive when they flow from the inverter to PMSM, and negative when they flow from PMSM to the inverter. There are eight switch combination states for the six IGBTs in the threephase voltage source invert
14、er, and during the duration of dead-time, there are correspondingly six current combination states for three-phase currents ia, ib and ic according to their polarity:(1) ia0, ib0 and ic0, ib0 and ic0;(3) ia0 and ic0;(4) ia0 and ic0;(5) ia0, ib0;(6) ia0, ib0.It is very important and difficult to dete
15、ct the zerocross point or the polarity of each phase current.Traditionally, if the zero-cross point is detect directly through A/D converter of DSP or MCU, bigger measurement deviation will be led especially under the condition of small current, which will result in bigger dead-time compensation dev
16、iation and also affect the result of dead-time compensation. Therefore, this paper adopts an indirectly method to detect the zero-cross point of phase current, which is based on the current vector angle in the two-phase static reference frame.For convenient analysis and illustration, place the three
17、-phase currents ia, ib, ic in the three-phase static reference frame and the two current components i , i of the current vector in the two-phase static reference frame into the same figure, which is shown in Fig.2. According to the polarity of three-phase currents ia, ib, ic, the i - i plane in the
18、two-phase static reference frame can be divided into six sectors: I(1), II(2), III(3), IV(4), V(5) and VI(6). For each sector in the i-i plane, there is a corresponding dead-time compensation rule. In other words, once the sector which the current vector belongs to is known, the dead-time effect can
19、 be compensated according to the corresponding compensation rule.Therefore, recognizing the sector number of the current vector is the key problem. In this paper, the sector number is determined by thecurrent vector angle which can be calculated through the - and -axis components of the stator curre
20、nt vector. Equation (1) shows the calculation method of the current vector , and equation (2) shows the relationship between the sector number and the current vector . =k+arctan（i/i） (k = 0,1)Fig.2. Current Polarity and Current Vector Angle TABLE IDEAD-TIME COMPENSATION RULES TABLE OF SVPWM(2)For th
21、ree-phase voltage source inverter, the essence of dead-time compensation is to compensating the voltage deviation. However, in the digital motor driving and control system, voltage regulation is implemented through pulse width modulation, that is, through regulating the duty cycle of voltage pulse w
22、hich has something to do with the pulse width T in one PWM period Tpwm. Therefore, in fact it is the pulse width T that is compensated in the practical application. TABLE I shows the dead-time compensation rules corresponding with the polarity of three-phase currents ia,ib,ic and the sector number o
23、f the current vector in the i-i plane. It can be seen that for different sectors of the i-i plane, the compensation values are correspondingly different. In one word, the proposed dead-time compensation method can be carried out through the following steps:(1) Calculate the current vector angle thro
24、ugh the - and -axis components of the stator current vector in the two-phase static reference frame according to equation (1).(2) Determine the sector number through the current vector angle according to equation (2).(3) Execute the dead-time compensation algorithm according to the compensation rule
25、s table TABLE I.III. EXPERIMENTSIn order to test and verify the proposed dead-time compensation method of SVPWM, experiments are established and made. The experiment system consists of PMSM, three-phase voltage source inverter, control platform, dynamometer, heat dissipation system, et al.The type o
26、f IGBT in the inverter is CM600DY-24A produced by Mitsubishi. The control platform is based on DSP TMS320F2812 produced by Texas Instrument.It is a special motor control DSP which has many advantages and can implement high-performance motor control such as FOC (Field Oriented Control) and DTC (Direc
27、t Torque Control). The main parameters of the control objectPMSM used in experiments are listed in TABLE II.For different pulse width compensation values of 0.76s,1.10s,1.33s and 1.60s, the dead-time compensation experiments are all made. Fig.3 shows the experiment waveforms of three-phase stator cu
28、rrents and the sector number of stator current vector for different pulse width compensation values, and Fig.4 shows the corresponding frequency spectrums.TABLE IIMAIN PARAMETERS OF PMSM USED IN EXPERIMENTS(a) No Compensation(b) Pulse Width Compensation Value = 0.76s(c) Pulse Width Compensation Valu
29、e =1.10s(d) Pulse Width Compensation Value =1.33s(e) Pulse Width Compensation Value =1.60sFig.3. Experiment Waveforms of Three-phase Stator CurrentsHere, the CPU frequency of DSP is set at 150MHz,the switching frequency of IGBTs in three-phase voltage inverter is set at 10kHz, the dead-time is set a
30、t 3.2s through the hardware and software of DSP,the motor control method adopts FOC algorithm, the dc link voltage is set at about 330V,and the phase current is controlled at about 10 A.(a) No Compensation(b) Pulse Width Compensation Value =0.76s(c) Pulse Width Compensation Value =1.10s(d) Pulse Wid
31、th Compensation Value =1.33s(e) Pulse Width Compensation Value =1.60sFig.4. Frequency Spectrum of Stator Current (Phase A)It can be seen from Fig.3 and Fig.4 that, compared with experiment results of no compensation, through the proposed dead-time compensation algorithm the threephase stator current
32、 waveforms of PMSM are all improved effectively and the harmonic components of three-phase stator currents are also decreased effectively. Especially when the pulse width compensation value is set at about 1.10s,compared with experiment results at the other pulse width compensation values of 0.76,1.
33、33s and 1.60s, the compensation result is the best and the harmonic components of three-phase stator currents are the least. Therefore, the proposed dead-time compensation method is correct and feasible.IV. CONCLUSIONSThe proposed dead-time compensation method can be implemented easily through softw
34、are algorithm without any extra hardware design. So long as the current vector angle is determined by the - and -axis components of stator current vector in the two-phase static reference frame, the dead-time compensation algorithm can be carried out effectively according to the corresponding dead-t
35、ime compensation rules table. Finally experiments are established and made on the PMSM driving platform based on DSP TMS320F2812 and the results indicate that the proposed method can improve the current distortion and decrease the torque pulsation effectively, especially when the pulse width compens
36、ation value is equal to about 1.10s.Therefore,the proposed method is correct and feasible.REFERENCES1 Song Chi, Zheng Zhang, Longya Xu, “A Robust,Efficiency Optimized Flux-Weakening Control Algorithm for PM Synchronous Machines”, Proceedings of the 2007 IEEE Industry Applications Conference, pp.1308
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43、.5, pp. 1150-1160, 2005.外文资料译文基于TMS320F2812 DSP的有死区时间补偿的SVPWM调速永磁同步电动机宋雪蕾*温徐汇，郭新华和赵峰北京电机工程学会，中国科学院，E - mail：songxl抽象的死区时间的影响可导致逆变器三相电压源电压损失，电流波形畸变和转矩脉动。为了改善目前的波形，并减少转矩脉动，提出了一种SVPWM的死区时间补偿方法。这种方法划分i i平面为六个扇形区域，进入和补偿的死区时间的SVPWM矢量根据定子柯部门数目这种方法划分 i - i 平面为6个扇形区域，补偿的SVPWM死区时间，根据部门的数和组件的定子-轴由定子电流矢量的决定。此外，
44、这一方法可以通过软件实现完全没有任何额外的硬件数字信号处理器TMS320F2812的基础上最后的实验，建立和作出的，而实验结果表明，该方法是正确和可行的。关键词：指数条款 - 死区补偿，SVPWM的，永磁同步电机，TMS320F2812一， 引言由于永磁同步电机（PMSM的）有很多优势，例如，高功率密度，高效率，高惯性力矩比，高可靠性等1，因此，永磁同步电机驱动系统已被广泛应用于许多应用领域，尤其是在最近几年应用在混合动力（HEV）用电动汽车上2 - 6。在永磁同步电机驱动系统，三相电压源逆变器通常采用的IGBT和MOSFET也因为它们的开关频率而普遍使用。为了避免短路的同时转向装置的直流环节
45、发生的时候，双方在同一阶段的切换，死区时间通常是在门信号驱动开关的时候。在持续死区时间中，相都相同的两个开关装置处于关闭状态。当时现有的死将导致一系列问题的死区时间的影响，例如，电压损失，电流波形畸变和转矩脉动，特别是在高速条件下的小电流或低。空间矢量脉宽调制（空间矢量脉宽调制）在电机逆变器是一种流行的调制方式为3相电压源驱动系统。为了提高电动机的电流波形，降低电机转矩脉动，几个死区时间补偿的SVPWM方法进行了研究和系统在驾驶汽车7-11. 大部分的补偿办法是根据偏差理论的平均电压。在此提出了一种新颖的死区时间补偿的SVPWM方法，这也是基于平均电压的偏差理论。这种方法划分i - i平面成6
46、个部分，并弥补了时间的SVPWM根据定子电流矢量根据定子电流部门角度。确定的 -和 -定子轴的组成部分的电流矢量中- 参照系。另外，该方法通过软件可以实现完全没有任何额外的硬件设计。最后的实验，是基于数字信号处理器TMS320F2812的驾驶平台，测试验证了提出的PMSM和补偿方法。二， 死区补偿方法图1显示了逆变器的拓扑图的永磁同步电机驱动系统的转化装置采用了三相电压。在图1，Q1，Q2，Q3，Q4，Q5和Q6有6逆变器的IGBT的三相电压源，和D1，D2和D3，D4，D5和D6中的反向平行二极管。另外, 开关的驱动信号G1，G2，G3，G4，G5和G6是系统提供的驱动控制装置。定义相电流I
47、a，Ib和Ic从永磁同步电动机变频流向为正，当决定逆变流流向永磁同步电动机为负时。有8个开关的三相电压源逆变器的六个IGBT组合状态，并在死区时间中，有相应的6个当前结合态对应三相电流IA，IB和IC根据自己的极性：(1) ia 0, ib 0 and ic 0, ib 0 and ic 0; (3) ia 0 and ic 0;(4) ia 0 and ic 0;(5) ia 0, ib 0;(6) ia 0, ib 0.图1。拓扑图的永磁同步电机驱动系统零交叉点或每个阶段极性电流是非常重要和难以检测的。照惯例，如果零交叉点检测单片机直接通过数字信号处理器或/ D转换器，较大的测量误差将导致
48、特别是在小电流条件下，这将导致更大的死区时间补偿的偏差，也影响了死区时间补偿结果。因此，本文采用一种间接的方法来检测零交叉点，是在两相静止坐标系上基于电流矢量角来检测的。为方便分析和说明，定义三相电流ia,ib,ic在三相静止坐标系的两个电流分量i,i在两相静止坐标系电流矢量有相同的数字，这显示在图2。根据三相电流ia,ib,ic的极性, 两相静止坐标系i-i可分为6个部分：I(1),II(2),III(3),IV(4),V(5) 和VI(6).对于两相静止坐标系i-i每个部分，有相应的死区时间补偿规则。换句话说，一旦该部分的电流矢量属于已知，死区时间可以根据相应的补偿规则得到补偿。因此，认识到当前的矢量扇区数是关键问题。本文，该扇形的数目取决于电流矢量角，它可以通过计算 - 和-轴定子组件的电流矢量来得到。方程（1）显示当前向量的计算方法，和方程（2）显示了扇形和电流矢量之间的数量关系
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